Seeking thoughts setting up ships battery systems - 12V

[Larks]

Mocking up cabinetry and looking at space requirements for my H28 fit out has me jumping forward a bit to what batteries I need and therefore what battery management system I might need.

I’m a complete numpty when it comes to anything electrical (it’s akin to witchcraft to me) so I had wanted to keep my electrics simple enough for me to fit and manage myself - but for the same reason all and any comments and advice will be very welcome.

I estimate a maximum daily draw of @100AMPS, the alternator that comes with my Yanmar 3YM20 is rated at 125AMP. I’m not looking at any solar charging options just yet but I want to set up so that I’m ready for it (budget pending) and I am questioning whether I should allow for shore charging or not - ie whether to ignore shore charging and just plan for solar charging to maintain the batteries..?? Or make sure that I have allowance for both.

I’ve had a chat with my local battery supplier guys (Battery world Australia) about deep cycle house batteries and, although we didn’t talk about my start battery, they have offered the following options:

- Lithium battery: Enerdrive ePOWER B-TEC 200Ah Lithium Battery 40A DC2DC + 40A AC with ePro+ Monitor Charger Pack - $AUD 4152.00 (though I’ve found the same system elsewhere on-line for $3590.00). The benefit of this as I see it is that the battery is only 25kg, doesn’t need to be readily accessible and has a 7 year warranty. This system will also manage my start battery.
https://www.mygenerator.com.au/enerd...rger-pack.html

- AGM battery: 2 x 100AH AGM batteries with Enerdrive ePOWER B-TEC 40A DC2DC + 40A AC with ePro+ Monitor Charger Pack - $AUD 2378.00
https://www.mygenerator.com.au/enerd...ation-kit.html

These options are both more complicated than the basic house and start battery setup that I had initially envisaged but I can see the long term value for money in each of them.

This is the basis of how I’m estimating a 100AMP daily draw so would appreciate any suggestions/corrections if I’ve completely ballsed this up:

				AMPS min		AMPS max		approx Hrs use/day Min AMPS		approx Hrs use/day Max AMPS		AMPS/day max
Engel MT35F				0.5		2.6		22		2		5.2
Nav lighting						0.08				12		0.96
Electronics		B&G Vulcan 7 GPS/Chart plotter				1				24		24
		B&G VHF/AIS V60				1				24		24
		B&G Wireless handset charger				0.5				2		1
Cabin lighting		LED				2				6		12
TMC Toilet				18		18				0.25		4.5
Fresh water pump						18				0.5		9
Bilge pump						2.5				2		5
Deck/anchor wash pump						18				0.25		4.5
												90.16
Yanmar 3YM20		From start battery
Anchor windlass		Manual										0
Yanmar Alternator		12V 125 AMP

Any thoughts? Suggestions

[cstevens]

Looks pretty good to me. Two comments though. You can discharge 80% of the lithium battery against 50% of the AGM so you could reduce your battery bank capacity with the Li-Ion battery or just keep the 200Ah bank and have extra capacity (likely a good idea). And having had solar panels for a couple of years now, courtesy of the previous owner, I will say that they are absolutely 100% worth it. Otherwise you would have to run the motor every day or two which is not ideal.

Oh, and I can’t imagine going without the option for shore power but I might care less if the boat were kept on a mooring and had adequate solar charging.

[Slacko]

The fridge use looks a little light.
I would work on 1 amp average over the 24 hours or 24 a/h per day.
That pile of boxes you bought didn't look simple or low maintenance by the way.

[Andrew Donald]

Greg , thanks for starting this thread.
I think your fridge calcs are way off though. While I’m not sure about duty cycles but let’s imagine an average 50 % runtime @ 2.6/hr works out at 12hrs x 2.6amps = 31.2amps but that would a minimum I’d guess especially in hotter areas.
‘Also if your bilge pump is going 2hr/day you’ve got more probs than battery life ??? Correct me if I’m wrong but I’d imagine a strip planked boat should be pretty dry.
And you wouldn’t use your Plotter or radio that much would you? You could prob get away with just leaving the radio on standby and plotter occasionally. AIS shows on radio screen doesn’t it?

And as Chris said Lithium can be run down 80%. They can be left half charged (which to my mind is a big plus) . They can be charged more aggressively than LA, therefore can be “brought-up” more quickly. They weigh about half/useable amp, take up less space/useable amp. Low self-discharge. Too many pluses to go on. Except $$$ But long term they’re cheaper. BTW they’re best left long term partially charged.

