Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Chinese Xiaoxing BMS with Calb cells
#11
Well it looks like it charges at 13.8v and refuses to supply 0.3A, disconnecting the mains, and putting a power supply in parallel at 14.6v seems to charge without interfering with the UPS. So making it an inverter and separate charger effectively
Reply
#12
But it charges up to 13.8 thats not bad at all. You get longer life out of the batteries if not Smile
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
Reply
#13
(08-29-2020, 08:48 PM)daromer Wrote: But it charges up to 13.8 thats not bad at all. You get longer life out of the batteries if not Smile

Yes but at 0.3A, so a full charge of 100ah would take about a fortnight. So, the batteries would last lots longer cos they'd never get used, or atleast not very often Sad

Had a thought overnight, try a car battery charger that should supply 14.4v which would be ideal, and a readily available.
Reply
#14
(08-30-2020, 04:58 AM)dragonfly Wrote: Had a thought overnight, try a car battery charger that should supply 14.4v which would be ideal, and a readily available.

Depending on the circuitry/logic inside the UPS, it might start burning energy to reduce the voltage to what it thinks is the proper level.  Possibly overheating components inside.  Monitor the current flow with a DC clamp meter to make sure nothing funny is going on.
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
Reply
#15
I guess the alternative is to find an inverter/charger that supplies the correct charge voltage. Only need about 200w of supply, at the mains, as it's a backup for a central heating pump.
Reply
#16
But 0.3A at 13.8V is since its fully charged... It will reduce the Current the closer it comes to full

What is the charge during lower voltage? And no, smaller UPS systems are not ment to have 100x bigger battery if thats what you are trying to archive. The charge time will then take many hours more. Most UPS systems have very very very small charge current Smile
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
Reply
#17
Oh, that reminds me... most cheap small UPS have virtually no active mechanism to cool itself, the thinking being that the battery will run out (15min?) before components inside get too hot. So it may overheat when you attach a much larger battery with much longer runtime.

I did a similar project years ago, and cut cooling vents into the sides with a 80mm fan blowing air through.
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
Reply
#18
Yes it was meant to be 7ah and is now 100ah, maybe I have reached the limit of this little experiment. Think I really need to find something better suited. BTW It appears to charge at a constant 0.3 amps
Reply
#19
I ran 150Ah in my 600VA ups when i started 25 years ago or whatever it was... Yeah im a tad old.

That took 1.5 day to charge atleast when i drained it. But i had power for a day with it.. It ran my old router, server and other gear Smile

Now im running a 120kWh battery bank with full solar Big Grin
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
Reply
#20
+1 keep the LiFePo4 cell voltage max 3.45 - 3.5V = full , 3.65V is overvoltage level not daily charge too voltage.
Running off solar, DIY & electronics fan :-)
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)