Battery Heat loss and excess cycling (not Wonder spacific)

4watts

Hi
being new battery storage I am wondering about the relative value of importing/charging at say a 13p HH slot and using at say an 18p HH slot.
What do people think is the breakeven/loss factor and hence is it worth buying and storing at 13p and using in an 18p slot rather than just holding it in the battery and using direct grid power?
I guess there is also a cost of cycling the battery more than needed, and hence if a £2k battery will last 10 years at heavy use / high cycle rate will it last 20 years at half the cycle rate?

I am not looking for a technical response but trying to get a feel of the differential % I need to allow to consider it worthwhile charging and discharging excessively say between HH cheap slots.
I am guessing it is around a 10 % loss but I may be way out.

Thank you in anticipation of some constructive feedback

kerregan

4watts I’ve been wondering too and in the absence of any real guidance I am assuming 85% end to end efficiency. This is without taking any account of additional wear and tear on the battery.

perfrank

4watts I have spent some time in search of those data (for battery lifetime). Without any luck. Maybe partly because the issue is very complex.

A hint: Growatt bloks for inverter discharging below 10 %. You can have them change it, but then you are without any warranty. That is properly for a reason. So dont go too low in charge.

Others state, that time with full charge (100%) is not healthy either. But no data or numbers.

My own logic ( as an engineer with some knowledge of chemistry ) says, that the total amount of charge in or out will contribute to degrading.

Time are important. Batteries get older too, and time itself will degrade your battery.

But again, nothing is quantified. My own conclusion: Have the extremes in mind when setting up inverter, Wonderwatt or not, enjoy the benefits of having a battery and hope for the best.😏

I find the estimate of an efficiency in the order of 85-90% reasonable.

Gazzagreen

I believe you can use the full range of a GivEnergy battery (8+9+allinone), 4% up to 100% for instance, without any worry of damaging the battery. Normal degrading is unavoidable though, but I think you'll get many many years out of one of these givenergy batteries. It's all in the chemistry! Givenergy batteries comprising of "Lithium Iron Phosphate" is one of the best, if not currently the best chemistry you can get for home batteries.

Quote from GivEnergy

The newer batteries in our range now allow unlimited cycles for 12 years and still be covered, at 100% depth of discharge. In terms of impact, this improved life span has not only made battery storage more economically viable, but has also reduced environmental footprints. (By minimising the need for replacements.)

source of quote:
https://givenergy.co.uk/the-evolution-of-energy-storage-batteries-from-emergent-technology-to-a-mature-market/

4watts

I have just noticed the flow diagram doese not add up and indicating a loss when converting battery to home.
Interesting that the GE app has no loss and the numbers add up perfectly. I suspect this is intentional / adjusted to avoid questions over energy loss.
I trust your data over GE
Maybe the WW display will answer my post question regarding % losses in conversion from battery to home & grid to battery.
Earlier I was seeing .25 kw from battery supplying .20kw to home. If that's a true indication of the loss its more significant than I thought. Given there will be loss both ways it compounds the loss.
_

4watts

Hot tub has cut in and WW showing
Discharging: 3.51 kW
Load: 3.22 kW

4watts

System Energy Flow
Generating: 0.02 kW
Discharging: 3.03 kW
Load: 2.96 kW
Importing: 0.16 kW
[Last updated: 2024-03-27 06:18]
I am presuming generation and import both go to service load without any loss. Would that be correct.

admin

4watts Yeah, I presume any discharging is after loss. Not sure though, we're just displaying values for the various flows that are available in the API. 😄

4watts

admin
That is fine and great, as I say I think GE adjust the data to make 100% in their display - I have no issue with what you are displaying