Everywhere Ive looked when using a lithium house bank, a LA start batt is recommended BUT I have been touch with a supplier that has a 20amp start lithium (apparently equivalent to a 50amp LA starter) that weighs 3.5kg and about half the size. I’m busting to find out if it’ll work and not just his “just use a switch”.
See here https://www.lfp.net.au/sealed-batteries

Ive been researching this for what seems ages but haven’t found anyone that can supply an answer even for $.

one thing I’m trying to get straight is the alternator and lithium’s. As far as I can tell OEM’s aren’t up to it, dunno about your 125 one though. External regulators can control things though, although I’m still figuring that.

Enough for starters. Hopefully someone here can be light-shedding.

[Larks]

Thanks for the comments guys.

In regards fridge draw for the Engel fridge, I was talked down to what I’ve shown in that chart by the guys at Battery World but am happy to revisit and check that.

That usage chart is essentially for worst case/heaviest draw scenario, so I originally used the max’ draw over 24 hours being 62.4 AMPS but the Battery world guys suggested the fridge door would have to be open all day for it to draw that much power and they came up with the figure that I’ve reduced it to, suggesting that unless the door is opened continuously it will only draw 0.5 A/H.

And you’re right, the 2 hours for the bilge pump is well and truly an overestimate, the only water in the bilge should be from the stern tube so I threw that in really just as a worst case.

The radio draw is supposedly based on it being on standby but in all honesty I don’t really understand what I’m reading in the manuals for that bundle of electronics so, again, I picked what I thought was worst case. So I’ll go back and see if I can get a better understanding of what they’re saying.

In regards the Lithium and the alternator Andrew, the BW guys were very quick to let me know that I’d need the DC-DC converter/management system for the Lithium battery to be charged from my alternator. I trust them so believe them but I need to read up further on that to understand it better.

The “MyGenerator.com” guys that I linked to above are not far away so I might see if I can get in and have a chat with them as well.

[Larks]

The fridge use looks a little light.
I would work on 1 amp average over the 24 hours or 24 a/h per day.
That pile of boxes you bought didn't look simple or low maintenance by the way.

They’re the easy bit - pretty much plug and play and I can drive them fine, it’s the juice that makes them light up that I struggle with.....

[Larks]

Looks pretty good to me. Two comments though. You can discharge 80% of the lithium battery against 50% of the AGM so you could reduce your battery bank capacity with the Li-Ion battery or just keep the 200Ah bank and have extra capacity (likely a good idea). And having had solar panels for a couple of years now, courtesy of the previous owner, I will say that they are absolutely 100% worth it. Otherwise you would have to run the motor every day or two which is not ideal.

Oh, and I can’t imagine going without the option for shore power but I might care less if the boat were kept on a mooring and had adequate solar charging.

Thanks Chris, at this stage I’m hoping she’ll stay in a marina berth. Moorings don’t have much of a rep' for security around this neck of the woods, mostly because of vandals/thieves but also from being washed away in a flood.


I should also add that I’m trying to approach this from a commercial perspective more than a personal “what I’d like” perspective, so looking very much at cost benefit and functionality.

[Andrew Donald]

One other thing I’m considering too , is to run two house batteries in parrelel to help finding somewhere to stow them. For you I’d imagine a 200 amp is pretty big ( that’s 160amp useable BTW)
‘Come to think of it Enerdrive does a narrow lithium 200 amp which may suit you better. https://enerdrive.com.au/product/200...m-battery-12v/

And there’s a mob called KickAss that do AGM slim-lines as well. https://www.australiandirect.com.au

re-treading #5 Greg , sounds like I’d be researching a Lot more if I was you. If they’re quick to talk you around to flogging their product. There’s several ways to run lithium’s, B2B is only one and Looking at that price - must be some cream. Hmmmm

heres another place to look at http://nordkyndesign.com/electrical-...-battery-bank/

and anotherhttps://shop.pkys.com/Alternator-Lithium-Battery.html.

Dare I mention them but Outback Marine has a fair bit of info on their site too.

I just had a quick look at Enerdrive B2B manual and it doesn’t look like there’s an alternator temp control which from my research is necessary with Lithium’s. Can’t see an IP rating either.

https://sterling-power-australasia.c...-12v24v36v48v/

[John B]

I don't have an electrical mind either, I go on that's enough or need more. I haven't used shore power for years, the fridge has been running since 2015, I turned it off once for a couple of months but that's it.
Still on lead acid. What they don't mention in the brochure is when you retrofit to lithium, which you're not doing with a new installation, you throw away your battery monitor and replace it with something specific. Not doing that yet.
Solar solar solar, our sun is strong here, maybe 20 percent more amps than in the tropics, or more.
We have a shortfall when sailing with everything on at night so I need something else for sea passages, otherwise in practical terms for local use she's pretty much always charged up.
And I suggest when you buy a controller for the solar you double and add some capacity. They like to see up to about 75 or 80 Percent use but you want some space so you can add more panels.

