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capacity testing Large format cells
#11
Nice going Carel!
Appreciated it very much...
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#12
(01-28-2020, 06:02 PM)Mazlem Wrote: I got an iCharger x8 to test my 25Ah cells in batches of seven.  ~5.5hrs to test about 125Ah at a time and it's been rock solid.

I am looking at the x8 glad to hear it works great, although I could get by with the x6.

later floyd
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#13
I have an iCharger x6 and love it. I didn't know of the x8 when I bought the x6, or maybe it wasn't available yet. Either way, both are a great choice for testing large format cells or large battery packs. I use it to test my 300p batteries at 30A with the regenerative mode Smile
floydR likes this post
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#14
How many AH are the 300p packs? A lot I bet

Later floyd
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#15
A couple of years ago I tested 400+ LTO pouches, 55 AHr each, using this discharge tester:
[Image: EOeN07k.jpg]
Sourced from ebay; same vendor no longer active, but similar units still available for under US$20 each.
I bought 16 of them and mounted in pairs, all powered from one lab power supply:
[Image: jJmj5gc.jpg]
Discharge is up to 10A, up to 60W (I never used them beyond ~25W). They beep when discharge to a selectable voltage is finished.
Then they display the total amp-hrs and watt-hrs discharged, and the average voltage.
In between discharge tests I charged the sixteen cells per batch connected in series, using the Chargery BMS-24T, which I found worked quite well. Here is a picture of a stack of pouches being charged:
[Image: p0R964b.jpg]
Note the plastic sheet insulators between alternate electrodes! Also how I numbered the clips I used to extend the Chargery's leads, and a bit of color coding that helped me avoid errors at connection time (as you all know, cell testing can be mind-numbingly tedious and repetitive!). The larger red and black insulated clips are simply joining pairs of + and - electrodes in series; so alternate pouches are flipped upside down.
I recorded the data using a rudimentary OpenOffice ODB database:
[Image: G4jlDUH.jpg]
This database accepts multiple discharge session entries per cell, using the cells' serial numbers to identify them. So afterwards I could summarize the max, min, and average AH for each cell, from which I develop a sorting list to ensure each "supercell", or block, gets the same average AHrs as the others (I think of this like choosing team members for school-yard sports teams; you want to have an equal mix of strong and weak players on every team).

I have more photos showing a bit more detail of the construction of the discharge rack, in case anyone wants to see.
So to answer the OP's question, these little ebay dischargers worked well for me; and I see there are many new versions available now, with substantially higher power rating, bigger heat sinks and fans, nice enclosed cases, etc.
Jim Jr. likes this post
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#16
Thanks quite impressive
later floyd
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#17
Ok I have an icharger x8 on the way. and some balance leads will need them to test with the 1010b+ at 7 amps.( for my 36volt hoverboard battery tests/36v ups build)

On the BYD batteries need to check individual cell voltage.
A couple years ago I bought this bms:
https://www.aliexpress.com/item/32710469...4c4dAcfK7z

Should I install it on the BYD battery then charge the battery up to 28.8v then test the individual cells?

Charge up each cell to 3.6v then test the cells?

Charge it up with bms installed and if all the cells are balanced call it good, hook to 24v inverter (1kw) with a load and see how long it last?


Later floyd
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#18
I managed to check cell voltages on one battery, not too sure how accurate this is hard to hold the negative lead from my cheap harbor freight multimeter on the negative post.
vt0:26 vt1:22.6
vt2:19.4 vt3:16.1
vt4:12.9 vt5:9.6
vt6:6.5 vt7:3.2
vt8:0.0
all the vt#'s are printed on the circuit board. just a hair out of balance. Almost half a volt.
These weigh 164 lbs about 80 kg something to remember I am not as young as I once was.

Later floyd
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