Did I get the wrong stuff?

fred schmidt

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Sorry if this is repiticiou . I bought a 100 watt renogy suitcase, 2000 watt inverter, and a chinns 12 volt 1080 AH lithium battery. Is this a mismatch? Will the alternator in my 2019 Durango charge this? Not using a ton of power… 2 I heated cpaps
 

NVS

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Most cpaps are dc voltage so all yo need is a 12vdc adapter. Like this.
KFD Car Charger DC Adapter for Resmed S10 Series,ResMed Airsense 10 S10 AirCurve 10 Series CPAP and BiPAP Machine,90W Resmed S10 370001 37297 Rockpals 300W/500W Vehicle Power Supply Cord Cable Charger https://smile.amazon.com/dp/B07P6H9...abc_PRG8FQJD3D6V6CXWP8JQ?_encoding=UTF8&psc=1


It's a waste of battery to convert 12v to 120vac just to convert it back again to dc voltage.
 

rmaddy

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A 12V 1080Ah LiFePO4 battery would cost $5k-$10k. Post a link to the battery you bought.
 

rmaddy

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That is a range of $400 to $800 per kWh. There are some good options in the $300 per kWh price point.
Even at $300/kWh this would be a nearly $4200 battery.

I wonder if the OP actually has a 12V 100Ah battery which would be 1280Wh. 1280Wh vs 1080Ah? Could be a mistake.
 

Ampster

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at $300/kWh this would be a nearly $4200 battery
Yes it would. I did a DIY pack for less than $150 per kWh so that is another data point of $2100. My only point was that the range of values can be large. Answering the OPs question about a mismatch may depend on where you are standing.
 

fred schmidt

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Even at $300/kWh this would be a nearly $4200 battery.

I wonder if the OP actually has a 12V 100Ah battery which would be 1280Wh. 1280Wh vs 1080Ah? Could be a mistake.
I see now it’s 1080 watt hours not amp hours. Oops
 

time2roll

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100 AH is a bit light if you will be using the inverter at 800+ watts. Does it mention a maximum discharge rating?
 

rmaddy

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It’s 100 AH
A 12.8V 100Ah battery is 1280Wh.

If you read the details about this battery the specs state:
Max continuous discharge current: 100A

You have a 2000W inverter. 2000W / 12V / 0.85 is about 200A. But the battery only supports 100A. So you can only use 1000W of your 2000W inverter. You would need a second battery in parallel to be able to fully use the 2000W provided by the inverter. A 2000W inverter is probably serious overkill for 2 CPAP machines. Also note that you should run the CPAP machines directly on DC without any need for an inverter. It would be a lot cheaper and far more efficient.
 
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rmaddy

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Sumpin not adding up with the specs
The specs clearly state 1280Wh, not 1080Wh. At least the Amazon page for the battery states 1280Wh. Maybe some other Chins page is showing 1080Wh by mistake.
 

Dzl

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At first glance, this is a somewhat mismatched system. But not necessarily. More detail is required.

A 2000W inverter is somewhat oversized for a single 100Ah battery (with max discharge of 100A, and reccomended discharge of ~20-50 for longevity). A full 2000W would be in the ballpark of 180A, but of course, just because you have a 2000W inverter doesn't mean you ever need to use the max power available, a little overhead isn't a bad thing.

A ratio of 100W of solar to 1280Wh battery is pretty anemic on the solar side. It would take multiple days of good sun to fully recharge the battery. But the variable that makes a bigger difference is your daily usage. If you only plan to use 10% or 20% of the battery capacity per day, 100W might be plenty. Additionally alternative charge sources matter, you mention alternator charging, if this is your primary recharge method, and solar is just a supplement, 100W might be fine. Determining how much you expect to use in an average day and in a 'worst case' day will help you work the rest out.

note: if you do want to charge via the alternator, you will need a DC-DC charger designed for charging lifepo4 from a vehicle alternator. Victron, Renogy, Kisea are a few of the companies that make these.
 
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rmaddy

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with max discharge of 100A, and reccomended discharge of ~20-50 for longevity
The specs state "max continuous discharge current: 100A". I don't see a recommendation for 20-50A. But otherwise your reply makes good sense.
 
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Dzl

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The specs state "max continuous discharge current: 100A". I don't see a recommendation for 20-50A. But otherwise your reply makes good sense.
Actually you are probably right, I may have misspoke, my recall of a lot of the details that were previously committed to memory are hazy right now, Its been 6mo or so since I've been thinking about lifepo4/solar, and I skipped coffee today. I believe I'm erroneously conflating recommended charge current, with recommended discharge current (of lifepo4 in general, nothing specific to Chins). 0.2C to 0.5C are the general rec's for charging, but maybe discharge this is not a big factor, time for a refresher I think.
 

time2roll

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I would have minimum 4 batteries if pulling above 1500 watts on a regular basis such as to make coffee or use the microwave.
 
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