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Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 10:45 am
by richbee
I've now got my Sunsynk PV & battery system working - trying to find out the best way to set it up & use it.
One thing I notice is that the maximum discharge power seems to be ~2.5kW (50A). The battery manual states normal discharge rate of 50A, with max discharge rate of 100A (max temp of 27 degrees). The inverter settings are at 90A for battery discharge, so it seems that the battery is overriding the inverter settings.
It would be very useful to be able to have 90A discharge for eg. kettle, tumble dryer, oven & hob usage when there is little or no solar input, to avoid having to use the grid when the battery is full.
Does anyone know how or if you can tell the battery to allow higher discharge rates, or if it is actually a bad idea in terms of battery life?

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 11:20 am
by nowty
How much capacity in kWh have you got ?

Example, for Pylontech's unless you have over a specific capacity of kWh's, (3 modules of the US2000's) the max discharge rate is limited.

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 11:40 am
by nowty
Reading your previous thread, I think you have 10kWh, probably 2 x 5kWh modules ?

If so, the only thing I can think of is the dip switch positions on the batteries. Are they correctly set up as master and slave.

Page 14 of the installation manual.
https://portal.wholegreenrenewables.co. ... tralia.pdf

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 12:05 pm
by richbee
Thanks Nowty - I've currently only got the 1x 5.1kWh battery - maybe that is it

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 12:17 pm
by nowty
richbee wrote: Fri Sep 23, 2022 12:05 pm Thanks Nowty - I've currently only got the 1x 5.1kWh battery - maybe that is it
In that case I'd happily live with the 50A limit. :mrgreen:

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 12:25 pm
by nowty
I've just checked out the equivalent Pylontech 4.8kW US5000 battery and the recommended max is 50A. It does have a higher peak value but will derate if temp increases.

As an aside, the Sunsync batteries are 16 cell LFP so slightly higher operating voltage than the 15 cell LFP Pylontechs. So, if anyone is thinking of doing a DIY battery extension to them like Joeboy, you would need 16 cells and not 15 cells as for Pylontechs.
https://camelot-forum.co.uk/phpBB3/view ... =14&t=1194

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 2:28 pm
by richbee
I had begun to wonder if I should add another battery now, while the first one is new, so they are well matched - but then thought I should see how it all goes first, before splashing out another chunk of money.
I don't like to see the lovely PV energy 'wasted' going back to the grid once the battery is full, but realistically it will be the law of diminishing returns if I'm already using most of the generated energy.

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 2:35 pm
by nowty
richbee wrote: Fri Sep 23, 2022 2:28 pm I had begun to wonder if I should add another battery now, while the first one is new, so they are well matched - but then thought I should see how it all goes first, before splashing out another chunk of money.
I don't like to see the lovely PV energy 'wasted' going back to the grid once the battery is full, but realistically it will be the law of diminishing returns if I'm already using most of the generated energy.
You should have bought it from the outset to avoid the VAT.

Re: Sunsynk battery discharge rate

Posted: Fri Sep 23, 2022 3:10 pm
by richbee
nowty wrote: Fri Sep 23, 2022 2:35 pm
richbee wrote: Fri Sep 23, 2022 2:28 pm I had begun to wonder if I should add another battery now, while the first one is new, so they are well matched - but then thought I should see how it all goes first, before splashing out another chunk of money.
I don't like to see the lovely PV energy 'wasted' going back to the grid once the battery is full, but realistically it will be the law of diminishing returns if I'm already using most of the generated energy.
You should have bought it from the outset to avoid the VAT.
You are correct - I'm half wondering if the company might give me a discount now on a 2nd one, rather than money off my final bill for the main install - due to many many cock ups and delays - might still get away with it VAT free as I haven't paid the final invoice yet?