More power-Bigger panel or another battery?

[Grvlrdr]

Rubberlegs, the AGM battery is 100Ah. After being on a charger for 24 hours, it is still completely dead.

 

[rubberlegs]

You're probably aware the lithium battery intended for RV use at 100Ah has considerably more practical range than the AGM -- close to twice as much. They can go from 100% to 0% with little damage (to 20% is better for long life), but the AGM should be 100% to 50%. So the 200Ah battery you mentioned will have 3 to 4 times the energy output.

But your AGM battery isn't that old. Was it at low percentage for a lot of the time?

 

[rando]

Lithium is so much lighter and more energy dense than lead acid, that you can easily fit a 200Ah LiFePO4 and still be lighter than 100Ah of AGM/lead acid. If price is not a limiting factor, then 200Ah gives you a huge amount of margin. But if you were fine with the 100Ah AGM (before it died), then 100Ah of lithium should be plenty.

 

[CPT Davenport]

I vote for adding additional battery storage. I have the 206ah SOK with 175w flexible panel on roof and 130 folding aux panel. I have never ran out of juice. I do not have a DC/DC charger and disconnected the alternator from my house battery, so only power in is from solar. I have gone five days in the rain/no sun and still did not deplete the battery.

 

[Grvlrdr]

You're probably aware the lithium battery intended for RV use at 100Ah has considerably more practical range than the AGM -- close to twice as much. They can go from 100% to 0% with little damage (to 20% is better for long life), but the AGM should be 100% to 50%. So the 200Ah battery you mentioned will have 3 to 4 times the energy output.

But your AGM battery isn't that old. Was it at low percentage for a lot of the time?

It isn't that old at all. I didn't really monitor it that precisely, as all I have is the monitor for battery and water that shows E, 1/3, 2/3, full. I guess I better add a battery monitor to the shopping list?

 

[Grvlrdr]

I vote for adding additional battery storage. I have the 206ah SOK with 175w flexible panel on roof and 130 folding aux panel. I have never ran out of juice. I do not have a DC/DC charger and disconnected the alternator from my house battery, so only power in is from solar. I have gone five days in the rain/no sun and still did not deplete the battery.

I'm going to add the additional battery storage to be on the safe side. Now just deciding if I can handle the additional 20 lbs of solar on the roof.

 

[rubberlegs]

It isn't that old at all. I didn't really monitor it that precisely, as all I have is the monitor for battery and water that shows E, 1/3, 2/3, full. I guess I better add a battery monitor to the shopping list?

A battery monitor is an excellent idea. Your built-in monitor won't work with lithium, because it was designed for an AGM battery. It'll show full until close to 0%. There are shunts that measure accurately. Some batteries can report state of charge, but our SOK brand battery state of charge measurement is useless. (I think SOK has improved though).

What electrical gadgets do you use in your camper? We only have a few (fridge, heat, lights, charging phones...) and could get by with a 50Ah battery (but have a 100Ah). We're way on one side of the spectrum though.

 

[Vic Harder]

New batteries and a monitor first. Track your usage for a few trips, then decide if you need/want to add more. As for the roof, I vote tossing the existing glass panel and adding a much higher power glass panel. I'm 67 and can still lift the roof with: 330W glass panel up there, plus our canoe, traction mats, and multiple antenna's.

 

[Grvlrdr]

Thanks for the input and help! I've ordered a new 200Ah lithium battery and a battery monitor and am looking around at possible solar options.

 

[CPT Davenport]

I went with a flexible panel on the roof to keep the weight down. It weighs about 7 pounds with the custom mounting bracket I fabricated. Rigid panels come in around 25 pounds.