Tow Vehicle charging Lithium Batteries?!

[artfuldodger]

I,ve heard this is hard on the TV alternator. Is this true and can it be done using additional equipment?

[Beldin]

You can use a charger that plugs into an ac cord. Charging with the truck will not be a problem, just might take a little longer.

[PNW Fireguy]

A dc to dc charger is the way to go. There are those who charge directly with the TV alternator and have not had an issue. Under the right circumstances this scenario can ruin your day. It works until it doesn’t. Googling the topic will give you info to help you determine what works for you.

[rohrmann]

Some vehicles can be set up with an additional alternator that you can use exclusively for providing power to the trailer, but it can be costly and you will still need to run the truck a long time to squeeze that much power through a fairly small wire.

[R.S.O'Donnell]

Some good info on the subject:

https://www.youtube.com/watch?v=VY2b71zoyvg

[Lee-CI]

Unequivocally the answer is yes. Due to extremely low internal resistance of LiFePo4 batteries, one can literally smoke a TV alternator within a handful of minutes.
Daryles did an excellent writeup on this very topic which I whole heartedly agree with and pretty much followed word for word other than I utilized a 40a DC-to-DC charger vice a 60a DC-to-DC. Let me know if you have any questions. See link below
https://www.montanaowners.com/forums...hlight=charger

[Lee-CI]

https://www.youtube.com/watch?v=jgoIocPgOug

[Cat320]

Originally Posted by artfuldodger

I,ve heard this is hard on the TV alternator. Is this true and can it be done using additional equipment?

Not worth the risk to me.

[dfb]

Do lithium batteries start fires more than standard or gel batteries?? not meaning to be Danny downer... just wondering...

[scottz]

I have a 397A alternator but chose to not connect it to the RV. Two reasons; protect the alternator and it would not do much good unless I installed larger wiring back to the RV. I just charge the batteries on solar, shore power and/or on-board generator.

[Daryles]

Thank you Lee.
Here's a followup to our last trip to Ocracoke Island OBX NC.
https://www.montanaowners.com/forums...hlight=charger

This year when we went to Ocracoke Island OBX NC NPS Campground (dry camping for 10 days) the weather was a LOT cooler. Everything got a good workout.
We had to run the furnace at night. The solar panels got the batteries charged back up every day.
The last three days we had clouds and rain. No solar charging. I connected the truck to the rig via the Anderson connectors (you also have to attach a jumper cable from the frame of the rig to frame of the truck when they are not hitched, this provides a ground between them) and ran the DC-DC charger for an hour twice a day for those last three days we were there.
I found out only one of the alternators runs until it reaches more than 80% of the load (200A alternators = about 180A) before the second 200A alternator kicks in. So only one alternator carried the load for the charging. It got to 214⁰F. I plugged in a fan and had it blowing on the alternator to help keep it cool. The other alternator was only 90⁰F.
We also ran out of propane. We had 1 and 1/5 tanks starting out. They do not refill propane tanks on the island. We had to buy a 20lb BBQ grill tank to get us through the last two days.
Like I said, it was an unusually cold spring (March) on the island. No worries, we use it on the Blackstone grill.

[Lee-CI]

Originally Posted by Daryles

Thank you Lee.
Here's a followup to our last trip to Ocracoke Island OBX NC.
https://www.montanaowners.com/forums...hlight=charger

This year when we went to Ocracoke Island OBX NC NPS Campground (dry camping for 10 days) the weather was a LOT cooler. Everything got a good workout.
We had to run the furnace at night. The solar panels got the batteries charged back up every day.
The last three days we had clouds and rain. No solar charging. I connected the truck to the rig via the Anderson connectors (you also have to attach a jumper cable from the frame of the rig to frame of the truck when they are not hitched, this provides a ground between them) and ran the DC-DC charger for an hour twice a day for those last three days we were there.
I found out only one of the alternators runs until it reaches more than 80% of the load (200A alternators = about 180A) before the second 200A alternator kicks in. So only one alternator carried the load for the charging. It got to 214⁰F. I plugged in a fan and had it blowing on the alternator to help keep it cool. The other alternator was only 90⁰F.
We also ran out of propane. We had 1 and 1/5 tanks starting out. They do not refill propane tanks on the island. We had to buy a 20lb BBQ grill tank to get us through the last two days.
Like I said, it was an unusually cold spring (March) on the island. No worries, we use it on the Blackstone grill.

Daryl - you are the one needing thanked. Posts like yours that I linked to take a tremendous amount of brain work, scheming and planning out of certain projects. With the resettable circuit breaker in the TV compartment as well as the one for the Output side of the DC-to-DC charger, I came up with no valid reason for this to not be a safe setup. Looking forward to future upgrades to where we have a Multi-Plus II inverter and a soft start on the rear AC to help cool the coach down during the last hour or so of summer trips next year. Happy wife happy life then when she is doing the inside setup as I set up camp outside.

[artfuldodger]

OP here. Is there any downside to leaving that little wire from the TV connected to the Monty with lithium batts? I know the amp draw is small but every little bit helps, right?

[R.S.O'Donnell]

Originally Posted by artfuldodger

OP here. Is there any downside to leaving that little wire from the TV connected to the Monty with lithium batts? I know the amp draw is small but every little bit helps, right?

I disconnected mine entirely in the junction box behind the pin box. I've got 1,200watts solar 600AH lithium.

Sun has always kept the batteries fully charged or very close.

[R.S.O'Donnell]

Originally Posted by dfb

Do lithium batteries start fires more than standard or gel batteries?? not meaning to be Danny downer... just wondering...

To be honest I'm more concerned with my drill and Dyson lithium lon batteries that I am our LiFePO4's.

https://www.youtube.com/watch?v=WzdYXyST81Y

https://www.youtube.com/watch?v=pOIM--Kmyqw

[Daryles]

Originally Posted by artfuldodger

OP here. Is there any downside to leaving that little wire from the TV connected to the Monty with lithium batts? I know the amp draw is small but every little bit helps, right?

I left my 12v pin connected in the 7 way cable when I installed the DC-DC charger.
The most I have measured through the 7 way connector is about 7A, batteries were at 39%.

https://www.montanaowners.com/forums/showthread.php?t=83767&highlight=charger

[bcrvman]

Originally Posted by artfuldodger

I,ve heard this is hard on the TV alternator. Is this true and can it be done using additional equipment?

It can, Victron has DC to DC, Renogy also, you will also need heavy gauge wire and marine grade connectors and double layered glued heat shrink.