[Larks]

Looks pretty good to me. Two comments though. You can discharge 80% of the lithium battery against 50% of the AGM so you could reduce your battery bank capacity with the Li-Ion battery or just keep the 200Ah bank and have extra capacity (likely a good idea). And having had solar panels for a couple of years now, courtesy of the previous owner, I will say that they are absolutely 100% worth it. Otherwise you would have to run the motor every day or two which is not ideal.

Oh, and I can’t imagine going without the option for shore power but I might care less if the boat were kept on a mooring and had adequate solar charging.

And as Chris said Lithium can be run down 80%.

This is one area where I’m a bit confused - some of the stuff that I’m reading refers to discharge levels as well but it is in regards to Deep Cycle versus Start batteries, rather than Lithium v AGM - advising for example in regards deep cycle batteries (with no reference to type) "They are designed to provide a steady amount of current for a longer period of time.A deep discharge (down to 20% of power) can be recharged to 100% over and over without damaging the battery".

[Garret]

Battery technology is complicated, especially adding Lithium into the mix. Refrigeration is a big draw and really dependent on how well insulated the box is - it's certainly the biggest single draw on my boat.

On shore power - if at a marina, I think you want the option. When looking at chargers (shore power battery chargers) I was surprised to learn how expensive they are. Having lived off-grid for many years I was already familiar with inverters & inverter/chargers. Having regular AC available at sea is handy, so I put in a 1500 watt inverter that has a built in 30 amp charger. Cost about $250US more than just a charger - so I thought it was well worth it.

[wizbang 13]

You call that stuff simple?
I don't even know what half of it IS !

[Andrew Donald]

This is one area where I’m a bit confused - some of the stuff that I’m reading refers to discharge levels as well but it is in regards to Deep Cycle versus Start batteries, rather than Lithium v AGM - advising for example in regards deep cycle batteries (with no reference to type) "They are designed to provide a steady amount of current for a longer period of time.A deep discharge (down to 20% of power) can be recharged to 100% over and over without damaging the battery".

Deep cycle AGM = has about 50% useable amps so a 100amp battery is really a 50 amp useable battery.

Deep cycle Lithium = has about 80% useable so a 100amp batt is really a 80amp.

LA ( inc AGM’s) batteries have the 3 stage charging regime , bulk/absorption/float which means they take a long time to get back up to 100% full if ever.
Lithium’s can be much more efficient as they take a lot of amps for longer and so can fill up quickly.

generally start batteries don’t like having large deductions of their capacity but can supply large currents for short periods.

I have only found one company that claims their battery is a Lithium Start battery but I haven’t looked into what makes it different from a normal lithium. I’m guessing it’s to do with the plate thickness much like LA start batteries. Most lithium’s are deep cycle. And then there’s the construction of a lithium, prismatic/cylindrical etc. Apparently Prismatic is the type recommended for boats being more rugged. Dunno exactly how that works though.

[suzyj]

Are you sure you want to go with 12V?

There are a lot of advantages to 24 or even 48V for the battery system. Not having to deal constantly with voltage drop issues is the main one.

I reckon a 48V battery system with inverter/charger built with gear for remote area power systems, then distribute 240V mains around the boat. Your fridge will run on that. 12V stuff (radios etc) can then just go on a 12V power supply off the 240V. It massively simplifies the wiring, plus means you’re good to plug straight in to shore power.

Keep the motor separate, with it’s own starter battery. If you really want to charge your house battery from petrol or diesel, use a little portable generator.

[suzyj]

I have only found one company that claims their battery is a Lithium Start battery but I haven’t looked into what makes it different from a normal lithium. I’m guessing it’s to do with the plate thickness much like LA start batteries. Most lithium’s are deep cycle. And then there’s the construction of a lithium, prismatic/cylindrical etc. Apparently Prismatic is the type recommended for boats being more rugged. Dunno exactly how that works though.

I have a lithium starter battery on my motorbike. It’s made with lithium iron phosphate (LiFePO4) cells, made by A123 systems, that are more commonly used in power tools. The cells are only 2.3Ah, but have a huge 120A short circuit current. The whole mess only weighs a few hundred grams, but has started my bike (Ducati) reliably for about 8 years.

Batteries for starting things are different from batteries for running things. You can use a tiny battery for starting, as long as it has adequate current delivery (maximum power density). Batteries for running stuff like fridges and lighting etc want to maximise energy density (as long as they have adequate power to supply peak loads). Chemistries like lithium polymer or lithium ion (think laptop battery) do this really well.

