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Thread: 8 D Batterries

  1. #1
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    Default 8 D Batterries

    My starting battery is toast. It's a conventional 8d almost 8 years old

    Should I replace it with the same or go with an AGM battery?
    Elect a clown expect a circus

  2. #2
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    Default

    8 years is OK. I'll watch with interest to see what folks say about AGM. My lead acid 8gs are about the same age but still going for the moment.

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  3. #3
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    Default Re: 8 D Batterries

    I need to replace the starting battery in Skookum Maru as well. Old one was AGM of unknown age. Planning to replace with an AGM.
    - Chris

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    Default Re: 8 D Batterries

    8D batteries are like white oak to me...I only take it OUT of boats, never put it in .

  5. #5
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    Default Re: 8 D Batterries

    I'm a big fan of AGM. Would not hesitate for a moment to replace any conventional LA with one. Charging specs are usually almost identical and no fussing after install.
    I swear I'm half done.

  6. #6
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    Default Re: 8 D Batterries

    Quote Originally Posted by Bobcat View Post
    My starting battery is toast. It's a conventional 8d almost 8 years old

    Should I replace it with the same or go with an AGM battery?
    All else (amp-hours, voltage, discharge limit) being equal, AGM batteries withstand shock and vibration better than wet-plate or gel batteries. If your boat goes fast enough, or if you are bold enough to go out in truly nasty weather, to really bounce around an AGM would be the better choice. Gel batteries overcome the problem of leaking due to being tipped over or a cracked case that wet-plate batteries suffer, so if your boat heels excessively or it's battery location leaves it vulnerable to damage, a gel battery would be a better choice than a wet-plate battery. (Gel batteries are often touted as being sealed and therefore do not need venting, but I'd still want my battery compartment vented.) Wet-plate batteries are lowest cost, so if your boat doesn't beat up its batteries (eight years of service seems to indicate this), a wet-plate battery is your most wallet-friendly selection.

    In all cases, I would pay the premium and get a deep-cycle battery, regardless of type. Not only will you retain the high cranking-amps necessary for engine starts, but will also have a deeper discharge capability that will allow house lights and electronics to operate longer on battery power without compromising the battery's recharging capability.

    Finally, just to stir the pot a bit, have you heard of the newest type of marine battery - carbon-foam AGM? https://oceanplanetenergy.com/advanc...asis-group-31/
    Last edited by mmd; 02-13-2020 at 10:58 AM.
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  7. #7
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    Default Re: 8 D Batterries

    Thanks for the replies. Just to be clear: I will be buying a starting battery and a deep cycle battery as a house battery
    Elect a clown expect a circus

  8. #8
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    Default Re: 8 D Batterries

    The only Achilles heel with AGM is that they do not like being left deeply discharged for any length of time, like a couple of weeks.
    i would also recommend checking your charging profiles on the shore charger and alternator to make sure they are optimum for AGM

  9. #9
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    Default Re: 8 D Batterries

    My boat does not go fast and I avoid bad weather when I can

    So I don't see a need for AGM batteries.
    Elect a clown expect a circus

  10. #10
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    Default Re: 8 D Batterries

    Bobcat, If you go with LA, I’ve had really good luck with my Dyno brand batteries, like 11 years on my L-16s. I originally bought them direct from Dyno over on Magnolia, but when I replaced them I found that I could get them cheaper through Fisheries.

  11. #11
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    Default Re: 8 D Batterries

    I wouldn't put a wet lead acid into a boat. Not worth the risk of spilling battery acid. Just a thought.

    Cheers,
    Mark

  12. #12
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    Default Re: 8 D Batterries

    Quote Originally Posted by ron ll View Post
    Bobcat, If you go with LA, I’ve had really good luck with my Dyno brand batteries, like 11 years on my L-16s. I originally bought them direct from Dyno over on Magnolia, but when I replaced them I found that I could get them cheaper through Fisheries.
    I bought the last battery directly from Dyno. I should up in motorcycle gear and bought an 8d. The fella was a bit leery as we wheeled it out. He brightened up when he say the motorcycle had a sidecar
    Elect a clown expect a circus

  13. #13
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    Default Re: 8 D Batterries

    Quote Originally Posted by Mark0 View Post
    I wouldn't put a wet lead acid into a boat. Not worth the risk of spilling battery acid. Just a thought.

    Cheers,
    Mark
    Not meaning to be snarky, but that risk can (and should) be ameliorated by installing the battery securely in a proper battery box.
    Hope for the best, but plan for the worst.

  14. #14
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    Default Re: 8 D Batterries

    I currently have gel house 8Ds & a separate group 28 lead acid starting battery (in a proper battery box that's fastened down ). The demands are different (high amp/short time on starting, low amp/long time on house) - so it made sense to me to use different types.

    However - they have entirely different charging characteristics - so you can;t use the same charger on them. Balmar makes a product called the Duo Charge (http://www.balmar.net/products/digital-duo-charge/) that handles this nicely. I've been very happy with it.
    "If it ain't broke, you're not trying." - Red Green

  15. #15
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    Default Re: 8 D Batterries

    Quote Originally Posted by Bobcat View Post
    My boat does not go fast and I avoid bad weather when I can

    So I don't see a need for AGM batteries.
    Bobcat, I think lead acid batteries are just fine. It's all I used for 20+ years after all, and all anyone used until 1980 or so. And as mmd notes, proper installation addresses any concerns about movement, acid, hydrogen from charging, etc. For me though, it's worth the extra cost for the AGMs to avoid the maintenance requirements for the lead acid batteries. The whole regimen of checking the electrolyte level, testing the specific gravity of the electrolyte, topping up with distilled water and trying not to drip acid anywhere, all while inevitably crouched in the most inaccessible, poorly-lit spot in the machinery space was always my least favorite job aboard. I'm entirely happy to never have to do that again.

