Lithium battery BMS app - simple mistake (if you don't know what your doing)

[Dolmen]

My lithium battery, B2B and battery master were installed about 10 months ago. I wanted fit and forget and therefore only occasionally look at the app if for some reason I want to see the state of battery charge. For some reason I decided to play with it (the app) just before putting it in for service and must have toggled off the discharge button on the solar overkill app. When the depot serviced the van they saw the 12v system wasn't working and a multimeter across the terminals read near zero, so they rang to tell me the battery was flat and I would need a specialist charger to bring it back to life. Knowing the battery was 100% charged I shot back to the garage and sure enough it was reading zero. What the garage didn't know, nor did I, was that when the FET module on the BMS cuts power it takes place within the battery case and so the terminals are near dead, obvious once you know, however, took much reading up on lithium batteries that night before I realised that the discharge must be off. Quick flick to the right on the app and everything burst into life, lesson learnt, should have made an attempt to have a basic understanding of the system when it was fitted. Also goes to show that motorhome service centres still have a lot to learn about lithium technology.

 

[CAB96]

So if discharge was turned off, the battery master would not have been working?

Regarding the service centre, is it reasonable to expect them to connect an app to the battery? Just wondering, this is the way things are going but would we all expect them to connect to the equipment every time.?

 

[Dolmen]

The battery master was working perfectly and relaying to the app that the battery was 100% full, however, the battery master had also been inadvertently told to turn the battery discharge off. This gave a zero reading at the posts and despite the app saying 100% charged they declared it flat and said go back to where you had it fitted, they clearly didn’t know that the two conditions can coexist in lithium, I’m guessing as lithium becomes more common this sort of problem solving will become second nature. Fortunately google knows everything and it was a simple clumsy fingers error on my part.

 

[funflair]

The battery master was working perfectly and relaying to the app that the battery was 100% full, however, the battery master had also been inadvertently told to turn the battery discharge off. This gave a zero reading at the posts and despite the app saying 100% charged they declared it flat and said go back to where you had it fitted, they clearly didn’t know that the two conditions can coexist in lithium, I’m guessing as lithium becomes more common this sort of problem solving will become second nature. Fortunately google knows everything and it was a simple clumsy fingers error on my part.

When you say "battery master" I am thinking of the VanBitz trickle charge thingy, are you referring to something else?

 

[Dolmen]

Yes, apologies, my terminology is all over the place. The battery has a Battery Management System and that is what I meant, as you rightly say, the battery master is something completely different. I do have a Votronic battery master which works perfectly, however, in my last post I meant battery management system (bms). Sorry for the confusion, you can see why I asked for fit and forget!

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[StillGoing]

As a general comment (which may not be applicable in this situation) I’m not sure motorhome service centres can ever be expected to support all the different LifePO4 BMSs that are available, only the ones they install. As a lot of BMSs are password protected, they probably can’t get into the settings anyway.