MaxAmps comparison w/Zippys

[Bondonutz]

Mods dont cringe seeing my name and Maxamps on the same page I'm merely showing some results of the 2 packs against each other.

I have 2 3s 5200mah MA packs that I aquired thru a deal a while ago and have ben useing them on and off the last few months in a 4wd Slash along with 3s 5000mah 30c Turnigys.

Anyway, this last Monday night I used them all during pratice,heats and mains in my 4x4 Slash Ashpault racer (Thread if interested)http://www.rc-monster.com/forum/showthread.php?t=28130
I raced the first and second heat with the MA packs about 55-57laps, and raced the Amain with one of my Turnigys and ran 59laps.

I was chargeing them all today and the 2 MA packs took 4770 and 4759mah where as the Amain Turnigy only took 2680mah ? The MA packs dont quite balance perfectly, the cells are a 3&4 tenths of a volt away from each other where as the 3 Turnigy packs are 4.20v across the board
The MA packs are "like new" still and have ben properly maintained and neither show signs of swelling(yet) The Turnigys were bought in Jan and have 70-75 cycles on each ! I can't help but wonder WTH is going on w/ these packs to use so much juice with exact same truck and set up ????

(yes, I charged all the packs Monday afternoon)


I practiced with 2 other Turnigys but there was no controled run like the others, the power on tap didn't seem any different between any of 5 the packs I ran.

[suicideneil]

Whats the C rating on MA packs? Any noticeable difference in temps between the HK and MA lipos at the end of the runs?

I'd be inclined to do a little testing myself- discharge both packs down to 3.0-3.2v per cell or whatever your charge allows, note mah capacity removed if it displays that info, then do a normal 1c charge and compare the mah put back in again.

All things considered, it seems like the mah capacities are over and underrated perhaps?..

[Bondonutz]

Underrated on the Turnigys and overrated on the MA, Sure I'd believe that

The MA packs are 3490 "surge watts" what ever the hell that means really ?

Temps, yes the MA packs were about 10*F higher than the Turnigys which were 95-97* after each run, even the pratice packs (Turnigy) which I ran roughly 100+ laps were only 95-97*F

With the Castle Blower fan, the motor was only 106* after the longest practice run. I had temps of 160* with this motor befor it was repaired so it obvisously had "issues" prior but def not now.

[Arct1k]

Keep nice - More likely the maxamps might have hit the lipo cutoff early...

[Bondonutz]

Originally Posted by Arct1k

Keep nice - More likely the maxamps might have hit the lipo cutoff early...

Trying
OK, but why both packs ?
The Turnigys were run the same amount of laps and drew half the juice ??????

FYI, I dont have the ESC LVC on. Knowing I will not use the full capacity of the packs and wanting to win at any expense I elected to have it off.

[Finnster]

Well I would say either the charger display is not accurate, the turnigies cut off early, or there was a large energy drain during use of the MA packs. (heat) A larger internal resistance may lead to heat produced while charging also, exaggerating the amt of E that was put back in.

IDK otherwise

how long was the race?

[Bondonutz]

I probably should have waited till I had more info befor starting this thread, If I go race again next Monday I will make a serious effort to make more of a controled test. I will accurately note all findings and repost and hopefully have more to work with to try and make sense of this.
I honestly feel the MA packs just arent up to snuff due to getting warmer but to take 2k+ more E is awlfully excessive ? Since I did aquire them used maybe they are older and used much more than I was lead to believe, anything is possible I guess.

Till the next race ...........

[Finnster]

Yeah, def wierd. GLWTR.

[Bondonutz]

Thanx....

[BrianG]

It will be extremely difficult to provide exact testing parameters when they are being tested in a very loosely controlled environment. A logger would make results a little more useful since there would be hard data which would show relative current/voltage/runtime values. Without that, results are too objective.

Not saying your tests have no purpose Bondo, just that it will be your preceptions. So hope you don't take this post as bad.

[Bondonutz]

I understand Brian, I dont have a logger and didn't plan on buying one so what results I'll be able to collect are going to have to be good enough.

I do have a E-Station Voltage and Watt Meter that I bought early this year but haven't even taken it out of the box, would it's results be viable or of any use for this ?
http://www.sussex-model-centre.co.uk...d.asp?id=25507

[BrianG]

The watt-meter looks like it is good for only up to 100A. Unless you are running HV on a low kv, light/small setup, geared conservatively, you will be hitting peaks well above 100A.

[Bondonutz]

You really think I'll be hitting over 100amps with my set up ?? I dont doubt you but it suprises me a little.

1509 2Y-1820kv running 3s, vehical weight is 6.4lbs w/battery & body geared 50/20

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 50
Pinion Tooth Count: 20
Total Voltage: 11.1
Motor KV: 1820
Tire Diameter (inches): 3.85
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0.018
Spur/Pinion Ratio: 2.5 : 1
Total Ratio: 7.11538 : 1
Tire Circumference (inches): 12.1 inches (307.22 mm)
Rollout: 1.70:1
Total Motor Speed: 20202 RPM
Vehicle Speed: 32.52 mph (52.24 km/h)
Effective KV Value: 1820
KT constant: 0.74 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

[pinkpanda3310]

Have you played with the speed vs amp calc Bondo? If you can predict time taken to top speed and drag coefficient you will get a ball park figure.
http://www.scriptasylum.com/rc_speed/_speed_amp.html

[Bondonutz]

Vehicle Weight (lbs): 6.4
Vehicle Width (in): 12.0
Vehicle Height (in): 6.0
Pinion Tooth Count: 20
Spur Tooth Count: 50
Transmission Ratio: 1
Differential Ratio: 2.8461538461538462
Other Ratio: 1
Tire Diameter (inches): 3.85
Tire Ballooning (in): 0
Drag Coefficient: 0.35
Total Voltage: 11.1
Electrical Efficiency: 85
Target Top Speed (mph): 32
Time to Get to Top Speed: 1.5
Usable Output Power: 425.15 watts (0.57 HP)
Input Power Required: 666.9 watts (0.89 HP)
Input Current Required: 60.08 amps
Motor Torque: 0.24 ft-lbs
Axle Torque: 1.68 ft-lbs
Average Acceleration: 9.54 inches/sec
Acceleration Force: 27.68 meters/sec^2
Acceleration Gs: 0.97 G
Required Motor RPM: 19879 rpm
Required Motor KV: 1791
KT constant: 0.76 oz-in/A