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AC run time at night on 48V LiFePO4 103AH - 5.3KwH ?

davo727

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May 25, 2021
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Hello, Thanks for letting me in on the fun here. Pretty cool that now finally solar parts prices are making this a viable option.

Questions - Say a new LG 9500 btu window AC that shows 920 cooling watts, im assuming that is full blast, so what would be a good guess on watts on low cool low fan?

Next on low cool whats a good guess on how long overnight it would run off a 5.3 KWH , 48V Lifepo4 battery set for a safe conservative shut off voltage?

Theoretical for a small cabin with a Magnum 4400 watt inverter and 5.3 KWH 48V Lifepo4, and the AC being the only load other than the inverter loss.

Planning stage as far as the battery and inverter , and I have a 3000 watt inverter gen that could be used to kick on at a certain point overnight if really needed.

Thanks, Dave a little north of Houston
 
Welcome to the forum.

5300*.8/920 = 4.6 hours of presumably full-blast running. No knowledge of lower power settings, so no guess. The window unit Will uses in his shed is closer to 5000BTU/450W and might be a better option if it's sufficient for the heat load.

Need to factor in the idle consumption of Magnum inverter. Probably on the order of 30W even when no loads are present, i.e., 30W * 24h = .72kWh or .72/5.3 = 13.6% of your battery capacity.

Safe cut-off voltage is hard to say. It's capacity and load dependent. Would be best to use the battery monitor to establish when you're at 20% SoC under the loads in question and identify that as your cut off voltage.
 
Thanks. So which battery company in the US has a good reputation and service and reliability and has ready to ship 48V LifePo4 5KWH -6KWH batterys available?

Edit,,,, If said battery is available for pickup in person near Houston, Dallas, Austin that would be a plus.
 
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Thanks, what was the price on their 48V 100AH ? Looks like they took the price off the site while not in stock. Thanks
 
around 1500 plus 70 shipping for 1, got free shipping on 2, these newer ones could be more??
For 51.2 x 100=5120 5.1kw
 
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This is from Big Batteries? They are located in California near L.A. I was going to get my 24-volt 100ah batteries from them and pick them up as I'm only 250 miles from them. For the cost of $1500 and they weigh 200 lbs. - the weight is a problem for me.

However, a post was made in this forum sometime back about the Ampere Time batteries from Miller. These batteries are available on Amazon and this battery costs $998 and only weighs 47 lbs. The battery I will be getting is 24v at 100ah.
 
The difference between running the fan on high or low will only make about a 100 watt difference if that. At night, you'd have to be in the tropics for it to run continuously all night & if you're in a small cabin as I am too, mine runs maybe 15 minutes out of a hour at night so if that matches your senerio, you're using 1/4 of a kw per hr divided by 5kw battery capacity which should give you about 20 hrs using the A/C alone but I'm sure you have other stuff running so figure the peripheral drain & add it to that & you should have your answer but it looks to me you're in the safe range from killing your batts overnite.
 
I got the window AC unit Will mentioned in video that is supposed to be one of the highest efficiency window AC units on the market. It's the Midea 8,000 BTU U-Shaped Window Air Conditioner. I've only had to use it once so far this year and had it set for 66F overnight and used a little over 3kWh. Looks like that LG unit is just slightly less efficient. It's going to be in 90'sF rest of week so will be able to get better data. Most annoying thing about it so far is the LED temp reading on front is way too bright in dark room. Going to have to put tape over it. Also not as quiet as what I think of as quiet but still much better than regular window AC unit
 
Im going to also have to find out if these window AC units pick right back up at the last setting when power is restored-- say if they were on a timer that cycled power every few hours.

EDIT ; The LG 9500 I bought has auto restart according to LG site so thats good. I havent tried it yet, just dropped it off at my place out in the woods.
 
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