Power question: REDARC DC-DC charger? What gauge of wire would be needed?

[murrayargo]

batteries really wont overload wiring like loads will.. yeh see if the wiring is too small, the voltage just drops far enough its no longer changing battery.. so you can basically limit a batteries charge rate with the wiring, while it may get a lil warm its not gonna catch cabling on fire like trying to run something like say a motor on too thin of a cable.. the motor is going to need lets say 200W and as voltage drops the amps goes up and the wattage remains constant.. so the wiring is going to catch on fire.. whereas charging a battery, the loads drop linearly with the voltage.. the wattage is not constant, if you cant provide higher voltage than the battery its not charging.

If you want your AGM's to charge as fast as possible, I believe they want to be setup for 0.4C but its not that much faster than 0.2C in the end, 1C = Capacity in AH.. so a 68AH would be between ~14A-28A ideally to charge it.

will this work for something like the renogy dc- dc converter? I thought it might. I got the 40a for a solid deal. I already have 6 ga wire, so I thought about just using it. The amperage doesn't really matter to me if it charges at a slower rate. I do not need to use it all the time.

 

[dcg141]

I have 6 ga on my Redarc and its been working great for over 2 years now. That is the best second battery charger I have ever used.

 

[ConcordCarlos]

When the house battery is fully charged, and the redarc is also fed with solar(model with built in MPPT) does it then charge the starter battery? I think the Renogy has that feature.

 

[broncobowsher]

The nice part about using wire gauge to limit charge rate is when the other battery starts getting really close to full the amp rate will drop, That will reduce the voltage drop through the wire. And that will allow the battery to get full voltage and top off.

I've used a company van for some trips over the past couple of years and all I did was put a spare AGM battery in the back. I have a plug that goes into the 7-pin trailer plug at the back and has about 10 feet of 16AWG wire attached to that, it might even be 18AWG, it's old speaker wire. So all the book engineers will think I will die with that much wire run in that small of a gauge trying to keep a battery charged and run a freezer fridge at the same time. Reality is it works just fine. By the time I get home the battery is fully charged or really close to it and the fridge is still keeping the drinks cold. No monster battery cable, no battery to battery charge controllers, absolutly nothing special. With time you don't need speed to charge a battery. How fast do you need the house battery charged anyway?

Keep in mind that for the past 50+ years the way you charged the house battery in your travel trailer was to just run a charge wire from the tow vehicle to the trailer and connect it to the battery on the trailer. There was nothing special going on there. When the trailer was low, it put a load on the tow vehicle's charging system and it charged the battery. No special chargers needed, no full length super sized cables. You are looking for solutions for problems that don't exist except in your mind.

 

[Rbertalotto]

Following for interesting replies to this last post.....?

 

[john61ct]

How about a raspberry?

Takes all types of owners, and personality drives the use case as much or more than the other factors.

So long's you know the pro's and cons

each can make up their own minds about the trade-offs

Sorry if that's not very interesting