Alltrax xct settings

[Cruise Master]

Having my coffee this morning and thinking you're one lucky man to have a wife who complained. That controller as it was delivered to you, with what I'm guessing was a 6,000 rpm best guess limit would turn your motor into a 12 grand grenade if given enough voltage.

If perchance you have that magnet that's in the picture, I would bet it does not have 4 poles in it. If that was the case, now you're sitting on a (best guess) 8-10 grand grenade after you lower the limit to 4 poles.

If you don't want to be called a snowflake then go for it. If you don't want to be grouped into that Darwin pool, then this is what I would consider doing.

Find yourself one of those small screwdrivers with a magnet in the end. They fit in your shirt pocket and can be found in electronic stores. Guessing it will be the perfect size for the next step.

With that magnet slowly move it around the other magnet counting the number of times it either pulls or pushes away. That should give you the definitive number of poles that magnet has. Don't forget to give your wife a kiss for being a snowflake.

[Raystar57]

Originally Posted by Sergio

Is just kind of hard to guarantee a consistent pulse count under high rpms based on the method used to convert the 8-pole magnet to something less than 8-poles....

This is obviously not an issue with a stock OEM controller where it makes no difference as long as the pulse count per rotation is less than 8.


Edit:

To be fair I don't know if this is still their current practice and that is why I recommended that you verify for yourself.

What I don't understand is how many pulses that modified magnet generates.
Also does it mater on the spacing between the pulse counts?
Pics are from standard 8 pole and speed magnet 4 pole.
It seems with that modified grind of an 8 pole it would be generating 2 or three pulses at max.

[Sergio]

Let's put things back in perspective here...

The previous line of Alltrax controllers (DCX) did not use speed sensor feedback.

The OEM Controllers only use the speed sensor feedback to limit the speed.

Lots of folks use speed magnets in their carts.

I don't think this is an issue of imminent life danger but rather how to get the best performance out of the latest technology offered by Alltrax in the XCT line.

The Hall effect sensor used is a bi-polar sensor that once turned ON by a magnetic pole, it requires a pole with the same magnetic strength but reverse polarity to turn it OFF.

The specifications call for a maximum of 0.030" gap between the magnet and the sensor.

The north/south poles can be any distance apart and even if you have:

North-Pole - Nothing - North Pole - South Pole

You will only get one pulse as the "north pole" on the middle will not trigger the Hall effect sensor to change states.

If You look closely at your picture of the 8-pole and the re-shaped magnet, it is possible to get 4-poles if you ground half of a pole.

Unlikely all other controllers (popular ones anyway) before the XCT, the XCT has a "Dynamic Field Map" that weakens the field at rpms greater than 2,500rpm.

If the Controller never receives a 2,500rpm feedback, which would be the case when you have a 4-pole magnet and set the Controller for 8-poles, You will not get the maximum performance as the Controller will keep the Field current at a higher level.

We (I anyway) also don't know exactly how the Field Map is adjusted so the Field Current may in fact be higher than the old "static" Field map below the rpm threshold.

Speed magnets or broken/ground magnets work well for OEM Controllers but perhaps PQ should ask if the bandit is going to be used with an XCT Controller and if so leave the magnet alone.

The Hall effect sensor is only exposed to the magnetic poles for an extremely small amount of time when the motor is traveling at higher RPMs, so I would personally rather have the components as designed by the engineers that know what they are doing.

Using another magnet is only helpful when trying to identify an otherwise "complete" magnet, but if the one installed has been ground, the test will not tell you the magnetic strength that will reach the hall effect sensor.

[JohnnieB]

I agree it is doubtful if the ground down 8-pole magnet disk has four poles, since it would have to be pretty close to a half circle to have 4 poles.

Fortunately, we can get a fairly close estimate if we know the simultaneous cart speed and the RPM shown on the monitor as well as whether the 4-pole or 8-pole option is selected.

The cart has 17.5: tires and 12.44:1 gears, so the motor spins at 238.9 RPM per 1 MPH.

At 10.0 MPH the motor spins at 2389 RPM, so the ratio of the monitor RPM vs the mathematically calculated RPM is the ratio of the number of poles the poles selected vs the number of pole on magnet disk.

