Battery questions

dlochner · Aug 9, 2014

John_F said:
A couple questions:

1. Our current house battery is a lead-acid, which is under the aft bunk. We have a charger. I've heard some concerns about the dangers of outgassing during charging (we keep the charger on when running the fridge, which is hooked to the battery.

I need to change batteries, so for safety do I go to an AGM? I would think the manufacturer (Beneteau) would not have situated the battery under the bunk.

Is this something I should worry about?

2. I think I may need to use a wrench to undo the nuts that keep the cable connections on the battery...isn't it bad to touch a battery terminal with a pliers or a wrench?

AGMs have different charging voltages than flooded cells. If you change battery types you will minimally need to change the charging voltages on your charger if you can, or replace the charger.

As long as there is adequate ventilation and the battery is being charged properly, I wouldn't worry to much about off gassing. The gas is primarily hydrogen which is lighter than air and will drift out of the boat, given the opportunity.

Don't use pliers, use a properly sized wrench or socket. Don't use wing nuts, you can't tighten them properly.

Dave

Benny17441 · Aug 9, 2014

There should be no problem on a healthy battery. Excessive gassing is usually experienced with batteries that have a problem charging or maintaining charge.

Stu Jackson · Aug 9, 2014

Don't bother with the added cost of AGMs, here's why:

AGM Battery Issues (from Maine Sail)
http://forums.sbo.sailboatowners.com/showthread.php?t=124973

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn%20agm

celticwinds · Aug 9, 2014

AGM batteries are not necessary. AGM batteries do not require different chargers. Make sure the existing batteries do not overcharge. An overcharged battery will lose electrolyte and will appear wet on top. When disconnecting the connections always remove the negative side first. Any battery acid on the connections can be nuetralized with baking soda and water.

Big Windy · Aug 10, 2014

Here's more battery info:

http://www.vonwentzel.net/Battery/01.Type/index.html

jibes138 · Aug 10, 2014

Just don't ground the positive terminal by hitting the wrench to a ground point while loosening the nut. The battery could explode in this case and will at the very least melt some of your wrench.

Chris Patterson · Aug 10, 2014

jibes138 said:
Just don't ground the positive terminal by hitting the wrench to a ground point while loosening the nut. The battery could explode in this case and will at the very least melt some of your wrench.

Hehe. I don't think I still own a 1/2" long handled wrench that doesn't have an arc on it..

alexco38 · Aug 10, 2014

That's why I always always remove the negative terminals first. Doesn't matter if you short anywhere that has 12v to ground.

jibes138 · Aug 10, 2014

Unless the wrench hits the negative terminal of the battery which is very easy to do. Best to cover the terminal with a rag or something to prevent arcing if the wrench hits it.

Gunni · Aug 11, 2014

I am in the process of making this installation and for many of the concerns you have. I don't want gassy open wet batteries in my cabin. Period. In addition to the potential for charge-fault overcharging creating hydrogen gas in a confined space, there is the potential for chlorine gas production in a seawater flooded wet cell. The install requires a much more sophisticated charger than the OEM, and if you go with AGM (I am) you can greatly shorten your charge times. I have a genset, but you could simply change out your alternator to one of the high-output serpentine belt systems, with adjustable output. And you can confidently park your batteries under your backside and sleep with confidence.