XB-600 "Shunt Mod" instructions
Hello All,
I finally got around to documenting the process for those still unsure of the process. Hopefully this will help a few people out who still aren't sure of the procedure.













Nice post, Rob.
You got almost as much solder on there as I did! LOL. Good pics.
Wow...thanks for taking the time to provide this!
I'm wondering though...since you solder the new "shunt" on the underside of the board...why is it necessary to solder on the top side as well? If it's making good contact with the other two shunts on the underside wouldn't eliminating the soldering on the top of the board be a good thing...since it's not as easy getting to the base of the new shunt on the top with all those wires sort of in the way? Or could you put a 90 degree bend in each end of the new shunt, provided you can work it into the holes, such that the ends of the new shunt touch the welds of the existing shunts on the underside of the board...soldering each end directly into the existing solder bed of the existing shunts...and again forget about any soldering on the top of the board? What do you think?
Gushar
Oh...so there's not much space between the bottom of the board and the case. I just recall my electronics friend who taught me how to solder always had me soldering things on the underside of the board. And the goop of solder that you see on the topside sometimes was the flow of solder running through the hole to the top from the underside. Anyway, hey I'm the novice asking the questions...not the expert here! Wish my expert friend still lived in my town cause I'd just have him take a look and I can tell you he'd have that shunt in there looking like it came that way from the factory! He lives a state away now...but I'm telling you the guy is an electrical/electronics genius!
Well, you know I'd like that zip...but I also like the XB600 so much even like it is...and so I'm still debating. Of course this past weekend when lightning began popping all around me when I was out for a ride...I sure thought about more zip!!! YIKES!
I just want it to last as long as possible without a motor, controller, or other major component replacement...or lots of extra work/maintenance. That's one of the things I've enjoyed the most this past year since I got it...not having to do any work on it. It seems like "stuff" around the house is always breaking and I get tired of fixing stuff rather than using them! BTW, this month marks 1 year since I took delivery of my XB600. Can't recall exactly which day...but July of last year. Till I replaced the keyswitch recently...the only other thing I had to do was replace a tube.
I sure like hearing that Zerogas put 72v to the motor and controller, even for minutes, and didn't realize any adverse affects. That makes me think those components will last an awful long time...certainly with the stock power. And again, it's not really the cost of parts...but the time to work on things. So I don't know. I'm sure itching to do this mod...so we'll see....:-)
Gushar
Actually, the solder on the top side of the board is not a good thing for the shunt. A shunt is supposed to have a measured resistance, and putting solder on the top of the board reduces that resistance substantially. It is better to just solder on the bottom side of the board and if some solder wicks up to the top of the board, that is ok.
Yeh...I hear what you're saying. I'm a records and information manager by profession...but I as well (although not for a living) have built houses and done about every mechanic's job on a vehicle. So I'm pretty handy. My electrical and electronics knowledge and abilities are more than the average person I think...but far from that of "real" electricians and electronic technicians. So, I'm always learning something new here when it comes to these things. I just appreciate the sharing of knowledge here. I'm like you. The more I see explained, etc. the more I know about my ride, and that makes me confident that I can repair it when something fails.
Like I wrote in another thread...I may just have to buy the upcoming 700li...and I may want to keep everything "stock" on the 600 so I can resell it easily. But then I may not buy the 700li in which case I will be itching to do this mod! That's why I wanted to make sure I understood exactly what you guys were doing.
I really like the fact too that Zerogas is doing the experimenting! I just think if I got that heavy into it I'd have to spend that time converting one of my cars to electric! But I can certainly appreciate his desire to see just what he can get out of this ride! And he certainly seems to be enjoying the experience...which is what alot of this is all about!
Gushar
Ummm, I'd say all you guys have more knowledge about this stuff than me!! LOL What knowledge do I have?? I just try stuff out. :D If it works.. GREAT! If it doesn't, I change it back. LOL. My prior electric vehicle "mods" include raising the voltage on my daughter's power wheels from 6v to 18v... and that's it! I just figured, "Hey, if it worked on that piece of crapola it should be killer on this xb 600!" It is!!!!!!!! I love electric vehicles... they are so easy to mod. For the record, Gus, I'm already planning a vehicle conversion, as soon as I find a decent car with a manual tranny. I already got the "green light" <---- (pun intended) from my wife. I've even picked out a kit from cloud-ev.com that should propel me to 70+mph electric bliss! But that's another thread and another time... Stay Tuned
-Warren
Hi,
I'm also trying stuff out cautiously...The way to go!
