I agree.
Any cell voltage over 3.8 volts is a waste, and doesn't do the cells any
good. The cells don't gain SOC over 3.45 volts.
While LiFePO4 cells will _withstand_ 4.2 volts, you really don't want to
go above 4.0 volts. Doing this long term or routinely would be detrimental.
Bill D.
On 5/12/2020 2:14 PM, paul dove via EV wrote:
With LiFePO4 cells you can charge them to anything over 3.4. Some people use
3.5, 3.55, 3.6, 3.65. It doesn’t matter the next day they will read 3.38 to 3.4.
Sent from my iPhone
On May 11, 2020, at 7:10 PM, Lawrence Rhodes via EV <[email protected]> wrote:
It seems to me there is some wiggle room. I have seen 3.2 to 3.4 top voltage
for A123 batteries. Official specifications:
Nominal Voltage: 3.3v.
Standard Charge: 3.6A.
Max Charge: 10C.
Max Allowable Charge Voltage: 4.2v Charge voltage is 3.6 volt.
Max Discharge: 30C (Continuous)
Burst Discharge: 60C.
A normal charge on 20 cells would be 72vdc and it could handle up to 84vdc. I
am looking at this BMS:
https://www.ebay.com/itm/20S-72V-60V-25A-35A-45A-60A-LFP-LiFePo4-Li-ion-Lithium-Cells-Protect-BMS-IP65/312688099275?ssPageName=STRK%3AMEBIDX%3AIT&var=611407917579&_trksid=p2060353.m1438.l2649
I also inquired about a charger. I don't know however if I need one unit per
string or not. I suspect 5ah would be plenty. 2strings. According to the specs
one string has just enough power. I don't know if the chargers are smart or
not so much to learn. Lawrence Rhodes
On Monday, May 11, 2020, 2:08:38 PM PDT, paul dove <[email protected]> wrote:
A 3.7 volt battery charges up to 4.2volts. 20 would be 84 volts fully charged.
3 to 2.5 volts x 20 is 60 to 50 on low end
so depends on what range you want and the max your system will allow.
An A123 is LiFePO4 and they charge to 3.4 volts. 20 is 68 Volts.
On Monday, May 11, 2020, 3:50:59 PM CDT, Lawrence Rhodes via EV
<[email protected]> wrote:
I am having trouble deciding weather 20, 21, or 22 batteries are the right
series string for a 72vdc battery. for a 3.7 volt battery 20 seems to be
right. However I have A123 batteries and nominal is 3.3vdc. Videos on YouTube
are inconclusive. Sellers details not complete. Any advice appreciated. I'd
like to run 1 or two strings for a small ebike battery. The controller only
draws 40amps. Lawrence Rhodes
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