Solar Charger no output in full sun

Wooly

WoolyAdventure.com
Joined
Oct 2, 2021
Messages
18
Following on from my dead BMS (Post here) I have bypassed the BMS temporarily to enable me to continue my trip. I've adjusted the charger inputs to 13.8v and am manually monitoring the cell voltages regularly.

However now I've got the battery working again I've noticed the solar output from my Kisae Abso DMT1250 is not sending any charge to the battery.

My system is:
310ah Lifepo4 4s
Daly 300a BMS
Abso DMT1250
415w bifacial panel - https://www.bimblesolar.com/solar/large-panels/LG-415W-bifacial-solar-J5?sort=p.price&order=ASC
3000w puresine inverter
Installed in a 2016 Renault Master motorhome

I installed the system several months ago without the solar panel and its been working fine charging from the vehicle battery. Last month I installed the solar and it worked great for weeks.

I'm now part way through a road trip in Europe and the solar charging has stopped working. The 1250 is still charging the house battery from the vehicle battery fine when the engine is running but in full sun with no shading the 1250 shows 48v output from the panel on ch2 but 0.0a charge output to the battery.

All connections seem secure.
There is no visible damage to the panel.
The battery is at 60% state of charge, 13.2v.

What am I missing here?
Starting to wonder if the Mppt charger in the 1250 did something odd and fried itself and the BMS?
 

mikefitz

Photon Sorcerer
Joined
May 28, 2020
Messages
1,302
Starting to wonder if the Mppt charger in the 1250 did something odd and fried itself and the BMS?
I was thinking this after reading your other post. On the other hand the controller fault may have occurred when the controller lost battery volts.
The Kisae controller is not designed for high voltage panels.
The panel OC voltage is at the limit of the controller, ( 50 volts) a cold sunny day could take the voltage over the limit and damage the controller. This is what I suspect happened although a good design would normally have headroom
I always recommend separate chargers for the marine installations I carry out for redundancy in case of failure. At least the Kasie is still providing engine charging.

Mike
 

Wooly

WoolyAdventure.com
Joined
Oct 2, 2021
Messages
18
I was thinking this after reading your other post. On the other hand the controller fault may have occurred when the controller lost battery volts.
The Kisae controller is not designed for high voltage panels.
The panel OC voltage is at the limit of the controller, ( 50 volts) a cold sunny day could take the voltage over the limit and damage the controller. This is what I suspect happened although a good design would normally have headroom
I always recommend separate chargers for the marine installations I carry out for redundancy in case of failure. At least the Kasie is still providing engine charging.

Mike
I did wonder about that but the panel is within spec (just) for the charger with 49.5Voc and the charger has an overvolt protection and error code which says to me there is some head room built in.

What also doesn't add up is the weather was overcast and raining on the day the issue occurred. We were driving most of the day and only noticed the issue when we stopped for the evening.

I agree with the redundancy strategy but space is limited so the Kisae seemed the best option. I have some redundancy with a separate mains charger, if all goes to pot we will hook up at a campsite.

I've emailed Kisae but still waiting to hear back.
 

Attachments

  • Screenshot_20211008-142401_Google PDF Viewer.jpg
    Screenshot_20211008-142401_Google PDF Viewer.jpg
    248.6 KB · Views: 2

TomC4306

Solar Addict
Joined
Mar 2, 2021
Messages
311
You overvolted the charge controller. Those numbers on the solar panel label are at a given temperature. As things cool off and move below THAT temp, voltage goes up. ½ volt is NOT headroom. In Maryland, 20% is headroom.
 

Wooly

WoolyAdventure.com
Joined
Oct 2, 2021
Messages
18
You overvolted the charge controller. Those numbers on the solar panel label are at a given temperature. As things cool off and move below THAT temp, voltage goes up. ½ volt is NOT headroom. In Maryland, 20% is headroom.
Everyday is a school day...... this one just became an expensive lesson. 🤦

Id heard about PV thermal efficiency but didn't relate that to Voc. I stupidly assumed that max meant max.

I also assumed that the charger would have been built with some headroom as it has an error code for overvolt (which I havent seen). Doing the maths it was about 8*C so that means it would have been around 54Voc....

ASSume = me right now 😔

So the next question is the solution?
Sounds like I'll need a new solar charger anyway. I'm limited for space which is why I went for the Kisae so ideally I'd replace it with the same or similar in size and output (Inc B2B).

That leaves the panel. Id rather not have to buy another panel too. Is there a way to limit the Voc Max with a resistor or voltage regulator?
 
Last edited:
Top