Adding a battery one year later.

bmetbmet Solar Expert Posts: 630 ✭✭
I was concerned I might be under charging my power pack since my remote shop sits unattended for 2-3 weeks at a time. This week I arrived right at solar noon. Vmp was 17.4V to the controller, Battery was 14.01 V. It appears everything is getting a good recharge after running vent fans from sun-down to sun-up.

Now I'm thinking of adding another 75Ah battery via Marine switch, but it'll be a year newer. I know that combining the different age batteries is potentially bad and would put me under 5%, but it'd be nice to have 150Ah for inverter needs.

Any issues with charging separately, but combining for inverter? Thanks.


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Adding a battery one year later.
    bmet wrote: »
    Any issues with charging separately, but combining for inverter? Thanks.

    Yes: it's a logistical nightmare.

    Unless you have two separate arrays/controllers and one switch or two switches (one for charger, one for inverter) you can't separate the functions completely. If you use two switches you have to remember to switch the charger from one to the other. There are a few controllers that can charge two separate batteries, but on the whole it's more trouble than it's worth.

    If your battery is only a year old and lightly used it is probably still in "good as new" condition and can be paralleled without trouble to an identical one. Providing you have enough panel to charge them both. If you do use separate charging then there is the risk of your being away for 2-3 weeks and one of those batteries sitting without any charge; not the best situation.
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