I've been trying to figure out the self consumption of my gen 2 9.5kwh battery and my back of the envelope calculations are showing 58w per hour. Has anybody else worked this out?
It dropped 4% (6% to 2%) in 6 hours 45 minutes.
186ah max (factory) x 53v = 9858watts.
9858 ÷ 100 = 98.58
98.58 x 4 ÷ 6.75 = 58.41w
Is my working out correct?
Marren2016 Sounds about right - I get 60W when the battery is paused. Of course whether that's accurate or not is entirely dependent on SoC, which is a different (well-trodden) discussion path....
Marren2016 Its not the BMS, its the links to the inverter etc.
Edit - I have a recollection the BMS has a static draw of 30mA, so about 1.5W idle.
This is mine over 5 days, Battery on, DCMCB off
About 6 hrs to 1% SoC, or 95Wh per 6 hrs, or 16Wh.
16% in 4 days using 1524Wh / 96hrs = 15.87 Wh
That is it still fully in comms with the inverter, but no ability to supply power.
If I turn the battery off then then SoC doesn't appear to drop meaningfully.
And yep, it is an ARM.,
ARM7
What does DCMCB mean?
I've just done an online search, it's an MCB for GE products.
Marren2016 that's an immense amount of power for a BMS to be sat there idle doing nothing
what is happening is that the BMS is sitting there with the power bus still powered up, even when its doing nothing, its sitting there ready to respond to house load. You can reduce the load by setting the battery discharge rate to zero and setting pause charge and discharge on the battery, but most of the time you want the inverter and battery to be able to respond to house load quite quickly. It does this by keeping the power bus active all the time
Older gen 1 inverters and older firmware didn’t do this and there was a much more noticeable lag in them responding to house load changing, both to start and stop discharging
geoffreycoan thank you for this information.
So can we disable the bus and revert to the slower response time?
Marren2016 unfortunately not, the mode of operation is intrinsic to the inverter firmware. The closest you can get is to reduce the battery discharge rate and pause the battery