new solar generator questions

[ColoJim]

Hi, newbie here. I have a cabin up in the CO mountains with a 17 year old solar setup so I know just enuf about solar to make me dangerous. I have a barn up there with a tractor that I want to connect a battery maintainer/charger to while I'm gone, it would be connected continuously. That is rated about 40watts. I also want to plug in the tractors block heater when I get up there to make it easier for the diesel engine to start. I've hooked that up to a kilowatt meter and it uses just less than 400watts. I would only run that for about an hour and only when I am up there. I've been trying to come up with some solution to power those without running about 200' of extension cord from the cabin. Then I ran across the words "Solar Generator" - voila - perfect. I looked around and came up with a EcoFlow Delta2 1Kw lifepo4 with two 100watt panels.
After giving it a 100% AC charge(panels aren't hooked up yet), as a test I plugged in some xmas lights, the solargen display showed 22watts usage which seemed correct. It also showed a runtime of 26 hours which didn't make sense. I figured 1024 watts / 22watts should give me 46 hours. Why does it show 26 hours?

So then I disconnected the lights, recharged up to 100%, and checked things 12 hours later. The solargen display showed the battery at 88% full after 12 hours with no load.

2 questions -
1. Is my math wrong? 1024 watt battery / 22watts should give me 46 hours

2. Is that normal for a brand new lifepo4 battery to lose over 10% in 12 hours? I sure hope not. And this was all done inside a warm house, not inside some freezing, unheated barn at 8000 feet elevation.

Is there some trick to these solar generators? Do I have a bad battery? Thanks for any help!!

 

[MakeMePower]

there are efficiency losses, your not accounting for. be aware these batteries can't be charged below freezing, and are limited on discharging when below freezing

 

[Hogheavenfarm]

Two 100w panels sounds pretty weak for charging that, so the long charge times are to be expected, plus the sun angle is bad at this time of year, short sun duration and low angle are killing the panels output. You wont get the full output on the battery either, being LiPo you can go deeper than Flooded or AGM but not to the bottom. So 80% use would be more like it, especially with only two panels recharging it.

 

[ColoJim]

there are efficiency losses, your not accounting for. be aware these batteries can't be charged below freezing, and are limited on discharging when below freezing

Thank you, I had seen that and I was usually up there around noon time on nice days. I was hoping that it would continue charging once the weather warmed up automatically. Do you know of other options for me and my circumstances?

 

[ColoJim]

Two 100w panels sounds pretty weak for charging that, so the long charge times are to be expected, plus the sun angle is bad at this time of year, short sun duration and low angle are killing the panels output. You wont get the full output on the battery either, being LiPo you can go deeper than Flooded or AGM but not to the bottom. So 80% use would be more like it, especially with only two panels recharging it.

I have not tried charging with the panels yet. Charging with the AC was relatively quick. My concern was about losing over 10% of the batteries storage in 12 hours.

 

[Nobodybusiness]

I have not tried charging with the panels yet. Charging with the AC was relatively quick. My concern was about losing over 10% of the batteries storage in 12 hours.

Seems strange to me but I’ve never had one of those before.

 

[MakeMePower]

10% with it running or off?

 

[Buck0]

If your inverter (AC in the app) is turned on, it draws power continuously even if you don't have any load on it.

 

[JWLV]

Most solar generators use about 20-40 watts of power just being turned on, with or without load.

 

[ColoJim]

there are efficiency losses, your not accounting for. be aware these batteries can't be charged below freezing, and are limited on discharging when below freezing

It appears Tesla uses LFP batteries, how do they work in below freezing weather and this solar generator does not? Do they have heaters for their batteries? My SIL has a tesla and it developed an antifreeze leak, maybe they cool and heat with the antifreeze? I don't understand lithium battery technology enough to have bought this thing, worried now about fire up at an unattended building.

 

[MakeMePower]

It appears Tesla uses LFP batteries, how do they work in below freezing weather and this solar generator does not? Do they have heaters for their batteries? My SIL has a tesla and it developed an antifreeze leak, maybe they cool and heat with the antifreeze? I don't understand lithium battery technology enough to have bought this thing, worried now about fire up at an unattended building.

they have entire heating and cooling system built into them