battery question

[Rich (P303)]

General battery questions. I purchased a boat with a couple of GEL batteries, (1 house and 1 starting 5 years old now). The house will not hold a charge for very long now. I have a simple set up... 30 amp alternator/13HP Yanmar with no frills. If I replace both batteries with GELS again... (1) does the alternator know when to stop charging the GELS (I know they are sensitive to charging)? (2) Can I overcharge the batteries from the alternator? (3) Can I charge both batteries @ once (if the same or different)? (4) Can I run different batteries, use and charge at the same time if needed? I have a typical off/1/both/2 setup. Any advise would be greatly appreciated... I don't want to buy a couple of new batteries and wreck'em.Rich

 

[Landsend]

You are near the end of the lifespan of the gels..

I suggest you buy three acid lead flooded batteries hook two in parallel as you house battery and tho othe as you starting battery. Keep it simple and use a battery selector switch. I'f you have a battery isolator diode bank...toss it out!

 

[Don S/V ILLusion]

mix and matching problems

1) does the alternator know when to stop charging the GELS (I know they are sensitive to charging)? Unless you know for sure how the regulator is set, check it with a voltmeter to ensure it is properly managing the charge voltage for gels.(2) Can I overcharge the batteries from the alternator? Yes, see above. Presuming the previous owner set it up properly is not wise. If it's an internal regulator, it was likely not.(3) Can I charge both batteries @ once (if the same or different)? Yes if the same type and age, otherwise, it's genwerally not a good idea unless you know how.(4) Can I run different batteries, use and charge at the same time if needed?Generally no.Given the cost of batteries these days, it might be worth a few extra dollar to buy one of the many boater's battery/electrical system maintenance books available.

 

[camaraderie]

Time to change...

to flooded cells! (1) does the alternator know when to stop charging the GELS (I know they are sensitive to charging)?Sort of...the batteries become more resistant to the charging as they become full so they essentially self limit what you can do with an alternator in most situations. (2) Can I overcharge the batteries from the alternator? YES...the standard Yan alternator can put out more than 14.1V generally which is the limit for gels. Unless you have a separate regulator, you can damage gels with a standard alternator with built in regulator. They are designed for wet cells.(3) Can I charge both batteries @ once (if the same or different)? You can charge both batteries at once BUT you should NEVER mix types. Just turn the battery switch to both if you want to charge them both. (4) Can I run different batteries, use and charge at the same time if needed? I have a typical off/1/both/2 setup. See #3...never mix types.Unless you are living aboard or hve some special needs, a good wet cell battery will be your best and most economical choice. Depending on your space available and how much of a house bank you want, you might consider golf cart type batteries ...but a couple of 12V wet cells will suffice for casual use.