Question about wiring/charging trailer battery

[AdventureBuddies]

Hi. I just got a trailer and have a couple of questions regarding charging the trailer batteries.

Tow vehicle has a starting battery and an AGM battery linked via a selectable 200A solenoid. The second battery runs the winch and all accesories so the starting battery is used only for fully stock applications.

I have #4 cables already routed from the second battery to the back of the vehicle to power my fridge, compressor, and rack mounted aux lights.

The trailer has two Optima blue tops. How should I charge them? I believe the "standard" method is to route #10 wires from the main battery to the 7pin RV plug for trickle charging the trailer batteries. The trailer is already setup up for this canfiguration, but the tow vehicle is not.

The other method (I think) would be to have two plugs - one for the standard RV 7pin and another for the #4 cables. That way the two trailers batteries would essentially be connected to the two vehicle's second battery and they could be brought in and out of the charge loop by my 200A solenoid.

I read somewhere that AGM batteries allow current to move very quickly and gell (optima) batteris require a very slow charge. if the AGM and optimas were linked, would I risk damaging the optimas if they were low on charge and the AGM rapidly flooded them with current?

So - which method is preferable? can I wire both methods? Any opions or experiences. Thanks!

 

[Hugh Heifer]

Sounds like you have quite a set up/

I think you are on to it here:

The trailer has two Optima blue tops. How should I charge them? I believe the "standard" method is to route #10 wires from the main battery to the 7pin RV plug for trickle charging the trailer batteries. The trailer is already setup up for this configuration, but the tow vehicle is not.

I would think the #4 wire, if you split it might do it. (guessing). ut why don't you do what you said? Run another #10 to the hitch?

I have no experience and am nearing the wiring stage on my trailer .

 

[OlympiaFJ60]

If your only trying to charge the trailer batteries, not running trailer accessories the #10 should be plenty. I have used this method for years and have had not problems. I don't have a fridge in the trailer or anything else that needs to be powered while driving.

 

[AdventureBuddies]

There will be a fride in the trailer that needs to be powered while driving. Does that mean the #10 wire won't be sufficient for maintaining charge so the fridge can operate without drainging the trailer batteries?

 

[Rambrush]

The 10ga wire will handle 30 amps which is quite a bit considering most rv plugs to run the whole trailer are only rated at 30 amps.
Unless you have ac units and the wiring jumps up to handle 50 amps.

 

[Hugh Heifer]

The 10ga wire will handle 30 amps which is quite a bit considering most rv plugs to run the whole trailer are only rated at 30 amps.
Unless you have ac units and the wiring jumps up to handle 50 amps.

Good tech

 

[9180ltd]

the trailer "charge" pin on your rv plug is meant for just that, charging.......not running acc loads.the charge line on the tow vehicle should also be coming from a relay that is only triggered when the vehicle is running to negate dead starting batteries.and as far as i know an optima "gel cell" is an AMG (absorbed glass matt)