Controller going into and not exiting from under-voltage mode.

[Roop]

I have this kit: https://uk.eco-worthy.com/products/...el-trickle-charger-kit?variant=40700172304533
It is connected to this battery: https://batterygroup.co.uk/batterie...-agm-deep-cycle-vrla-screw-connection-m5#gref

The battery is set up as per 'setting 1' for lead acid. The attached manual is for the same device rebranded. The supplies manual is ostensibly the same.

When the battery drops to 11.3v the controller goes into undercharge mode. The unit does not 'come out' from under-voltage mode (ie when the sun comes out or the load is removed) and I have to manually shut it down and power it up again.

The manual doesn't reflect this situation. Also, the charge controller does not charge beyond 12.1v.
Voltages read by a shuntometer.
I appreciate this is a poverty level/noob kit but I would expect the controller to continue to attempt to charge the battery. Am I mistaken in this assumption.

I was also advised by the vendor to disconnect the battery from the controller when using a (inverter) load.
Anyone any thoughts?

 

[scrubjaysnest]

1. Not enough panel. It is for maintaining battery at or near full charge.
2. Charge curve for AGM are different then flooded batteries.
3. At 11.3 volts the battery is dead, anything below 12.2 to 12.4 is below what you want. AGM's typically like 14.8 volts to charge.

 

[mikefitz]

Anyone any thoughts?

Your system,
25 watt panel, I max 1.1 amp, PWMsolar controler, AGM 15Ah battery, inverter 600 watt, typical load, bike battery.

This is a very small system, charge current maximum is just over 1 amp and typically will be less. Even on a good day maximum solar yield will be less than 5 amp hours. Thus with no load on the battery , 3 to 4 days to charge from empty.

Load is ebike battery, (say 400 watt 36v) with a 2 amp 36 volt charger, say 70 watts of power. The inverter will not be efficient, as will the charger, so the battery and solar will need to deliver at least 80 watts.
Assume the battery is fully charged, it holds 15 x 12 watts of power, 180 watts, so will only run the e bike charger for just over 2 hours.
Will the solar help, 5 Ah x 12v = 60 watts per day. Not really.

Thus your system is not powerfull enough. It's adequate to power a few 12v led lights that's all.

What is needed,

More solar, if the intention is to charge a 400 watt e bike battery in one day , then the solar has to deliver that, thus at least a 100 watt panel, 200 watts would be better. Add a quality solar MPPT controller and increase the battery capacity to 100Ah

The under voltage issue is due to too low a battery voltage with not enough power to operate the system

 

[Roop]

I appreciate this is a poverty level/noob kit but I would expect the controller to continue to attempt to charge the battery. Am I mistaken in this assumption.

 

[scrubjaysnest]

It will take days to do so without any draw from the battery.

 

[Roop]

It will take days to do so without any draw from the battery.

Well, as we managed to get about 4 hours uninterrupted sunshine last week it seems to have become a bit clearer. While the controller does seem to be a 'bit off' from it's noted params is does roughly what it's supposed to when there's enough sunlight.