Maybe I am missing something, but could you not simply solder a cable between the soldering points on the underside of the PCB?
No drilling etc?
I believe the electrons don't mind which way they go around to the other side...
And a cable would be no thicker than the solder blobs, but insulated against contact with the case.
I'd also add some hot glue if the clearance to any conducting cover is too small.
Mr. Mik
Mr. Mik,
You are missing the point of the shunt. The shunt serves as a fixed, standard resistance. The voltage drop across the shunt is proportional to current. We are lowering this fixed resistance value to lower the perceived current so that the controller sends more current to the motor than it was originally designed to do.
If you "simply solder a cable" you will short out the shunt. Globs of solder on the top of the board partially short out the shunt.
Just using "coat hangar wire" is enough of a compromize, because we are assuming that coat hangar wire has enough resistance in it so that a 1.5" length of it will not short out the shunt. Now if you start soldering wires to the back of the board, you are not even coming close to reducing the resistance of the shunt in a controlled way.
It doesn't matter whether you solder the loop of coat hangar wire to the top of the board or the bottom of the board, you need to make sure the coat hangar wire does not short out the shunt or anything else on the board. And you should solder it somewhat neatly so that you get as much of the 1.5 inches of coat hangar not compromized by solder as possible.
I decided to perform this mod today and now my bike is dead. I did everything as noted in the instructions but as I connected the power I heard a pop. I could not tell where the sound came from but I checked the fuses and they were all good. The green 30amp and the small glass (near the controller) fuses are ok. I don't know if there are any other fuses. The only thing not working is the hub motor. I get horn, lights, hi beams, turn signals working.
Where can I get a new controller and how much?
Check for smells.
Check your solder joints. Check any capacitors on the board. Inspect the circuit board for any blown traces.
If you can take high-res pictures of the board, please post them.
If the pop came from inside the controller, you will be able to see it by looking at the controller board. If the controller board still looks fine, your controller is still fine, and some wire got shorted and probably a connector is fried.
What kind of coat hangar did you use?
Some other thread suggest to short thick red and black wires on the controller to avoid any unwanted electrical charges by way of the solderer .Soldering batteries with butane is safer as it has damaged my batteries operated pinpoint solderer.
Mr. Mik,
You are missing the point of the shunt. The shunt serves as a fixed, standard resistance. The voltage drop across the shunt is proportional to current. We are lowering this fixed resistance value to lower the perceived current so that the controller sends more current to the motor than it was originally designed to do.
If you "simply solder a cable" you will short out the shunt. Globs of solder on the top of the board partially short out the shunt.
Just using "coat hangar wire" is enough of a compromize, because we are assuming that coat hangar wire has enough resistance in it so that a 1.5" length of it will not short out the shunt. Now if you start soldering wires to the back of the board, you are not even coming close to reducing the resistance of the shunt in a controlled way.
It doesn't matter whether you solder the loop of coat hangar wire to the top of the board or the bottom of the board, you need to make sure the coat hangar wire does not short out the shunt or anything else on the board. And you should solder it somewhat neatly so that you get as much of the 1.5 inches of coat hangar not compromized by solder as possible.
Thank you for the explanation, but I am still not clear about it...
Do you mean there is so much current going through the wires that it raises their temperature and so increases the resistance?
Or is the resistance fixed and the wires are not supposed to heat up?
Why not use a high wattage resistor instead of coat hanger wire? (I do not believe the USA have standardized coat hangers...yet!)
Could you not just put some solder onto the ends (on the upper side of the PCB) of one or both of the existing wires to reduce their resistance?
I believe I also remember someone (Andrew or LinkofHyrule ?) posting that you could just add one or a few strands of wire to a shunt...but that might have been for a different vehicle altogether.
Or cut out part or all of one of the existing wires and replace it with a resistor, instead of drilling holes and adding solder blobs on the underside which can apparently make contact with the case?
Hope this does not sound like I want to nag or something....but it seems to be an important issue. (And as the last few posts show, not without risks...sorry to hear about your misfortune, audiophil2)
In case it has all been discussed and explained in detail before, then please give me the link to it and I'll read up!
