I am considering getting a small boat with a trolling motor.   My problem is -- I live in a high-rise apartment, so I can't keep the boat where I live.  That means I'll have to take the batteries out and recharge them between trips, rather than plugging in an onboard charger in the driveway like I could if I lived in a normal house.   My question is:   is it safe to charge a marine battery indoors?

Yes it is safe. 2 things, 1. Use a trickle charger that shuts off or stops charging when the battery is fully charged and 2 . Do not place or store the battery on a bare concrete floor. Concrete will drain and weaken your battery.

Just make sure you have ventilation. Hey Barresi, I think that's an old fish story about the battery on concrete. I left one on the back porch one time as a test...I gave up after a year...darn thing never did lose any charge!

What would be in concrete that would drain a batteries charge? It is an old wives tale in my mind.

After spending nearly 40 years as an auto mechanic, I feel I have learned a few things about lead /acid batteries. The story about batteries losing their charge on concrete at one point was valid, but that only applied to batteries constructed with a rubber case. The newer plastic cased batteries do not have this problem. As far as charging indoors, it is not the best of situations but can be done.When a battery is charged a discharge of hydrogen gas is normal and ventilation is critical especially if there is a smoker or gas pilot light nearby. These puppies can explode in a pretty spectacular fashion spewing acid everywhere. I would also recommend placing a piece of thick plywood underneath the battery to catch any acid that may leak. Common baking soda can be used to neutralize the acid in case of a spill and is also good for cleaning the case.

Because the charging process produces highly flammable hydrogen gas, though in small amounts, charging indoors is not recommended. Kurt NAF-Editor.

Posted By Pegsguy on 07 Nov 2011 09:46 AM
After spending nearly 40 years as an auto mechanic, I feel I have learned a few things about lead /acid batteries. The story about batteries losing their charge on concrete at one point was valid, but that only applied to batteries constructed with a rubber case. The newer plastic cased batteries do not have this problem. As far as charging indoors, it is not the best of situations but can be done.When a battery is charged a discharge of hydrogen gas is normal and ventilation is critical especially if there is a smoker or gas pilot light nearby. These puppies can explode in a pretty spectacular fashion spewing acid everywhere. I would also recommend placing a piece of thick plywood underneath the battery to catch any acid that may leak. Common baking soda can be used to neutralize the acid in case of a spill and is also good for cleaning the case.

No kiddin'? A rubber case? Guess I'm not as old as I thought, because a rubber battery case is news to me. Elaborate Pegsguy, why would rubber bleed away charge? This is interesting...to me anyway.  

maybe because the rubber is a more porous material than the plastic

Here's your anwser.
http://homepower.com/article/?file=...pg12_ATE_5

I get emails/news letters from Boat US, and in their winterizing tip...they stated not to store your battery on concrete...the concrete will slowly drain the battery...I store my batteries in my basement,I just put them on a piece of 2x4's, so there not touching the concrete floor...Everyone I know says the same thing...just putting it out there...remember, it says concrete will "SLOWLY" drain your battery.

I agree , i'v always been told that the batteriers will drain if they are stored on concrete. It is also agreat idea to have a battery charger that dose shut off when charged, i got lucky my old one did not and if my son had not gone out to my shop it would have burned to the ground along with my truck, wifes car and all my tools and yes my boat also. SO YES GET ONE THAT SHUTS OFF WHEN DONE .................JOHN

Yes, just dont cross the wires!!!

Any lead/acid battery will self discharge over time just like many rechargeable cells for flashlights, electronics etc. This will occur no matter what material a battery is stored on. Thanks to Wellsley for the link. I knew about the rubber cases but not some of the earlier designs.