Newbie battery capacity testing 280ah EVE cells

hammick

Solar Enthusiast
Hey guys. I have 16 280ah EVE cells arriving on Wednesday. I want to test the capacity of each individual cell before I put them together into a 16s bank. I was planning on buying the 150w capacity tester Will recommends from Amazon. If I fully charge a cell to 3.65 volts and set the capacity tester to 140 amps am I correct that it should take 2 hours to pull the full capacity of the battery? (assuming they can deliver 280ah). Four hours if I set the tester to 70 amps?

Can I harm these batteries by taking them down to 2.5 volts for the test? I don't plan to ever charge them to 100% or take them down to 0% once they are installed. I will probably never take them below 20% or above 90% and more like 50% - 80% during the Summer, late Spring and Early Fall (off grid solar place).

Thanks for any advice.
 

hammick

Solar Enthusiast
My dumb ass was thinking the tester could test at 150 amps. It's 150 watts. So I'm thinking it would take 10 hours or longer to test each battery. I'd really like to find something that can test at .2c without breaking the bank.
 
Last edited:

Just John

Photon Sorcerer

cinergi

1.21 Jigawatts
Don't worry about the watts when testing cells. It's amps times hours. So the tester Will recommends maxes out at 20 amps. 280 / 20 = 14 hours. The tester you just ordered is 40 amps, so 7 hours.
(the only reason to worry about watts is if the watt limit is lower than the amp limit. At these voltages, that's typically not true)
 

cinergi

1.21 Jigawatts
... And no, you won't harm them by testing down to 2.5. Make sure your wire is big enough to handle that current without a lot of voltage drop. The test will terminate prematurely under higher amperage due to voltage loss on the wire but it's likely close enough.
 

hammick

Solar Enthusiast
Thanks for the info guys. 7 hours is sure better than 14. I can test two batteries per day or three if I trust it to go unattended.

Getting these things charged back up is going to be a problem. My adjustable CC/CV power supply is only 10 amps. If I had a 40a 12v cart charger could I put 4 of these in series and charge them to 13.6 volts or so as long as I monitor them closely with a good voltmeter?

I can't use my solar equipment to get them charged because it's 1,200 miles away.

Another question. Can I discharge and charge these on their side when doing the capacity testing? I'm thinking stacking 4 on their side and putting a flat plate with something heavy to keep them from bloating.
 
Last edited:

FoxMeister88

New Member
Another question. Can I discharge and charge these on their side when doing the capacity testing? I'm thinking stacking 4 on their side and putting a flat plate with something heavy to keep them from bloating.
Is bloating common/normal on these cells/chemistry?

So I ordered this for capacity testing. More than I wanted to spend but should save a ton of time.

Amazon.com
Have you had a change to test it yet? I have 16 280ah cells on the way and will have to capacity test them as well and would like to do so in the least time consuming way possible.
 

hammick

Solar Enthusiast
Have you had a change to test it yet? I have 16 280ah cells on the way and will have to capacity test them as well and would like to do so in the least time consuming way possible.
Yes. See the Lischen thread:

 

Capt Bill

Sailing Options
So, it has a max current of 40 amps at 3.65 volts. 40 x 3.65 = 146 watts. It's still going to take some time.
here's a less expensive route I considered; would have to run amps through an inverter with load; have not yet tested but looks doable: https://www.amazon.com/gp/product/B07W7XXKVF/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

also purchased a couple of low cost Ah testers on on Alibaba Express that require your own amp draw load, but could draw down battery at up to 80 amps (purchased inspired by Will Prowse Youtube lessons :+)
 

Capt Bill

Sailing Options
I think this is the one will P recommends....
I tried on a similar one of those /a Yecoo (brand name) 10-90V 0-200A ... and got it to measure amps, but sent it back, as it was hard to make work proper by pushing the buttons (especially w poor manual ... Here's a couple of others I purchased from AlibabaExpress, at super low cost /which i have yet to test; ... if you are not in hurry, I thought why not have these on hand for options (inspired by Will P video lessons ... note these are rated 100A, but via Will P's Info, are good for about 80A, plus unlike that 200 Watt fan heater Ah (multimeter) unit (got one too)/ one has to supply your own amp draw, like setting up an inverter draw down on battery. I believe these both have low battery cut outs, but would not depend on that feature until confirming that feature worked:


 

Bud Martin

Solar Addict
I tried on a similar one of those /a Yecoo (brand name) 10-90V 0-200A ... and got it to measure amps, but sent it back, as it was hard to make work proper by pushing the buttons (especially w poor manual ... Here's a couple of others I purchased from AlibabaExpress, at super low cost /which i have yet to test; ... if you are not in hurry, I thought why not have these on hand for options (inspired by Will P video lessons ... note these are rated 100A, but via Will P's Info, are good for about 80A, plus unlike that 200 Watt fan heater Ah (multimeter) unit (got one too)/ one has to supply your own amp draw, like setting up an inverter draw down on battery. I believe these both have low battery cut outs, but would not depend on that feature until confirming that feature worked:


I have two of the $11 one, they do not have load disconnect function when it reaches your Voltage alarm set point, it just gives alarm tone. The one with the fan and heatsink ($30) does have load disconnected when the set point is reached.
 

