question

laurent-2626 avatar image
laurent-2626 asked

ESS (extremely) slow charge

Hello community,

I have a Multiplus-II 48/5000/70-48 with AGM batteries

ESS is activated

when batteries are below min SoC, I can see the ESS #5 (slow charge in progress)

My issue is the **very** slow charge rate, 0.1 A max, usually lower...

Any ideas on where I could investigate ?

thanks

laurent

Multiplus-IIESSAGM Battery
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

What would you like the system to do?

The slow charging is only trying to maintain battery voltage, not recharge the battery.

If you want to recharge the battery, you could use the scheduled charge feature, or wait until the battery is recharged by the solar panels.

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laurent-2626 avatar image laurent-2626 commented ·

Hello Guy,

thanks for reply, it helps, however my concern is still there: batteries are about 60%-63% and cannot charge above

I tried several ESS options, nothing works:

- scheduled charging

- optimized with battery life (with 80% or even 100% min SoC)

- optimized w/o battery life

- keep batteries loaded

laurent

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laurent-2626 avatar image laurent-2626 laurent-2626 commented ·

here is my panel, currently on "schedule charge"...

2022-09-07-15-07-27.jpg

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nickdb avatar image
nickdb answered ·

What are your charger and ESS settings for these batteries?

Do they align with the manufacturers specs?

Do you have a shunt?
You don't have panels so presumably some form of load-shifting/shaving setup?


If keep batteries charged isn't charging them, most likely cause is incorrect inverter config. No shunt and the SOC will also be unreliable.

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laurent-2626 avatar image laurent-2626 commented ·

1) panels: I have a grid tie inverter (Fronius) so, yes, there are panels on the AC loads side.

2) ESS settings are the ones I mentioned with different options also mentioned, what do you require as information ?

3) concerning the shunt, I don't have the smart Shunt neither the BMS, I can understand this will reduce the precision of the SOC, st that should be improved as the behaviour gives me the impression that the measured load of 60% is actually higher based on voltage & currents. Maybe I need to have better understanding on how SOC is estimated without shunt / BMS. Any experience on "how unreliable SOC is without shunt ?"

4) concening the charger settings (Multiplus) and respect of manufacturer spec, what I can say is that this was installed by a professional installer (which I am not, being the end user) and worked in the past. I can fetch information if you ask me.

thanks

laurent

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