Combining GEL and Lead-Acid batteries

[VinceB]

Hello

My battery setup is the following: Two 12V lead-acid batteries and two 12V GEL batteries. At the store, the  guy told me it was fine to charge them altogether. But I had a different advice somewhere else. From what I understand, the maximum charge voltage of GEL batteries is lower that for Lead-acid. Some guy suggested I use a regulator in between the two sets to take care of the voltage problem. What kind of regulator would that be? Would I be able to build/purchase one?

Thanks!

Vincent

[AbyssUnderground]

Are you 100% certain that they are GEL and SLA? Its a common misconception that GEL is SLA and SLA is GEL etc and it may have simply been labelled wrong where you bought it.

It is true however that their charge voltages are different but both should charge well at 14.2v unless stated otherwise on their label.

[Nando]

Just a warning:

Gel cell should not be equalized.

Nando

[Dzisko]

Gel and Lead-acid batteries are almost the same and contain lead electrodes and sulfuric acid, with only difference that there were made some troubles in servicing (and then enclaimed they are "non-serviceable" Gel batteries - you have break out plastic tabs to reach banks and add water.

So you can use Gels as an usual lead-acid batteries, but not overheat them - as I did say, there are some troubles with water adding.

Of course, when you parallel various batteries, check firstly, will they charge/discharge each other with a big current - in case wires give good sparks, do not connect them untill voltages will be equalized.

[jnh]

As an earlier poster mentioned, there's a good chance your "Gel" batteries are actually AGM-type.  AGM's seem to be much more common.  They're also a type of SLA (Sealed Lead Acid), but are closer to normal flooded batteries in terms of voltage setpoints and charging regime.  Neither type should ever be equalized, or otherwise overcharged.

If your application allows for it, it might be better to set up two battery banks, with an A/B/Both paralleling switch in between, and charge them separately whenever possible.  Paralleling both banks for discharge should be OK, so long as they're near the same state of charge.

Keeping them paralleled fulltime may work out OK, though, with careful choice of charging voltages to compromise between underchaging the flooding batts, and venting irreplacable water from your SLA's.  Expect at least a small reduction in service life...