Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
testing the batteries/cells out of an LG Chem RESU-7H system
#1
testing procedures wouldn't be much different than testing a 18650 7s pack?

The individual cells are LG jh3 in 7s configuration out of the LG Chem RESU-7H ESS I picked up last weekend. I have multiple packs that won't charge on the X8. Out of the 6 packs I may have two that will sorta charge, the rest are all very low voltage. The average voltages is 8.5 volts. so barely above 1 volt. The cells are 63  amps each when new.

I made an balance connector adapter  with an 8s connector (9th wire cut off) to the two 4 wire connectors used on the packs. and tried charging two packs one of the sub 8v and 1 @ 10.22v  the 10.22 pack charged to 15v in about 15 minutes it is now sitting at 14.5v, I charged it last night just  to see if it would charge.

Would this work and would it be safe?
Alligator clips connected to a plastic/wood 18650 cell then placed in a dumb charger may work. I can remove the covers at either end of battery exspoing the 7 cells.

Even if none of the 6 battery packs can be recovered I have 2 heavy aluminum cases. The larger side for the batteries and the smaller side for a charge controller/solar inverter charger might fit.

later Floyd
Reply
#2
^^ ^ The 63A rating must be for a pack (vs. cell), since these are surely energy (not power) cells. Do you have a photo of the label on the cells?
Reply
#3
Lipo single cell let me take a photo. very little writing on the cells The 63A is from the specs on the LG Chem RESU-7H which could be different as I think theses were prototype systems. I  dropped the h in Ah. My mistake
6s7s batteries connected in series  feeding a dc-dc converter that boosts the voltage to 350v-550v for use with storage ready Grid tie inverters.
back of the pack
  front of pack with only writing on the cells
side view of the pack
 later floyd
Reply
#4
Wow, your pack was in much better condition (higher voltage than mine. And that's saying something with how low your cells are...

My highest cell isn't even 1.0 volt.

Charge, the cells slow. Watch carefully for hot ones or run away voltage on single cells however you do it.

I'm not familiar with 18650 chargers, but are the negative or positive connections bused together? That wouldn't work for a pack already built in series.

Did your DCDC have a prototype sticker?
Reply
#5
(07-19-2020, 06:07 AM)400bird Wrote: Wow, your pack was in much better condition (higher voltage than mine. And that's saying something with how low your cells are...

My highest cell isn't even 1.0 volt.

Charge, the cells slow. Watch carefully for hot ones or run away voltage on single cells however you do it.

I'm not familiar with 18650 chargers, but are the negative or positive connections bused together? That wouldn't work for a pack already built in series.

Did your DCDC have a prototype sticker?
Right now I have put up the batteries for the night. I have three of the batteries charged to17v-17.50v, I probably restarted the charger 100 times the x8 has a pre charge that only charges when the cells  are real low. only runs for 3 minutes.@.01 amp

I thought about that after I posted. Would have to take the batteries apart  to charge a single cell.

Yes the dcdc converter has a prototype sticker on at least one of  the units.

Btw I ended up with three LG Chem top covers.
later floyd
Reply
#6
I concentrated one one battery today. charging it on the pre harge settings till 9 am then had to run out to my parents, got back around 3 pm.

when I left this moning the battery was sitting at 20.95v ish after6 hours it was 20.896v three more cycles of the precharge and the charger switched to the chargong program for "lipo @2A" at 21.45v. going to charge it till 24v checking every 5 minutes. the cells look to be charging pretty much equally only 15 mv difference @22.104v.

I am happy about the way the batteries have responded. Will charge till this one is 24v then take the next and charge it to 24V. so on till they are all charged to 24v

Later floyd
Reply
#7
Be very careful. Generally LiPos don't handle well such severe overdischarges. Even though these are high-end cells likely with chemistry tweaks to improve safety, if you notice any swelling or other anomalies then immediately stop charging. In particular don't charge them unattended (e.g. an RC hobby shop owner stepped out for 10 minutes while a lipo was charging and it burned down his shop)
Reply
#8
every 5 minute checks and are about 10 feet from me 2 amps is about .30 C , I check them more often that 5 minutes more like 2.5 minute intervals. have stayed the same temp since I started charging again this afternoon.
Later floyd
Charged up to 24v in a bit over 2 hours now charging the next one start 17.68v
Reply
#9
More testing
LG Chem RESU-7H ESS test procedures
1) Took the heavy aluminum Case apart so I could get to the batteries, DC-DC converter and wiring. smell check burnt wiring smell, leaky battery smell

2) Disconnected the DC-DC converter from batteries. Removed dc-dc convertor.

3) Removed the series connections and the balance leads from the batteries

4) Removed the batteries checked for swelling cells, leaking cells


5) tested the voltage of the batteries 3@~10v , 3@~7v-8v.

6) Was able to charge the ones at 10v slowly to 21v by using the pre-charge funtion of the Icharger x8 at first 3 minutes at a time@.09-.1 A at a time, later Iincreased the pre-charge time to the max 5 minutes and also increased the amperage to .5 A.

7) first three batteries charged to 21 volts at which time the icharger switched to a 2A charging progrm. I stopped the charge at 24v,

8)The last three were a challenge. I connected The last three in parallel hooked the x8 to the top postive post and the bottom negative post this shouldn't have worked but it did. I ran the pre-charge 2 times. I now had a fourth battery that charged up to 24v.

9) On the last two batteries the x8 would not work voltage too low even for lipo pre-charge to work. I needed to figure out a way to raise the voltage just a little. what I decided to do is charge for 2-4 seconds on the NiMH setting on the x8 balance leads still connected. That raised the voltage to above 10v didn't need much less than hslf a volt. Probably not the way to do it, but it worked.

10) I charged one of the last two batteries last night to 19v and the other battery is now charging should be around 21v by the time I have to leave to pickup a friend.
11) 21v for 7s lipo is the magic number for the normal charging programs to work and all the cells need to be above 3v. or it will stop. Once both these conditions are met the precharge program switches to the normal charging program.

12) Once all the batteries are at 24v I will charge them to 28.7 and do a discharge test with the x8.

I did some recalculations today and it appears 63Ah is wishful thinking. For 7000 watt/25.2/6= 46.3 Ah.
Later Floyd
Reply
#10
For step one, did you have burnt wiring and leaky cells? Not sure I'm reading that correctly.

And congrats on getting them all up to a healthier voltage! I haven't been back to mine since tearing it down (and finding see very, very low cells)


I'm not sure the math is that simple, I wonder if LG included losses from the DCDC in the kwh reading? I think the 63Ah spec comes directly from the individual cells, but I can't find a spec sheet for these cells.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)