Lance TC - lithium - DC-DC charger question

otrfun wrote:

mbloof wrote:

BFL13 wrote:
Another factor is to keep the input voltage high enough so the DC-DC buck/boost converter can maintain the set output amps and voltage to the camper battery. This is a separate issue from fusing the input side for its wire size, and having the input wire gauge match the input amps.

I think your on the right track here.

For camper applications, we have the wiring of the truck, then the connector(s), pigtail and then the wiring in the camper itself.

I swear my 97 Ford had 18AWG wiring! I tapped the output of the alternator and ran to a solenoid (switched on with the engine running) and 6AWG to ~1' of the 7Pin and then spliced in as large of a AWG wire as I could fit. The ground went from the 7Pin to the trucks frame.

At least Lances have 8AWG wire in their pigtails, a quick look at the wire sizes used in most 7Pin cables is 14AWG. :( My NL uses 10AWG to go to the battery.

Lets face it, all wire has resistance and higher currents will create higher voltage drops. Depending on efficiency of the step up charger/converter itself (which BTW 'stepping up' a voltage is difficult to do with anything resembling 'efficient') it could be easily trying to draw 50-60A on the input.

However, given the wiring in the camper itself (and the batteries state of charge) the battery may never see 40A of charge current. For example I recently viewed the charge current at the battery after a 2-day trip that the PD6045Li I have in my NL was providing when I got home. ~19A at the battery. :)

Personally I'm debating getting a 20A or 40A model myself. I do know that some of them have a switch/configuration option to operate at 1/2 power. :)

- Mark0

NL used 15-20 ft. of 10 gauge wire for the battery to converter run on our 8-11, too. Like you we got less than 20a of charge current from our 45a PD converter. We replaced the 10 gauge with 2/0 (now get a full 45a). Used 2/0 'cause we sometimes quick charge our lifepo4 using both our 45a converter and 40a dc2dc charger at the same time (85a of total charge current). FWIW, we used a 25 ft run of 2 gauge cable from our truck's battery to the 40a dc2dc charger mounted inside the TC. 43.5a alternator/battery load with 40a of charge current.

I've heard of others rewiring from the converter/charger to the batteries with similar results.

Personally, I'm just looking for a 'fail safe' of sorts. If/when it might happen that I'm low on juice and digging the Yamaha out is not convenient, three button presses on the Trucks remote could not be easier. :)


- Mark0.