Hello,
Looking for information on how to protect the battery system on my truck from my trailer. If the truck is connected to the trailer and the solar system is turned on, the solar system can have a higher voltage resulting in power going on the wrong direction and damaging the trucks electronics. I’ve heard adding a diode solves this, but I don’t know where to start.
Thanks!
Do you know what amount voltage and current your solar panel produces? We could be of more help if you had part numbers/model numbers and an idea of your battery situation.
Typically the problem related to diodes is the battery backfeeds into the solar panel when the solar panel isn’t getting sunlight.
For Solar DC Blocking applications typically Schottky diodes are used because you lose the least amount of voltage to the diodes internal forward voltage (most efficient). The following option is good up to 40 Volts DC with a 25 Amp current capability
Part Number SBX2540-3G
Just remember, the stripe is what they call Cathode which is the negative side and you put it in the direction of the circuit where you do not want current to flow. In this case you connect the non-striped leg of the diode (Anode) to the positive output of your solar panel and the striped cathod to your battery’s positive terminal, like in the diagram below:
Otherwise, if your solar panel truly is producing too much voltage you might need a method to drop that voltage down to 14V or so for your batteries.
Good morning! I did some more research last night after posting (which I should have done first). From what I can tell the solar charge controller is a Furrion 40A MPPT. The spec sheet says during a boost mode it can charge with 14.8V for a period of time. If my truck (2025 GMC 2500) is idling, it would only produce 13.6V. with the higher voltage at the battery, I was told this damaged the trailer light module on the truck. Does this sound right?
Good morning to you!
Many modern vehicles will dynamically change their charging voltage based on the batteries’ need, so your truck will deliver more voltage (and current) often around 14.4V, when the battery is low, when the battery is fairly full, 13.6V would be expected.
In this post, the last entry spells out what worked for him…
“This can be fixed by putting a diode in the charge line between your truck and trailer. Use a diode that’s big enough for whatever amperage your charge circuit is fused at/running at. The diode will keep the backfeed voltage from going to the truck and triggering the fault. You want the current flow in the diode to only go towards the trailer, not from it. I’ve put them right before the 7 way connector on the truck side.”
This would be done for all wires other than the ground.
These are similar but not spelled out quite so well…
https://www.etrailer.com/question-302092.html
https://www.etrailer.com/question-230444.html
Hopefully this is helpful. I’d imagine any place specializing in RVs would have plenty of experience with implementing this fix.
Kind regards,
Brian
That is awesome. thanks!
