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APC UPS 3000 overcharging my battery
#11
(05-01-2020, 08:22 PM)Korishan Wrote:
(04-30-2020, 03:03 PM)OffGridInTheCity Wrote: The other one, which has very light load during the winter - e.g. K-Cup - decided to start overcharging one of the batteries.   I found one battery was normal but the other starting floating at 4.27v/cell - YIKES.

I read that these APC max float resisters can 'get off' - so I bought another unit on eBay - but its the same problem.   One battery was at 3.0v/cell and the other was at 4.0v/cell and after a couple of hours - it was 3.5v/cell and 4.22v/cell.   Again YIKES!!

Do you have a bms on these?? If not, why not? Even a cheaper unit would be better to help keep the voltages in check.
I use BattGo(s) as my BMS because they show the voltage and will beep with trouble - e.g. undervoltage.   However, I've discovered that they don't do anything on overvoltage (I expected them to beep).   

>why not?
I'm not OK putting a BMS on that I can't see what its doing - I want to see the voltages.  I don't have android for the cheap BMS interface and I don't want to fool around with some GitHub iPhone hack - don't want a phone interface at all.    

I'm looking for a solution.    Chargery 16 is a bit expensive for what you get...   Looking for cheaper BMS with screen of voltages - maybe something like this:
https://www.ebay.com/itm/10S-24S-Smart-A...Ggqh8SgrAg
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#12
I suggest using diyBMS by Stuart Pittaway. There's plenty of work that's been done on it and it's quite versatile because each parallel section has it's own monitoring system that all report back to a central system.
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#13
Using Li-ion in server APCs was something I always wanted to test and I will when I get my hands of a good APC UPS.
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#14
You are not ok with a bms that doesnt show voltage but you are ok running without protection? You do unde stand how thta sounds like? Smile

Any bms is better than No bms.
You can Always add a voltage display on the Side. You can even run The simplest Arduino or esp with multiplexer and added adc to report thta data with those dumber bms systems
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#15
(05-08-2020, 06:30 AM)daromer Wrote: You are not ok with a bms that doesnt show voltage but you are ok running without protection? You do unde stand how thta sounds like? Smile
 I have no confidence in cheap BMS that I can't monitor doing anything at all.   The BattGo's visible voltage (for monitor) and audible alarm makes them a cheap BMS.  I just didn't realize they didn't sound alarm at overvoltage. However, due to visible voltage they did they're job and alerted me to a bad condition.    

 I also didn't realize that the individual batteries in APC 3000 are not charge voltage limited - they're just 'dumb' serialized.   

So I agree in that I'm moving ahead and will try Chargery 16  and a 'cheap BMS with voltage panel' - both seem similar cost and I'll see how they work out Smile

I'm nearing 3 years in now... and since I'm in the 24/7 power production business (rather than now and then ebike riding) one thing thats gotten clearer is you have to take the long view - as things may be fine today or next year but what about 3 years from now when you've stopped looking. You need reliable equipment / systems for the inevitable battery degradation/failure. So yea, BMS is needed - but I want it to be something I can monitor and not just close my eyes and hope its working.
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#16
This is how you always should look for a bms

1. Protection, Over and under voltage is key including temp. Most Cheap ones have this and it actually do work. Its easily tested.
2. Reporting. reporting is very nice but do you really sit at the battery 24/7? If you dont its just useless more than for casual checking.
3. balancing and management. This is the last step and its there for longeivity.

You can always monitor a cheap BMS. Just add a voltage display or 14 or whatever you have. As you all know, stuff doesnt fail when you stand watching but when you turn your back around.

And cheap stuff or not. I do hope everyone do test the equipment? For instance i have tested both over and undervoltage and know that the breaker will be triggered and shut down. (As an example)

Thats also why you have a test button on for instance fault protection Smile
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