Hi all,
When connecting the on board shore power, battery charger to two house batteries, should I connect the positive wire of the charger to the positive battery terminal and the negative wire from charger, to the negative of the same battery or can it/should it, be connected to the negative of the second battery.
I was wondering it I connect the charger to one battery, will it charge the second battery fully, even though they are connected in parallel to one another?
Thanks, Larry
Charger hookup
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ready123
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It would be best to use a 2 leg charger which ensures that both get fully charged. Also the ground from the charger is best connected to the ground bus for the boat.
The downside of using a single leg charger is when those batteries in parallel end up with a different discharged condition the weaker battery will not be brought back to full charge while the better one is still being charged heavily while it is almost fully charged.... causing early battery failure problems.
Unfortunately you seem to be going the route of selecting the worst way of doing things which may be cheaper initially but not over the long run. Parallel batteries opens up a number of negative possibilities. You are likely to end up with more frequent battery replacement, reduced available battery power compared to when using one larger house battery.
If you are determined to go the parallel route make sure the batteries are identical in model and age. I would use a two leg charger so that you can be certain both are brought back to full charge effectively without any negative effects of having mismatched batteries. Of course at some point one of those batteries will end up being in poorer condition and then you will have problems with lower available battery power.
The downside of using a single leg charger is when those batteries in parallel end up with a different discharged condition the weaker battery will not be brought back to full charge while the better one is still being charged heavily while it is almost fully charged.... causing early battery failure problems.
Unfortunately you seem to be going the route of selecting the worst way of doing things which may be cheaper initially but not over the long run. Parallel batteries opens up a number of negative possibilities. You are likely to end up with more frequent battery replacement, reduced available battery power compared to when using one larger house battery.
If you are determined to go the parallel route make sure the batteries are identical in model and age. I would use a two leg charger so that you can be certain both are brought back to full charge effectively without any negative effects of having mismatched batteries. Of course at some point one of those batteries will end up being in poorer condition and then you will have problems with lower available battery power.
Michael
Rum is the reason Pirate's have never ruled the world
Done Dreamin'
1987 President 43' Twin Lehman 225SP Turbo
Highfield 310 Ally 15 HP Yamaha 2cycle
1978 F32 Sedan twin 318 Chry SOLD
Safe Cove Marina, Port Charlotte, FL
Rum is the reason Pirate's have never ruled the world
Done Dreamin'
1987 President 43' Twin Lehman 225SP Turbo
Highfield 310 Ally 15 HP Yamaha 2cycle
1978 F32 Sedan twin 318 Chry SOLD
Safe Cove Marina, Port Charlotte, FL
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larglo
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- Location: Mt Juliet, TN. Percy Prist Lake, Fate Sanders Marina
In fact, I have not made up my mind to any route yet. If I had, I would not be still asking questions.
I am leaning toward having a single starter battery and a single house battery and they will be separated from each other. (no switch) The starter battery will recharge from the eng. alternator. The house battery will be charged from an on board charger when hooked to shore power. I am now looking at solar charging the house battery when away from shore power. The panels can be installed on the Hard Top.
I believe the power I would require when out, would be minimal. But I have asked questions that go beyond those needs, and will scale down from there.
I may even have more questions before I decide on a final plan. But if hooking batteries in parallel is not a good way to go, there are a lot of people that has made the wrong decision I think.
Thanks, Larry
I am leaning toward having a single starter battery and a single house battery and they will be separated from each other. (no switch) The starter battery will recharge from the eng. alternator. The house battery will be charged from an on board charger when hooked to shore power. I am now looking at solar charging the house battery when away from shore power. The panels can be installed on the Hard Top.
I believe the power I would require when out, would be minimal. But I have asked questions that go beyond those needs, and will scale down from there.
I may even have more questions before I decide on a final plan. But if hooking batteries in parallel is not a good way to go, there are a lot of people that has made the wrong decision I think.
Thanks, Larry
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alexander38
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- Joined: Sat Sep 27, 2008 6:48 am
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alexander38
- Ultimate User
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- Joined: Sat Sep 27, 2008 6:48 am
The advice you're getting is good, but only partial and from the perspective of bigger boat owners who have the room and need for more batteries than your boat (and mine) can carry.
Here's what my advice is from the perspectve if an F-26 owner - this is how I first wired my engine and house batteries before evolving to the more sophisticated 2-battery parallel house bank and Auto Charging Relay (ACR).
1. Buy a good deep cycle battery for the house bank - 120 amp hours if you can get it and fit it in the boat.
2. Buy a good marine cranking battery for the engine. Group 24 or 27.
3. Indeed spend the $50 (as has been advised) for the battery switch (1-2-all-off)
4. Buy a good 20 amp single lead charger that can be wired into your shorepower (AC) breaker box. Be sure to protect this with an AC breaker. You should have this on the boat already.
