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Sherman Max board on OG Sherman


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The Ecodrift teardown highlighted that both Sherman Max and Original share a lot, including the same motor internals besides the axle itself.

I think that a lot of original Sherman like me thought that the Max board would be a pretty nice and hopefully reasonably priced upgrade, solving one of the main limitations: risk of burning the mainboard while climbing.

I personally know 2 Sherman owners who had their board burning entirely, and my first Sherman board started to fail as well on an inclined street where I live as I was naively testing a new pads setup.

Since then, I had good luck by always using extra app alarms and essentially avoiding hard climbs, which has not been that big of a deal but still a bit of a bummer during group rides once in a while.

The Max board looks like it would be easy to retrofit. Heck, I don't even understand what is different and appears to make it a lot more resilient than the original one. Does anybody have a clue?



I think my OG Sherman, not even a year old still have a lot of years ahead but solving this "should I try to go up here or will it burn" limitation would certainly be nice.

Anybody upgrading to the Max mainboard on OG motor takes some risk overheating the motor phase wires however, since the Max ones have been beefed up.
So an OG Sherman with a Max board should probably not try to do this, but still, seems worth it.


Anybody else thinking the same?

Edited by supercurio
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It's an interesting idea if it works and if there's no risk of damaging motor, I would much rather do this to my Sherman than upgrade to Max if it was feasible.

Edit: I did a completely non-scienticic ocular comparison of the new LK21-38 motherboard in the max with pictures I could find of the LK-21-20 motherboard in the OG Sherman, I could see at least 3 changes:


Edited by Rawnei
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  • 3 months later...

Follow up on that.

I switched to the Sherman Max now and must correct some invalid info I republished here:

  • OG Sherman and Sherman Max motors are different: magnets config is not the same, motors sound different (Max motor has a whistle while OG is quieter)
  • the Max motor requires significantly less phase current to climb the same gradients as the OG
  • the Max did lose top speed, unlike previously reported. Typical beeps at 63 kph instead of 67 (GPS) with a full battery on the flat

Sherman Max is a strong hill climber indeed! Torque in between 100.8V HS and HT wheels, closer to HT wheels.

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