[cstevens]

Greg, I didn't actually check the math in the table on my first read. As others have pointed out the power estimates for the refrigerator are much too low. Here's a good post on real-world power consumption by a 35 liter Engle refrigerator:

https://www.campertrailers.org/fridg...onsumption.htm

From that information I'd estimate your 24-hour power draw for the Engel at more like 25-35 Ah rather than 5.5. Refrigerator power draw varies widely based on a bunch of factors though. Outside temp, storage temp, how much food is stored inside, how often it is opened, etc. Best to estimate on the high side.

A few more things to note on the consumption numbers:

First, the right-hand column should be amp hours/day not amps/day. A minor point but it helps to clarify things when you look at everything. A 1 amp draw for 1 hour = 1 Ah. The math is pretty easy after that: Battery bank capacity Ah * max draw down % = usable capacity. So your 200 Ah Li-Ion bank will give you 160 Ah of usable capacity while your 200 Ah AGM bank will only give you 100 Ah. Given that your power draw estimate should be more like 120 Ah I think the battery bank size is marginal. You might be able to get away with it if you supplement with solar but you would always be managing your power use.

As a real-world comparison, we have similar power usage on Skookum Maru, or possibly somewhat less. We have larger, less efficient refrigerator but also we are always running the engine when we are running the nav electronics and we don't have an electric head. Our power draw at anchor is the fridge, cabin lights, and fresh water pump. So call it maybe 50-75 Ah/day. Our house battery bank is 2 AGM 8D batteries giving around 250 Ah in usable capacity. That gives us 3-4 days at anchor without charging. But we also have approximately 300 watts (25 amps) of solar charging and that is enough to keep the batteries topped up indefinitely as long as the sun is out (less of a guarantee of that here than down there I expect).

In your case I'd want a minimum 200 Ah of usable battery capacity plus 200 watts of solar panel charging. That would be enough to give you a bit of margin on the battery bank plus enough solar capacity to keep the batteries charged without running the engine very often. And definitely include a shore power connection and charger if you will have it available.

[Breakaway]

Hey, Greg, the guys have given you plenty of good advice to help make your choices. I will add three things.

1. Amps daily use: Have you factored in resistance? The longer a device is energized the hotter it gets and the more it and its circuit build up resistance. There's also corrosion, length of wire run, number of connections in a circuit.... I believe Nigel Calder suggests a sort of, " standard," multiplier for all this ( maybe 10-percent??) Worth researching.

2. Your alternator outputs 125 amps--at what rpm? Also, what will cruising rpm be and what is alt output at that engine speed? How ow many hours can your run a day at that rpm? Yanmar will have the specs.

3. AFAIK, many/most AGM? LiIon are, " dual purpose," batteries: able to deliver a lot of amps rapidly AND be deeply discharged. Example, these Optima batteries (Full Disclosure: I am on my second set of these in 10 years and am posting them because I use them as starting and also deep cycle them) They produce 900 cold cranking amps AND deliver 75aH reserve capacity. ( Not enough for your application but presented as an example). I draw them down 50-, sometimes 60 percent and still have enough juice to restart V-8, 250-hp outboards ( Starting amps required = 800CCA)

Your project is interesting!

Kevin

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Kevin

[Rumars]

Look at this atricle detailing a simple small install: http://honeynav.com/category/lfp-bat...ne-electrical/ I would go to something like this if starting from scratch with lithium.
You definetly don't need a DC2DC chager if going AGM, only the shore charger is needed. How is your alternator regulated?

[Larks]

Thankyou for all of the responses, they really are all terrifically helpful for an electrical numpty like me.

And thanks for that link on the Engel Chris, that makes much more sense and is likely more in line with what the Battery World guys were suggesting (instead of the 62.4A/H that I’d shown to them) so if I bump the fridge usage back up to something more plausible like 31.5 I come up with a maximum daily usage of say 125 A/H, allowing for resistance as Kevin pointed out:

							AMPS min	AMPS max	approx Hrs use/day (at min AMPS)	approx Hrs use/day (at max AMPS)	AH/day maximum
Engel MT35F							0.5	2.6	12	12	31.2
Nav lighting								0.08		12	0.96
Electronics			B&G Vulcan 7 GPS/Chart plotter					1		24	24
			B&G VHF/AIS V60					1		24	24
			B&G H60 Wireless handset charger					0.5		2	1
Cabin lighting			LED					2		6	12
TMC Toilet							18	18		0.25	4.5
Fresh water pump								18		0.5	9
Bilge pump								2.5		2	5
Deck/anchor wash pump								18		0.25	4.5
											116.16

However I’d appreciate if anyone can interpret the electronics power consumption better than I can - the manuals only show the following in that regard and I’ve interpreted it as I’ve shown in the table.

