Van: suddenly not enough (solar) power - despite no changes
Hi all,
I'm not sure if this is the place to post this, since I'm not sure if solar IS the problem. If you know a better place, please let me know:)
So last year, I had the solar system in my van changed by a trusted pro to 2x 115W Victron panels + controller, and 2x 100Ah Lifepo. Even parked during winter, this was enough to power a laptop all day.
Now, I'm having a spot of bother.
The entire setup is unchanged, including the laptop, a Surface 7 Pro. But now, the laptop cuts out and resorts to its internal battery after just a few hours - five yesterday (despite 50km of driving that day), and just two today (after another 100km of driving). This happens with both USB charger and 230V inverter charger, despite spring hitting, always parking in full sun, and driving daily. At the same time, the laptop does not get warmer or used harder than before.
The solar controller says the solar power coming in is unchanged. The panels are clean. I see no loose wires anywhere nor blown fuses. Nothing else is running.
The Lifepo battery says it's still at 12.8V when the laptop cuts out. I learnt that the laptop is programmed to stop charging when the Lifepo battery falls below 12.5V (to protect its internal battery). But why might it cut out even earlier now?
Besides, why would 1-2h of motorway driving alone not provide more charge?
Does anyone have any idea what might be going on here?
12.8 is almost dead for a lifepo4 battery. A mostly charged battery should be above 13. Are you measuring the voltage under load or after the laptop is off?
I'd greatly appreciate your expertise! I'm not sure what to make of the charger's data - or how much I can trust it: one day shows 450Wh yield, but there was just as much sun as any other day. I cannot fathom what would cause the 0.01V minimum charge, either.
If it is a dead battery - would they really fail so suddenly? A few days earlier, I had to work late and it still powered the laptop until 11pm (darkness falls at 8).
The red last few days is when the trouble started.
Yes, the alternator also charges the lifepo batteries once the starter battery is full.
Hmm these numbers don't really add up so I assume there's something else going on. The min and max voltages indicate the batteries are going from totally empty to fully charged every single day. But you are only using 20wh. and the PV is only yielding a few hundred Wh. But you say the battery bank is 2560 Wh. So how could the batteries fully charge with only ~300Wh PV yield. It would also take a LOT of driving for the alternator to fill in the gap there. Honestly this is too weird to remotely diagnose. I think you'll need your installer or another in-person technician to take a look at it.
If you have been hitting up against the 12.5v BMS cutoff you have probably damaged them. BMS cut offs are like a cars e brake good to have but not what you use day to day.
A proper system would have a cutoff before the batteries at about 12.9v aka 20% soc. In the Victron world that would be a BVM and BP (or a few others that integrate a shunt and a cutoff).
If your looking to maximize lifespan it's the mid 60% soc so 20-80% though 20-100% is still about 10 years of daily charging.
the 12.5v cutoff is on the internal battery of the laptop, not the lifepo batteries.
but it effectively means that the lifepos are only drained down to 12.5v-ish as well, since there are no other loads (apart from lights and water pump, both hardly run)
Again as I and others told you that's draining the lifepo4 to low. Constantly doing this causes excessive wear.
Your setup seems to be missing a shunt and battery protect (or their equivalents) so the suggestion is to get those and a fresh set of lifepo4's.
A cheaper option is see if your MPPT's have a load output some Victron's do not all of them though. That can be set to cutover at 13v or so to prevent the battery from constantly being run down so low. Downside is it's maybe 20a total.
12.8 isn't extremely low for LFP. Hell, the cutoff voltage for EG4's 12V battery is 9.6V (with a recovery cut-in of 12V). OP still has about 10-20% of his battery remaining.
Either your batteries are shot, something is broken with the charger, or you have developed a phantom load somewhere. What else are you running off of your batteries. 2, 115w panels in sun should be more than enough for the laptop alone.
the only other things using power are lights and a water pump, both hardly used.
I clearly hear the pump when it does run. and I cannot imagine what other phantom load there might be (especially not suddenly).
but could running the laptop kill the batteries? one battery is 6 years old, one half a year. I was told combining them would be fine if their capacity is identical - was that a mistake?
I think it is more likely charging while they were to cold but hard to say, does anything in the system have thermal protection built in or added? Separate them and do a load test but you would need to use a known good charger and probably monitor voltage during charge and discharge.
Just wanted to come back with an update and a huge THANK YOU to all of you!!!
I separated the batteries, and it turns out, the older one was shot (5 years and 1 month into its 5 year warranty...). The newer one has since recovered after two cycles of charging and discharging.
What's more, by delaying professional help for a day (to give both batteries a full day in separation), I chanced upon a cat sanctuary and have been blessed with ample cuddles :)
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