Cab Battery High Voltage Issues! (1 Viewer)

[Orion]

Bit of a strange one that has occurred on two, maybe three separate occasions. A bit long winded but I’ll give as much info as possible for any sparky gurus who can offer advice. First the installation specs:

Aria Compact Fiat chassis 160 auto with standard cab battery arrangement. Nordelettronica NE350 charger/shunt with NE266 digital control/display panel. Also has the factory installed NE325 40amp DC-DC converter fitted. There’s 340w of solar up top connected via an NDS SCE 360 MPPT Suncontrol2 and the NDS display panel hooked up to it. 2x 100amp NDS hab batteries. No EHU connected at any time this has happened and no gas appliances in operation - supply isolated at cylinders. The engine had not been run prior to it happening on the first two occasions.

1) Sometime early March, parked on drive, very early morning so little to no chance of any solar input. Heard an internal alarm sounding and found the 2xAA battery CO alarm going off. Removed it from the van, and as it wasn’t dated although probably new at delivery in Dec 2022, replaced it with a 10 year battery life model ans possibly defective and thought nothing more of it.

2) Mid April, again earlyish in the morning, heard the CO alarm sounding and this time gave the display panels the once over after venting the van. Very little solar being generated and none going to the cab battery according to the display lights on the SCE 360 unit. Hab batteries at 13.4v and 100% but the cab battery showing 18v! Turned the ignition on along with the cab aircon/fan and interrogated the dash display which started out up at the top segment of 18v but started dropping immediately, so I turned off and went back to see if the NE266 mirrored it, which it did until it hit 14v and started climbing slowly again. Started the engine and this brought the reading(s) down to the expected 14 or so volts and stabilised there. Checked again over the next few days and it was showing 12.4v consistently and no further issues.

3) Fast forward to 4th July and stationary on a campsite in France after a 1 hour drive. Before leaving the van I checked the panel and the hab battery was at 100% 13.2v with the solar inputting and the cab battery at 91% 12.4v (after dropping the E&P levellers I guess?) and no solar going in. Went out for a few hours and the CO alarm was sounding on our return. Almost identical readings as 2) above but cab battery at 16.8v on the panel and roughly equivalent to that on the segmented dash display. Ran the engine and it all went back to normal.

Hasn’t occurred since and we have had the 3 hour drive home from Newhaven plus some decent solar input today - both batteries are receiving input from that source as I type this - cab 100% 13.9v and hab 100% 13.2v with both indicator lights on the SCE 360 illuminated.

What’s the verdict? Duff cell(s) in the cab battery causing gassing off? Or something else? The van is back at the dealers next week for some minor remedials before the warranty runs out, so I’m keen to present them with the fullest information possible.

 

[autorouter]

First thing to say is that if the battery terminal voltage is in any way higher than the battery resting voltage (11.9V to 12.8V depending on state of charge and battery type) then something is charging it. A battery can decrease its terminal voltage if a cell is faulty, but can't increase its terminal voltage itself. So if the voltage is over 16V then whatever is charging it must be faulty or incorrectly set.

I'd suspect the solar charge controller. It's probably quite capable of charging a 24V battery, so it certainly has the capability to output 18V. I would think it's a faulty component inside, causing the output to flip to the 24V option. But that's only a guess. Can you try a different controller for a bit, to see if you still get the problem?

 

[Orion]

Thanks, that makes sense but there was very minor to nil solar input in the first two instances and wouldn’t the hab batteries be exhibiting the same overcharge if the controller was flipping over to 24v occasionally?

I have a 230w Suncontroller that I can swap in if it reoccurs and that should handle the panels given our current weather!

 

[DBK]

Thanks, that makes sense but there was very minor to nil solar input in the first two instances and wouldn’t the hab batteries be exhibiting the same overcharge if the controller was flipping over to 24v occasionally?

I have a 230w Suncontroller that I can swap in if it reoccurs and that should handle the panels given our current weather!

Your solar controller has separate outputs for cab and hab batteries and as the charging voltage can be set to match the battery type these must be controlled separately, ie they aren't just wired in parallel.

My suggestion would be to simply disconnect the +ve wire going to the cab battery at the controller and see if the problem occurs again. If it doesn't then I think you can assume the controller is faulty. The lack of sun when it happened may not be significant as a faulty controller could just conceivably take power from the hab battery.

For safety, secure the loose wire with a zip tie somewhere out of the way with insulation tape on the end.

I've had two solar controllers fail with over-voltage. The problem in my case was I think they were overheating due to sharing a small space with a B2B so I've now fitted a fan to cool it.

 

[Orion]

Your solar controller has separate outputs for cab and hab batteries and as the charging voltage can be set to match the battery type these must be controlled separately, ie they aren't just wired in parallel.

My suggestion would be to simply disconnect the +ve wire going to the cab battery at the controller and see if the problem occurs again. If it doesn't then I think you can assume the controller is faulty. The lack of sun when it happened may not be significant as a faulty controller could just conceivably take power from the hab battery.

For safety, secure the loose wire with a zip tie somewhere out of the way with insulation tape on the end.

I've had two solar controllers fail with over-voltage. The problem in my case was I think they were overheating due to sharing a small space with a B2B so I've now fitted a fan to cool it.

Thanks, all good info and gratefully received. The Suncontroller does share the same compartment with the charger and the B2B and the boiler sits directly behind it, so overheating could possibly be a factor - although the controller does have its own onboard fan and I’ve never noticed it running.

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[Awboxster]

Hi, I have the same controller as yourself and had a very similar issue with regards to the Veh battery voltage. I had seen 16-17v on occasions. The thing I did to address the issue was to disconnect the habitation battery and solar panel and wait 30 mins or so. I then reconnected the Battery first and then the solar panel and that sorted the issue. I believe at some stage when I worked on the habitation battery I disconnected it (but not the solar panel) and for that reason the Sun controller reverted to 24v. This happened a couple of months ago and it has been ok since....hope that helps.

 

[ontheroadagain]

I'd suspect the solar charge controller

Our Adria Compact also had an NDS controller fitted. It was very unstable, sometimes overcharging and on other occasions it stopped charging and had to be reset by disconnecting it for five minutes. It was replaced by a NDS Suncontrol2 which worked for about 6 months then it too started playing up. I replaced it with a Votronic controller about 14 months ago and have had no problems since.