# Altrax 7245 Controller / Drivability Woes



## eRev (Jan 10, 2009)

Under heavy throttle my (72V) eBike pulls around 450amps and tops out fine - no shutter or dead spots in speed - all battery cabling checked for tightness no hot spots - I cannot inspect inboard battery terminals w/o significant effort but judging from the rest the problem is not connection to battery or motor.

Using a 0-5k pot twist throttle - it gets shunted under braking - when throttle is held staionary my eBike will not maintain steady-state speed w/o surging as the load varies from say road undulations or wind buffetting - feels to be too much IR Comp but it cannot be tuned with the throttle response slider controls on the configurator (PC app provided by Altrax).

It's not a throttle issue seemingly unless it is noise but me thinks not - the controller reponse to throttle is very repeatable - it has too much intial speed-overshoot when the load is applied.

A linear throttle profile selection is too abrupt at zero speed - the only option that works is the exponetial profile and the speed-position slope is quite steep under the speed conditions the surging occurs which generally is anything over 20mph.

I emailed Altrax to no avail - they tout customer service is priority so maybe I should call but way busy at work so hoping to tweak someone's ear on this forum for help instead.


----------



## major (Apr 4, 2008)

eRev said:


> Under heavy throttle my (72V) eBike pulls around 450amps and tops out fine - no shutter or dead spots in speed - all battery cabling checked for tightness no hot spots - I cannot inspect inboard battery terminals w/o significant effort but judging from the rest the problem is not connection to battery or motor.
> 
> Using a 0-5k pot twist throttle - it gets shunted under braking - when throttle is held staionary my eBike will not maintain steady-state speed w/o surging as the load varies from say road undulations or wind buffetting - feels to be too much IR Comp but it cannot be tuned with the throttle response slider controls on the configurator (PC app provided by Altrax).
> 
> ...


Hi Rev,

Are you running in torque control? Some controllers have a selection parameter. It sounds like maybe it is in speed control. If so try torque control.

major


----------



## MalcolmB (Jun 10, 2008)

I believe the original (AXE series) Alltrax 7245 is speed control only. I used one on my motorbike and had similar problems with poor control at low speed. The bike would also seem to surge as you went over bumps and involuntarily moved the throttle very slightly. It's not ideal for a motorbike, though you can improve it a little by softening the throttle ramp setting.

The new Alltrax SPM controllers let you choose between torque control and speed control. I've been looking for feedback from users, but not found any yet.


----------



## eRev (Jan 10, 2009)

Indeed - the throttle position sets up a speed reference - no joy on selection parameters for the axe series as mentioned but today I did revert back to linear throttle profile and bumped the throttle high-side response to the lowest setting and I was able to compensate and hold steady speed with very close focus now to startup situations - not ideal but mo-drivable.

One of my very first posts on this forum went unanswered until now re: torque control. The altrax product is rather bullet-proof and it sounds like there is a path for improvement w/ the SPM series (they will sell me on new before helping me on old - don't ask how I know).

My wallet isn't happy about this but dang good place to float such woes - per usual I appreciate the knowledge base on this forum.


----------

