Lithium - Auto detect

[Rogers iPhone]

I have a new to me 2023 Grand Design Imagine XLS. I swapped out the factory battery with a 12v 230 amp hour lithium battery from Li Time. I have 2 issues/questions:

1) Can I trust either of the battery readings in the camper - either the low/med/high LED lights on the compass connect panel or the digital readout on the shunt in the pass through? Neither seem right. I started using a multimeter on the battery itself and comparing the reading to a chart in the battery manual to get an indication of charge, but even that is questionable since the manual says to do this when the battery has been disconnected for 3+ hours.

2) I don't think the battery is charging while driving. Is it possible the battery cables that came with the travel trailer are not of sufficient gauge?

 

[Soundsailor]

It looks like you're new here, welcome to the forum.

1) No, I wouldn't trust the readout on the Compass Connect panel, those are based on voltage which is not a good indicator of SOC (state of charge) for a lithium battery. The digital readout on the shunt should be accurate once you've calibrated it. The shunt needs to know how much capacity you have in the battery.
2) Any charging while driving would come through the 7-pin connector. Have you tested that to confirm current is flowing from your TV (tow vehicle)? Do you have any solar? If so, the battery may be fully charged; in that case, no current would flow until the controller detects a need for it.

 

[Rogers iPhone]

It looks like you're new here, welcome to the forum.

1) No, I wouldn't trust the readout on the Compass Connect panel, those are based on voltage which is not a good indicator of SOC (state of charge) for a lithium battery. The digital readout on the shunt should be accurate once you've calibrated it. The shunt needs to know how much capacity you have in the battery.
2) Any charging while driving would come through the 7-pin connector. Have you tested that to confirm current is flowing from your TV (tow vehicle)? Do you have any solar? If so, the battery may be fully charged; in that case, no current would flow until the controller detects a need for it.

Thanks for the welcome and your reply

1) I guess I need to find out how to calibrate the shunt.

2) I've not tested the 7-pin connector, however I do believe it is working since it did charge up the lead acid battery in place when I purchased the TT and the only thing changed is the battery. My question comes because after installing the lithium battery we drove with the trailer from Houston Tx to Montana and the lithium battery dropped (according to the shunt) from 100% to about 50%. Then again, the same thing happened on the way back home from Montana. This TT has a DC refrigerator so there would be some battery draw.

 

[Soundsailor]

Do you know which shunt you have? There may be some info in the owner's packet if you have that. Or reach out to GD customer service with your VIN.

 

[Rogers iPhone]

Do you know which shunt you have? There may be some info in the owner's packet if you have that. Or reach out to GD customer service with your VIN.

TT in storage unit with owner's packet currently. I'll check when I pick it up this weekend for a Utah trip next week. We will have full hookups in Utah, so battery SOC is not as critical as it was in Montana where we were dry camping.

Thanks for your information!

 

[Harvestmoon]

For a 2023 XLS series (I have similar) it will most likely be a Furrion battery monitor. You can probably find a user manual online or the tiny one in your stack of component manuals.

If your vehicle is not providing charging to the trailer battery, suggest get a meter and check for voltage on the aux power pin at the back of the truck. Truck may have to be running or in acc mode to power up the trailer aux. If no voltage check for a blown fuse.

 

[Rogers iPhone]

For a 2023 XLS series (I have similar) it will most likely be a Furrion battery monitor. You can probably find a user manual online or the tiny one in your stack of component manuals.

If your vehicle is not providing charging to the trailer battery, suggest get a meter and check for voltage on the aux power pin at the back of the truck. Truck may have to be running or in acc mode to power up the trailer aux. If no voltage check for a blown fuse.

I thought it would be Furrion as well - I'll check though. Thanks

I suppose I should simply put a meter to the truck to be sure, but it does run the refrigerator while driving and it did charge the old lead acid battery so I thought it might be something to do with the lithium battery. Only thing I could think of is if it maybe needed different gauge battery cables since it has a bit more voltage.

 

[Harvestmoon]

I run a DC-DC charger between the truck and trailer and set it for lithium charge mode and limit max charging current to 10A. This gives me the correct charge profile for the LFP battery bank and I also know at 10A I am not overloading the truck wiring harness. I know not everyone bothers with the DC-DC charger when going to LPF batteries and generally works fine charging directly from the truck. Large LPF banks can be power hungry and I would expect the truck has a way to regulate the charge current to a safe level for the wire harness and at the very least be fuse protected appropriately for the wire capacity. I never dove into this for my particular truck because I went the DC-DC route. Some guys will run high amp DC-DC chargers (50-80A) with dedicated heavy cables. For my application I never figure on that much charging from the truck and just want to more or less break even with the DC fridge running.

 

[Rideblue51]

I agree with Harvestmoon. Not much charging going on via the TV. But having the dc/DC charger for Lithium would be a necessity, I would think.

 

[edaniel]

Thanks for the welcome and your reply

1) I guess I need to find out how to calibrate the shunt.

2) I've not tested the 7-pin connector, however I do believe it is working since it did charge up the lead acid battery in place when I purchased the TT and the only thing changed is the battery. My question comes because after installing the lithium battery we drove with the trailer from Houston Tx to Montana and the lithium battery dropped (according to the shunt) from 100% to about 50%. Then again, the same thing happened on the way back home from Montana. This TT has a DC refrigerator so there would be some battery draw.

Be sure to have the attached grounds to the battery to be on the other side of the shunt.

 

[jas451]

We have a 2023 22MLE and our first trip to the the Northeast noticed that the battery wasn't keeping charged with the original acid core battery. We got home I figured I'd put a lithium battery in and that
would fix the problem. We had a trip this past fall and the same thing happened, and drove home with a dead battery. Contacted GD, got a tech involved, determined that the solar charger was bad.
Tech also suggested a dc to dc charger for the TV. Also, found that the circuit breaker box in the trailer was not recognizing the lithium battery (even though the sticker on it said that it would) manufacturer had us remove the circuit box and send it in to upgrade the firmware. Once the weather breaks, will re-install the circuit box, new solar charger, and dc to dc charger and should be good.