Maxamps and Neuenergy lipo testing

[lincpimp]

Originally Posted by glassdoctor

lincpimp... I hope you are not using this maxamps pack as a test pack?

It's not likely that the remaining cells are in 100% condition.

Also, the bottom cell in the pic above actually looks like it might be slightly puffed. A good cell is completely flat... no curve to it.

One of those cells has to be swelled...

I had a pack that had a very slight puff to it... barely noticeable. It lasted a long time like that but eventually did get worse and puffed more. That was a pack that got taken out with an ESC meltdown.

I think the non-copper tab is tin, not aluminum...? Alum is very soft and requires special flux to solder.

I am going to run this pack, just to see how it does. All of the the other cells are fine, no bulges, or puffing. I had a good look at them. Plus they were all in balance when I got the pack, a bad cell would lose voltage slowly. I will leave it fully charged and see how it does. The tab looks to be just like MA old cells, and they had al tabs, and required zinc sloder and the correct flux. Plus they were very fragile, and fell off easily.

[Arct1k]

Vehicle is a CRT .5 geared i think 16or18/46 with a 7L on 2.8 talons.

First pack is an old maxamps 5000 3s - Second a used 5000 2s

Now if someone can help me interpret that would be great!

Humbug - done!

[lincpimp]

Chris, any chance you could get a clearer pics of that. I cannot read it!

[lincpimp]

Question, on your 3s run, was that with the 3s pack the entire time? Looking at the bottom of the graph it lists min voltage at 6.11v! Not sure if that is right.

The 2s pack shows a max draw of 105 amps, and a low voltage of 6.01v. If that is correct, then the cells cannot keep voltage over 3.5v at their rated constant.

[Arct1k]

Well the graph is all from that run - I selected session 1 so i would assume the max/min are updated...

[VintageMA]

Looks like the newer 5000 cells were at least able to hold a better voltage than the old ones in the 3S pack - they showed a lot more votlage drops into the sub 10 volt range.

Let's how that Neu pack compares now..........

[DrKnow65]

hhhhmmmmm seems to me that one could do a better test of load vs. amperage with a carbond pile load tester (used in auto applications to load test a vehicle battery). You could hook it up to a lipo (one cell at a time would be best), then raise the amp load until LVC is reached. That would give you a solid number as to what the cell will put out. Beyond that I think you get into (controlled) tests that could potentialy damage the cells.

[lincpimp]

Well, if any of the batteries let go during my tests, at least I will know what not to buy next time.

I will start off with low gearing and slowly try to creap up on the correct load.

[VintageMA]

Originally Posted by DrKnow65

hhhhmmmmm seems to me that one could do a better test of load vs. amperage with a carbond pile load tester (used in auto applications to load test a vehicle battery). You could hook it up to a lipo (one cell at a time would be best), then raise the amp load until LVC is reached. That would give you a solid number as to what the cell will put out. Beyond that I think you get into (controlled) tests that could potentialy damage the cells.

I agree that this would produce a very "controlled" test, but it's also what you usually see in the graphs that manufacturers produce. (And at that - probably from a brand new cell that is in it's best condition) In general none of our buggies are going to run at over 20A continuous and they really high amp draws will be seen during hard accelerations and at top speeds. It's important to me how the Amp draws at top speed effect voltage drops as that's where you'll feel the most impact.

I kinda like this testing comparison as it's showing what these cells will be doing after being run for a while - a little more real-world.

here is what i just did

i ran my truck and i came in and checked V and both of my 2s packs were at 7.5v , my lvc is set at 12.4 so 3.1v/p/c

i decided for fun to try something, i hooked up my volt meter and it read 15v, my truck is on a stand and the wheels were allowed to free spin, my set-up is a mm/9xl with maxamps 2 x 2s 5k lipos wired together , geared 14/46 with heavy basher badlands

anyway on to the good stuff.............

with basically no load my V dipped from 15v to 11.88v under full throttle

i will try this again once i have recharged my packs and my V will be at 16.8V


i will be tring the neu energy packs or at least something rated higher then these in the future, but as far as i can tell a 30c discharge pack would give great runtime and also be better for the batterys, i guess i am pushing these

just tested 5s, same except for battery V

new 20.5v to 14.9 @ full throttle=2.98v/p/c on a fresh charged and balanced battery

i think i just puffed another 5k m.a. today

[lincpimp]

Originally Posted by entjoles

i think i just puffed another 5k m.a. today

Thats sucks, I'll hand you an oar, as we are in the same boat!

What size pack is it?

Originally Posted by DrKnow65

hhhhmmmmm seems to me that one could do a better test of load vs. amperage with a carbond pile load tester (used in auto applications to load test a vehicle battery). You could hook it up to a lipo (one cell at a time would be best), then raise the amp load until LVC is reached. That would give you a solid number as to what the cell will put out. Beyond that I think you get into (controlled) tests that could potentialy damage the cells.

I have done this on my lipo's and they all have come up short. Maxamps 4s6000mah 20c tests at 70 amps @ 12 volts which makes it 11.66c . Trinity Lipro 2s 4500mah 20c tests at 40amps @ 6 volts which makes it 8.88c. The trinity packs I tried to get the rated 20c (90 amps), 70 amps was max I could get and the voltage went down to 2 I only held it there for a few seconds. Basically you could dead short the Trinity packs and 70 amps would be all you would get. I don't have alot of faith in the manufactures numbers.

[lincpimp]

Originally Posted by Cowboy

I have done this on my lipo's and they all have come up short. Maxamps 4s6000mah 20c tests at 70 amps @ 12 volts which makes it 11.66c . Trinity Lipro 2s 4500mah 20c tests at 40amps @ 6 volts which makes it 8.88c. The trinity packs I tried to get the rated 20c (90 amps), 70 amps was max I could get and the voltage went down to 2 I only held it there for a few seconds. Basically you could dead short the Trinity packs and 70 amps would be all you would get. I don't have alot of faith in the manufactures numbers.

Great info! Any specs, or info about your test gear? How was it setup? Any chance of a pic?