For the past several weeks John, my commercial radio station engineering friend, has been helping me attempt to repair my GPR-S (now renamed Sparky, as it rolls off the tongue easier) and get it back on the road – without buying an entire set of new Hi Power batteries (which are not available anyway). We first determined that the Modalis BMS master board had failed. An obvious point of failure was the blackened transistor at the extreme left side of the board. After some searching, my friend found a replacement transistor and installed it on the board. That got the system charging again, but then we found that the BMS was slowly shorting out the batteries under the board and after charging the pack you would return the next morning to find all four of the batteries had discharged below two volts. Without a circuit diagram, which was not forthcoming from Modalis, it was back to the drawing board and we decided to just replace the sucker.
Another very curious discovery was that Electric Motorsport had cut the wires to the 90V to 12V converter, which had blown its 2 amp fuse, and connected the 12 V chassis circuit directly to the four battery pack that was under the Modalis master board. We figured that didn’t help the life of those batteries. All it took was to replace the blown 2 amp fuse which was connected in line to the converter and replace it with a 10 amp fuse. When we hooked up the converter to the main power circuit, the bike powered up and the chassis electrics seem to be working just fine. Neither of us has a clue why the converter was not connected to the power system and why EMS had elected to power the chassis off of four of the batteries, instead of using the converter which was already installed directly under the seat.
The next move was for me to open my wallet and to purchase 24 miniBMS boards and a head-end board from CleanPower Auto. Although they do not take credit cards, they did take my check and I received the boards just two days after they received my funds. We removed the battery packs and then removed all of the Modalis circuit boards. The slave boards still seemed to be performing their BMS function, but with the master board toast and no way to purchase a new one, I gave them to my son-in-law, who might try to sell them on eBay.
Then we performed the somewhat tedious task of hooking up the 24 miniBMS circuit boards (only blowing up one of them when attaching a power cable) and the head-end board. See attached photos of the installation. All seemed well upon completion of the work. The system was now charging steadily until it was cut off by a cell that reached 3.6 volts. This was a big improvement compared to the Modalis system which would cause the charger to cycle on and off every few minutes. For the first time since I owned the bike, Sparky was showing 81 volts, as all of the cells were finally alive and working.
So we installed the bodywork and I jumped on the bike and rode off. It took off with a nice thrust of speed and reached 50 mph quickly. About a mile away, as I stopped for a traffic light, the bike suddenly quit running and after turning the ignition and kill switches off and on to try to reboot it, it still would not move, although all other systems seemed to be working properly. It acted like the “kill switch” was on, no matter if I put it on or off. After about 5 minutes, the bike suddenly and without warning, started up again and I was able to ride another mile, before the same thing happened again. After a few minutes, I was able to ride off again and returned to the shop.
We then checked the operation of the kill switch and brake switches that operate the regen feature of the sepex motor. Everything seemed OK. The regen relay was working and the kill switch seemed to be doing its job. So my friend, who is much heavier than I am, jumped on the bike while I followed on his 1978 Honda CT90 (eek). He was able to ride for five miles without any stalling, although he did use full throttle most of the time and never had to stop for more that a few seconds. When we returned to his shop, he gave me the bike and told me to ride it. As soon as I got on Sparky, it stopped sparking and the main power system would not turn on. Since it was getting dark, we gave up for the day. He told me that the following morning; the bike turned on and ran fine. So we still do not have an explanation for the apparently random stalling when stopped – the power never failed while Sparky was moving. Further investigation is needed, as well as my services to get the bike to stall by showing up.
Personally, I think there is something about me. Dogs hate me and so do electrons. Whenever I get near a dog it barks and lunges at me and when I come close to a piece of electrical equipment it seems to die. The last time I visited Circuit City, their electronic cash register failed just as I arrived at the checkout counter.
So that is the saga so far. I will detail our continued investigations and attempts to get Sparky running (while I am sitting on it) on this thread. Any suggestions are welcome.
Attached are photos of the original Modalis master board, photos of the naked Sparky and the repacked Sparky with the miniBMS boards installed, along with a photo of my friend’s shop.
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Here are a few more photos.
Did CleanPower Auto provide instructions on how to interface the Mini BMS's LVC signal to the Sevcon controller? If that signal has a problem it might explain the spurious cutouts. Just speculating here... the voltage level for the LVC signal may not play nicely, there may be spurious noise on the line, the Sevcon may behave differently than the CleanPower Auto guys expected. As a quick & dirty test, disconnect the LVC signal and see how it behaves. But don't leave it disconnected long-term or you'll risk over-discharging them again.
Sounds like you're close to getting the bike back in shape. The final thing left is to program the controller so it doesn't kill the batteries by pulling more than they can handle.
