Low battery and shut off Multiplus 5000/48/70-100 around SoC limit in ESS

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rs0882 asked Jan 31, '19

Low battery and shut off Multiplus 5000/48/70-100 around SoC limit in ESS

Hi All,

I've been looking around for answers but can't find the specific answer to my problem. I have the Multiplus 500/48/70-100, Blue solar 150/70 connected to 4 x 183AH 12V Deka Gel batteries. The system is setup in ESS, optimised mode with battery life and a SoC of 70%. I've also set the 'limit inverter' function to a max of 3200W in the ESS setting which should be well within the power margin of the inverter. The batteries are connected with 50mm2 cables of 1.5m.

During the day there is no problem usually, but at the end of the day (close to the SoC) limit the inverter trips when using >3500W for some reason and tells me that the battery is low. First of all the inverter should not be doing anything above 3500W and should supplement battery power with grid power above this point. Secondly, the notification of the alarm tells me that the battery power is around 45V but after the system restarts again I get a reading of 49V, also in VRM.

I am wondering what the problem is. I also have a 156A DC breaker in between the battery banks which sometimes trips, meaning the inverter does draw far above 3200W which at 48V = 67A.

Hope you guys can help me out!

RS

ESS inverter current draw low battery warning

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Answer 1 · 2019-01-31T15:15:50Z

Peter Polz answered · Jan 31, 2019 at 03:15 PM

Did you use a seperate Batterymonitor like BMV which is doing peukert correction for batteriesystem SOC? If you just use internal SOC of Multiplus it will not work because it doesn't correkt it and your real SOC will be much lower as showed in ESS. Thats one reason you may run in undervoltage protection. For further information see https://en.wikipedia.org/wiki/Peukert%27s_law

Another problem could be that you put wrong capacity in Battmonitor

"Or" one of you batteries have problems.

"Or" you dont have fully charged your batteries before

... aso....

BTW such a small gel batterie for such an applikation is not recommended. That means your batterie will not last very long under such conditions

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Answer 2 · 2019-02-02T01:14:14Z

boekel answered · Feb 02, 2019 at 01:14 AM

These batteries are not up to the job. if they're still ok I'd replace them with something adequate, and use the gel batteries for another job.

Further more: measure!! measure at battery terminals, measure at inverter, etc. than you know what goes wrong (probably the batteries sagging, after restart they spring back up a bit)

About the inverter limit: measure...batteries will sag but shouldn't get to 150A, breaker itself might be the problem, or a situation where the inverter limit isn't respected.

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Answer 3 · 2019-02-16T06:44:16Z

Paul B answered · Feb 16, 2019 at 06:44 AM

When you setup the multiplus and set the assistance up did you set all the parameters correctly as there are voltage warning and shutdown voltages in there as well.

worth looking at if you have not solved it yet

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Answer 4 · 2019-03-05T07:18:11Z

dwmarine answered · Mar 05, 2019 at 07:18 AM

Have you used 2x50mm cables to connect the batteries or 2 pairs of 50mm cables (four in total).

As I read it, The manual specifies 2x70mm cables minimum for distances of 0 to 5 metres.

If voltage gets low, current draw will increase and may be the cause of the breaker tripping?

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