Mr. Mik
I'll post pics when I get home from work today in about 9 hours. Thanks for the help everyone.
Phil,
That's horrible bro, are you sure you put the coathanger in the right place? I've run this mod for several months now with absolutely no problems. Even at 72v my controller held up. Seems to me you may have a loose connection. These little white connectors are crap. I had to push some of the terminals back into the connectors on mine, because they were "falling" out. :( Hope you get it straight.
- Warren
Thank you for the explanation, but I am still not clear about it...
Not your fault. I am not good at explaining it.
Do you mean there is so much current going through the wires that it raises their temperature and so increases the resistance?
Or is the resistance fixed and the wires are not supposed to heat up?
The shunt wires should never have so much resistance/voltage drop that they heat up. They only provide a small voltage drop that can be measured to indicate how much current is used by the motor. The electronics uses this measure of current to keep the components in the controller and external wiring from being damaged. The controller limits the maximum current that can be used by the motor.
Why not use a high wattage resistor instead of coat hanger wire? (I do not believe the USA have standardized coat hangers...yet!)
There should not be many watts of power consumed by the shunt - the resistance is very low. So we aren't really looking for a high wattage resistor - we are looking for a highly accurate low-resistance resistor. A fixed length of shunt wire is a better controlled resistance for that low of a resistance than any resistor could be - that is why they make shunt wire. The accuracy of the resistance of the shunt wire determines the accuracy of the current measurement used by the controller. There is no question that a better solution would be to use shunt wire instead of a coat hangar. Maybe not all coat hangars are made the same, and they definitely are not manufactured to the precision of shunt wire.
Could you not just put some solder onto the ends (on the upper side of the PCB) of one or both of the existing wires to reduce their resistance?
You could, but it sure seems that would be even less accurate than using 1.5" of some unknown coat hangar wire.
I believe I also remember someone (Andrew or LinkofHyrule ?) posting that you could just add one or a few strands of wire to a shunt...but that might have been for a different vehicle altogether.
Maybe. But while the voltage drop across the shunt is low, the current passing through the shunt is 20 amps or more. It seems to me that thin strands of highly conductive wire would burn up, while a length of not-too-good-conducting coat hangar wire would carry the current easily.
Or cut out part or all of one of the existing wires and replace it with a resistor, instead of drilling holes and adding solder blobs on the underside which can apparently make contact with the case?
Hope this does not sound like I want to nag or something....but it seems to be an important issue. (And as the last few posts show, not without risks...sorry to hear about your misfortune, audiophil2)
Not nagging at all - it is helpful to understand what the shunt does, at least enough to stress to people that they should try to follow the directions exactly. Seemingly subtle changes, like putting too much solder on top of the shunt or using copper-coated coathangars, could have disastrous results.
Here is probably more than you will ever want to know about making shunts:
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Here is probably more than you will ever want to know about making shunts:
Thanks for that!
I understand it now. I almost put a shunt into the Vectux to measure the amps going in and out of the battery, but then used an existing hall effect sensor around the cable instead.
Basically, all the current used by the motor goes through the two shunt wires. They have a very low resistance, but enough to cause a small voltage drop across them.
Ohms law lets you (or in this case the motor controller) calculate the current going through the shunt wires if you know the resistance and the voltage drop.
V/I=R --> I = V/R
The controller is fooled into "believing" there is less current going through because no-one told it there is now a coat-hanger reducing the resistance....
Mr. Mik
My controller is fried. I won't bother posting pics cause it does not show anything. I ordered a new controller today so hopefully I will be riding again by next week.
I plan on upgrading to a 3500Li in a few months but I am willing to try this mod one more time before the upgrade.
Phil
Any idea what caused it to fry? Did your solder spill over to other areas on the board?
Congrats, Rob!!
Glad to hear all is well with your 60v mod! Get some vids on youtube so we can all see you zooming around!! I got my 4110 mosfets in today, so 72v is not far off. Helloooo 35mph for good this time!






Hey Gushar,
I did the top and bottom to make sure that the shunt stays in place. There will be some vibration on the controller and I wouldn't want it shaking loose on the ride. Better safe than sorry and I don't want to have to open it again. Plus its soldered on both sides in the original as well.
Now that you have this...what's it going to be Gushar? Are you finally going to take the plunge? Get crazy with the Cheez-Wiz as they say and get some zip in that scoot?