Renogy 40A DC-DC charger- charging when engine has switched off

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sam9green1

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Hi all, i have installed the Renogy 40A DC-DC charger (see picture below for model of charger) in my T6 but im having issues. When the engine is running the Charger works fine and charges my leisure battery however when i turn it off, it contiures to charge.
I have used a piggyback fuse on an ignition live for the igntion feed and have tested the voltage feed cable and i am getting voltage there when i should. If i remove the cable from the starter battery to DC-DC charger at the batery end and reconect on the terminal the charging stops. Once i start and stop the engine again the same fault happens again.

Could it be a faulty unit or am i missing something?

Thanks
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Can you show photos of the connections to starter battery, leisure battery, DC-DC and the ignition live fuse?

How do you know it is charging with ignition off? Bluetooth/app or lights? What lights do you see?

As @Howzat says, -ALT should go to an earth point on the van, not directly to -ve on the starter battery. This is so you don’t bypass the shunt that tells the van how much current is being drawn on the van battery.
 
Most DC-DC chargers have the auto vsr feature where the charger stays working when the starter battery has a high enough voltage.

Have you left if running for a while to see if it stops after a while... Like 5 mins?

You can also try turning on the headlights to drop the starter battery surface charge too see if the DC-DC drops out after that.

Has that unit got BT to link to the app?.. what's the units settings?
 
drinfinity said:
As @Howzat says, -ALT should go to an earth point on the van, not directly to -ve on the starter battery. This is so you don’t bypass the shunt that tells the van how much current is being drawn on the van battery.
Click to expand...
That I would strongly suggest is the issue right there...
 
Which ignition live fuse have you used? A lot of these don't shut down immediately after turning off the engine, they'll stay live for a few minutes. Therefore the charger thinks the ignition is still on and will continue to charge.
 
TallPaul_S said:
Which ignition live fuse have you used? A lot of these don't shut down immediately after turning off the engine, they'll stay live for a few minutes. Therefore the charger thinks the ignition is still on and will continue to charge.
Click to expand...
Hadn't thought about that @TallPaul_S how does one figure out how particular ig-lives behave?

(Sorry to hijack OP's thread but I have a similar use case planned in the future and want to be forearmed!)
 
Should be easy to check with a multimeter - it may be that it does switch off immediately but worth checking first.

I honestly didn't know what systems run for a short period after switching off the ignition, but some do - my dashcam which is powered from the rain sensor is still powered on for a few minutes after turning off the van, for instance.

Of course if you had a factory leisure battery the engine run signal for the split relay is a true engine run signal, not ignition run - so it turns the charger off and on during stop/start etc.

The charger hopefully has settings to allow voltage detection rather than relying on the signal wire, that's another option to use.
 
Yep OK - I thought it might be as simple as 'that rail is true ignition live and that rail has a xx second run-on'

I'll do some tinkering and testing!
 
TallPaul_S said:
Should be easy to check with a multimeter - it may be that it does switch off immediately but worth checking first.

I honestly didn't know what systems run for a short period after switching off the ignition, but some do - my dashcam which is powered from the rain sensor is still powered on for a few minutes after turning off the van, for instance.

Of course if you had a factory leisure battery the engine run signal for the split relay is a true engine run signal, not ignition run - so it turns the charger off and on during stop/start etc.

The charger hopefully has settings to allow voltage detection rather than relying on the signal wire, that's another option to use.
Click to expand...


The engine run signal used by the factory leisure battery install isn’t a true engine run signal either: Certainly on a T6.1.
It actually activates the engine run signal based upon the voltage it senses. As a consequence, you can put a standalone charger on your starter battery and it will sporadically activate the engine run signal without the engine running.
Had fun with that one, until I understood it, as the lights in the rear of my camper originally also used the “engine run” signal to disable them. When I originally put a charger on my starter battery my DC-DC converter kept turning on and off as did the rear camper lights; not in sync either as my DC-DC just uses the “engine run” signal to configure its enable/disable voltages whilst the lights were directly via a disabling relay.
 