Capt Bill

Sailing Options
I have two of the $11 one, they do not have load disconnect function when it reaches your Voltage alarm set point, it just gives alarm tone. The one with the fan and heatsink ($30) does have load disconnected when the set point is reached.
I know from personal experience, there is a "cut off voltage" feature on that 180 -200 Watt Fan heater units/... to get a cut off of amp draw at < 2.5v (or whatever you adjust it to); and the amp draw actually stops when it gets down to 2.5v. I also notice I can get a few more Ahs measured if I reduce the Amps drawn (to very low as compared to max), and run the unit again. I thought the others larger amp draw units I listed above had a similar feature; ... thought that from the Will Prowse clip I viewed where he uses them (or very similar), where Will also noted the the 100 amp rated units could only pull 80 amps (are over rated). I thought Will's Ah testing lesson showed a cut off function, but not gona investigate that specific at present/ thinking there might be similar but contrasting models (the $14 looks newer than what Will used, w its' Mobile App function). I really wish it was easier to get the manuals for these Ah measuring multimeters. IMO: a beep only vs stop amp draw cut off would be a huge handicap for Ah Testing. Also: I would want to be there to see the cut off work the first time or few times. I tested my fan heater unit at a higher voltage first (as a failure is risking a LiFePO4 cell kill). Its' great when these units work like you hope they will :+) ... with a second set of 8 cells x 280Ah LiFePO4s on way to my home in California; I think it would be great to see better options, w larger amp draw down ability than those 180 - 200 Watt fan heater units that, IMO: that 200 Watt fan/ heater is practical for single 3.2v battery cell (when you get upward in Ahs Capacity), or possibly a small Ah 12v set (unless you are open to days for a single test cycle). ... Maybe some newer affordable options will show up soon.
... Looking for more options on AlibabaExpress: (searching for: "100A DC digital voltmeter battery capacity") ... this looks interesting to me; while specifics of cut off function is sketchy; I notice info. saying protection function needs an external relay ... & for low price/ looks worth testing https://www.aliexpress.com/item/328...earchweb0_0,searchweb201602_,searchweb201603_
 
Last edited:

Bud Martin

Solar Addict
The $11 or the $14 cannot do the cutoff function becuase it does not have Power MOSFET (in series with the load) to act as switch or power relay to cutoff the load, it has High/Low Voltage, and Over current setting for the alarm. I have two of them and also the one with the fan which is Electronics load (150W version) and it does have load diconnect (the MOSFET on the heatsink is the Load). I will be using the Electonics load one to test single 280Ah battery when I receive them, to test the 12V 280Ah pack I will be using the inverter and hair dryer and have the $11 power meter connected to the batteriy pack output to check the Ah and manualy stop the test when the Voltage drops down to 12V.
I do plan to add the cutoff circuit uisng relay on the $11 power meter..
 

WilliamC

New Member
Ok slightly different question. I have two big batterys inbound. Specs say 24v 170ah. Will says we should capacity test these batteries and send back if they fail. I have not yet purchased any of my other components. I havent eve made the final decision on 24v or 48v yet. I dont want to be rushed into buying an inverter just to capacity test the batteries. What should i buy to be able to complete testing?
Which charger? So i can top out the battery Charge pre test?
What device will provide a 24v dc load and then measure the discharge and shut off before damaging the battery.
 
Last edited:

WilliamC

New Member
Is this any good? Would it work for my stated application?


Electronic load tester 180W upgrade version 4-wire color screen DC tester electronic adjustment constant load meter lithium battery capacity monitor discharge charging power meter check
 

Just John

Photon Sorcerer
Is this any good? Would it work for my stated application?


Electronic load tester 180W upgrade version 4-wire color screen DC tester electronic adjustment constant load meter lithium battery capacity monitor discharge charging power meter check
It's just the updated version that Will recommends for capacity testing cells.
Very easy to use, I'm not sure that the updated color display is worth double the cost. On Aliexpress you can but it for $20 plus $10 shipping, if you are willing to wait a few weeks to receive it.

Will's video explaining how to use it.
 

WilliamC

New Member
than
It's just the updated version that Will recommends for capacity testing cells.
Very easy to use, I'm not sure that the updated color display is worth double the cost. On Aliexpress you can but it for $20 plus $10 shipping, if you are willing to wait a few weeks to receive it.

Will's video explaining how to use it.
Thanks. If will likes it or one like it thats good enough for me. Just to clarify my battery is a sealed 24v 170ah battery so I wont have access to the individual cells unless I want to break the warrantee seal. So I will be using this to test the capacity of the entire battery. Will it work? I do need it sooner so will probably just pay the extra bucks.
 
Top