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Battery - Different amp rating combine.

PostPosted: Thu Dec 05, 2019 4:38 pm
by harrydiculous
Hi

I've been offered a 200 amp/hr 12 volt deep cycle battery. (I *think* it's an AGM) It's from a backup system, kept fully charged. They are replaced every two years regardless.

I currently run 4 x 100 amp/hr deep cycle flooded batteries in parallel (12 volt system).

It's probably not "best practice" but it will save me about $450 as I don't want to expand it beyond 600amp/hr at this stage.

Any issues with this?

Thanks

Graeme

Re: Battery - Different amp rating combine.

PostPosted: Thu Dec 05, 2019 7:21 pm
by davef
The first thing that popped into my mind was equalisation:

https://discoverbattery.com/EN/battery-101/general-charging-information-for-agm-and-gel-batteries/

See the warning about 1/2 way down.

The float voltages are probably slightly different, don't know whether or not that will affect the lifetime of battery.

It involves labour but if you can control when equalisation takes place maybe just disconnect the AGM.

Re: Battery - Different amp rating combine.

PostPosted: Thu Dec 12, 2019 11:42 am
by harrydiculous
Thanks Dave. I'll fit it then. It should be coming next week. I did read somewhere that maybe some diodes can be fitted to control it, but no method was given. I can't remember where I saw this now, anyway.

Re: Battery - Different amp rating combine.

PostPosted: Fri Dec 13, 2019 8:37 am
by jaahn
Hi Graeme :)
My suggestion would be to make the battery connections between the new one and the others so you can easily disconnect it. Then you can check the charge of both seperately and also charge them seperately occasionally to get them fully charged up to their own specs. That should help to keep them going as best as possible.
Jaahn

Re: Battery - Different amp rating combine.

PostPosted: Fri Dec 13, 2019 10:24 am
by harrydiculous
Thanks Guys. I'll await my donation.