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Is there any difference in charging a 6 volt battery, compared to a 12 volt battery?
I have the 6 volt battery for my 1951 Packard. Putting it on my 10 amp charger, it charges down to between 5 and 6 amps but doesn't seem to go any lower? With a 12 volt battery a battery charges down to between 2 and 3 amps.
Taking the caps off the 6 volt battery, I see little bubbles rising to the top. The battery doesn't seem warm from charging. Is the battery bad?

Thanks John

Hey John,
Re the charging amps, I would think your battery should get down to the 2-3 amp level when charged. I am charging mine as we speak and I just checked the amps digital readout and it's saying 1.1, so I'm thinking I'm pretty close to fully charged.
This charger pops off when full charge is reached and it is still showing 'charging' and I'll check it again in a couple of hours. Re the condition of your battery, I would put a hydrometer on it and see how she 'floats'. That, and a proper load test, are the best ways to ascertain battery health and condition. Also, the plates in batteries left unused and uncharged for an extended period, will sulfate, (think of shiny lead vs. dull, oxidized lead) and they become less efficient and will not take a charge as readily either. That's why it's a good idea to throw any lead acid battery on a charger every once in a while, when it's sitting idle during the winter months. Chris.

It might be bad, or not. The definitive tests are either using a battery hydrometer to measure the specific gravity of the electrolyte in each cell, or using an electric load test. I prefer the hydrometer test.

Yes, it's normal to bubble hydrogen gas while charging. It's normal to not get hot when charging at such low rates. The fact that your charger is not tapering its charging rate suggests the battery may not be capable of achieving a full charge condition.

Most any auto parts store will test your battery as a courtesy.

Thanks Chris and Owen. I have a hydrometer around here somewhere, haven't used it for years.
It is a tractor battery from Rural King that was bought for the car by the previous owner in 2013. So it might be past its life.

Thanks John

Might be 'getting old' John. One thing to keep in mind is that a lot of 6 volt cells are made way more heavy duty than your average car 12 volt cranker. They often have thicker plates which translates to longer life, provided they are charged and maintained. I have huge 6's ganged together to make 12's on my sailboat and I got 12 years out of the last set and they were cheap Walmart 'Exides'. I replaced them with top-of-the-line 'Trojans' last year, and some guys are getting 15+ years out of them. Those are XHD golf cart batteries, so I wouldn't expect that kind of mileage out of the 6's we're burning in our cars, but they should definitely go a few years... Chris

Not sure how much sitting this battery has done before I got it. John

This is just a little aside that is not an answer as you've already gotten good advice.

Because my shop gets bitterly cold in the winter and unbearably hot in the summer, batteries don't last long so I keep the 12v batteries on a system powered by a 100w solar panel on the roof. It is currently set up to maintain three batteries but I've not found any kind of controller to handle 6v batteries unless I buy two and connect them in series.

Don, you've just answered the solution to sulphation!! ANY kind of charge, no matter how small, as long it is regular and consistent, will eliminate the plates from sulphating and both prolong their life and make them more efficient in terms of taking a charge and holding a charge when in use. If one does not have a setup like yours, then throwing them on a charger a couple of times a winter and giving them a good, full charge, is the next best thing. Chris.

Chris, I've been getting on average 7-8 years from the NAPA Group 4 Commercial 6- volt batteries in my '34 Eight. The battery winters in the car, installed but disconnected, in an unheated garage. Typical New Jersey winters, often below freezing but rarely below 0 F. My practice for many years has been to use a trickle charger about once every 6-8 weeks for about 5 - 8 hours. Typically it will start at about 4 amps and taper down to 1-2 within a few hours.

I think I posted this elsewhere but here are my charge controllers which are quite inexpensive but they do the job! The upper one can handle one battery (or more if the same capacity when connected in parallel) while the lower one can handle two separate dissimilar 12v batteries. The upper one also has a load output allowing for timed or permanent lighting controls so as shown here, the upper wall switch turns on three bright 12v LED floodlights which illuminate well enough to safely maneuver around in the shop even when there is no AC power. The panel also keeps my iPad charged while out there.

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