Battery Charging

bgretired · April 2015

Is there a way to charge batteries with different A/Hs (50,100,130) tied to a common buss?

BB. · April 2015

If the batteries are the same brand/type/condition, you can parallel them and charge with one charge controller.

The more different the batteries, the less satisfactory they will charge (slower, less than 100% charge, etc.).

Of course, if you have a battery with a shorted cell, etc. It will cause problems charging the other batteries.

Slow charging/lower voltage (14.2 volts vs 14.8+ volts) should work fine.

If you need to equalize (high voltage charging like 15.0+ volts), you should do one battery at a time.

I would not make a mixed battery bank... long term life/ability to deep cycle will be poor.

-Bill

BB. · April 2015

You can fuse each battery to protect against shorts, and get a DC current clamp DMM to ensure each battery is charging with the correct current.

-Bill

bgretired · May 2015

Actually what I am going to do is get rid of the lower A/H batteries and just stick with the 130a/h agms. The problem I am going to run into is how to charge them in parallel. I have 96 130a/h agm batteries, putting 4 in series to get 48v. This gives me 24 sets of 48v which are paralleled back to a common bus. So how do I charge them using 2 Xantrac Sw5548 in parallel and 20kw generator.

vtmaps · May 2015

bgretired wrote: »

Is there a way to charge batteries with different A/Hs (50,100,130) tied to a common buss?

It is not safe or practical to charge 24 batteries in parallel... even if they are all the same amphour rating. The current will not divide evenly among the parallel paths.

Even if you started with 24 strings of matched batteries, before too long you will find that after the charger is turned off some strings will be discharging into other strings.

Most authorities consider that three strings is the maximum acceptable, but even that is controversial with some authorities claiming that only two strings is the maximum acceptable.

btw, all of the problems that occur with parallel charging are worse with AGM batteries because of their lower internal resistance.

The exception to the rule is for batteries that are rarely cycled... for example telecom batteries which may float for years waiting for a rare grid failure. Many of these batteries can only be deep cycled a few times in their lives.

--vtMaps

SolarPowered · May 2015

vtmaps wrote: »

Most authorities consider that three strings is the maximum acceptable, but even that is controversial with some authorities claiming that only two strings is the maximum acceptable.

btw, all of the problems that occur with parallel charging are worse with AGM batteries because of their lower internal resistance.

--vtMaps

Although I disagree with the use of marine deep cycle batteries this seems to be the great debate. The always asked question for the value, is Marine deep cycle worth its advantages VS true AGM

SolarPowered · May 2015

In the case of the O.P. He has some advantages of building a few battery bank systems, and installing a few isolation/transfer switches. It would potentially increase the life span of the entire system switching from one bank to the next, possibly transferring to another bank once a week, or month, etc. Or lets say he can swap using a larger bank during the winter isolation, and smaller banks during spring and summer insolation. That many batteries does have some potential to perform differently during the seasonal insolation.

Battery Charging

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