Alltrax AXE 4865 Is it toast?

[DaveTM]

It's always harder than it looks....and then there are times you just make it harder!!

I wanted to bolt the new controller onto the existing (factory I assume) aluminum heat sink. I measured two existing holes and they lined up with the wide two hole mounts on the new controller. But I looked and figured I needed to drill\tap the other two holes as I didn't see any.

Now, the existing heat sink was likely installed by the factory....it's aluminum and the bolts are....were steel. After 20 years the steel bolts were pretty much welded on the aluminum heat sink. So, the 4 bolts holding it on snapped right off. Some drilling and tapping new holes worked fine....and the BEST part (not really) was there were existing holes already drilled 'n tapped!! But, so full of crud\mud that I didn't see 'em. So....yeah.....it wasn't necessary to remove the heat sync to begin with.

I reviewed and changed the new controller settings....or so I thought....to have a higher HV cutoff and LV cutoff of the pack voltage.

After swapping out the controllers, then hooking everything up....had to make a longer cable from the solenoid to the B+, and fortunately I had some cable and cable ends in my stock of "stuff".

So, after everything was hooked up, I turned on the key....got the correct voltage reading on the digital key read out, but when I press the go peddle I got 4 green blinks, followed by a pause, then one green blink and three red blinks.

If I read the codes right that is a "overcharge" signal. I'm running lithium which is higher voltage than FLA's and my guess is (cause I'm to tired to hook up the laptop tonight) the HV setting went back to the pre-set, which is below the current 56V pack voltage.

I'll have at it tomorrow.

[DaveTM]

Got everything buttoned down and then time to test the setup and then go for a ride.

At first, in the "Controller Settings" tab, I set the max amps from battery to 300amp. I set the max motor amp to 325. I left the Throttle Rate at it's existing setting of 12.5%.

Took it for a short ride and it wouldn't climb a short, yet steep hill. Hmmmm....Ok.

Then set the Throttle Rate of 100% (from the 12.5%). Took the same short ride, and again....could not climb a short steep hill.

Then, set the Max Motor Amps to 500. Took the same short ride and "snorted" up that little hill like it was nobodies business!!

But I did notice that the first 20% of go peddle did nothing but engage the solenoid (click), but the cart went nowhere until the peddle was (my best guess) pressed past 20%. Well....that won't work when I'm starting from a dead stop on a steep hill.

So, I begin looking at the Speed Curve and the Torque Curve.

I'm thinking it's the Torque Curve that was the issue, so I set the TC to almost vertical on the first 4 graph marks. That didn't do much of anything...well some fast torque engagement when the throttle did engage.

So, I look at the Speed Curve. The lowest left position was set at "0", "0" which makes sense. But the second was "2","0" and finally at throttle position 13 the speed was 5. I found the culprit. So, I changed the "Linerized Throttle Position" of "2" to have the speed of "10". And the rest I engaged the speed number higher as the peddle was pressed more.

That worked great....except now when I did a "slow" start the cart was very jerky. This was because I had the torque numbers set to high when the speed was low. I don't recall the numbers at this point, but I backed off the torque amount at the lower speeds and now I have a smooth start at low speeds.

I may mess with it a bit further as I drive it more, but all is good and it's working like it always has!!

[Volt_Ampere]

I like it that with Alltrax you can fool with all of those parameters. It takes some testing to get it optimum. I would be a bit careful with max current set real high as it will fry the motor if you use it for more than a real short burst.

[JohnnieB]

There is a hierarchy to the throttle curves. Linearization is topmost, then the speed and torque curves. (Don't know, but the last two may be at equal levels and they don't interact much, if any.)

I have my linearization adjusted so I can push the pedal halfway down and only get 30% throttle. Better control at low speeds and helps me maneuver in tight places.

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Max Battery Amps limits the amps drawn from the battery and with Lithium batteries it may have to be toned down from the SR's max amp ratting.

On the other hand Max Motor Amps can be turned all the way up to the SR's max rating since Motor amps exceed Battery amps when the throttle is less than 100%.

That may sound strange, but it is true. Amps are only drawn from the battery when the MOSFETs are conducting, but the magnetic fields collapsing in the motor when the MOSFETs turn off causes amps to continue to flow in the motor circuit via a network of freewheel diode. The net result is motor amps exceed battery amps until the PWM output of the controller reaches a 100% duty cycle, or straight line DC instead of pulsed DC. (Attached page from the Curtis 1204/5 manual explains it better)

I've seen my motor amps read 525A while the battery amps were 350A.

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Play with it some. See the effects of the different adjustments. It'll take some time, but you'll be able to tweak it into just right for your needs.desires.

[DaveTM]

Well.....I get kind of a headache when reading the technical "stuff"....but what you have just explained is right in line with what my Son explained to me. (He's an engineer) I told him to use the KISS principal with me or I'd talk back in tax code.

Plus....it sort of makes sense to me that setting up the motor amps to 500 and the battery amps to 300 on the SR is very similar to the setup I used on my old AXE controller. I set that controller up to 40% of max. Being a 650amp controller that would limit the battery amp draw to roughly 300 amps (really 260) and the motor would demand whatever it wanted to, but the batteries would only allow the max (300amps) I set it to.

I know I will tinker with the speed\torque settings a bit more before I get finally happy with the results.