72v xb-700Li Mod

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onemanprotest
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Joined: 08/07/2008
Points: 19

I am going to guinea pig my xb-700Li out for a 72v mod. Any input from the grand masters of the board are certainly welcome. I am inspired by the 600 72v mods that seem to have added about 15mph to the bike's speed.

I plan on trying to make things as simple as possible by trying to find the most compatible as-close-to-drop-in replacement 72v 40a controller possible. For now, I think I will probably end up adding two SASL's instead of more lithium ion to the bike. I anticipate charging the SASL's separately to keep things simple for now.

The first place to start is the controller. I have located a few potential 72v 40a replacements and would like input from others as to possible reputable people to buy from.

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Craftkiller
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Joined: 07/13/2008
Points: 54
Re: 72v xb-700Li Mod

sorri that I am no help but good luck man, major credit for jumping straight to 72v, look foward to seeing the result... and zerogas, are you gonna let this guy tie you? get 84 on that thing! (jk, dont destroy your bike)

depetro
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Joined: 07/24/2008
Points: 43
Re: 72v xb-700Li Mod

I'm only recently becoming familiar with the 700. I'm kind of thinking I should have spent the extra money and gotten one a month ago when I got my 600, but they didn't seem to be out on the market yet or whatnot.

Anyhow, that being said, I am running my 600 at 72V (about 4 days or 50 miles). I suppose I'll lend whatever support I can. Any idea how similar the 700 controller is to the 600 controller? For as shoddy as some of the stuff on the 600 is, the controller and the motor are pretty damn good. Correctly modified, the 600 controller doesn't need very many modifications to go from 48V to 72V, my guess is that the 700 won't either. In any case, does anyone have pictures of the inside of the 700 controller? That would go a long way towards seeing if you even need to replace the whole controller.

Btw, 35mph is great. Each time you up the max speed anything less seems ridiculously slow.

onemanprotest
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Joined: 08/07/2008
Points: 19
Re: 72v xb-700Li Mod

Before I rip open the controller for the pics, a few observations and questions about speed on the 700.

No matter what conditions I'm riding under, this bike will strangely hold at 45kph which is right before the speedo starts redlining. For example, I rode my 44 mile round tripper today and the first half of the trip had a 15mph tail wind and the bike would only go 45kph. On the return trip, heading the opposite direction into the 15mph (now) head wind, the bike went 45kph. Anytime I go down a really big hill, full throttle... doesn't matter... 45kph. There is headroom on the speedo up to 60kph. 45kph to 60kph is redlined.

This leads me to believe there is some other governor besides the blue wire that is connected on Canadian models and disconnected on American models when shipped.

Interestingly, the speedo cuts completely off and drops to zero when you apply brakes. This is supposed to be an indication that no electricity is going to the motor during braking. But doesn't this mean the speedo is also tied into the electrical system and not just a mechanical speedo? A totally mechanical speedo would tell you the speed while you were applying brakes. The point being, is it possible the speedo is tied into limiting the speed of the bike via the electrical system/controller?

I'll try to pull apart the controller this weekend. I still need the bike for a few commutes this week.

win32forth
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Joined: 07/24/2008
Points: 126
Re: 72v xb-700Li Mod

Onemanprotest,

You are right about the speed limiter. I notice that I can go faster down hill (on my XB-600) if I release the throttle completely and let it coast. The speed will climb several miles/hr faster than if I use full throttle.

Tom

Craftkiller
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Joined: 07/13/2008
Points: 54
Re: 72v xb-700Li Mod

not sure how much this helps, but the speedo acts the same on the xb-600 with braking

depetro
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Joined: 07/24/2008
Points: 43
Re: 72v xb-700Li Mod

I believe that someone else on the forum (in the XB-500, 600, etc section) postulated that the incredible speed drop caused when braking is a result of the electric motor being used for breaking. I think if you check (on the 600 at least) braking with the right brake causes the fast speed drop, but braking with the left one does not. I think the reasoning is that speed measurement is made from the motor's rpms via a hall sensor. In my experience the speedometer is fairly unreliable. I'd suggest a small bike computer or a GPS for actual speed benchmarking.

onemanprotest
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Joined: 08/07/2008
Points: 19
Re: 72v xb-700Li Mod

Before ripping into the controller, are there any possibilities for a drop in replacement controller from other x-treme models? Can a controller from the xm-3000 or xm-3500 (both higher voltage) be used?

onemanprotest
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Joined: 08/07/2008
Points: 19
Re: 72v xb-700Li Mod

I've decided to search for a drop-in replacement controller instead of ripping open the stock controller. At the least, the stock controller is still under warranty so I'll just pull it out and replace it with a comparable 72v 40a controller... when I find one.

I've tried emailing ecrazyman as per some of the other posts but have not heard any response in two weeks. I was in touch briefly with Kenny from crystalytemotor. He seemed to have a 72v 40a controller that would work but I haven't heard from either in some time.

Does anyone have any other ideas as to where I can locate a new controller?

rossasaurus
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Joined: 07/03/2008
Points: 159
Re: 72v xb-700Li Mod

Hi OMP,
If you mod the controller for the 700Li, would you go for increased current out of the batteries, as well as voltage?

Was just wondering about the suggested increase in volatility/stability of the LiMn chemistry over the LiFe, and the possible result of drawing more current from the LiMn packs than a stock setup.

Would this be likely to cause increased expansion & contraction of the pack and separation or distortion of electrolyte in the cells?

From what little I've read, the LiMn's are perhaps less forgiving of being stressed ??

If you missed the posts by bocabikeguy? you might want to review them.

R

onemanprotest
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Joined: 08/07/2008
Points: 19
Re: 72v xb-700Li Mod

rossasaurus wrote:

Hi OMP,
If you mod the controller for the 700Li, would you go for increased current out of the batteries, as well as voltage?

I am going to try to keep this as simple as possible by finding a drop in controller that is the same as the 40a stock setup but will handle 72v. That's it. I hope just to be able to throw on two more batteries and see what happens.

I don't really care too much about speeding up the demise of the batteries as long as they don't catch fire! If the stock batteries are supposed to last 3 years or so, I don't really care if they burn out in 1. Although it is a nice side effect, I'm not in this to save money. I'm already saving $300.00 a month on gas. If I have to buy a new battery every few months, I'd still be saving money.

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