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joolster avatar image
joolster asked

ESS - Off peak charging and Solar, Li batteries (BYD) - Battery life? (UK)

Hi there,

I have a new 3ph system, 3 MP II with cerbo gx, 24kwh pooled BYD LVS batteries (Li), with victron meters on 3ph and solar (1ph) heaviest load is heat pump.

I have smart tariff - cheap 6 hours overnight, 5x expensive during peak

I have 3.6 kwh solar (which will be increased)

Installer set up system with Battery life, with 95% charge limit. Regulation across phases is on.

Reading the forums and watching victron youtube, it's not clear whether really need battery life? or indeed whether

I charge batteries off peak and discharge to power loads. Then if there is excess solar (not much in winter), it tops up batteries a bit.

In this scenario, should battery life really be used / does it actually help?

In contrast, in summer I intend to charge overnight (but to a lower SOC) and then top up more with solar as there is more of an excess.

In this scenario, would battery life be useful (would typically expect to capture 10kwh from solar) and charge battery off-peak to between 40% (or higher when no solar forecast next day)

Would very much welcome the communities help on this!




ESS
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1 Answer
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matt1309 answered ·

Hi @joolster

With Batterylife option the system will increase the "activate SOC limit" by 5% each day the battery doesn't get to 100% SOC. I believe the theory behind this is to allow the battery to get to 100% to let the BMS balance the cells.


However if you're charging the batteries using the grid overnight then odds are batteryLife will just act the same as without battery life as you're regularly reaching 100% (or close to it, I forget the exact number).


My setup is somewhat similar to yours (but mines smaller, I'm jealous of the 3ph in UK). I started off with batteryLife but now i dont bother now. If i notice the battery has been low for a long period of time due to low sun in winter I set it to charge from grid just to allow cells to balance, however if you're not monitoring the system then leaving batteryLife on might be the better choice.

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