Maximum voltage drop

[panteramatt]

On a flat road gunning it from a dead stop my 7s leaf pack will drop from 55.47-49.19 with the mods in my sight. Is this acceptable? This is on 22" tires

[Sergio]

That is a power hungry motor, what is the maximum battery amps you have set on the alltrax controller?

[Volt_Ampere]

I think you are pushing a bit too much current for a 7 module pack if it's dropping that much voltage.

[panteramatt]

Set to 500

[Sergio]

Lower it to 300 amps (Leave Armature amps at 500) and check the voltage drop vs performance as You drive.

I agree that you likely need two modules in parallel to support that kind of current.

[Volt_Ampere]

I have 14 module setup and I have my current limit set at 400 amps. I get plenty of performance at that current level.

[panteramatt]

Ill change it to 300 tomorrow and see how much performance suffers. It has great acceleration but Im surprised it only gets to 29mph in about a 1/4 mile. Thought for sure Id be hitting 35.

[WalterM6]

Without knowing the entire story I'm taking a wild guess here. I'm thinking you have your Alltrax undervoltage set to 50V. When it drops to 50v the controller starts limiting your motor current to keep the voltage above 50v's. Try setting the Alltrax undervoltage to 45v's. Again I'm just guessing but I believe you might get that 35mph you have been looking for. And 45v's well above the min voltage for Lithium Ions.

[Sergio]

The lower the final voltage the lower the final speed.

The Low Voltage on the Alltrax should be set slight Higher the LV cutoff of your BMS so the cart goes into "limp mode" when the battery SOC is very low.

The Max Voltage level on the Alltrax should be set slight Lower than the HV cutoff of your BMS so a Sepex motor will not cause a pack overvoltage during Regen.

If You limit the maximum current the battery pack can deliver, it may not impact the performance at all if it was allowing the Motor to go into a inefficient area and will increase the Top speed by keeping the battery pack voltage higher.

[WalterM6]

I checked my voltage drop this morning on the way to the store. If I floor it, it will drop into the high 40's for a second or two and recover. No decrease in performance and battery usage seemed normal. (max current 400A and undervoltage 45v)