For years I've had a giant high amperage charger on wheels like you'd see in shops to bring batteries back from dormancy from storage. A few years back I switched to the AGM (glass mat) batteries from Optima since they seemed to be an advance over traditional lead/acid designs like my '66's were born with. My program with the old charger was watch the charge until the battery isn't taking much voltage, then shut it off. That worked fine, but I never really knew if my battery was at 90%, 80% or 99%.

The Optimas have been working great. Last summer I brought my 98 out of storage, put it on the big charger and let it rip for about an hour. Usually I let the cars sit unattended for a few weeks at a time so the batteries run down. No big deal, but that day I heard the battery bubbling inside the case toward the end of the charging window and thought that was probably not good for it.

Maybe I'm behind the times, but I picked up a couple of microprocessor-controlled chargers from Schumacher to maintain my batteries. 9 months in I'm please to report that they work just great, have settings for lead/acid and AGM batteries and helpfully show the charge level if you push a button. When the battery is <80% full they charge at full rate, then taper off the voltage as the battery approaches full to keep from cooking it like a bad voltage regulator.

It's n​​ice to find a good tool, so I wanted to share. Here's what one of mine looks like:

Works with lead/acid & AGM batteries. Shows the charge level. Won't charge unless it's hooked up correctly.

The icing on the cake for me is that it won't spark and short like the old school ones. It requires 3 volts across the charging leads before the software will let it charge. It will also not charge if you've reversed the leads.

It's even been good when I have a door open and am working on some bulb, window or electrical thing and don't want to unhook the battery.

I still like my high amperage old-school charger for some stuff, but I think it will go into less and less use from here. Sorry if this is just me catching up.

Hope this helps some of you.
Chris

 

Hi Chris.

As you found, the big, wheeled chargers are great for the old flooded batteries but are not suited to ones where you can't check or replace water levels--such as AGMs.

There are two types of AGM batteries. You have a pure lead AGM (Optima), which needs to charge at a bit higher voltage than do the calcium-lead AGMs. Your Schumacher has the right setting for that as you stated.

However those who have a calcium-lead AGM will damage it if they use the higher voltage. The take-away is that you need to check with the AGM battery manufacturer to be sure which charge setting is best.

Thanks for the post about your experience--and the solution.

 

You can also do well with a CTEK 7002 battery maintainer. Around 100 bucks, but it'll keep AGM or lead/acid batteries topped off. Just plug it up when you park the car, then unhook it when you're ready to roll again, however long that may be. Keeps the battery topped and ready ALL the time. Even though it says for lead acid batteries on the side of it, it has two flowpaths on the face, one for optima styles and one for lead acid. Great unit with great reviews. I've had one for a while without issue. I've also used Battery Tender Jr. maintainers on AGM and lead acid without issue for several years. Around $25 Just don't get the regular sized Battery Tender box units, every one I've ever purchased has failed miserably.

 

Thanks for the product reviews. I got an Optima battery and installed it in my 71 98. It was dead from the start and wouldn't keep a charge so I sent it back.

 

Last year I bought a Pulse Tech charger / maintainer / desulfator and was able to resurrect a dead battery that my other high current charger and my battery maintainers couldn't charge. A co-worked recommended it to me as he was able to resurrect a couple of dead batteries as well.

https://www.pulsetech.net/store/xc10...esulfator.html