LIFEPO4 Battery discussion thread

If you really want to check open up the pack. Top balance all the cells to 3.65v with bench power supply.

Run the battery down.
 
cavedog said:
Yeah cell08 is low again. I think cell08 is cooked. The OVP was set at 3.7v so wonder if it got any damage. There is like 2800 ovp in the bms logs so yeah might have gotten some damage and has less capacity now compared to the others.

View attachment 1910268
Click to expand...
80% isn't that bad for 7k? Probably badly matched cells at manufacturing time caused it. What is cell 8 voltage at balancing voltage?
 
wingnut771 said:
80% isn't that bad for 7k? Probably badly matched cells at manufacturing time caused it. What is cell 8 voltage at balancing voltage?
Click to expand...

No probably not but after seeing the CFE batteries for so cheap it doesn't feel like a decent deal.
 
DTBA said:
If you really want to check open up the pack. Top balance all the cells to 3.65v with bench power supply.

Run the battery down.
Click to expand...

I might actually do this. I have a dc to dc buck converter I can use.
 
@cavedog, why you wowing about running as normal and doing nothing for a week and observing before removing headlights out of cars or wiring up dc-dc converters?
 
wingnut771 said:
@cavedog, why you wowing about running as normal and doing nothing for a week and observing before removing headlights out of cars or wiring up dc-dc converters?
Click to expand...

Because there is a clear imbalance of close to 500mV. That imbalance won't go away especially with a pacebms passive balancer when the ovp kicks in. I need to reduce voltages etc and then that affects my other 2 batteries in parallel.

So I want to just manually balance it as best I can today especially cell08 that is a problem and then use it from there because cell08 keeps giving me the uvp disconnect when the other packs are at 30%.
 
cavedog said:
Because there is a clear imbalance of close to 500mV. That imbalance won't go away especially with a pacebms passive balancer when the ovp kicks in. I need to reduce voltages etc and then that affects my other 2 batteries in parallel.

So I want to just manually balance it as best I can today especially cell08 that is a problem and then use it from there because cell08 keeps giving me the uvp disconnect when the other packs are at 30%.
Click to expand...
Sorry, didn't know you were in a rush. What method you going to use?
 
wingnut771 said:
Sorry, didn't know you were in a rush. What method you going to use?
Click to expand...

Charge the battery to full until the first cell hits ovp. After that set my dc buck to 3.6v and hit the cells with 3amp one at a time until they are all balanced and then see how the pack performs after that. Then I will be able to let the balancer do its natural duty.
 
wingnut771 said:
Sorry, didn't know you were in a rush. What method you going to use?
Click to expand...

Balancing plan out of the window.... These aren't prismatic cells o_O :cry:
 

Attachments

  • 20260524_142531.jpg
    20260524_142531.jpg
    334.2 KB · Views: 12
cavedog said:
Balancing plan out of the window.... These aren't prismatic cells o_O :cry:
Click to expand...
Should still be 3.2V cells. Prismatic is just a form factor like pouch and cylindrical.

That layout is melting my brain though? 12P5S, 5P12S? That doesn't math out to me. What does multimeter say? Cell 8 should be 3.2V x 8 right?
 
wingnut771 said:
Should still be 3.2V cells. That layout is melting my brain though? 12P5S, 5P12S? That doesn't math out to me. What does multimeter say? Cell 8 should be 3.2V x 8 right?
Click to expand...

Yeah its confusing me too because I was expecting to see 8 of those cells in parallel x 16 for 16S config that is what the BMS has. Since this is the bottom I think the leads are on the other side and I did not remove the pack.
 
cavedog said:
Yeah its confusing me too because I was expecting to see 8 of those cells in parallel x 16 for 16S config that is what the BMS has. Since this is the bottom I think the leads are on the other side and I did not remove the pack.
Click to expand...
Need to take 2 lifelines. Ask the audience and phone a friend.
 
cavedog said:
Yeah its confusing me too because I was expecting to see 8 of those cells in parallel x 16 for 16S config that is what the BMS has. Since this is the bottom I think the leads are on the other side and I did not remove the pack.
Click to expand...
What make is bat 3 again? Can you see a cell label?
 
You must log in or register to reply here.
Back
Top
Sign up to the MyBroadband newsletter
X