Hello. I purchased an Orion TR Smart 18 AMP DC to DC charger to charge the LifePo4 battery on my travel trailer while towing. The tow vehicle is a 2019 Ford F150. I ran (2) 4 AWG copper wires from the engine area to an Anderson style connector on the rear bumper. Positive attaches to the battery directly; negative attaches to the frame near the battery where another negative wire attaches. The run is about 25 feet (one way) and the Orion TR attaches to the back of the truck with about 10 ft of 6 AWG copper wire.
So, here is my question. When under full load (25-27 AMPs pulling from truck alternator, 20 AMPs going into the travel trailer battery) I’m seeing a .75 to .9 volt drop between the battery and what the charger reports as input. Given my setup is this amount of drop excessive? Based on some simple calculators I found online it’s almost twice as much as I was expecting. Maybe those are based on the rosiest of scenarios.
Hi and welcome.
Yes, it is a bit high, things I would do/check (if not already done)
First check with a clamp meter at start and at the end to confirm other readings.
Type of wire used? Wiring Unlimited DC Wiring page 22.
Check all connections are torqued to correct manufactures recommendations
Check all connections are good, any getting warm? (probably not at a small loss)
Are any of the wires close to a heat source? (or ignition) heat will increase lost as resistance increases.
Are any of the wires getting trapped or crushed?
I know it can be a pain to do this, but it will get to the root cause of the problem.
Good luck.
To confirm, checking with a clamp meter, do you mean at the start of the wire run (near alternator) and the end (at Orion TR)? I will check that.
I’m using marine grade tinned stranded copper wire. It’s labeled as 4 AWG. Ancor is the brand.
I’ll go through all the connections and the run again but when I last checked i couldn’t find anything that was loose or crushed. As for heat - part of the cable does run through engine compartment of the truck which will obviously get warm. I did keep the wires as far from the obvious heat producers like engine block and exhaust as I could.
To confirm, checking with a clamp meter, do you mean at the start of the wire run (near alternator) and the end (at Orion TR)? I will check that.
" .75 to .9 volt drop between the battery and what the charger reports as input"
Yes, very often there can be small variances between equipment, so first let’s see if there is a problem, this way you will know for sure.
Then it’s a process of elimination.
The wire looks fine and should not cause a problem. (the link goes to the spec sheet please confirm this is what you have)
After you have checked with a clamp meter and gone through the connection let us know what you find or not. It might only be a small thing causing this so don’t discount anything.