Charging amperage

Hey everyone. I'm new to this and just got a large batch of laptop batteries I purchased from a local recycler. I paid $2 CAD/lb for 67 laptop batteries (51 lbs total), mostly 6 cell but some were 3 and 9 cell and I'm in the process of testing each one.

I have the OPUS BT-C3100 v2.2 and my question is what amperage do you all test with? I'm doing the standard 'charge/test' mode at 500mAh and it's taking a very long time as it will charge the battery to 4.2 and then do a fulldischarge to test its mAh rating.

Do you recommend speeding things up by moving to 1000mAh or more, or do you think getting a second OPUS would be better?

Thanks in advance.

Welcome!

500/1000mAh ist not a current, it is a capacity. mA is the current. This is an important difference, don't mix them up!

Most of us test at 1000mA (1A) charge and discharge, this is something a used cell should be able to do without too much trouble.
The logistics of testing change with the amount of cells you want to process. If you only need a few then one Opus is enough. If you are going to process lots of cells then you want a separate solution to charge the cells and then one or x Opus that only test the cells.

Ooops 1000mAh <> 1A....
1000mA = 1A

Edit:
Thanks for the little correction....

DarkRaven said:

Welcome!

500/1000mAh ist not a current, it is a capacity. mA is the current. This is an important difference, don't mix them up!

Most of us test at 1000mA (1A) charge and discharge, this is something a used cell should be able to do without too much trouble.
The logistics of testing change with the amount of cells you want to process. If you only need a few then one Opus is enough. If you are going to process lots of cells then you want a separate solution to charge the cells and then one or x Opus that only test the cells.

Click to expand...

Aha! You caught me being lazy. I know the difference but clearly I wasn't paying attention when I wrote my post. Thank you for the correction.

1A is good then, OK. I wasn't sure if discharging at a higher amperage would skew the test on the OPUSthat shows total mAh capacity.

That will speed up my testing by double so I'll start there and if I find it's still too slow, I'll get another OPUS or perhaps another similar device.

Thanks again.

Oderus420 said:

DarkRaven said:

Welcome!

500/1000mAh ist not a current, it is a capacity. mA is the current. This is an important difference, don't mix them up!

Most of us test at 1000mA (1A) charge and discharge, this is something a used cell should be able to do without too much trouble.
The logistics of testing change with the amount of cells you want to process. If you only need a few then one Opus is enough. If you are going to process lots of cells then you want a separate solution to charge the cells and then one or x Opus that only test the cells.

Click to expand...

Aha! You caught me being lazy. I know the difference but clearly I wasn't paying attention when I wrote my post. Thank you for the correction.

1A is good then, OK. I wasn't sure if discharging at a higher amperage would skew the test on the OPUSthat shows total mAh capacity.

That will speed up my testing by double so I'll start there and if I find it's still too slow, I'll get another OPUS or perhaps another similar device.

Thanks again.

Click to expand...

Discharging at a higher rate will give you a different result (lower capacity reading). That's not a bad thing though. The important thing is to be consistent with your testing methodology. Use the same model of charger (if you buy more) and charge and discharge at the same rate for all of the cells.

Discharging at 1A instead of 500mA will hasten voltage sag at the bottom and end the test sooner, showing less total capacity. How much sooner will depend on a few factors, including the cell spec and the health of the cell. If the cell was designed to support a 10A continuous discharge, there's not likely to be a noticeable difference between 0.5A and 1A discharge. (Those high drain cells are unlikely to be found in laptop packs though)

Also if your completed project is likely to regularly draw around 1A per cell, it makes sense to test at that level to weed out cells that can't handle it (eg heat up or have a big capacity reduction)

Yes exactly, if you want to get more devices to speed up processing and started with an Opus than stick with that and get more of those. Results aren't always comparable between devices but that is what you need, consistant and comparable results.

Thanks to all that replied. Unfortunately I found a new problem with this charger, namely it overheats when charging/discharging all 4 cells at 1000mAh. I need a fan to keep it cool but it can't blow on the cells which I'm not sure how to do yet.

Have I caught you being lazy again?

While charging it shouldn't get hot, at least not so hot that it overheats and shuts down. While discharging, yes, that can happen as all energy is dumped as heat into the heatsink, which is small and not very well ventilated. The Opus always has a small fan built in. From my experience this thing is extremely annoying due to its noise, you would clearly hear it. Maybe yours isn't working? Or is it and it just isn't enough?

DarkRaven said:

Have I caught you being lazy again?

While charging it shouldn't get hot, at least not so hot that it overheats and shuts down. While discharging, yes, that can happen as all energy is dumped as heat into the heatsink, which is small and not very well ventilated. The Opus always has a small fan built in. From my experience this thing is extremely annoying due to its noise, you would clearly hear it. Maybe yours isn't working? Or is it and it just isn't enough?

Click to expand...

I sure hope not.

When doing a charge/test, I will watch the mA draw and then I see it go 000 which according to others, is a heat issue. The problem is it stops charging/discharging so the testwon't be accurate.

The fan does work, I hear it whirring away so that's all good.

The only odd thing I noticed is the power supply that came with the OPUS. The OPUS shows 12V@3.0A but the output on the power supply shows 12V@0.8A.

I've read in these forums someone saying to get a more powerfulpower supply if you want 1000mA chargingall 4 cells at once.

Not sure if I should have purchased a more expensive alternative.

Its normal but generally its not that of a big issue either. Because will you always pull your 1A out of the cells? if not that doesnt matter that much but the number what you get out matters.

To charge 4 cells at 1A lets say at 4V then you need 16W... 16W at 12V is= 16/12 = 1.3A. But in real life perhaps 1.5-2A. So yes you need the 3A at most when its pumping in the most power it can.

I have 2 x LiitoKala 500, and they only discharge at 0.5A per cell, which as per my calculation will be about double what my real-life discharge will be, so I am completely OK with this.

Zagy said:

I have 2 x LiitoKala 500, and they only discharge at 0.5A per cell, which as per my calculation will be about double what my real-life discharge will be, so I am completely OK with this.

Click to expand...

I think I'm just going to stay at 500mA and let it take longer. I bought a second OPUS to compensate.