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aaron-pe4a avatar image
aaron-pe4a asked

Err 67 - BMS Connection lost - Possible backup charging solution?

Hi Everyone,


I have installed a quite a few systems with LFP batteries and victron charge controllers (35,45, and 60) and I usually when I get the error 67 it is because a cable is loose. Since the installs are in very remote areas this is very annoying and is difficult to solve because it is a physical problem and the charge controller stops charging until the problem is fixed. This is obviously very bad because the battery will then discharge to 0%.


My question is: Is there a way that I can program the charge controller or tell my Cerbo GX that if the connection with the BMS is lost, that it automatically takes instructions from the charge controller to keep charging the battery?


Thanks in advance,


Aaron

Lithium BatteryBMS
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2 Answers
Paul B avatar image
Paul B answered ·

The issue here is what if there is a over voltage cell issue, if you do a override then you may cause a battery issue, yes I agree if its a lost bms this maybe unlikely, but you can still cause a high cell voltage once they are full without bms control.

however bms units can shut down when a battery is overly flat. and that's the only time I have seen a 67 lost bms error without it being a cabling issue. but why are you loosing the bms connection in the first place.

There is a setting in the cerbo under dvcc that I think you can override the BMS control. have not used it myself so don't know how well it works.

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Alexandra avatar image Alexandra ♦ commented ·

If the cable/comms is the problem, best to solve that. Easier than solving a damaged battery anyway.

The switching off of bms control in DVCC works very well. But does not solve the actual problem.

And you should probably also put things in place to stop the discharge to 0% as well.

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aaron-pe4a avatar image
aaron-pe4a answered ·

I have set the low voltage disconnect at 50V which will not let the battery drain to 0% (50V is about 5-7%) but I still have the issue that if a cable does come loose then it will stay at around 50V and inverter will shut off and stay off. Of course we have done our best to ensure that the cables are installed correctly, aren't under strain, and are working before we leave. We have set DVCC to 56V (3.5V per cell) which allows room for some cells to be slightly unbalanced and being at a higher voltage than the rest. So there shouldn't be any problem with a high cell voltage alarm.


I am looking for a backup solution in case the cable comes loose. Or else it seems like there is a lot riding on the connection of those ve direct cables to the CerboGX which in my experience, don't feel like they are solidly connected all the time.


Thanks in advance,


Aaron

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Alexandra avatar image Alexandra ♦ commented ·
The ve direct is coming loose? Weird. Goong to say this as lots of mobile applications dont have the issue. And I have never had that happen. If it is secured or supported can't do so. A zip tie or hot glue gun spot will stop that.

The bms cable coming loose? Re terminate with a good rj45 plug. They have solid clip locators.

Good old fashioned tug test is the way to check on things.

The dvcc removed is the only workaround for dodgy connections. Still allows monitoring but no control from the battery and then no bms lost issues.

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