5. Wire the whole shooting match this way:
Mount the switch in a central location - mine is on the riser of the stairs into the cabin.
Using 2 or 4 gauge battery cable and lugs you size and make your own positive and negative cables or have them made for you so you don't have a lot of extra cable length running around the boat.
You'll need proper sized marine grade wire to wire charger to the battery switch - follow the directions with the charger.
Wire the postive engine battery post to (1) on the switch.
Wire the positive house battery post to (2) on the switch
Wire the center post of the battery switch to the alternator lead AND the positive lead of the charger.
Wire the negative leads of both batteries and the charger to the ground on your battery buss or to the engine block.
Now you have a system that can power either or both batteries off the alternator or the shore power battery charger, by turnng the switch to (1) - engine battery (2) house battery or (all) both batteries.
Until I wired in the ACR and made life less confusing here's what I would do.
At the dock, hooked to AC shorepower, I would switch the battery switch to (2). That would ensure the house bank was being charged by the battery charger and the engine bank (presumably charged when underway) was idle of charge.
Before leaving the dock, disconnect the shore power (duh!) and switch the battery switch to (1) to power your blower and start the engine. Once underway you can leave it on (1) or switch to (all) to charge one or both batteries via the alternator.
At anchor or away from shorepower switch to (2) to run off the house battery and preserve the engine battery for starting.
You can switch the battery switch while underway just DON'T turn it to (off) you will fry your alternator (been there done that TWICE).
If you wire in an ACR or a "Smart" charger this will help elminate the need for manual switching since both will sense the state of charge on either battery and will prevent over-charging (battery charger) or accidental discharging of the engine battery (ACR). A simple ACR and manual override switch will can you $100.
Hope that helps.
Here's what my advice is from the perspectve if an F-26 owner - this is how I first wired my engine and house batteries before evolving to the more sophisticated 2-battery parallel house bank and Auto Charging Relay (ACR).
1. Buy a good deep cycle battery for the house bank - 120 amp hours if you can get it and fit it in the boat.
2. Buy a good marine cranking battery for the engine. Group 24 or 27.
3. Indeed spend the $50 (as has been advised) for the battery switch (1-2-all-off)
4. Buy a good 20 amp single lead charger that can be wired into your shorepower (AC) breaker box. Be sure to protect this with an AC breaker. You should have this on the boat already.
5. Wire the whole shooting match this way:
Mount the switch in a central location - mine is on the riser of the stairs into the cabin.
Using 2 or 4 gauge battery cable and lugs you size and make your own positive and negative cables or have them made for you so you don't have a lot of extra cable length running around the boat.
You'll need proper sized marine grade wire to wire charger to the battery switch - follow the directions with the charger.
Wire the postive engine battery post to (1) on the switch.
Wire the positive house battery post to (2) on the switch
Wire the center post of the battery switch to the alternator lead AND the positive lead of the charger.
Wire the negative leads of both batteries and the charger to the ground on your battery buss or to the engine block.
Now you have a system that can power either or both batteries off the alternator or the shore power battery charger, by turnng the switch to (1) - engine battery (2) house battery or (all) both batteries.
Until I wired in the ACR and made life less confusing here's what I would do.
At the dock, hooked to AC shorepower, I would switch the battery switch to (2). That would ensure the house bank was being charged by the battery charger and the engine bank (presumably charged when underway) was idle of charge.
Before leaving the dock, disconnect the shore power (duh!) and switch the battery switch to (1) to power your blower and start the engine. Once underway you can leave it on (1) or switch to (all) to charge one or both batteries via the alternator.
At anchor or away from shorepower switch to (2) to run off the house battery and preserve the engine battery for starting.
You can switch the battery switch while underway just DON'T turn it to (off) you will fry your alternator (been there done that TWICE).
If you wire in an ACR or a "Smart" charger this will help elminate the need for manual switching since both will sense the state of charge on either battery and will prevent over-charging (battery charger) or accidental discharging of the engine battery (ACR). A simple ACR and manual override switch will can you $100.
Hope that helps.
Randy P
1977 F-26 HT
"Blue Heron"
1977 F-26 HT
"Blue Heron"
Charging batteries seems to be the bane of every boater. Sometimes I think I need to do a witch dance because of all the conflicting advice, and I studied electrical engineering! The folks at Yandina who make combiners give a nice explanation of why it is ok to parallel batteries while charging:
http://www.yandina.com/combInfo.htm#Q32
Perhaps you don't need a multi bank charger. On the other hand, when I decided to replace my charger, I went for the three bank model. Wanna buy a low mileage combiner?
Brett
http://www.yandina.com/combInfo.htm#Q32
Perhaps you don't need a multi bank charger. On the other hand, when I decided to replace my charger, I went for the three bank model. Wanna buy a low mileage combiner?
Brett