B&G Vulcan 7 Power consumption typical - 12W
B&G Vulcan 7 Current drain (transmit): ≤ 6 A @ 25 W / 1.5 A @ 1W (12 V DC)

VHF Current drain: - V60 (receive): Less than 820 mA in standby
- H60 (handset) cradle charger: ≤0.5 A


I’m comfortable going with 12V however but I’ll definitely look further into the idea of a 24V (or 48V) system Suzy as I can see the potential benefit and I’d like to understand the option better. But in all honesty I can’t say that I’ve ever sailed on a yacht under 54’ with anything but a 12V system and I’m only 28’ with not really a lot of services to power and not enough space to fit a generator. Everything that I already have ready to install is 12V so I need to better understand what you’re saying about running the 12V systems off of a 240V supply off a 24V system….that’s the witchcraft bit that I really struggle with…..

How does my 12V alternator cope with a 24V battery system.

I understand inverters and running a 240V drill from a 12V supply but going from 24V/48V to 240V and then back to 12V makes me beg the question “Why?” and “Huh?” ……..and shortly after that my eyes glaze over ……

I certainly hadn’t looked at that 80% available usage factor that Andrew and Chris have pointed out so I’ll allow for that as well when I talk to the guys at MyGenerator.com to see what they can offer in regards battery size and cost to give me what I need - probably closer to 300 Ah

I’m feeling more and more that I need to up my budget and go for that Lithum option regardless. The cost benefit is stacking up for my fitout in regards to space, weight and access requirements, aside from the longevity and efficiency factors.

In regards my alternator – in all honesty I can’t find any more information in any of my documentation other than “12V – 125AMP”– there’s no indication of RPM’s for that output or how it is regulated…..or at least none that I can find.

Thanks for that link Rumars - I’ll sit down and read it properly right now.

[DoctorB]

A little comment: Be careful expressing A/hr versus A-hr. The latter is useful. As a sidebar, stored energy in a battery equals Voltage*current*time. The "current*time" business is capacity and in our application is generally expressed in A-hr. Energy in SI, for instance, is in units volts*amps*seconds (Power*time). So a 12V, "100 A-h" battery stores 12V*100A-hr*(3600s/hr) = 4.3 MegaJoules (for reference, a stick of dynamite is approximately 1MJ)

I now see your latest table column heading read A-h / day. Great.

[Garret]

12 volt is easier because there are more things that run on it. To charge a 24 volt system. you need a 24 volt alternator. And a 24 volt charger. Many inverters are set up for 24 volt - =but they are mostly bigger ones - more than you'd need. IMO, 12 volt system keeps it simple. Yes, wires have to be bigger, but it's not that big a deal on a boat - especially a 28 footer. 80 ft. boat - 24 or 48 volt for sure.

Watts, volts & amps: watts = volts x amps. 1 amp on a 12 volt system is 12 watts, 1.5 amp is 18 watts. So - basic formula w=v*a, a=w/v, etc.

[DoctorB]

Watts, volts & amps: watts = volts x amps. 1 amp on a 12 volt system is 12 watts, 1.5 amp is 18 watts. So - basic formula w=v*a, a=w/v, etc.

...and Energy = Power*time = v*a*t = v*capacity
Power is a more practical figure of merit here, but it's fun to know how much TNT is shoved in a 60lb wet cell. Not that you can release that energy the same way, but interesting nonetheless, I think. Total nerd, yes.

[Andrew Donald]

Greg, please remember that what I say is taken from what Ive researched over the last 6 months. I don’t accept an opinion unless it’s backed up by at least one other source and/or a sensible explanation. So the usual grain of salt applies but remember I’m in the same boat as you, figuratively, but even more so as regards weight and space.
‘What I’ve learnt about alternators is that there are two types OEM and aftermarket. OEM are provided as a means to restock the start battery and maybe cope with a small house battery setup but they aren’t up to the task of charging a lithium unless dialed way down with an external regulator. Your alternator is equiped with an internal regulator presently. Lithium’s need a different charge regime than what an OEM alternator is equiped to provide therefore you’ll need to at least get an external regulator or, now this where I get a bit foggy, go for a bat2bat charger. Lithium’s can accept, and will take a huge charge, but you’ll find the manufacturers recommend a much smaller rate but that is usually continuous until the battery is nearly full then the “box o tricks” reverts to float for a specified time which is in the lithium charge regime.
OEM alternators apparently don’t give out nearly their full capacity for one reason or another especially once they get hot and they won’t start to put a decent amperage until the revs get up a bit which is not a big deal because we usually get about at 2k or more revs. Just don’t expect much from sitting idling your engine to fill up the batteries ,at anchor.
Aftermarket Alternators (Balmar etc) are built more robustly (somehow) and the amperage dials in at lower revs. They are generally run with external regulators which give a much more controllable regime especially with lithium’s.
given that external regs can be dialled down I’m tempted personally to try running my 70amp OEM alternator ( which I’m not expecting much more than 50 from) for as long as it will last then upgrade to a Balmar. Otherwise it’d just sit in the shed.
oh then you’ll need a serpentine belt to run the bigger alt, but you may have that already with the 125 OEM.
over and out

