XTreme XB700li +7,4V voltage mod

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Joined: 05/18/2012
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Points: 102

Ok, there's a lot of bull out there on info on this bike; and a lot I had to wade through by experience.
I want to post some of it here on this thread!

First of all, the XB-700li has a LiMMn or LiPo4 battery. It's not the higher quality LiFePo4 battery.
That means that the bike only has a good 700 recharge cycles.

A user on visforvoltage has said that the internal battery gives 35MPC and after a good year and a good 3500 miles, the bike has less than a third of the mileage.

Second, the bike has regen capabilities. These regen properties depend on the batteries' BMS. If you connect a battery without BMS, regen simply won't work.

The stock battery is connected with a 'computer cable' to the bike. There's a similar plug found under the seat for charging the bike. On that plug you can plug in another LiPo battery. The battery does not need to be of the same properties. All it needs to have is 48V.
If you find the suspension too hard on the 700, just place the extension battery in the rear trunk. It should put more weight on the rear tire, allowing the suspension to soften a bit.

The bike stock goes ~23MPH, 23,6MPH fresh from the charger, and ~22,2MPH when half empty.
The internal speedometer measures 27,5MPH, an outside meter (or GPS) shows 23,6MPH.
The speedometer is voltage dependent. When opening the throttle but keeping down the bike, it'll show 15MPH, eventhough the bike is not moving. The overall impression is that the speedometer is showing 5MPH too fast, the higher the load, the more the speedometer will measure incorrect.

The speedometer reads it results from the rear wheel. You can set the bike on a stand, and see the speedometer go up as you engage the throttle.

The bike has an internal limiter in the controller which regulates the amps to 20Ah. Meaning, adding batteries in parallel won't give you more torque. The controller regulates output to 48V, 20Ah. In other words, that's 960Wh. Know that your motor is only rated 700W. You can burn your motor going uphill on long stretches. In most cases the motor has torque enough to push a rider of ~170LBS at 20MPH up a 15degrees hill. This is where the motor starts to heat up!
Going uphill the motor accelerates much slower, but after a while the controller (with the limiter disabled), pushes the motor to 20,2MPH anyway.
For this reason I believe the shunt mod is not necessary on this bike, as the motor has everything within itself to perform admirably in most cases. Like any electric, it's weakness lies in torque; meaning carrying weight uphill.

Going downhill the motor is uncontrolled. I was riding on a sidewalk, with lots of bumps, and could not test the max speed, but the bike rolls downhill 30MPH or faster, if you don't brake.
At 170LBS, and a 20% downhill drive, the regenerative braking can barely keep up with the mass (meaning, it keeps the bike at the same speed rather than slowing down).

The bike is equipped with drum brakes and regenerative braking. When lightly pulling the brake lever, the electronic circuit gets engaged, and the brake light goes on. It takes about 1-2 seconds before regen braking kicks in. One can use regenerative braking for most travel. Regenerative braking works well with speeds over 5MPH. Below 5MPH the electricity harvested from braking is too low to charge the battery with, and it feels like it's not doing much. At that point the battery BMS just won't recharge anymore, and you're literally braking on the brake light (energy harvested goes to lights).
The more lights are on, the more braking will work. It's a 700W motor, braking lights are 2x~20W; headlights are same. So you'd be braking at 1/10th of the real motor generating capacity.
As soon as you squeeze the brake lever harder, the brakes will kick in. Regular drum brakes working together with regen braking.
Braking distance from max speed on regen to 5MPH is about 36-40ft. Min Braking distance with brakes is about 12ft.

Overvolting 56V:

I Overvolted the bike, without applying any other mod. When overvolting, make sure you connect a battery with BMS.
Without BMS, regen braking won't work; either that, or overvolted the regen voltage is too low to generate enough voltage for the internal batteries to harvest it.
I overvolted the bike with 2x 16A 7,5V RC batteries. I've heard of +12V mods reducing controller lifetime, so I wanted to make sure my controller won't be fried.

At 56V the lights function the way they supposed to.
The voltage meter goes beyond it's limit, and the internal speedometer adds another artificial 5MPH to your speed; showing 35MPH, when in fact the bike only goes upto 25,6MPH.

Adding 7,5V to the stock battery improves speed by a meager 2MPH. Very disappointing!
The shunt mod would have not improved this speed, as the motor has plenty of torque to work with! The shunt mod would only allow more amps to flow to the motor, thus improving it's climbability, or startup speed.
The 700 starts about as fast as a cyclist, much faster than most people on their bikes; but it starts much slower than most cars.

For a reasonable speed increase, you'd have to overvolt the bike with 12V; as the 7,5V speed increase really does nothing worth mentioning; and on top of that, your fuel gauge and speedometer will be totally incorrect, and regen braking will not work! Maybe the same with +12V overvolt mod.

The speed is limited by the controller. If you can hack the controller and mess up the sync clock or perhaps reduce some capacitor's size (to get a shorter timing) or something, it might be possible to increase speed.
I've said it many times before, but the motor has enough in itself to go at least 30MPH, if not 35MPH!
It's just the controller...

Hope this info helps some who are thinking of buying this electric bike.

For me it's a useless bike, as it goes too slow in the place where I live.
I need a bike that goes at least 30MPH, 22MPH is just too slow. If it did 25 or 27MPH I could live with it, but not like this.
I probably will be selling mine soon!

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Joined: 06/22/2009
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Points: 157
Re: XTreme XB700li +7,4V voltage mod

Thank you Heman! That was a fantastic, and very informative post. I didn't realize that even the LiPO4 batteries on the newer 700li were of such lower quality. 700 charge cycles is righ in line with what I saw from my 700li. Brand new the bike could do 30+ miles on a charge, and 18 months later and probably 550 charge cycles later, my range was down to around 12 miles. Max. At that point, you have to spend another 600 for a new battery pack. Wow. Not cost effective.

My 4000li has 12,639 miles, and so far my range with the Thundersky 40ah cells is only down about 5 to 10 %.

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Joined: 05/18/2012
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Points: 102
Re: XTreme XB700li +7,4V voltage mod

Thank you,

Because this forum did not allow me to update my post, I've posted it somewhere else, and updated it there:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=42320http://endless-sphere.com/forums/viewtopic.php?f=3&t=42320

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