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MWJ68

Proper Charging Procedure

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MWJ68

2015 23 LSV with duel battery bank. I've been charging the batteries after a few weeks of storage using the following procedure: Battery switch to OFF. Remove the HOT lead from each battery and charging each battery separately. I was wondering if it was possible to charge both batteries at the same time? If I leave the batteries connected and have the battery switch to OFF, can I connect the charger to one of the batteries? Will this charge both? Can this technique damage the system?

 

 

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hethj7

I'd have to think about how they are actually wired to answer you question, but you may look into the Promariner 2 bank chargers.   You could permanently mount it connected to the batteries and then just plug it on as an on-board charger.    

 

I'm sure others will chime in as to the original question as well.   

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t a

With the switch off, the batteries should be isolated from each other.  With the switch on, I think you could technically charge both but could cause problems or kill a battery if they were at different charges and you overcharge one of them.  

Dual bank smart charger with battery switch off is what I’m doing

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Slurpee

When you connect two batteries of different charges they will balance to the same potential voltage. That’s not the same as charged energy capacity mind you. Just voltage.  

That balancing is done by a rapid dumping of energy via current over a period of time from the battery at higher voltage to the battery at lower voltage. The only thing limiting this current is the resistance of the cabling and the impedance of the battery. The formula is Ohms Law. The difference in voltage equals the current in amps times the total system resistance which should be pretty dang low. So current can get high. VRLA cells are pretty robust so they can take that hit and are consequently also popular for starter batteries. 

If both batteries are within a quarter volt or so then you are likely going to be okay hooking em up and charging them together. It’s the time immediately after hooking them together that’s in question. Not the actual having them hooked together. Lead acid batteries are routinely hooked in massive arrays for backup systems. And we do increasingly complex things to maintain their balance as they age. Boat systems are Childs play. 

Best long term bet is a dual marine charger. 

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formulaben
11 hours ago, Slurpee said:

Best long term bet is a dual marine charger. 

+1

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Infinitysurf
On 6/19/2018 at 9:42 PM, MWJ68 said:

2015 23 LSV with duel battery bank. I've been charging the batteries after a few weeks of storage using the following procedure: Battery switch to OFF. Remove the HOT lead from each battery and charging each battery separately. I was wondering if it was possible to charge both batteries at the same time? If I leave the batteries connected and have the battery switch to OFF, can I connect the charger to one of the batteries? Will this charge both? Can this technique damage the system?

 

 

I have a dual battery bank with switch on my 2014 boat. #1 is the starter....then #2 is acc (and I have a 3rd battery wired to that #2 acc battery to give me extra juice).

Whether wrong or right, I do not know for sure, but what I was told I could do and have done since last Feb 2017 on this boat....is to turn the battery switch to OFF (my switch is always off if not using the boat), since I have not yet installed a 2-3 on-board battery setup even tho I do plan too.....I have 2 separate smaller "smart" marine battery maintainers and I just hook them up to each battery and plug them in until the batteries are topped off. After #1 and #2 are topped off, I move one of them to #3. Typically the starter battery has barely lost any charge since alternator is always giving that one juice and its not used as much....#2 main acc is always topped off overnight since it gets the most use from the stereo, pumps, etc (its a trickle charger, so not many amps, a better one would certainly charge them faster)....and #3, 2nd acc battery also usually takes very little time since it just supports the #2 main acc battery. I have had no issues doing this and understood as long as your battery switch is off then its no issue and you do not have to unhook the "hot" lead since they are isolated with switch off....having the switch ON which charging can potentially create issues with some systems, but I know some people do it that way too. I prefer to use safest way possible.

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