How to measure state of charge with lifepo4?

[Gueyog8a7]

I agree. However that is about all that is needed for many people. If every percent is critical I would call poor design. For example I want a minimum two day battery to have time to intervene. I plan to be sleeping at 3am where nothing is critical if there is enough battery to begin with.

Indeed. I am stuck on 13.0 now so seems I am about on empty with no way to refill now except the tiny trickle from solar per day. So looks like some cold mornings ahead for me for a while or back to mummy's electric heater.

Ballpark seems just fine as @Warpspeed says the fuel gauge on the car is fine for ball park. No need for minute detail.

As for load vs unloaded I think my system is so simple that this isn't an issue. Correct me if I'm wrong? I only have a couple of dc loads which I turn on and off manually except the little lights that power the mppt and mt50 which should be constant.

All I am running are a fan and diesel stove/heater. I have also put in a couple of usb ports but again I will know if I plugged something or not. None of this fancy automated system on off stuff.

 

[time2roll]

Indeed. I am stuck on 13.0 now so seems I am about on empty with no way to refill now except the tiny trickle from solar per day. So looks like some cold mornings ahead for me for a while or back to mummy's electric heater.

Yes the priority would seem to me to increase solar long before adding a monitor. May need to limit the heat run time.

 

[Gueyog8a7]

Simple voltmeter does work at the critical points. ebay has them with 2 or even 3 decimal accuracy.

Easy to see if battery is down at 12.9 the solar is not keeping up and a manual charge is needed.
Likewise if the voltage stays at 13.2+ battery is good all day long.

With a 2 to 3+ day battery this works fine. With a 12 hour battery some additional monitoring is needed. Maybe even an alarm.

Just need to get used to the loaded vs resting values to interpret correctly.

I have not been in the van much while I am house sitting and have been leaving the solar to charge. I am up from the high 12s back to 13.3 so looking good!

On the other hand the van has gotten wet again on the roof I presume from not running the heater .

 

[time2roll]

Not allowed to plug in? I assume there is an on board charger to power up when available.

 

[Gueyog8a7]

Not allowed to plug in? I assume there is an on board charger to power up when available.

What do you mean on board charger? I didn't buy an rv I made it myself so there is nothing on board I didn't install myself and I certainly have not installed that.

I spoke too soon about 13.3. I see it was only in charge state and 13.2 seems to be resting volts. I am getting a feel for how it works now though resting vs charging vs load volts.