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hardwarepimp asked

Multiplus Charging Current Drop Glitch

Hi everyone,

I have a Multiplus 800/48 with a 102AH lead acid battery which I use to provide power to a chest freezer overnight. The charger of the Multi is timed to come back on at 9am. I use approx 15% of the battery and the absorption current is around 4 amps, slowly decreasing as the battery charges to 100%. The current is 4 amps on the first recharge only after I first turn on the Multiplus after connecting it. The second day charging, the charge current is only ~1.1 amp and takes an insane amount of time to get to 100%. If I turn the Multiplus off and then on again, it goes back to 4 amps charging current, then the following day, it’s back at ~1.1 amps.


Does anyone know what is going on? I have the max charge current set to 9 amps (bulk charging). But this glitch has got me stumped.


All thoughts welcomed!

Thanks,

James


battery charging
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knownot avatar image knownot commented ·
I'm not sure its a glitch, do the parameters under the charger tab match those of ur battery?
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7 Answers
hardwarepimp avatar image
hardwarepimp answered ·

Hi Kownot,

Thanks for the reply. Well, I used the USB MKIII cable and Victron Connect with my laptop and adjusted the charge parameters to match the correct battery voltages for absorption and float and increased the charge current from 6A to the rated 9A (as it had been set low). All seemed OK, but maybe the previous owner changed a setting or two. I will check again today to see if everything is as it is supposed to be.

It definitely seems like a setting issue as opposed to a hardware problem, as when rebooted, it goes back to normal for 1 charge cycle before dropping again.

I’ll take a look and repost here when I have taken a look under the hood.

Thanks,

James

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kevgermany answered ·

To answer this we need to know the charger state - bulk/absorption/float when you're getting these readings. Also the charge settings and the other absorption rated settings.

Note that apart from being able to set the max charge current, the multi does not control current. The battery does. The charger applies a voltage, the rest is down to the battery and any resistance between it and the battery.

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hardwarepimp avatar image
hardwarepimp answered ·

Hi there Kevgermany,

Thanks for the reply. I have written down the numbers. They are as follows:

State of charge: 85.4% (BMV700)

AH used: 13.6

Charging from mains grid power @ 52.72V (13.18V per battery)

The Multi did the same thing this morning when the timed charging switched on at 9am. The inverter switched back to charging and the charging amps very very slowly ramped up to 1.21 amps. I tried switching back to inverter and then back to grid mains charging and it did the same thing again with this “go-slow’ issue.

I then powered the multi OFF and then back ON again and the Multi charges perfectly, with the current ramping up to 9 amps within about 10 seconds, and then slowly decreases when moving from Bulk charging into Absorption and then into float.

The problem will come tomorrow when it will do the same thing again. It’s almost as if it”s going straight into Float charge.

I’ll get the voltage numbers for what I programmed for Absorption and Float charge, but the Multi did this even when on default settings.

Thanks for reading,

James

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hardwarepimp avatar image
hardwarepimp answered ·

One other thing, probably the most important thing to note; The Multi is going straight into Float charge after grid power turns on, as the Yellow Charging light is FLASHING.

Where as when the Multi is powered down, then back up again, the Yellow Charging light is Constantly ON and going into Bulk Charging.

Thanks,

James

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hardwarepimp avatar image
hardwarepimp answered ·

From what’s i have read here:

https://diysolarforum.com/threads/anything-wrong-with-these-multiplus-settings.16643/

It appears I might have an Assistant or 2 still active from the previous owner of the Multi, so I will hook up my laptop and take a look.

Thanks,

James

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hardwarepimp avatar image
hardwarepimp answered ·

Well I connected my laptop and ran VE Configure and there were no Assistants active. I restored ALL default settings and then put in my specific voltages and preferred settings like output voltages etc (UK) and i will hope for the best.

BTW should have of the terminal connections underneath have any jumper cables as standard? Like with the remote terminals on the old Victron inverters?

I will check again the day after tomorrow to see if the issue has resolved itself.

James

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hardwarepimp avatar image
hardwarepimp answered ·

SUCCESS!

I found the solution to this issue. I turned off Storage Mode and now it works perfectly and goes into Bulk charging as soon as grid power comes on at 9am.

The issue was related to the need for the battery to have dropped 1.3V below the Float voltage i order to start a new Bulk charge cycle, but only if Storage mode is active. As soon as I unticked the Storage mode box in VE Configure, voila!

Job’s a good’un! Get ‘er done!

Thanks to those who chimed in.

James

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