Acepow 2s1p 5000mah 40C Hardcase Review

[snellemin]

I used the 2s1p 5000mah in my big Flashlight and I could see in the dark. Was pretty cool for 20 minutes, when I figured that I still had my dark sunglasses on.
I tested the 2 packs in series in my Rustler. Gearing was set at 58/25 with a Tekno Neu 1400kv 1512 motor. I need swap the motor out or increase my gearing to bring the load out. I peaked at 80Amps which is quite embarrassing for me. I mean I'm used to 180+ amps with my A123's. But that is due to me swapping out the heavy beadlocks for those lightweight Jaco's.
At 80.14A, voltage was at 14.9! Peak watts was at 1214W. Not too shabby, but I want to see something higher than that. More will follow.

[nativepaul]

Nice cells, a 13 min run without the voltage dipping down to 15V is pretty decent.

Where did you get these batteries? they are hard to find..

[snellemin]

I got them from the owner of Formuladrc.com. He's planning to sell them in the near future.

[snellemin]

2268Watts!!! Finally did it.

[BrianG]

Hmm. Judging by the amp vs voltage peaks, I would personally rate those as "solid" 25C, 40C burst cells. 181A @ 5Ah is 36C and the voltage fell to under 3v per cell. But that's just my opinion...

[snellemin]

I agree. Solid 25C cells.

[snellemin]

I forgot to update this thread.

I used the 2 5000mah packs in series in my GTP in a dragrace. ONE pack didn't make it after a few rounds. I swapped in my 4s2p A123 pack instead and the feel in power at launch is greater compared to the Acepow packs.

So I opened the pack at home and found the cells were nicely labeled with the Acepow brand. The cells were not one bit swollen and each cell had voltage. There was just no voltage at the output bullet. The copper trace right beside the bullet connector was burned off. Slapped some solder and pack is as good as new.

I'm still waiting for their 4s1p hardcase pack to arrive and see how well those behave.

Originally Posted by BrianG

Hmm. Judging by the amp vs voltage peaks, I would personally rate those as "solid" 25C, 40C burst cells. 181A @ 5Ah is 36C and the voltage fell to under 3v per cell. But that's just my opinion...

How can we rate C ratings according the graphs? Is there a calculation or some tricks?
I'll get a eagle tree data logger soon and try to get some info for analysing it's graphs.

[suicideneil]

There is a simple enough calculation, you just need to decide on what the minimum voltage the cells should hold- 3.2v per cell is recommended as the cutoff point generally, so thats what I tend to use. So ....

When you have a good graph showing the voltage level & current drawn, and you know the pack size/ cell count, you can work out A) the voltage per cell at any given time ( total voltage / cell count = voltage per cell ) and B) what the C rating is based on the amount of current drawn divided by the rated mah capacity of the pack ( say 100amps / 5amps ( 5000mah ) = 20c @ whatever voltage level per cell, obviously above ~3.2v ideally in order for the C rating on the packs label to be concidered at all accurate ).

You can also use the maximum ( current draw ) & minimum ( voltage ) figures provided by the 'dashboard' display of the Eagletree unit to get a snapshot of how the pack performs- with the displayed values you get a worst-case scenareo of how the pack performs; usually these numbers are generated from bursts/ peaks, and can sometimes be a little misleading ( warm packs perform better than cold ones for example ), but are generally pretty sound.

[sabongi]

where are you getting the a123 packs?

[suicideneil]

Ebay, Hobbyking, most larger online stores carry them- its cheaper to build your own though from loose cells & then add your own balance lead/ harness & power wires ( I used dewalt packs and harvested the cells, bought them a few years ago from a member here who had a contact working for dewalt so he could get cheap battery packs ).

Originally Posted by suicideneil

There is a simple enough calculation, you just need to decide on what the minimum voltage the cells should hold- 3.2v per cell is recommended as the cutoff point generally, so thats what I tend to use. So ....

When you have a good graph showing the voltage level & current drawn, and you know the pack size/ cell count, you can work out A) the voltage per cell at any given time ( total voltage / cell count = voltage per cell ) and B) what the C rating is based on the amount of current drawn divided by the rated mah capacity of the pack ( say 100amps / 5amps ( 5000mah ) = 20c @ whatever voltage level per cell, obviously above ~3.2v ideally in order for the C rating on the packs label to be concidered at all accurate ).

You can also use the maximum ( current draw ) & minimum ( voltage ) figures provided by the 'dashboard' display of the Eagletree unit to get a snapshot of how the pack performs- with the displayed values you get a worst-case scenareo of how the pack performs; usually these numbers are generated from bursts/ peaks, and can sometimes be a little misleading ( warm packs perform better than cold ones for example ), but are generally pretty sound.

Sorry my english is not well and couldn't understand second paragraph. Can you please explain it more simple. BTW I know what C raiting is.

[suicideneil]

I'll try my best:

When you know the number of cells in a lipo pack, you will also know the total voltage & the fully charged voltage of each cell- in this case 16.8v & 4.2v per cell. When you look at the graph, you can see where the big spikes in power happen ( massive current draw, in amps ), and at the same time on the graph, you can see how the total voltage drops. By comparing them together you can work out the voltage of each cell as it is heavily loaded ( by the current draw ) by dividing the total voltage at that point by the number of cells ( say, 13.19v / 4 = 3.29v per cell ).
You can also work out a fairly accurate C rating for the pack based on the current draw at that point in the graph too. In this case its 150amps ( the maximum current pulled during that run ) divided by the pack's rated capacity of 5amps ( 5000mah ), so 150 / 5 = 30C, since the C rating is just the rated capacity multiplied by how much current it can produce before the cell voltage drops below a certain level. In this case the 'certain level' is 3.3v per cell, an acceptable level in my book, though it would be nicer if it was a little higher ( its always nicer.... ).

Hope that makes a bit more sense.

[snellemin]

I'm using these batteries on my Ebike now. I wanted to know about safe these really are. So I sacrificied the 2s 5000mah Acepow and charged it in parallel with a 4s pack. The 2s pack didn't even puff up. No drama whatsoever. The cells are dead now, but I feel safer running these batteries.


Update:
I cracked the pack open and the cells were a bit puffy, but not enough to crack the pack open by itself. On further inspection, I noticed the copper traces on the pcb board where blown. Soldered them back together and the pack is good as new. Well sortof.