AGM to Lithium battery question

[Airlock]

I have a 2019 16' Bambi Sport. Currently I have 2, 6V, 240ah AGM SunCycle batteries (wired in parallel) and am considering an upgrade to lithium batteries. My first question in my research is: Can I go with one 12V lithium battery or do I have to (or should I) stay with the 2 - 6V battery configuration but with lithium instead of AGMs?

[Tyler2you]

I think you probably mean your batteries are wired in series. Two 6 volt batteries in series will get you 12 volts to your trailer. In a series connection, the voltages are additive, but the capacity (amp hours) isn't.

If you upgrade to a single 12 volt Lithium battery (standard sized), you'd end up with somewhere around 100 amp hours of useable capacity. Your current system likely provides a similar amount of capacity since you can't discharge AGMs as far as Lithiums. You wouldn't really be gaining much.

I'd look at either a single, large capacity 12 v Lithium (like the SOK 206 AH ones) or a pair of 12 v, 100 AH Lithiums in parallel for a significant improvement in capacity.

[field & stream]

If you provide us with more info it would be easier for us to help you. What problems are you trying to solve? What are your objectives? How do you “camp”, plugged in or boondocking? For how long? Electric only fridge or propane? Any solar, how much?

[Airlock]

Thanks for the correction to my post re parallel v series; you are correct they are wired in series. So if I understand correctly, I don't need to stay with the 2, 6V battery configuration, what ever the battery chemistry. I can, but I don't need to. I can go with a single 12V lithium if I got a 200ah model, which would double my current capacity.

[Airlock]

Originally Posted by field & stream

If you provide us with more info it would be easier for us to help you. What problems are you trying to solve? What are your objectives? How do you “camp”, plugged in or boondocking? For how long? Electric only fridge or propane? Any solar, how much?

My goal is more battery capacity for boondocking and less battery discharge while in storage. I usually am out for 4 days, 3 nights. My fridge is electric/propane and I almost alway use the propane mode. I do a fair amount of camping in the shoulder seasons so the heater gets a lot of use. Sometimes just at night and early morning; sometimes just early morning. I have a 200W Renogy suitcase solar set up.

[field & stream]

Very helpful, thanks. We have a 16’ with a propane fridge and camp unplugged almost exclusively. We are going 5-8 days with a single 100Ah lithium before hooking up a single 100w portable solar. However, we are really minimal users of other electric stuff.

Here are some measured Ah draws from our trailer:

Fridge: about 7Ah per day (electronics draw continuously)
Heater: 2A per hour, only when running
Fantastic fan: 1-2A depending on speed, only when running
Lights: converted to LED, use almost nothing.

I would be inclined to get one larger battery, but if you plan to move it around weight might be a consideration. FOR SURE: be certain you have a lithium compatible converter programmed for lithium.

[field & stream]

P.S. on the battery discharge issue, lithium batteries have very little, insignificant, self discharge compared to lead acid and AGMs. But, the Airstream switch does not disconnect all power users (propane detector, maybe others) so you will still have a parasitic draw that can add up. For this reason many of us have installed a true disconnect switch that completely isolates the battery from any demand. Very inexpensive and good to have.

[Airlock]

Originally Posted by field & stream

Very helpful, thanks. We have a 16’ with a propane fridge and camp unplugged almost exclusively. We are going 5-8 days with a single 100Ah lithium before hooking up a single 100w portable solar. However, we are really minimal users of other electric stuff.

Here are some measured Ah draws from our trailer:

Fridge: about 7Ah per day (electronics draw continuously)
Heater: 2A per hour, only when running
Fantastic fan: 1-2A depending on speed, only when running
Lights: converted to LED, use almost nothing.

I would be inclined to get one larger battery, but if you plan to move it around weight might be a consideration. FOR SURE: be certain you have a lithium compatible converter programmed for lithium.

Your usage is very similar to mine. Going 5-8 days before needing to haul out the solar suitcase would be a great change! My plan was to mount a new lithium battery (or batteries) in the same place on the A frame as the two 6V AGMs I have now. So it seems that replacing two 6V batteries with one 12V is not an issue to be concerned about.

And I realize that the battery is only one part of the cost and I would need to swap out to a lithium compatible converter.

I have a battery disconnect switch gathering dust in the garage so it seems that installing that would be a first good step in good battery management .

Thank you for all of your comments and advice; very helpful.

[Wazbro]

Originally Posted by Airlock

Your usage is very similar to mine. Going 5-8 days before needing to haul out the solar suitcase would be a great change! My plan was to mount a new lithium battery (or batteries) in the same place on the A frame as the two 6V AGMs I have now. So it seems that replacing two 6V batteries with one 12V is not an issue to be concerned about.

And I realize that the battery is only one part of the cost and I would need to swap out to a lithium compatible converter.

I have a battery disconnect switch gathering dust in the garage so it seems that installing that would be a first good step in good battery management .

Thank you for all of your comments and advice; very helpful.

I agree there is no problem going with a single lithium. It is a really good idea to get a battery shunt when you do. A shunt will let you know how you are doing on charge, one is needed since voltage will not tell you anything.

[daleyocum]

Also, be aware that lithium batteries don’t like being below freezing for charging. You’d want to either move the battery indoors or get a heated model if you anticipate doing that. +1 on the battery monitor. You can’t go by voltage any more with Lithium. The Victron SmartShunt or BMV-712 are popular.

[SouthForkAS]

I'm looking at the same thing. In 2021, I replaced an Aux AGM 12v 100AH with LiFePo4 and the difference was night and day.
My house Batts are the std pair of GC 6 volts in series, weighing in at 130#. I'm thinking 1 200AH Li weighs 60#.
As soon as you do, you'll wonder what took you so long (my GCs are only 18 mos old)

[Sport 16 STL]

Buy one 100ah battery, and add a couple of solar panels on the roof or second option portable.
Solar does a great job of keeping the battery charged in storage. We have a16’ Bambi, 2 90watt solar panels on roof and can stay off the grid using the furnace for 5-6 days with some sun.