Another upgrade question

[Fort Ord]

Hi,
I have a 750W DJ mountain bike, KT controller, Bafang rear hum motor. While the bike itself is decent, the thing is limited to 20MPH. I tried a "controller upgrade" from Vinh at Electroworld, which turned out to be a total waste of money and time, and a little bit of sleight of hand on his part.

So now I'm on the cusp of ordering a Voilamart 1500W conversion kit. The claimed top speed is 34MPH, if one removes one of the two blue wires
in the controller - otherwise, it too is limited to 20MPH.

So my question is: Has anyone in this forum tried this upgrade and, if so, are you willing to give me some feedback on the pros and cons? I'd be grateful.

 

[tomjasz]

What is the output specification on your battery? A battery output can be a limiting factor.

 

[AHicks]

I have not seen a KT controller with a speed limit that couldn't be changed. Most that want everything available set them to 99 mph.

If this is just about top speed, or maybe commuting over relatively flat terrain, the 1500w DD rear hub is a good plan.

If this bike is going to spend most of it's time between 0 and 15 mph, faced with much of a hill regularly, with just an occasional sprint to top speed, my bet is you're going to find the 1500w gutless. That was my experience anyway.

 

[Sierratim]

The Voilamart controller may be able to drive a motor up to 34 mph, but both the battery and motor need to have this capability as well.

You might want to take a look at Grin's Motor Simulator;

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

Your exact motor may not be modeled in the Simulator, but as an example the Bafang G60 with a 48V battery simply can't provide assistance above ~27 mph, regatdless of controller capacity.

 

[Fort Ord]

All, thank you for this valuable feedback. Maybe is isn't the KT controller, but the Bafang that is limited. The bike's got a 52V 13Ah nominal battery, Sierratim, I'll try the simulator.

 

[Fort Ord]

I have not seen a KT controller with a speed limit that couldn't be changed. Most that want everything available set them to 99 mph.

If this is just about top speed, or maybe commuting over relatively flat terrain, the 1500w DD rear hub is a good plan.

If this bike is going to spend most of it's time between 0 and 15 mph, faced with much of a hill regularly, with just an occasional sprint to top speed, my bet is you're going to find the 1500w gutless. That was my experience anyway.

How do I set it to 99MPH? I set it to 40MPH (not KPH) and it still putzes along at 20-21MPH.

 

[Fort Ord]

What is the output specification on your battery? A battery output can be a limiting factor.

Hi, the battery output is 52V, 13AH nominal.

 

[AHicks]

How do I set it to 99MPH? I set it to 40MPH (not KPH) and it still putzes along at 20-21MPH.

I don't think you have a KT controller, or a KT display, BUT, if you did, you would enter the setup parameters, and change the speed in the same area you would set your tire size, km or miles per hour, etc.

To get in to the parameters, you turn it on, then, within 5 seconds of the time you turn it on, hold the top and bottom buttons down at the same time. Max speed will be the first thing you see.

There is no chance the motor itself is limiting your speed. It should crack 20mph easily.....

 

[Fort Ord]

Hi, Thank you for this information. I'll give it another go.

 

[harryS]

What KT display do you have? And which controller? What dos it say for tha max amperes?

Also, there are a few KT controllers that have a speed limiter wire coming out of the controller. Scroll down to bottom of this diagram.

 

[Fort Ord]

Good Morning, Harry. I have the KT LCD3, with HIGO connectors. It would be great if it just took unplugging a wire, but the LCD has a single HIGO I/O cable

 

[Fort Ord]

Oh, reading more closely - so I'd take the controller apart to look for this limiter wire? I have the KT 25A controller.

 

[AHicks]

Awesome, so you DO have a KT controller!

Were you able to get into setup?

I would NOT take the controller apart to look for that wire. I've seen no mention of it on the waterproof versions of the KT's.

I currently have a KT20a w/Higo's en-route (my first). If there's still questions when that gets here I'll be happy to address them. -Al

 

[harryS]

Right. No jumper in the waterproof versions.

Hmm. 52V. You ought to get up to at least 24 mph. The newer LCD3's have L1-L4 parameters, which come up after the C parameters. I've not seen an LCD3 program spec that covers the L parameters. Basically you want
L1 = 0
L2 = 0 if L2=1, speedometer might read 1/2 true value.
L3 = 1
L4 = 5

They're described in this LCD8H manual. The P1-P5, and C1-C12 are also covered.

 

[Fort Ord]

Good stuff. I'm headed to the garage right now. I'll give it a go.