NDS solar back feed charging into starter battery

[Motorhomer14]

Hi all.
I have been talking to a few people on a Facebook group about the NDS SC300M solar controller. This controller is a MPPT device which charges the leisure and starter battery from solar panels

They have found when the sun goes down there is a current draw from the leisure battery with all the van switch off. If they pull the fuse from the NDS control unit the current draw goes to zero. So seems the leisure battery is reverse charging back into the starter battery (balancing both batteries).

If they operate the central locking on the van there is a small current draw from the leisure battery 2A for a few seconds which drops back of to zero.

So my question is are these solar controllers designed to balance the starter battery with leisure battery when solar has gone off(no sun).

If so when starting the engine will there not be current draw from the leisure battery.

Will it actually be feeding from the starter battery to van system and potentially draining the starter battery

 

[Wombles]

Bump - can anyone advise?

 

[Jimbohorlicks]

I think they may need to download the manual for this controller and check that first.

NDS SUN CONTROL MPPT USER MANUAL Pdf Download

View and Download NDS SUN CONTROL MPPT user manual online. SUN CONTROL MPPT inverter pdf manual download. Also for: Sc300m.

www.manualslib.com

 

[Lenny HB]

It is not normal and I wouldn't expect it to happen, controllers normally have diodes inline with the input to stop back feed to the panels. I've not heard of a controller that feeds the starter battery from the leisure battery unless its faulty.
I'm assuming you haven't got a Batterymaster or CBE solar split charge relay fitted.

Get yourself a DC clamp meter then you can find out what is going on.

Like this.

UNI-T DIGITAL UT210E 100Amp 600V AC DC CLAMP METER Multimeter True RMS VFC diode | eBay

1 Cloth Bag. 1 Gift Box.

www.ebay.co.uk

 

[Jimbohorlicks]

In the manual ,page 8 item 6 How It Works
Indicates that once the leisure batteries are charged to 80-100% and the starter batter is below 12.5v then it does transfer a charge of up to 4 amps to the starter battery .
Maybe this is what the op is experiencing.

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[Lenny HB]

In the manual ,page 8 item 6 How It Works
Indicates that once the leisure batteries are charged to 80-100% and the starter batter is below 12.5v then it does transfer a charge of up to 4 amps to the starter battery .
Maybe this is what the op is experiencing.

Should only do that when solar power is available, he is getting a current draw after the sun has gone down.

 

[Jimbohorlicks]

Should only do that when solar power is available, he is getting a current draw after the sun has gone down.

He could be in a well lit area which will generate some solar current albeit small but that's what is being observed. A small draw ?

 

[Lenny HB]

He could be in a well lit area which will generate some solar current albeit small but that's what is being observed. A small draw ?

2 Amps, I don't think so.

 

[Motorhomer14]

Thanks for the comments. I have read the manual and this is something happening on a number of vans in the FB group.
To add to this the starter charging should only be from solar panels and this is at night no light.
Someone on the group noticed at night when central locking is used the leisure battery on his victron shunt is showing a small current draw on the leisure battery for a min which then falls to zero. Seems to me the batteries are connecting through the Nds controller and balancing.
We have also had reports of the Nds fuses blowing. I would think this was when engine starts and pulls current through the Nds controller.
This is all on new Adria vans with EBLs fitted so has a working charge relay.
From your comments you have confirmed my thoughts that this is not normal and must be a fault with the Nds controllers.

 

[Jimbohorlicks]

2 Amps, I don't think so.

The 2 amp draw is for when the central locking is operated ,not while it's stood doing nothing.

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[Motorhomer14]

The 2 amp draw is for when the central locking is operated ,not while it's stood doing nothing.

The 2 amp was not the same person who did the central locking test. The 2 amp was for a longer time and most nights
The central locking guy tested his van with victron shunt and noticed a small current draw on the shunt when locks operated. Showinf there is a connection between the two batteries

 

[m0xmx]

Trying to help "full-timer friends" with Adria out with this. They have the exactly same issue. They have just spent a load of money on a 300Ah LiFePo4 battery as they need every Amp and this is happening. I thought taking the red wire for the Starter battery off the suncontroller would fix it but sadly not. Please help.

 

[Aly1]

Sorry I’m no help but when I got my Murvi Pimento with a NDS battery manager I got a buzzing from my van speakers once the batteries were fully charged and then solar was going in.
Murvi sorted it in the end but apparent it was caused because it was on a Ford chassis?? It was sorted with the help of RoadPro.

 

[Fontie]

+1 for RoadPro they have helped me out no end. And they will give a 5% forum discount