[Larks]

Thanks Doc, Garret, I’ll confess that I’ve just been using this on-line calculator: https://www.rapidtables.com/calc/ele...alculator.html
Does that look suitable to you guys?

Andrew, what you’re saying re the alternator and charging the Lithium batteries is what the Battery World guys ere saying and their solution was the Enerdrive ePOWER B-TEC 200Ah Lithium Battery 40A DC2DC + 40A AC with ePro+ Monitor Charger Pack
https://www.mygenerator.com.au/enerd...rger-pack.html

I took it that the DC-DC charger resolves any disparity between the alternator output and what particular flavour of juice the battery wants for charging. Have you had a look at that setup and, if so, (battery size aside) what do you think of it?

[gypsie]

Onboard I have a crank battery and two 100A/H AGM House batteries running through a 100amp trip switch. 12v
I control the charge using a CTEK 250SE charge control system https://www.ctek.com/au/all-products...e-sport/d250se with a CTEK Smartpass https://www.ctek.com/au/all-products...smartpass-120s

The charge controller can work on its own, but only delivers 20amps of charging (a little lower than i need, my alternator is 90amps), the addition of the smartpass brings delivery up to 120amps (more than I need, with a spike load capacity of something like 300amps).

The 250SE charge controller can be wired for; lead acid deep cycle, AGM or Li-Ion.
It selects the best charging source and sends that to the batteries, solar if your motor is not running, or the alternator if the donk is on.
If there is no charging source, night time and engine off, the house batteries will trickle charge the crank.
The whole system is designed to keep your crank battery full first, then manage your house and then any spare power can go to an appliance outlet if you choose.

I find the whole thing very user friendly - simple.
https://www.ctek.com/storage/C0580F4...-low-AU-EN.pdf


I also forked out $80 for a little blue tooth battery monitoring thingy. It connects to your phone and keeps a record of your battery condition, when it charged, when it dropped charge, when it got hot and current voltage/temp/condition. Not much else but somewhat useful, especially if you like a good graph (or rather a small bad graph). I was able to catch that my shore power was disconnected which I may not have noticed otherwise.


Total system about AU$1,500 for the house batteries and approx $350 for each of the CTEK boxes (roughly AU$2,200). Crank battery was a butch thing i got in a garage when my old motor was being a PITA, price unknown.


Extra, My house batteries go to a 100amp switch, then an isolation switch. Then to the switch panel where its broken into two streams, windlass and house - each with its own isolation switch. Then every house circuit has at least 15amp fuse, some smaller depending. I haven't paid much attention to wire diameter (boat could probably do with full rewiring - another project....), but I err toward everything being at least 10amps, going up where i know the draw is greater (head/fridge).
if i did rewire, I'd run a solid heavy duty negative backbone around the boat, to buzz bars in key locations (approx 6). Then run out positives to each appliance, and ground to the nearest negative buzz bar.

[Hugh MacD]

Oh my....another reminder of just how igner't I really are! Since I'm in the process of rewiring my boat as well I'm watching with vast interest!

[Larks]

Thanks Trev - that’s the next bit that I’m trying to get my head around......again.....the wiring circuit and switchboard requirements. I thought I’d worked it out a while ago using a CTEC system but I’ve forgotten everything that I read, can’t understand my old notes and so now I’m needing to start again. How many services do you reckon you’d hook up to one buzz bar? Or does it depend on their current draw?

I’ve been taking notes furiously but I need to start sketching this up.


Meanwhile, I’ve just spoken to one of the Enerdrive support guys and he advises that their Lithium batteries supply what they are rated to - ie the 200Ah battery allows you to draw down the full 200 Amps.

