# PowerLab 8



## Zak650 (Sep 20, 2008)

I've been using mine for processing my A123 cells, a great device I agree. 

When you charged your 100ah cells to 3.0 volts and then discharged them to 2.6 volts how long did it take to discharge a single cell to 2.6 volts from the previous 3.0 setpoint?


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## Jozzer (Mar 29, 2009)

Best of all is most of the energy is recycled - when you've got a large batch to do (I tested around 250kw/h of cells so far this year) it saves a fortune and is very green


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## onegreenev (May 18, 2012)

Zak650 said:


> I've been using mine for processing my A123 cells, a great device I agree.
> 
> When you charged your 100ah cells to 3.0 volts and then discharged them to 2.6 volts how long did it take to discharge a single cell to 2.6 volts from the previous 3.0 setpoint?


Not long at all. The discharge was at 10 amps then finished at C/20 rate. The first part of the graph is where I charged to 3 volts then from the point it drops to finish is the time for discharge and that is a discharge that includes a CC/CV discharge curve. I could have just discharged it at 10 amps without the CV portion and the graph would not have the curve. I wanted to be sure it was at 2.6 volts at termination.


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## DIYguy (Sep 18, 2008)

I think it's the best unit on the market at this time. I just bought my second one a couple days ago. I've tested, balanced and charged both smaller cylindricals and larger prismatics with mine since last year. 
One word of caution, if you are using it in your car and and have any pack leakage to ground, be VERY CAREFUL with the charge leads. I damaged mine a few days ago and although no magic smoke leaked out, the display is locked up. I knew I had a leakage fault but never tracked it down (until yesterday!  )
If I can recall the event, I had just finished discharging a cell to 2.7 volts for bottom balance, when I removed one of the charge leads. I hadn't "stopped" the process though I don't believe. (removing a lead will not stop it unless you are doing a multi-cell cycle with balance leads and you remove a few of them. . it will fault and quit. . otherwise, you must click "stop"). Anyways, I removed one lead and inadvertently touched part of the frame. I don't recall if it was neg or pos lead, sorry. . but probably doesn't matter. When it touched. . POP! like a short. . .just momentary, but enough to damage it.

I don't know what level of resistance is required between pack and frame and I won't be testing it any time soon. I bought the second one because I can't do with out one. . .while I get my original repaired. (I'll l likely sell the new one when finished my bottom balancing with little use). Hard lesson learned.


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## EVPowers (May 17, 2012)

I just purchased a Prolab8. Are either of you willing to share the charge/discharge profile you are using for the A123 20ah prismatic cells?

Other batteries I have around:
- 2kw of 40ah lithium Thunderskys
- a half dozen or so 39ah Mottcell lithium cells
- 2kw of 20ah RealForce lithium pouch cells.
- several 48v (4 12v) lead acid setups. One for a bike, one for a scooter.
- 72v (6 12v) AGM lead acid batteries. ~100ah if I remember correctly.

Looking forward to playing with this new toy.


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## onegreenev (May 18, 2012)

Do you have yours in your hand yet? Once you do and have it installed then I can send you a copy of what I have but I am not doing my A123 pouch cells yet. I am building custom settings. 

Pete 

Mine are for my 100 Ah Hi-Power cells.


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## EVPowers (May 17, 2012)

I will have it in a few days. Being shipped right now.
I have seen the other guys on the forum are doing for PowerLab6 settings.

Basically charging the cell to 3.65v, then discharging it at 38amps down to 2.25v while keeping compression on it.

I thought I'd start there.


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## DIYguy (Sep 18, 2008)

EVPowers said:


> I just purchased a Prolab8. Are either of you willing to share the charge/discharge profile you are using for the A123 20ah prismatic cells?
> 
> Other batteries I have around:
> - 2kw of 40ah lithium Thunderskys
> ...


There is nothing to share really... There are charge profiles in there already for all the basic chemistries. If you are doing LiFePo, pick one of the "A123" profiles and customize it to what you want. Remember this charger comes from the RC world so, they don't say LifePo, . . for example... 
You'll get the hang of it if you play with it a bit. Set up your power supply first, either P/S or battery and the limits for it. Then go to the Preset tab and customize the voltage and current, for charge/discharge, balancing etc. etc. and u can rename it what you like and save it. 

I've never done the AMP20 cells. I've done a few hundred 8 ah cylindricals and a bunch of CALB prismatics, and some RC lipo, oh and a few pb batts.

edit; oh, and download the PC software and get the USB connection board if u don't have it. It's a free download and makes everything easy to understand, not to mention being able to view the graphs etc....


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## IamIan (Mar 29, 2009)

EVPowers said:


> I will have it in a few days. Being shipped right now.
> I have seen the other guys on the forum are doing for PowerLab6 settings.
> 
> Basically charging the cell to 3.65v, then discharging it at 38amps down to 2.25v while keeping compression on it.
> ...


As others wrote there are some default A123 presets to start with.

Remember the internal discharge is limited to less amps than the regenerative discharge into a battery... and the discharge into a battery is limited by that batteries ability to take the charge under the "Supply" setting tabs voltage and Amp limits.

Mind your good connections when going with higher amps ... and probably not a bad idea to check the resistance of your wires so you know about how much mOhms to expect from them.


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## onegreenev (May 18, 2012)

EVPowers said:


> I will have it in a few days. Being shipped right now.
> I have seen the other guys on the forum are doing for PowerLab6 settings.
> 
> Basically charging the cell to 3.65v, then discharging it at 38amps down to 2.25v while keeping compression on it.
> ...


I would do 3.65 for top voltages for charging but I would not go down to 2.25 volts. No need. No need for clamping either. Clamping will do nothing to save a battery from being over discharged. You will not have bloating issues at 2.25 volts. But if you take it below zero volts and a pretty healthy current you will kill your cell. 

I would go to 2.6 volts for the low voltage and I would bottom balance my cells. Remember that some of the cells will bounce up from that low voltage to about 2.7, 2.75 volts resting. If you then discharge it again to the same 2.6 volt you might get it to stay nearer 2.7 volts resting. Then connect all your cells together and charge to 3.5 or 3.6 for your ending voltage. You will be at about 90% full at that point. 

I will help with a log profile if you need. Be sure your USB driver is installed correctly so your CellLog 8 will see the computer. If you can't save a change in your profiles then your not talking between the cell log and the computer. 

Pete


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## IamIan (Mar 29, 2009)

onegreenev said:


> If you then discharge it again to the same 2.6 volt you might get it to stay nearer 2.7 volts resting.


Could also use the CC/CV discharge option ... That is a common method of trying to squeeze out the last of a cycle.


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## onegreenev (May 18, 2012)

IamIan said:


> Could also use the CC/CV discharge option ... That is a common method of trying to squeeze out the last of a cycle.


That is how I have mine set. CC/CV for both charge and discharge.


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## EVPowers (May 17, 2012)

Well, the PowerLab arrived today but got too much on my plate to be able to play with it today. Guess it'll have to wait. Dang.


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