Towing with solar and lithium batteries

[ep4me]

Just asking what everyone does towing with a new truck 2022 chevy and a new Montana high county with the factory solar flex package and inverter. i have heard that solar packages with lithium batteries can fry your trucks alternator. Some say you should disconnect the charging wire on your seven pin connector which is easy enough to do. Or is this even necessary with the new solar controllers and trucks.

Any experience with this or thoughts or suggestion would be a appreciated

Thanks

[Foldbak]

Welcome to the forums. I don't have lithium but I don't believe it's a problem. Or...but you should have a charge controller.

https://www.google.com/search?q=can+...kPIPwvegqAU_40

[PNW Fireguy]

It can be an issue. You actually have two design issues that should be addressed. I don’t have a Solar Flex system so forgive my lack of specific detail as to what the system includes. Several on the forum charge their lithium banks directly from their alternators and have not reported an issue. However this is the reason dc to dc chargers are on the market. The next issue is if the charging connection on the 7 pin is left connected when the vehicle is off the TV batteries can and will draw from the lithium bank since they are at a lower voltage. This usually addressed by an ignition sensing relay like the Cyrix available from Victron. Other options are available and Google is your friend.
I personally do not rely upon our TV for charging. Our PV array can charge at such a greater rate that it’s just not necessary.

[ep4me]

Thanks i think I'm going to disconnect the TV charging wire and just use solar and shore power for battery charging

Thanks for the replies

[Daryles]

The MOST I have seen through the 7 way cable to my 552Ah of lithium batteries at 30% State of Charge is about 7 A..
That charging circuit in the truck has a 30A fuse in it. No way it could damage my 200A alternators.

Here's a link to a write up I did of installing a DC-DC charger.

https://www.montanaowners.com/forums...hlight=charger

[rames14]

The ONLY way to fry the alternator is to run an un controlled voltage straight from the charging system to the battery. As Daryles said, you will only get about 5-7 amps from the truck system, which won’t even cover your normal discharge (my unit uses 10 amps just sitting there). It won’t hurt anything to disconnect it, but it won’t help, either. Many people have gone to DC-DC charging via BIM or Renogy. You can search and find a lot of information on the forum.

[Todd & Mary]

I disconnected the charge wire in the 7pin harness. Added a 6 ga wire from the truck battery to a DC to DC Victron charge controller. Now I get up to 30 amps. The 7 pin harness doesn't even keep the fridge running!
Yes, charging LIFPO battery directly off the alternator of the truck can be dangerous, particularly at low RPM's because the Alternator doesn't run fast enough to cool itself.

[Jamric]

2022 3121rl have not unhooked hit wire on 7 pin connection, no problem with alternator close to 10k miles .has 400i solar and 2 lithium batteries!

[rames14]

Todd, 6 gauge wire is undersized, especially with that length of run.
#10 gauge wire
For a 30 amp circuit, the appropriate wire gauge would typically be a #10 gauge wire. Using a smaller wire gauge, such as #12, with a 30 amp breaker can lead to the wire overheating and potentially causing a fire, as the wire may not be able to handle the electrical load safely. You need to run #10 AWG.
Jamric, this post is two years old. Todd is not referring to the nominal power coming through the 7 pin. He has installed a DC-DC charger, upping current significantly. I have 2/0 wire on mine.

[Todd & Mary]

Originally Posted by rames14

Todd, 6 gauge wire is undersized, especially with that length of run.
#10 gauge wire
For a 30 amp circuit, the appropriate wire gauge would typically be a #10 gauge wire. Using a smaller wire gauge, such as #12, with a 30 amp breaker can lead to the wire overheating and potentially causing a fire, as the wire may not be able to handle the electrical load safely. You need to run #10 AWG.
Jamric, this post is two years old. Todd is not referring to the nominal power coming through the 7 pin. He has installed a DC-DC charger, upping current significantly. I have 2/0 wire on mine.

Ron, 6ga THHN wire is rated at 75 amps. at 20' has a 2.5% voltage drop at 30 amps. I feel this is fine for this application.6 ga is much larger than 10ga. and the Orion will not accept any larger wire.

[scottz]

6ga is larger than 10ga. I ran 4ga wire (about 40' from truck battery to DC-DC converters) and can get about 45A using twin Victron 30A DC-DC converters.

Victron has a new DC-DC converter rated at 50A; worth looking at.

I use the OEM 12V off the 7-pin for powering my TPMS repeater and DC-DC converter cooling fans; things I only want to run when the truck is running.

[Todd & Mary]

They do, but the new Orion version is not isolated. And doesn't get as hot as the original does. If they come out with an isolated one I may consider it. The 7 pin is not really enough amps for the RV in my situation.

[Foldbak]

Originally Posted by ep4me

Just asking what everyone does towing with a new truck 2022 chevy and a new Montana high county with the factory solar flex package and inverter. i have heard that solar packages with lithium batteries can fry your trucks alternator. Some say you should disconnect the charging wire on your seven pin connector which is easy enough to do. Or is this even necessary with the new solar controllers and trucks.

Any experience with this or thoughts or suggestion would be a appreciated

Thanks

Been towing with solar and lithium for close to 2 years with a 2020 GMC and no problems.

[LeftOverParts]

We prob have about 40K miles on the trailer and before the solar was added this year, no problems charging through the 7 pin from a 200 Amp alternator in our ‘21 F350 but we only have to run the resi fridge.

We’ve had many cloudy days during 2 1/2 months so far into our 3 month trip so the 7 pin helped during travel since we don’t have a dc/dc charger.

[scottz]

I only get about 4A out of the OEM 7 pin charge line; not even enough to keep up with my DC fridge, much less charge batteries.

[ep4me]

i can now answer my own question. It is not aporblem after 2 seasons and 20,000 miles of towing. The vitron charge controller prevents any over chargeing or damage.