He also advised that based on a max usage of 125Ah the most that I’d need is the 200Ah battery but suggested a slightly different package to the Battery World guys, being their Enerdrive eLITE bundle with 2 x 100Ah batteries plus an EPRO monitor (because they are not their BTEC series they don’t have the bluetooth capacity): https://www.mygenerator.com.au/enerd...rger-pack.html

Size and price (AUD) wise they compare as:

Enerdrive ePOWER B-TEC 125Ah Lithium Battery 318 x 165 x 215 mm (L x W x H) 15kg 2 1668.00 3336.00 Enerdrive ePOWER B-TEC 200Ah Lithium Battery 505 x 172.5 x 265 mm (L x W x H) 25kg 1 2479.00 2479.00 Enerdrive eLITE 12V 100Ah Lithium Battery 310 x 170 x 225 mm (L x W x H) 12kg 2 999.00 1998.00

[DoctorB]

Thanks Doc, Garret, I’ll confess that I’ve just been using this on-line calculator: https://www.rapidtables.com/calc/ele...alculator.html
Does that look suitable to you guys?

Yes, for bouncing around among voltage, current, and power. You ought to get at least two of those numbers in any device spec. That calculator implements Garret's post #21.

[Andrew Donald]

Damn it ... lost my answer to #24. Anyway gist was I’m always suss when manufacturers make claims that nobody else is willing too. That’s the first I’ve heard of ANY battery claiming a full 100% draw down. But the times move on, even in months. I’m also wary that Enerdrive seem to be geared more towards the caravan/4WD set and so I’d like to see how w’proof that gear is in the salt laden marine environment. Does seem like a nice answer though especially built in MPPT for solar. Check what size panel can be run though.
Trevs answer warrants investigation.
Building an ideal system is like building the perfect PC, never seems to work properly and everyone has different ideas.
Id be confirming that claim of 100% useable amps before laying down the $ especially if you need those extra herbs,otherwise I’d be only going to 80% like everyone else says.

Im breaking my research into two sections 1. Power generation/storage. And 2. Power usage/wiring. Even still I get brain fade and glaze over. Any number of books for 2. But tech is moving too fast for 1.

Those new batteries that Enerdrive are talking about - do they have BMS ? Are they still run through that 40amp bat2bat?

[gypsie]

I'm fairly happy with my theory, my 'anally retentive electrician wiring' however leaves a bit to be desired... I think to do wiring neatly you need a smidge of OCD.

I'd pick 3 sizes;
AWG16 for your single runs (thinking 10amps). Your switch panel is probably prewired with AWG14 and a 15amp fuse for every 2 circuits.
AWG6 for a spine through the boat (thinking 50amps)
AWG2 from battery to switch panel and to windlass (thinking 100amps).

Tinned wire, using crimped connectors that are shrink wrapped.

I'm not an electrician!!

[gypsie]

That’s the first I’ve heard of ANY battery claiming a full 100% draw down.

I think maybe they have batteries that give what they say on the tin - which means they have a theoretical capacity thats greater.
A battery that delivers 100amp/H may be sold in other circumstances as a 120A/H battery. It delivers 100amps, but thats not 100% draw down.

from what i can tell, the better batteries do this.

[Slacko]

The alternator that your engine came with is basically designed to charge the LA start battery in a car.
In the morning after the batteries have kept the beer cold and the lights on during the night, the alternator will chuck out something like it's rated max current for about 15 minutes to get the voltage back up to maybe 80% from a "50% flat" LA battery.
At that point you can fry an egg on it.
The regulator then turns down the charge rate to protect itself, which suits the battery as well coz they don't like high charge rates when getting towards full.
It will then take the rest of the day at 5-10 amps "bulk" charge rate to get up to "full"
This profile suits using lots of solar panels on a sailboat to top the battery up each day. If you sail each day after motoring in and out out of an anchorage for 45 minutes, you can probably get away with a smaller bank of panels.

If you want to charge the batteries off the alternator without the huge bank of solar panels or extended running of the engine, you might be able to easily change the alternator to external regulator.
You will need to program the regulator for output current,battery bank size and style, and whether the alternator is "hot" rated (which the Volvo unit isn't). The external regulator will wait for the motor to get running smoothly (30 sec) then drag the max current out of it for 15 minutes until it can fry eggs. Then it will back off a little but still poke in significantly more than 5-10 amps until the battery gets up to "float" level. The charge time is significantly reduced. The external regulator may also have a temperature probe for the batteries so they don't get overheated.
If you spend the money on a "Hot" rated alternator the current for the "bulk" charge is higher again as the alternator can handle extended current draw. It will also put out the high current at lower revs.
If you spend even more money on Lithium batteries the charge rate can be held at maximum current for even longer, shortening the run time even more.

