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UPS and LiFePo4s
Did anyone test if generally a series of 4 LiFePo4s can be compatible with standard UPS units that use lead acid batteries ?

It could be really useful...

If anyone tried this please share some feedback.
It works on some UPS systems yes. BUT you need to read the specifications of the ups so it doesnt overcharge your LiFePo4.

LiFePo4 is basically 100% compatible with most LA systems since they are very forgiving. With that said some LA have higher voltage and therefore may trip the BMS.
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I have 4 x APC style UPSs with custom Lithium-ion packs in operation.  2 are the 1500 model and 2 are the 3000 model.  
- 1500(s) range from 27-28v as their top charge - e.g. these are 24v lead acid originally.
- 3000(s) range from 54.3v - 55.4v as their top charge - e.g. these are 48v lead acid originally.

If these voltages work for you - then you might try one.  Used/refurbished are super affordable on ebay and everyone I've bought on ebay has worked.  I've purchased 10 of them over the years Smile
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@OffGridInTheCity are these rackmount (high quality) like these: or just standard cheap versions ?
(07-08-2020, 05:12 AM)Overmind Wrote: @OffGridInTheCity are these rackmount (high quality) like these: or just standard cheap versions 
I don't have racks so I went free-standing like the picture below (with APC 3000 + Chargery 16 BMS) - which are more 'consumer' than 'professional' grade.   However, battery wise, I'm guessing they are all 24v or 48v nominal.    @Korishan has pointed out that some models of the professional grade will even let you set things like charge voltage max - but I don't know of a specific model to share.

Here's an example of an APC UPS 1500 (120v@1000w'ish continuous) of which I have 9 Smile.  $85 is pretty cheap!            You can even add an internet card ( for these 'Smart APCs' and get power logs every 10min and see status.   I use this to monitor and get power readings but since mine are regular (as apposed to commercial) I can't set very much - just email, and alarm settings, and log rotations - things like that.
Those are lower quality that the rackmount/server models.
Not sure about the sine-wave quality.
For general use, they should be fine.

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