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Incorrect SOC reading on Cerbo

Am having a battery SOC issue with the Cerbo GX on my new canal boat. Boat company saying they are going to look at it. But would like to try and work it out as well. Starting at 100% (Multiplus showing Float) SOC falls steadily 1% at a time at a rate one would expect with what electrical items are being used. I have seen it go as low as 73%. When we moor up and switch off engine, SOC shoots up to 100% within minutes with just 1800W solar panels. Same happens when generator (FP 48v/15.6kw inverter) is turned on. We know this is not a correct reading. We have lost power twice when SOC showed over 90%. We know the battery bank has emptied because it has slowly dwindeld over 20-30 minutes, not sudden loss, and the voltage which should be >48V has gone as low as 41v. questions: 1. how can this reading be corrected 2. is there another way knowing amount of Ah available in batteries 3. When the generator is on why do the Bulk, Float and Absorption lights not illuminate on MultiPlus Inverter/Charger?

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Your info suggests that your generator is a Fischer Panda 48V DC generator, therefore I would expect that this charges the batteries directly unless your info means you have a separate inverter running off the generator which then feeds the Multiplus. As stated in answer below, more info required.

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pwfarnell avatar image
pwfarnell answered ·

Do you have a BMV battery monitor or SmartShunt to measure the charging which is linked to the Cerbo. More detail of your system is required to really help along with information on how it is working.

Assuming you have a BMV or SmartShunt, what settings do you have for synchronising the SOC to 100%, the voltage and tail current, these may be causing the SOC to jump to 100% prematurely. What batteries do you have and I assume that the engine alternator(s) also charge the batteries. What was the battery voltage and charge current just prior to switching off the engine, and what battery voltage and charge current is there after you switch off and the solar continues with charging. When the generator is running, what battery voltage and charge current do you see.

This info may help to understand what you have and provide some clues.

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