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Old 12-25-2022, 01:06 PM   #1
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Towing with solar and lithium batteries

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

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Old 12-25-2022, 06:39 PM   #2
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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.
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Old 12-25-2022, 07:32 PM   #3
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It can be an issue. You actually have two design issues that should be addressed. I donít 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 itís just not necessary.
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Old 12-26-2022, 07:16 AM   #4
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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
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Old 12-26-2022, 07:42 AM   #5
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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.
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Old 12-29-2022, 04:43 PM   #6
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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.
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Old 12-29-2022, 10:40 PM   #7
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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.
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