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a weird problem
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Mon, 04/14/2008 - 03:09
Hey,
I have a question for you all. I have an xmods evo with Lion battery, v2.2 board and numerous alum parts- i but i a good penny into building this car right. It also has 2x2 stacked fets which atomicmods.com installed for me. My problem is when I try and run my vehicle it dies out after 10min. I thought i had binding issued in the front and rear differentials but I proved that wrong. So i though my wiring was not corrct, but its correct. So i took the motor and held it outside not touching any gears and letting it rip wide open- it winds down in rpm and just quits. this has happend on two motors! any ideas on wtf is going on here?
That's a little quick for regular "dumping"...
Check your li-ion voltage value when charged...that's the first thing I'd check at this point.
i put a stage 2 motor with this setup and i am still getting the same results. a dead motor. What do you reccomend as a solution to this problem? how do i regulate the power so it does not burn out my stuff. its a 7.2 v lIon pack. i run the motor for 10 sec before it dies.
It is very likely that that is what you are experiencing...the T2 and z2 are very high draw rate motors.
I assume since you went the Atomicmods route you have their flat pack li-ion which unfortunately doesn't make a solid performing pack for the setup you have(v2.2 and Z2 motor).
With the Evo line of xmods you're limited to specific size li-po...E-Tec used to have a great 700mAh cell that discharges at 10C. 7amp is just barely enough discharge for this setup to make it run well but you'll still only wind up with 25min runtime maximum.
Live with the flat pack and runtime you have or start researching some other choices. If i was to go the economy route I'd switch out motors to get better runtime and decent speeds. Even a stage2 on a v2.2 board is pretty fast. :wink:
good luck.
For the motor i have an atomic Z2 high current motor. THe batteries are about 6months old and have been used for a total time of less than 10min. it's a 7.2 LiOn flat battery pack. Yes it will free roll if i push, all of the gears seems to be working flawlessly. NO excessive noise that i have noticed in the time i have been able to run it.
To be honest i don't know why there are stacked fets, atomicmods installed the electronics and serviced it and sent it back in this condition..
Suppose you are correct about the voltage dump, how would you remedy this problem?
Im in agreement with CowboySiR. You'll prolly have to do an in-line current test while the throttle is open. However, battery drain sufficient to knock out a full charge quickly will also heat the batteries enough to determine by touch.
How old is the power pack in question? Keep in mind the age of the Ion pack. They only keep a full charge and give good performance for 2-3 years after the original factory creation date. Following that is a slow decline in performance in charge capacity and potential current output. At a certain point the chemistry of the battery breaks down, weakening the battery's potential. Exposure to heat will aggravate this scenario, shortening the overall life of the cells even more.
Aside from that.....
What motor is in the car?
Does the car free-roll when you give it a slight push, or is there friction?
Is the car making excessive noise?
Hope that helps. - mech
I'm confused as to why you'd have stacked fets and a v2.2 board but you may want to find out:
1. Final charge total of your li-ions
2. Amp flow rate of your system.
For the most part, if you have a high draw amp rate on your xmod you may be false dumping your li-ion pack. They are not meant for high output applications since they usally only have a 3amp max output(as an example).
Soemthing for you to research. :wink: