Multiplus-II 12 3000 120-50 2x120v Random Rebooting

Grabcon

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I am having issues with my Multiplus-II 12 3000 120-50 2x120v randomly rebooting.

The system 50amp shore power, Onan marquis gold 5500 generator, no solar, 4 - 100 ah lithium batteries.

The typically scenario for the random reboot, regardless of power source, 50amp, 30amp or generator. After the batteries have reached something less than 100 SOC and the source power is turned on the Multiplus-II starts the standard bulk charge it may or may not reboot when switching to absorption phase.

As an example: yesterday, batteries were at 92% SOC after a day of travel. I plugged in to 50amp and bulk charging was taking place. At some point before 100% SOC the unit rebooted several times than went to absorption. Another reboot happened during the absorption, once float was hit no more reboots. In yesterdays case there was no load other than the charger.

First is this normal? If not, how do I start to diagnose this issue?
 

sunshine_eggo

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What device is reporting % SoC?

What you describe can be caused by a BMS cut-off due to cell imbalance.

Recommend you reduce bulk/absorption to 13.8V and float to 13.6V.

If the problem goes away, increase voltage by 0.1V increments until the problem returns. Drop back 0.1V and operate for a week. After a week, increase 0.1V, etc.

EDIT: yes, your charge time will suffer substantially with your bulk/absorption at 13.8V, but this is just for troubleshooting purposes.
 
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HRTKD

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What is the charge amp setting on the Multiplus? Mine defaulted to 90 amps (DC) and I've had no problem maintaining that with my Onan 5500 generator providing power. I'm using a Multiplus 12/3000, not the Multiplus II.
 

Grabcon

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What device is reporting % SoC? Victron 500 AMP bluetooth Shunt. I will start tomorrow with the test of your recommended setting. I just changed to them.


What is the charge amp setting on the Multiplus? 120 AMPS
Once the bulk and absorption cycles are complete the unit does not reboot regardless of power source. I spent 14 days boon docking with only the generator and was impressed how well it worked. There were times where the SOC was in the low 60% and sometime it would go thru a complete charge cycle without issue. Other times as it started to near the 98% SOC on bulk it would reboot, maybe once maybe more.

Again this is random. Like yesterday there was no load other than the charger but I have loaded it up as well to see if that make it reboot. Again sometimes yes and sometimes no. Unfortunately I have no way of knowing what happened if I am not at the rig.
 

Grabcon

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Today I have the opportunity to load up the batteries and drain them down. First is to test the adjustments made the other day and see what if anything changes. One step at a time. If I change too many things at once I won't know what made the change.
 

Grabcon

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The first two tests are positive. Meaning that the Multiplus-II did not shut down during the Bulk, Absorption and float cycles based on the settings recommended above. Base on Sunshines suggestion I will start to increase and see what happens.

One more question. How hot should the Multiplus-II get during the bilk and absorption phases? My laser thermometer says 125 F. That seems really hot. The space where the unit is mounted is large, 10'x8'x8' with ventilation. Ambient 90 F.
 
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HRTKD

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The first two tests are positive. Meaning that the Multiplus-II did not shut down during the Bulk, Absorption and flat cycles based on the settings recommended above. Base on Sunshines suggestion I will start to increase and see what happens.

One more question. How hot should the Multiplus-II get during the bilk and absorption phases? My laser thermometer says 125 F. That seems really hot. The space where the unit is mounted is large, 10'x8'x8' with ventilation. Ambient 90 F.

Victron's data sheet says that the operating temperature range is -40 to 150°F. It will derate as it gets higher in the range.
 

Grabcon

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Still going thru voltage increases waiting to find the failure point. Up to 14.0 Absorption, Float still 13.6. No issues at these settings.
 

HRTKD

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This has been described on the community website. The value is not user-accessible.

Bummer.
Waaah1.gif
 

Grabcon

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This process takes a while to get thru. I just finished another week of a voltage increase to 14.1 on absorption. Still no rebooting issues. It will be at least another two weeks before I report back with new results. I need to make a trip without the RV so no changes until I get back.

Just as a not the Multiplus did hit 129 degrees while in bulk phase yesterday. Ambient was 92 degrees.
 
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