question

Todd Landfried avatar image
Todd Landfried asked

Are these reasonable readings for a Multiplus SOC shutdown?

I went out of town for several days and after three unplanned cloudy days, the system shut down as expected. What wasn’t expected was the readings when I got home and turned on the generator to charge the batteries. The first image below shows what the status was when I first turned it on. As you can see, the SOC is 41% after about 15 minutes of turning the generator on.

I was wondering why it was floating if the batteries were at 41%. After 90 minutes of no change, I started looking into why the Multiplus was floating instead of bulk charging. I found a couple of messages in the Community that suggested switching it to “Charge only” as a way to reset the Multiplus. So I did and it switched to absorption mode (at 9:11pm).

Immediately after doing that, the next reading I got was 85% SOC. Literally five minutes later, I got the following: 100% charge and back to Float at 9:59pm, for a total elapsed time of 48 minutes.

So my questions are:

  1. Is it to be expected that a system that was shutdown due to SOC settings should go from 41% to 100% in 48 minutes?
  2. Was it some kind of hiccup in the system that I needed to change it to Charger Only for it to go off Float to Bulk and then Absorption charge?
  3. If this is abnormal, what do I need to do to get a better understand and control of this behavior?
  4. Are there settings I need to change?

The battery bank is eight 6v 385ah batteries in series/parallel at 24v.

Thanks

Todd

Multiplus-IIbattery chargingGeneratorSOCfloat
img-0261.png (384.0 KiB)
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1 Answer
JohnC avatar image
JohnC answered ·

Please firstly explain where your 7.07V battery V is coming from. How can that be?


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Todd Landfried avatar image Todd Landfried commented ·

Don‘t know. The smartdongle is connected exactly as instructed and thats the reading it’s providing.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ Todd Landfried commented ·

You should use a multimeter to messure the voltage at the battery connections at the Multi.

Or do you have connected the VE.Bus smart dongle to + and - of one of your 6V batteries?

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Todd Landfried avatar image Todd Landfried Matthias Lange - DE ♦ commented ·

The latter, because that’s what the instructions I saw said to do. Is that wrong?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ Todd Landfried commented ·

Yes, that's wrong.
You have to connect the dongle to the same points where the Multi is connected.

I'm suprised that the dongle is working with such a small voltage.

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Todd Landfried avatar image Todd Landfried Matthias Lange - DE ♦ commented ·

To be clear, do you mean inside the Multi or on the batteries? How does that square with their diagram?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ Todd Landfried commented ·

It should be like this:

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Todd Landfried avatar image Todd Landfried Matthias Lange - DE ♦ commented ·

I just took this screen shot of the full app. The voltage looks better than the dongle.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ Todd Landfried commented ·

For a 24V system 30V are to much, you should now check your charger settings and the datasheet of your batteries.

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Todd Landfried avatar image Todd Landfried Matthias Lange - DE ♦ commented ·

The manufacturer sent me the settings...

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kai avatar image kai ♦ Todd Landfried commented ·

30v sounds in the right ball park? 37F ~= 3C which means the voltage should be bumped up re: tempco

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JohnC avatar image JohnC ♦ Todd Landfried commented ·

Yeh, perhaps try to sort this first, before relying on downstream soc readings which may/may not derive from it in some way..

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