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2 KiloWatt RACER
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Location: Houston
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Acepow 2s1p 5000mah 40C Hardcase Review -
04.22.2010, 11:24 PM
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
Last edited by snellemin; 04.22.2010 at 11:26 PM.
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RC-Monster Aluminum
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Posts: 522
Join Date: Jan 2007
Location: Sussex, England.
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04.23.2010, 05:52 AM
Nice cells, a 13 min run without the voltage dipping down to 15V is pretty decent.
Hot Bodies Lightning 2 Pro carbon, Mega 22/30/2, MMM, 4s3-5Ah.
Tamiya F201 carbon, Mamba 7700, MM, 2s A123 2.3ah.
Xray XT8, 1518, MMM, 4s5Ah.
Lots of boats.
fastelectrics.net
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Guest
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04.23.2010, 05:11 PM
Where did you get these batteries? they are hard to find..
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2 KiloWatt RACER
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Join Date: May 2007
Location: Houston
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04.23.2010, 05:29 PM
I got them from the owner of Formuladrc.com. He's planning to sell them in the near future.
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
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2 KiloWatt RACER
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Posts: 2,496
Join Date: May 2007
Location: Houston
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04.27.2010, 12:04 AM
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
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RC-Monster Admin
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Join Date: Nov 2005
Location: Des Moines, IA
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04.27.2010, 12:12 AM
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...
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2 KiloWatt RACER
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Location: Houston
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04.27.2010, 10:33 AM
I agree. Solid 25C cells.
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
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2 KiloWatt RACER
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Location: Houston
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07.01.2010, 12:44 PM
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.
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
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Guest
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07.03.2010, 05:44 AM
Quote:
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...
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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.
Last edited by alport; 07.03.2010 at 05:47 AM.
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They've been naughty boys, havent they Mr. Flibble
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Location: Devon, England
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07.03.2010, 10:17 AM
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.
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RC-Monster Carbon Fiber
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07.03.2010, 10:45 AM
where are you getting the a123 packs?
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They've been naughty boys, havent they Mr. Flibble
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Join Date: Feb 2007
Location: Devon, England
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07.03.2010, 10:53 AM
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 ).
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Guest
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07.03.2010, 12:56 PM
Quote:
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.
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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.
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They've been naughty boys, havent they Mr. Flibble
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Join Date: Feb 2007
Location: Devon, England
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07.04.2010, 07:09 AM
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.
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2 KiloWatt RACER
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Location: Houston
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05.11.2011, 11:55 AM
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.
6 KiloWatt A123 Racer
GTP-Pletty Big Maxximum+RX8. GTP-C50-6L Hacker+RX8. CRT.5-Pro4+ZTW esc.
24s2p EVG SX 49.6mph Ebike.
18s4p Raptor 60mph Ebike. 11.5KW
Last edited by snellemin; 05.11.2011 at 01:07 PM.
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