That is my top of the head shortened rough version of how I see battery management.
Nigel Calder's book has a really nice description of the basics of this stuff that is easily understood. It doesn't go into the more modern stuff ie Lithium technology, but when the basics are understood the rest makes a lot more sense.

Larks - That system that Battery world has offered you looks pretty nice from reading the glossy blurb as it manages both the alternator and panel input. One downside was that it can only output 40 amps, so your alternator capacity cannot be maximised.
The bypass feature on the stuff Gypsie talks about fixes that.
I don't understand why a shore charger for LA need to be so expensive though. If you are in a marina a $50 charger can get it done, as it has all night/day to charge.
I would be leaning towards the Lithium batteries if the budget can cope with them. As talked about above, they are heaps of plus features.

Andrew - I think that the 50% max discharge number for LA batteries is for start batteries. Deep cycle LA is 20% in my understanding.

[Andrew Donald]

[QUOTE=Slacko;6333096]The alternator that your engine came with is basically designed to charge the LA start battery in a car.
In the morning after the batteries have kept the beer cold and the lights on during the night, the alternator will chuck out something like it's rated max current for about 15 minutes to get the voltage back up to maybe 80% from a "50% flat" LA battery.
At that point you can fry an egg on it.
The regulator then turns down the charge rate to protect itself, which suits the battery as well coz they don't like high charge rates when getting towards full.
It will then take the rest of the day at 5-10 amps "bulk" charge rate to get up to "full"
This profile suits using lots of solar panels on a sailboat to top the battery up each day. If you sail each day after motoring in and out out of an anchorage for 45 minutes, you can probably get away with a smaller bank of panels.

If you want to charge the batteries off the alternator without the huge bank of solar panels or extended running of the engine, you might be able to easily change the alternator to external regulator.
You will need to program the regulator for output current,battery bank size and style, and whether the alternator is "hot" rated (which the Volvo unit isn't). The external regulator will wait for the motor to get running smoothly (30 sec) then drag the max current out of it for 15 minutes until it can fry eggs. Then it will back off a little but still poke in significantly more than 5-10 amps until the battery gets up to "float" level. The charge time is significantly reduced. The external regulator may also have a temperature probe for the batteries so they don't get overheated.
If you spend the money on a "Hot" rated alternator the current for the "bulk" charge is higher again as the alternator can handle extended current draw. It will also put out the high current at lower revs.
If you spend even more money on Lithium batteries the charge rate can be held at maximum current for even longer, shortening the run time even more.

That is my top of the head shortened rough version of how I see battery management.
Nigel Calder's book has a really nice description of the basics of this stuff that is easily understood. It doesn't go into the more modern stuff ie Lithium technology, but when the basics are understood the rest makes a lot more sense.

Larks - That system that Battery world has offered you looks pretty nice from reading the glossy blurb as it manages both the alternator and panel input. One downside was that it can only output 40 amps, so your alternator capacity cannot be maximised.
The bypass feature on the stuff Gypsie talks about fixes that.
I don't understand why a shore charger for LA need to be so expensive though. If you are in a marina a $50 charger can get it done, as it has all night/day to charge.
I would be leaning towards the Lithium batteries if the budget can cope with them. As talked about above, they are heaps of plus features.

Andrew - I think that the 50% max discharge number for LA batteries is for start batteries. Deep cycle LA is 20% in my understanding.[/QUOTE]

Beg to differ. Start LA only should be drawn down a few % if you run them down 50% it shortens the life. Deep cycle LA can be 50% and some AGM’s claim more .

[Andrew Donald]

I think maybe they have batteries that give what they say on the tin - which means they have a theoretical capacity thats greater.
A battery that delivers 100amp/H may be sold in other circumstances as a 120A/H battery. It delivers 100amps, but thats not 100% draw down.

from what i can tell, the better batteries do this.

I went on Enerdrive site and running one of their batteries down to zero while possible looks like a PITA

[Garret]

I'm fairly happy with my theory, my 'anally retentive electrician wiring' however leaves a bit to be desired... I think to do wiring neatly you need a smidge of OCD.

I'd pick 3 sizes;
AWG16 for your single runs (thinking 10amps). Your switch panel is probably prewired with AWG14 and a 15amp fuse for every 2 circuits.
AWG6 for a spine through the boat (thinking 50amps)
AWG2 from battery to switch panel and to windlass (thinking 100amps).

Tinned wire, using crimped connectors that are shrink wrapped.

I'm not an electrician!!

I think those sizes may be a bit small - except very short distances.

Decent chart here: http://www.offroaders.com/technical/...gauge-to-amps/

Way better to oversize wire than undersize.