    Of course having AGMs doesn't help when someone knocks the shore power cable loose, shutting off the charger and letting the house bank drain, as happened last year with Skookum Maru. It's quite a shock to come aboard and see the battery meter reading 0.00 in acusatory red LED numbers. It couldn't *actually* have been zero as the refrigerator was still running and cold (the reason the batteries drained) but even so I was worried that the house bank batteries would be ruined. So far they seem to be holding a charge ok at anchor though, so perhaps I got lucky that time.

    But I digress. If you are going with lead acid then I like Dyno batteries as well. Great product. And like Ron I have bought them directly from Dyno in the past but the last time I needed one (for a starting battery in Petrel, since replaced with an AGM battery) I purchased it from Fisheries.
    - Chris

    Life is short. Go boating now!

  16. #16
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    Default Re: 8 D Batterries

    I assumed that buying directly from Dyno, the manufacturer, would be the cheapest. Now I will call around.
    Elect a clown expect a circus

  17. #17
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    Default Re: 8 D Batterries

    Quote Originally Posted by mmd View Post
    Not meaning to be snarky, but that risk can (and should) be ameliorated by installing the battery securely in a proper battery box.
    No snarkyness taken I'm literally more worried when moving batteries in/out, not after they are installed. I'm pretty sure the AGMS also offer more cranking amps due to the increased plate surface area. Just a better all round product in my mind.

    Cheers,
    Mark

  18. #18
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    Default Re: 8 D Batterries

    So buying directly from Dyno is much cheaper, not that any 8D battery is cheap
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  19. #19
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    Default Re: 8 D Batterries

    I have found that AGM lasts e twice as long as flooded electrolyte batteries. They do not self-discharge hardly at all.( I charge them in November when I haul, leave them in the boat for the winter, and they are 99-percent charged when I pull the cover off in March. ) There is no maintenance, but for cleaning and re-greasing the terminals annually. Just bought my second pair after 9 years of deep-cycle/ dual-purpose use.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  20. #20
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    Default Re: 8 D Batterries

    Quote Originally Posted by Bobcat View Post
    So buying directly from Dyno is much cheaper, not that any 8D battery is cheap
    Interesting. I found the opposite. I bought my first L-16s directly from Dyno without comparing. But this time to replace them, I got a quote from Dyno then found out that my Fisheries discount made them cheaper there. Many times manufacturers will hold retail prices to protect their resellers, which seemed to be the case here. Like they say, no one pays retail. So I guess it just depends on who gives you discounts and who doesn’t.

  21. #21
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    Default Re: 8 D Batterries

    Quote Originally Posted by ron ll View Post
    Fisheries discount
    Fisheries discount? Is this something everyone knows about but me? How does one go about getting a discount!?
    - Chris

    Life is short. Go boating now!

  22. #22
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    Default Re: 8 D Batterries

    Now I am wondering if 4D batteries are the way to go. They would be easier to horse in and out of the engine room.

    I think a 4D would have plenty of juice to turn over my engine. As for a house battery, i don't run a lot of electrical stuff. The lights are LED. The only real draw is the fridge.

    I am being short sighted moving down in capacity from 8D batteries to 4Ds?
    Elect a clown expect a circus

  23. #23
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    Default Re: 8 D Batterries

    Quote Originally Posted by Bobcat View Post
    Now I am wondering if 4D batteries are the way to go. They would be easier to horse in and out of the engine room.

    I think a 4D would have plenty of juice to turn over my engine. As for a house battery, i don't run a lot of electrical stuff. The lights are LED. The only real draw is the fridge.

    I am being short sighted moving down in capacity from 8D batteries to 4Ds?
    For house, it might be. Refrigeration can take some juice. For starting, I'd be surprised if you needed even a 4D. Dunno what your engine is but my 53HP Yanmar uses a regular automotive battery (group 28 instead of 24 'cause it also runs the windlass).
    "If it ain't broke, you're not trying." - Red Green

  24. #24
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    Default Re: 8 D Batterries

    Snoose has a 4D starting battery, never had a problem with it until it ran its course and I replaced it with another 4D Has plenty of crank, even on really cold winter starts.

  25. #25
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    Default Re: 8 D Batterries

    I am going to go with a 4D starting battery. I have a 110 horse Volvo Penta and it doesn't need a lot of juice to start. The fridge is new (2 years old) and fairly efficient. The only other continuous power draw is a computer fan in the composting head.
    Elect a clown expect a circus

  26. #26
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    Default Re: 8 D Batterries

    I assume your fridge is not running off your starting battery. If it is, be sure to sign up for Boat US towing services.

  27. #27
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    Default Re: 8 D Batterries

    My mama had some dumb sons, but I'm not one of them

    I did some checking and I think the boat had a 4D starting battery when I bought her.

    In 2013, I got a great deal on a couple of used 8Ds---a big yacht upgraded to AGM-- and I now think that's why I have an 8D starting battery currently
    Last edited by Bobcat; 02-21-2020 at 01:24 PM.
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  28. #28
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    Default Re: 8 D Batterries

    The new batteries are in. Both 4D. The starting battery is from Dyno; the other one from Harbor Marine in Everett---it had a good deal on a deep cycle. There were three of us and so pulling the old 8Ds from the engine room was not the bear it could have been. I was glad to see them go. From the markings on the old batteries, they were from July 2011. I would say I got my money's worth from them

    The engine fired up and I was able to get away from the dock for a bit.
    Elect a clown expect a circus

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