View Full Version : battery switch hook up
07-24-2008, 11:47 AM
I am rewiring a newporter 40 and considering different hookups for a perko heavy duty 350 amp four way (1,all,2,off). I need comments on three ways of wiring to see if what i think will happen is correct. I am leaving out isolation diodes, etc for simplicity.
Situation 1: Battery bank 1 to position 1. Battery bank 2 to position 2. Starter to "all". Allows choice as to which batttery or both cranks, and allows switch to act as isolation switch (in absence of other loads.) Would work the same if house load distribution panel replaced starter.
Situation 2: battery bank 1 to position 1 (battery bank 1 wired directly to starter).battery bank 2 to position 2 (battery bank 2 wired directly to house load). Alternator conected to "all" INSTEAD of starter. Allows choice of which battery is charged, or both. Does not allow choice of battery loads, but in "all" it will allow non designated battery to help designated battery. I.E. both batteries, as well as both loads. Switch will not work as isolation switch on off.(also risks no cranking energy)
Situation 3:battery bank 1 to position 1. battery bank 2 to position 2. Alternator,starter, and house all connected to "all". Allows charging choice, allows which bank for TOTAL load, switch can act as isolation switch in off position. Trying, with compromises, for simplicity, to make one switch work. Comments please. Any implication of alternator and loads on same terminal?
07-25-2008, 12:50 AM
I have a setup on my 32 foot ketch with two batteries that originally came with a 1-2-both-off switch and an isolation diode. Yours may have the alternator output going through the isolation diode to the two batteries like mine did.
If you remove the isolation diode without doing anything else the batteries will tend to discharge into each other and run flat quickly.
Another issue is whether the 1-2-both-off switch is bridging. If not and you switch while the engine is running it will momentarily break contact between the alternator and batteries. This will cause a voltage spike that will fry the voltage regulator and maybe the diodes.
Just to add more food for thought here's what I did:
1) I got a battery combiner and two simple on/off switches. I then ditched the isolation diode. The alternator is connected to the batteries through the combiner. This is in essence a relay switch that connects both batteries in parallel when the engine is started. It disconnects them when the engine is stopped. The West Marine catalog has so called West Marine Advisors that describe the battery combiner and how it's hooked up. When I go out I turn on both switches and forget about them until I return to the dock. I've had mine installed for two years now without any trouble whatsoever.
2) I replaced my cabin and running lights with LED lights which use about 1/4 the electricity.
3) Finally, I went with a solar panel to trickle charge the house battery.
I find this setup to work quite nicely with minimal chance of a flat battery.
Good luck. I'd also be interested in reading comments from others.
07-25-2008, 08:42 PM
thanks for the reply - there so many considerations that I hate to think in isolation (sorry, poor southern humor). I have the solar panels, and the perko switch is bridging type. The "combiner, 2 on/off switches" system seems like a different approach. I guess the relay activator could be rigged to work with the shorepower charger as well. I will definitely look at the west marine combiner diagrams and think it through.
07-25-2008, 09:38 PM
at the moment I am full of 10-12 different pills andsome other make me go to sleep shots........so i ain't agonna tell anyone how to fry gronicals at this stage......I never like loose batteries around without proper terminations/diodes/loads and some place to put the extra sparks...it ruins alternators and regulators....
I haven't used the Combiner, but it appears to be OK. I have a Zap-Stop on the alternator to prevent inadvertent spikes if some one turns the bat switch.
I avoided diodes because of the voltage drop across them. I just charge the start bat after each start and switch over to house bats charging underway. The two house bats are paralleled since new (nine years ago) and likely need to be replaced next spring.
May try the Combiner though, so I don't have to keep track of charging. Does that sound correct?
07-27-2008, 07:08 AM
while looking up "zap stop" information I came upon a REALLY interesting site http://www.yandina.com/combInfo.htm that has pages of combiner information, questions, and discussion, as well as products, and discussions about a lot of other projects, including a great story with photos of their 71 foot sailboat surviving hurricane hugo. A site worth exploring!!!!
07-29-2008, 06:24 PM
another question i am thinking about is how to hook up the battery voltage sensor wire that goes to the regulator/alternator when you have two battery banks. If you only hook it to one the alternator will not respond when the other is discharged, or maybe only partially in Perko "
all" position? if you hook the sensor wire to both Perko 1 and Perko 2 it seems you could have a choice without providing a discharge path between the batteries except on Perko "all".???
Incidentally, the "combiner" site mentioned above had a discussion about what happens (the consequences) of a sensor wire becoming misconnected.
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