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Cheap 4kwh LiFePO4 batteries from Battery Hookup

How did you "balance charge" your 2 BYD's and get all your cells up to 3.6 v without one or more going overvoltage in this knee area? and why are yours staying at VPC of 3.6 when most of the rest of us are reporting an quick drop out of the knee area back down to 3.31 - 3.34 stable VPC as soon as we stop charging?

A couple or three cells in each pack drop by a few hundredths when charging is stopped. If all stayed at 3.6 then overall voltage would be 28.8. Mine are dropping a volt or so from that level when charging is removed.

I am using ISDT T8 and Q8 balance chargers with a DC power supply. They bring the cells up individually to 3.6v and then hold them there until the others are brought up to the same level.

I got my packs from battery clearing house. They stated that the packs were from a decommissioned solar power station and were less abused than the west coast packs. Not sure if that is BS yet or not but all my packs arrived at between 25.3V and 25.9V. They could have charged them prior to shipment but they told me that was the storage voltage and they needed to be balance charged before being put into service.

Here is my thread on balance charging with ISDT chargers:
 
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Here is how to match the packs to each other. (It is going to take a long time, be really be worth it). Put your one BMS on two and only two packs.

Charge them to 53.1 then let them sit there for 8 to 12 hours.

Write down the voltage of each cell. You should notice that the 1st 8 are near one voltage and the 2nd 8 are near a different voltage. Do this same thing with the other sets.

Once you have all the "cell" voltages at a "relaxed" voltage, you should be able to see some obvious differences. Some will be exactly the same and others will be different.

Whatever the others are different at, that is what you match the packs to. It's a lot of shuffling around, but that is why brand new cells perform so much better, they have practically the same internal resistance.

(this only applies to 48v setups)
 
A couple or three cells in each pack drop by a few hundredths when charging is stopped. If all stayed at 3.6 then overall voltage would be 28.8. Mine are dropping a volt or so from that level when charging is removed.

I am using ISDT T8 and Q8 balance chargers with a DC power supply. They bring the cells up individually to 3.6v and then hold them there until the others are brought up to the same level.

I got my packs from battery clearing house. They stated that the packs were from a decommissioned solar power station and were less abused than the west coast packs. Not sure if that is BS yet or not but all my packs arrived at between 25.3V and 25.9V. They could have charged them prior to shipment but they told me that was the storage voltage and they needed to be balance charged before being put into service.

Here is my thread on balance charging with ISDT chargers:
Thanks so much, DarkStar. That is way cool. Great videos also. I like the different charging method your T8 and Q8 charger uses. The ToolkitRC just stops charging once once the first cell reaches the HVC level. It makes way more sense for a charger to hold the cell that reaches 3.6 v first at that level and then bring the others up to the same state of charge. So then given that you can bring all your cells up to 3.6 v and they stay there, what is your battery capacity value when you discharge? PS: I am also using the same MeanWell power supply, its really great.
 
The ISDT units take several days to bring the rest of the cells up to the same level. It does a bulk charge first which takes a few hours but as soon as the first cell gets to 3.6V it cuts way back on the amps and just brings the rest of the cells up slowly, one at a time. That is the part that takes a long time...

I haven't done a discharge yet on these packs. I am going to hook up the 2 charged packs to an outback 48v inverter for the test. Hopefully tomorrow?
 
Only one vendor has been stepping up. techdirctclub.com / bigbattery.com still shafts me.
Sorry to hear that, Picasso. I thought all the vendors were offering rebates or some way to make things right. I assume you have talked to some of their higher ups directly? Maybe by pushing back more you and others will get results. Best wishes.
 
How did you wire your ToolkitRC M8S ? Can you post some picks?
Probably the easiest way to learn how to use the ToolkitRC M8S charge controller is to google it. You will immediately see lots of YouTube videos on how to use this charge controller as well as some reviews. The manual can be downloaded https://www.toolkitrc.com/filedownload/151629 . Be aware that it requires a power supply able to output at least 29.2 v for a 24 v battery to supply input power to this charge controller. You also need to give it a 8S/nine wire balance harness which Will Prowse videos will show you how to hook up. Input and output power is by means of XT60 plugs which are available on amazon with leads that makes it easy to construct power harnesses. That's it really.

Edited addendum: Please be aware that the only reason I bought the ToolkitRC M8S charge controller is because Tom at batteryhookup.com said that is what they were using the charge up the BYD's back in Nov. 2019 when I bought mine. It does the job for testing a single battery but that's about it. I just ordered the ISDT T8 that DarkStar above is using because it appears to have a better top balancing profile.
 
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How did you wire your ToolkitRC M8S ? Can you post some picks?
Here is an earlier picture of my test setup.
 
Just a note to let you all know that after a great deal of correspondence with TechDirect & BigBattery (including all of my charge/discharge and capacity measurements) they were good enough to provide me with another battery unit to make up for the deficit in my usable capacity vs. TechDirect's advertised figures. Will Prowse's intervention on all of our behalf was no doubt highly instrumental. Thanks Will. And kudos to BigBattery for stepping up.
 
sooo, this thread is old, but I am curious if any of you are using the lifepo4 abssm ? and how are they working for you?
 
I have two wired for 48v and they were only down a little bit and I used a 3a e-bike charger. I used a multimeter and charged mine up to 52v. After a few months, they are still sitting there at 52v. I did hook up the stock 24v fans to a 24v converter with a programable thermostat so those fans work. I haven't set them up yet on a property.
 
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