Undersize charging wire, WFCO to batteries, Upgrading to lithium in 2019 T@B 400

jimcenname

In my 2019 T@B400 (no solar) I just replaced the two original AGM Harris Batteries with a single Battle Born 100ah lithium. The original charger, 55 amp WFCO 8955PEC, isn't lithium compatible. Battle Born Rep offered a 55 amp Progressive Dynamics 4655V to convert the WFCO to Lithium capable. My problem was the factory wire between the WFCO and the AGMs is 8 gauge and runs 22 feet long behind cabinets and under the bathroom floor. Both Battle Born and nuCamp agreed that is undersized for that distance for a 55 amp charger. I don't know why it also isn't undersized for the existing AGM batteries. Though I know of no problem it caused in the 4 1/2 years I have lives in my T@B. Instead of running 22 feet of 4 gauge wire I bought a PD9345 "deck mounted" charger, installing it right next to the new lithium battery. Only 2 feet of cable required. Also I disabled the charging feature on the WFCO by removing a single power wire for the panel breaker. FYI, I also installed a shunt to monitor the lithium battery and an ANL fuse on the battery's hot wire. Progressive Dynamics said to run a dedicated ground wire from battery-negative to chassis-ground. The existing battery compartment vent hole provided a passage through the floor. Since Lithium doesn't require venting for gas I eliminated the battery encasement cover.

RMo

Thanks for the overview.  I’m considering something similar and have a few questions.  How difficult was it to remove the black cover?  Any tricks?  What are the dimensions of the space that remains after you remove the cover?  Any lessons learned that might be useful?

jimcenname

I removed the lower third of the bed platform. Then unscrewed about 10 screws holding the cover in place. I lifted the cover on the outbound side, disconnected the battery cables and feed them through the hole on the side of the cover. Then the cover lifted off. The AGM batteries weigh about 60 lb each. I flipped them on their side and pushed them out the cargo access door. The roughly 11 X 8 inch space of one AGM battery was used for the new charger, shunt and fuse. I gained no space but lost about 90 pounds. I'll have to see how much the tongue weight changed.

RMo

Did you use the original pos and neg leads from the battery, or replace them with larger gauge wires?

thanks,

jimcenname

They were 4 gauge cables about 2 feet long. That's sufficient to handle the current from the charger, which is at the end of a 2-foot long 4 gauge cable. They connect at the existing distribution studs.

Binghi

Nice mod, @jimcenname - I’m upgrading my 2021 400 to lithium and thinking of doing something similar.

A few questions:

How come you used the PD 9345 instead of the PD 9360? Wouldn’t the 9360 charge the battery faster?

It looks like you put in an AC outlet to power the converter. Did you create a dedicated circuit for the outlet by running the outlet cable back to the power center and installing another circuit breaker? What gauge cable did you use?

Did you keep the OEM inverter?

Thanks!

SLJ

When I installed my lithium batteries I also put in a Victron Smart Charger for charging them when on shore power. When on shore power I let my non-lithium WFCO (2021) supply DC and just shut off my batteries. If they need charging I switch on the Victron and let them charge. When I unplug from shore power I just turn them back on. I trust the Victron charger way more than any WFCO.

tphaggerty

I have a 2018 400 that looks very similar to your pictures with the battery located under the bed. I'm having trouble understanding the "22 ft" wire run. In my Tab, the wire from the WFCO (now upgraded to a Progressive Dynamics) runs from the converter directly under the bed (in a subfloor) to that back compartment, basically the width of the trailer, so maybe 10 feet.

I have 3 Renogy 100ah Lithium batteries in that space now. While I too have concerns about that wire being undersized, it doesn't seem to be an issue so far. I have felt the charge wire while charging at 55 amps and it hasn't been hot at all. I plan to install a larger gauge wire in the spring, but not sure where the 22 ft measurement is from/to. 

RMo

I'm having trouble understanding the "22 ft" wire run. 

When choosing an appropriate wire gauge you’ll want to consider the entire circuit length - negative from the battery and positive back to the battery.  Given this is a 22 foot run it would mean 11 feet each way.

jimcenname

My WFCO is under the dining bench seat by the door, the cable from the WFCO's 55 amp non lithium charger goes across the trailer to the space under the other bench seat then to the rear via the spacer under the shower and Alde compartment then back to the other side of the trailer to the battery. 22 feet of wire. That's a long run for 12 volts/55amps. Using a 45 amp charger reduces the gage wire requirement. I rarely boondock (at most overnight at a Cracker Barrel) so I don't do a lot of demanding charging. If the the battery is at 60 percent state of charge it takes about 30-45 minutes to get it back to 100 percent with the 45 amp charger. BTW the battery/charger area is not well vented so when doing that kind of charging it gets to 95-100 degrees briefly. I may install a vent and fan. For comparison, my Alde compartment is ~105 degrees right now, 50 degrees outside.

jimcenname

Binghi said:

Nice mod, @jimcenname - I’m upgrading my 2021 400 to lithium and thinking of doing something similar.

A few questions:

How come you use d the PD 9345 instead of the PD 9360? Wouldn’t the 9360 charge the battery faster?

It looks like you put in an AC outlet to power the converter. Did you create a dedicated circuit for the outlet by running the outlet cable back to th usinge power center and installing another circuit breaker? What gauge cable did you use?

Did you keep the OEM inverter?

Thanks!

Using Romex I did install an outlet by the new charger. I tapped into the circuit that powers the outlet by the kitchen sink and runs to the foot of the bed, so I don't use my Keurig on that outlet when I have to charge a lot. I don't have an inverter. I don't have solar. I don't boondock. I rarely deep dishcharge and recharge. I don't need the extra charging speed of a 60 amp charger and didn't want to deal with the bigger-yet gage cables.

Binghi

Got it, thanks a lot.