Community Forums

RickLight · 02-08-2023, 07:22 PM

Much has been written about DC-DC charging for LFP. Yet there seems to be a gap.

My trailer power fuse is 40A, which seems large, as the wire at the receptacle is 14ga at best. I looked inside it and only the ground is a larger than a very narrow blade. I've seen many posts saying most trucks have 10ga wire and I want to laugh. I really don't want to run new wire, especially an additional trailer connection. Yet as is I'm not getting much.

So what charger to use? A typical 20A version seems far too large, Victron's 18A isn't much better. Red Arc has a 12A device. https://www.redarcelectronics.com/us...attery-charger Also it seems expensive, at twice the others.

Are there other options? Am I missing something?

Old-Biscuit · 02-09-2023, 09:37 AM

In all my years of towing travel trailers and 5th wheel trailers I have never had an issue with truck 'charging' not being able to 'maintain' trailer battery voltage while in transit......which is all it is for.

Are you having trailer battery issues while traveling?
IF Yes
What is drawing so heavily on your trailer battery that truck 'charging' can't 'maintain'?

cletesingler · 02-09-2023, 06:29 PM

My 2017 F350 charges my 2 12VDC size 31 batteries at about 10VDC on hook up with high idle ON and the F350 pumping out 14.3 VDC to the RV and truck batteries. So, my RV batteries are pretty low (probably at 12.7 VDC) and 14.3 VDC really charges them in a hurry. I think the F350 has a 20 amp fuse on that circuit. Once charged, the RV batteries are being charged at less than 3 amp (VDC from the F350 varies between 13.6 and 14.3) with fridge and other stuff running while on the road. So whatever the gauge of the charging wire(s) it's more than adequate for the job especially for short periods of time.

cletesingler · 02-09-2023, 06:30 PM

oops that is 10 amps and not 1- VDC......

RickLight · 02-12-2023, 03:20 PM

Anyone added a 20A DC-DC without new wires?

traveldawg · 02-13-2023, 12:42 PM

I added a DC- DC system. It was probably a waste of time and money. I don't travel very long each day before stopping and then I have shore power. So just about all the time I don't bother to engage the Dc - DC charging system and just let the battery run the RC.

I could have (should have?) just let the truck's charging system provide whatever it was providing for my short travel days.

The plus side of a DC charger is that you can set a profile to charge a lithium battery at the right voltage(s).

TravelSolo · 02-13-2023, 01:55 PM

Quote:

Originally Posted by traveldawg

I added a DC- DC system. It was probably a waste of time and money. I don't travel very long each day before stopping and then I have shore power. So just about all the time I don't bother to engage the Dc - DC charging system and just let the battery run the RC.

I could have (should have?) just let the truck's charging system provide whatever it was providing for my short travel days.

The plus side of a DC charger is that you can set a profile to charge a lithium battery at the right voltage(s).

As you found out, it depends on your use case as to whether or not a DC-DC is useful to you.

I mainly boondock and am a power hog at times (system is built for that though). I also drive 3-10 hours each day so recharging the 400Ah of batteries for the next boondocking stay is critical to me. My solar can't always keep up do starting off topped off it vital to me.

oldenavy · 02-14-2023, 06:30 PM

We installed Solar along with the Li batteries in our last trailer, so I just pulled the fuse on the charge line in the truck. No DC/DC converter required, didn’t have to worry about overloading the alternator, let solar do its thing while driving and always arrived with full batteries.