Renogy battery health

[middle-englander]

After having recently purchased an Ablemail to keep the leisure battery topped up out of season, I think it's uncovered an issue with my Renogy Lithium battery (model RBT100LFP12-BT-RE-UK) as it seems to be draining very quickly and incorrectly reporting the remaining capacity. I understand the latter can just be the BMS being out of sync.

Here are the readings from both batteries taken at random days over the last 1.5 weeks (van not started):

Sunday 19/10 (after being charged on the mains)
Leisure 99.1% - 13.2V
Starter 96% - 12.4V

Thursday 23/10
Leisure 94.7% - 13V
Starter 34% - 12.2V

Sunday 26/10
Leisure 94% - 12.8V
Starter 18% - 12.1V

Thursday 30/10
Leisure 90% - 11.6V
Starter 3% - 12V

Does this seem to be dropping way too quickly?
I can't say I've ever monitored it so closely before but I did wonder if there was an issue earlier in the year when the Renogy gave out on us after a two day trip off grid, something we've done several times before without issue.

In terms of other sources pulling power, I have a few usb plugs which I understand use a very small amount even when not in use, a tracker, and a wolfbox dashcam.

I've included a graph of the starter battery for reference, which appears to show the Ablemail doing what is expected of it, given what is has to work with. There's also screenshots from the Renogy app showing the battery and DC50 this morning (the former after having just being plugged into the mains).

 

[Sim60]

What’s the 10.7 A load on your leisure battery? That probably has something to do with it.

( also, you seem to be trying to use the ablemail the opposite way round to most people who use it to keep the starter battery topped up from the leisure battery)

Simon

 

[CAB]

What’s the 10.7 A load on your leisure battery? That probably has something to do with it.

( also, you seem to be trying to use the ablemail the opposite way round to most people who use it to keep the starter battery topped up from the leisure battery)

Simon

I assume the 10.7A is the mains charger that was plugged in?

 

[CAB]

You have several days with a declining Starter Battery voltage, to me that says the Ablemail is not charging.

Whether it's the Ablemail or the Renogy I couldn't say.

 

[CAB]

The flat parts of the trace with the wiggles are clearly where the Ablemail was maintaining the Starter.

Although I might be wrong. I get a very wiggly trace when the Ablemail kicks off the Victron B2B and starts a charging loop. Maybe that's it?

Do you have a single day trace with wiggles (the Ablemail working)?

 

[middle-englander]

You're quite right about the wiggles showing when the Ablemail is doing it's thing - once to hold the starter at 12.3V, then stopped when the leisure battery dropped below 13V, and then started again when the starter reached 12.1V, until such time when presumably the leisure battery was too low to charge anything.

If I understand the Ablemail manual correctly this is expected behaviour, which is why I suspect the leisure battery is at fault.

 

[CAB]

The van has been sat on the driveway for 4 weeks. No solar, just the Ablemail feeding from the Fogstar.

It would be down to low 12s by now without dash solar (summer) or the CTEK through the EHU the rest of the year, so very pleased with the setup.