EAN said:
The engine run signal used by the factory leisure battery install isn’t a true engine run signal either: Certainly on a T6.1.
It actually activates the engine run signal based upon the voltage it senses. As a consequence, you can put a standalone charger on your starter battery and it will sporadically activate the engine run signal without the engine running.
Had fun with that one, until I understood it, as the lights in the rear of my camper originally also used the “engine run” signal to disable them. When I originally put a charger on my starter battery my DC-DC converter kept turning on and off as did the rear camper lights; not in sync either as my DC-DC just uses the “engine run” signal to configure its enable/disable voltages whilst the lights were directly via a disabling relay.
Click to expand...
Why would you want to disable the rear lights with an engine run signal? Asking for a friend…
 
Dellmassive said:
Most DC-DC chargers have the auto vsr feature where the charger stays working when the starter battery has a high enough voltage.

Have you left if running for a while to see if it stops after a while... Like 5 mins?

You can also try turning on the headlights to drop the starter battery surface charge too see if the DC-DC drops out after that.

Has that unit got BT to link to the app?.. what's the units settings?
Click to expand...
I posted this into a Renogy community forum aswell and someone on there informed me that it works how you’ve described it.
It stops charging when the starter gets down to 11v.
This seems very low but i looked through the manual again and it does say it there. Long term I think I’m going to replace it as don’t want to risk a flat starter battery.
Short term I’m going to fit an additional isolater and manual stop the charge. Just have to remember to keep switching it
 
sam9green1 said:
Short term I’m going to fit an additional isolater and manual stop the charge. Just have to remember to keep switching it
Click to expand...
Shameless plug for my content here:-

Will enable you to 'remotely' on/off the charger.

www.t6forum.com

Solar panel remote on off switch

Has anyone fitted a remote switch or circuit breaker to turn on and off the solar panel out put ? As many will know being able to turn off the solar input to the renogy charger allows faster dc to dc charging. Getting in and out to use a manual switch/circuit braker at the back of the van is a...
www.t6forum.com www.t6forum.com
 
sam9green1 said:
I posted this into a Renogy community forum aswell and someone on there informed me that it works how you’ve described it.
It stops charging when the starter gets down to 11v.
This seems very low but i looked through the manual again and it does say it there. Long term I think I’m going to replace it as don’t want to risk a flat starter battery.
Short term I’m going to fit an additional isolater and manual stop the charge. Just have to remember to keep switching it
Click to expand...
That totally doesn't make sense to me. I thought the whole point of ignition live is to stop something running when the ignition is off?
That's how my Sterling works, and most electronics that use ign live, but like @Dellmassive mentioned my charger does run for a couple of minutes after ingnition is switched off but that might just be the fan still cooling the charger. I've also just had another look at the manual and it says if you DONT use ignition live then it charges when the voltage gets to 13.5 (which it will on our vans) and stops at 11.5 which sounds like a better option in the meantime. Just pull that ignition live.
 
Salty Spuds said:
I wonder what their rationale was. After all it involves more work/cost for what benefit? It’s a weird one.
Click to expand...
The conversion had Whole Vehicle Type approval, was VW Qualified and had NCC approval.
I expect it’s to minimise any effect of the conversion on the operation of the vehicle and it gets you out of having to carry out certain electrical emission tests on the equipment in the conversion. Lots of motorhomes kill the habitation electrics when the engine is running.
 
EAN said:
The conversion had Whole Vehicle Type approval, was VW Qualified and had NCC approval.
I expect it’s to minimise any effect of the conversion on the operation of the vehicle and it gets you out of having to carry out certain electrical emission tests on the equipment in the conversion. Lots of motorhomes kill the habitation electrics when the engine is running.
Click to expand...
Which is great until you want to run the engine to charge the LB….in the dark
 
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