With the 4-pole option selected, at exactly 10.0 MPH a disk with 1-pole would show 597 RPM on the monitor.
2 poles would be 1195 RPM
3 poles would be 1792 RPM
4 poles would be 2389 RPM
5 poles would be 2986 RPM

[Sergio]

Let's remind everyone there is a lot of speculation in this thread since he may in fact have a perfectly round magnet.

If You took half of the magnet and then shaved half of each pole near the center line in each side, you could have 4-poles with that weird shape in my picture (the equivalent of 3 shaded poles in the 8-pole picture: 2 Full + 2 Half).

Also, even if it works at 10mph, the Hall effect sensor may not be exposed to enough magnetic strength (from a partial pole) when going 20mph.

Remember you can not sense an odd number of poles since the sensor is bi-polar.

[JohnnieB]

Originally Posted by Sergio

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The Hall effect sensor is only exposed to the magnetic poles for an extremely small amount of time when the motor is traveling at higher RPMs, so I would personally rather have the components as designed by the engineers that know what they are doing.

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Personally, I'd replace the PQ modified magnet with an OEM one, or clone.

Part# 73328-G01
https://shop.txtsv.com/speed-sensor-magnet-pds-ii

You can find it for less on-line.

[JohnnieB]

Originally Posted by Sergio

Let's remind everyone there is a lot of speculation in this thread since he may in fact have a perfectly round magnet.

If You took half of the magnet and then shaved half of each pole near the center line in each side, you could have 4-poles with that weird shape in my picture (the equivalent of 3 shaded poles in the 8-pole picture: 2 Full + 2 Half).

Also, even if it works at 10mph, the Hall effect sensor may not be exposed to enough magnetic strength (from a partial pole) when going 20mph.

Remember you can not sense an odd number of poles since the sensor is bi-polar.

Rats, I forgot about the the sensor being bi-polar in my speed vs RPM post above.

You get one pulse per pair of poles. That is why a Tach for a V8 engine reads correctly when driven by the pulse train from a PDS speed sensor.

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You are right, he might have a completely round 4-pole magnet disk, they are available. Might even cost less than having someone grind an 8-pole disk down.

I'd still pop the sensor off and look. If it is round - OK. if not replace it.
Having an imbalanced armature isn't good.

[scottyb]

I like Sergio's suggestion that PQ simply ask if you want 8 or 4 pole magnet when you order the Bandit mod.

[Mrquickycart]

Hey everyone! Brand new guy here to the forum. I hate to be the guy to revive an 5 year old thread as my first post but I think this might help but some of this speculation to bed for future readers. For reference, I have an 08 36v PDS cart where I had the bandit mod done and used the stock controller for awhile. I could get up to 25-26 with everything stock and 20.5” tires. Scored a good deal on a XCT400 and found that while I was almost chirping tires on takeoffs, I lost a bit of top end (ended up at 24ish with no torque to get past that wall). I spent two days going back and forth with PQ and Alltrax and learned the following straight from the horses mouths. Alltrax has the understanding that PQ uses a 4 pole setting. They tell you to use Turbo mode and set the rpm limit to 6500.

PQ told me turbo will overheat the motor. I’ve been running turbo for awhile and my motor runs cooler than it did with the stock controller so whatever. He also said they use a “two pole magnet.” I’m assuming this confirms they grind it down to two poles to trick the stock controller as mentioned above. My magnet after the bandit upgrade is not round. When I asked if they had a recommendation on how to deal with the issue of the Alltrax field map possibly not working to its full potential due to the (also above mentioned) lowering field at higher rpm to get that last bit of speed, two different guys seemed dumbfounded and said they never heard about this being an issue. I think I personally am going to put a new 4 pole magnet in and see what happens as no matter what setting I use on the toolkit, I can’t get the sensor to read above 2500 at max speed(should be reading double that). I have heard a lot of people speculate that the field amps are lowered above 2500 but haven’t heard anything concrete, so I’m not sure. Alltrax told me that I should be getting the max performance out of it by just disabling the speed limit compared to getting the rpm readings to read correctly because the field map will take ques from the voltage feedback from the motor instead of the rpm. I don’t know but that’s what he said. My goal still is to get the Rmp readings to read correctly so I can set the limit and forget about it. BTW, I’ve been reading this forum for awhile since getting my first cart earlier this year and I really appreciate everyone who’s chipped in and posted all this wealth of info. You guys are awesome!