Chef, my recollection is that CleanPower Auto doesn't mention the Sevcon controller in their published information, but I might have missed something. My friend is reading their entire manual, as well as the Sevcon manual for clues to a potential solution. We did not enable the miniBMS LVC feature because I was worried that the system would cut out under power and that would cause a safety hazard for the rider. I go up and down hills to get anywhere around here and if the the BMS cut the power because a cell dropped below 2 volts for a few seconds it would leave me stranded on a hill in traffic. I would rather the batteries suffer like they have been doing for the past 1500 miles, than take a chance on the power fading at 45 mph while some SUV driver on a cell phone is tailgating me. BTW, the HVC works great when the bike is charging. If I had installed new $$$ batteries I would probably feel differently.
The miniBMS boards have little green lights that are on when the batteries are below 3.6 volts and little red lights come on when the voltage hits 3.6 volts. Charging is then cut off to the pack. After a few minutes, the light may turn green again and then you can cycle the ignition switch and continue charging, until a cell hits 3.6 volts again - but that doesn't get you much added power storage, of course.
The problem with the Sevcon controller is that I can't alter the program parameters that were set by EMS. As it was, EMS claimed to only have one programming gadget and it took them weeks to retrieve it from somewhere so that they could correct the controller so that it would work with their build - or so they told me.
Not to be taken seriously
The MinBMS can be configured in several different ways. The way I intend to hook it up is such that it reduces throttle by 50% under a LVC warning. This is simply done by hooking it to the 5K throttle via another resistor. It's explained in the manual. I haven't actually hooked up the LVC yet because I haven't got everything back on the bike. I'm not sure if the Sevcon has a suitable input to take the LVC directly.
The Sevcon calibrators are hard to come by. I just managed to get one on eBay finally. I think EMS, Thunderstuck-EV, or Harlan at Hollywood Electrics all have them available to rent. Supposedly the first two just got new stock in after months of them being on order with Sevcon.
Yes, what Dave said about the LVC. Properly set up, LVC doesn't completely kill power, it reduces it, alerting the rider and allowing him/her to get home safely (albeit slowly). By not utilizing the LVC, you're wasting half the functionality of the BMS and risking more damage to the cells.
I discussed with CleanPower about using the Mini BMS with the Sevcon controller. They said it would work and that they would provide instructions. Contact them again and give them the exact model of the Sevcon (mine is a PowerPak PP784). As for programming the Sevcon, once again (for the 4th time??) you can rent the gear. It's less expensive than burning out another cell.
Thanks, Chef. I got the message. I was aware about the result of the miniBMS LVC, but reducing the power amounts to killing it for my type of riding. It would reduce my speed to about 25 mph up hill and that is too low for me. I would like to point out that the Modalis BMS did not have a LVC (at least one that operated) and my batteries survived the treatment. My guess is that the controller was programmed by EMS to compensate for the lack of a LVC. I am going to forward your comments to my friend. The bike is still in his shop. If he thinks that the stalling problem can be solved by reprogramming the controller, then I'll see about renting the calibrator. Right now I don't even know what model of Sevcon controller that I have. In any case, I still think that the controller programming is not causing the stalling problem, as my bike never stalled before and we did not touch the controller or its wiring. My thinking is that we pulled a wire or scraped some insulation, resulting in an intermittent ground, when we were yanking the battery boxes in and out and pulling wires here and there. But then I am just guessing, based upon my previous IC repair experiences. Every electrical problem that I have ever had was caused by bad insulation or corroded contacts or electrical junctions.
Empulse R #24
Then why even use a BMS? Doesn't sound like you give a crap about those batteries, so why spend the money on protecting them? Balancing is all good and fine, but at the bare MINIMUM you need to do LVC and HVC to protect the batteries. You need to protect the batteries from being overdischarged..... but you don't want to do that at the risk of not having power. Reducing power makes you able to slow down to the side of the road so you can turn the bike off/inspect/recharge..... If you ran out of gas, what does an ICE motorcycle do? It just stops. The LVC is NOT something so you can GET HOME. It's a mechanical/physical indicator that your batteries are too low to continue and you should pull over.
Thank god I don't live around you, I'd rather you pulled off the road slowly than drove home on a pack that could cause problems like overheating/venting/etc and cause you to lose control in front of my vehicle.
Travis might be on to something. Why not dump the BMS and just display pack voltage for a while? Check your individual cell voltages after each ride.
Your controller probably has an LVC setting too. You might rent the programmer and experiment with the Sevcon LVC, and get a sense of how it affects performance/reliablity. Then put the BMS back on and compare.
Maybe simpler is better?
Not to be taken seriously
I can't remember exactly how the Sevcon LVC is setup, but basically it's going to reduce power in some way. The MiniBMS can be set up to sound a buzzer when it hits LVC, without affecting power, however if you're half way up a hill and you hit a point where LVC would be triggered, I doubt you'll make it to the top anyway. Something's going to stop you be it a BMS event, controller event or batteries just not having what it takes because they're empty. The order in which I listed them is the preferred sequence.
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