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Thread: Putting together a GPR-S

              
   
   
  1. #11
    I should be working! furyphoto's Avatar
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    Does the domino throttle turn more than 1/4 turn? I haven't used it yet, but the Magura seems like it has a pretty short physical range of motion.
    -Andrew

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    My ElMoto Project "Electric Hurricane" - 1987 Honda CBR600 F1: Check out my Build ALBUM
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  2. #12
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    Update time!
    Kyle and his friend John came by to pick up the pile of Leaf cells I had sitting in my garage, which was a group buy. I was going to take some of them but had to sit it out due to cost. I picked them up since I drive past the seller's shop (Autobeyours.com, Southern IN) all the time. Kyle also needed to pick up his EIG cells.

    So, the GPR-S was stripped of batteries yesterday! I got to spend some time diving into the bike. I removed the charger as well and started digging into another problem I had- no response from turning the key! Big problem! The first thing I suspected was that I had killed Kyles cell's with phantom drain somehow, but a quick voltage check showed everything was fine. I spent about four hours working through the wiring harness, trying to figure out why I had no continuity from the keyswitch to the 'make things go' wire down in the main part of the harness. I eventually worked my way to a spotty-looking solder connection in the OEM wiring harness. I thought that was my problem, but when I desoldered it, it was just one adjoining wiring wrapped around the unbroken parent wire... which would not at all explain the lack of continuity I was getting. Damn! Then I traced that other wire to another device. I had been puzzling over the red indicator light on the handlebars for a while, wasn't sure where it went to. I grabbed it to check the connections, and -click!- WHAT? it's a switch! It was an illuminated kill switch without the illumination hooked up! It is seriously just a red lens which can be tilted to one position or the other. No idea it was a switch. I hadn't really thought about looking for a kill switch on the bike, but I guess it makes sense to have one in case of an 'Oh crap' moment. Well, that was it. My four hour dive into the wiring harness ended up with flipping a switch I didn't know existed. What a waste of time.

    With all that figured out, I wanted to make sure that everything still worked, which it did, except a wheel-up spin test. I had a bunch of SLAs and my cordless drill battery jumped together to get about 65v to wake things up- but turning the throttle got no response. No motion, no dip in voltage or current use on the CA, nothing. Zip. Earlier in the day I'd discovered that the existing throttle went through a very interesting setup involving a two-wire pass-through soldered onto the back of a "Fusion Brain" PCB. Turns out that was just for 5v supply for the hall effect 'Longma' brand throttle. Earlier I had checked that the throttle wires to the Alltrax did indeed create a 0-5v sweep and it was fine. Checking it then created some erratic results; I am not sure why. At the start I was getting a 0-5v sweep, then I got some voltage in the mV range jumping around, then later I got some small millivoltage no matter what I did with the throttle. Not sure what happened there- maybe I toasted the throttle somehow during my probing, or maybe I was just frazzle-brained after my hours-long ordeal of finding a cleverly-disguised kill switch. That Domino throttle would probably work- but dang, $90 for a throttle? The $8 Chinese throttle on the GPR-S had worked for 5k+ miles and may still be working so it's hard to see what 10x the price will buy.

    I am out of town right now, so when I get back to it, I am going to investigate again with fresh eyes. It DID work before, so it should now- unless I toasted something. We'll see.

    I still have my battery dilemma if anyone wants to chime in with opinions. My requirements are linked in the first post. In brief: ~1kwh, 72v, 15-20kw peak power capable. I have a 5 miles commute, RT. The two options for me right now are a stack of Turnigy Lipo (20s3p 5ah 20Ccells, in hardcase packs) or lead-acid. I can hear the groans now, but listen: I wouldn't consider the lead acid except that I already own (4) 12v/35Ah gel-cells from another project. Add two more for $125, bam, I've got a 72v/2.5kwh pack. Now, it'll be heavy like a boat anchor and the ampacity is unknown- but getting on the road as soon as I can pick up the two extra batteries for $125 is awfully tempting. By comparison, it will probably take at least a month to get any Turnigy cells in my hands because they are on backorder. Lead looks pretty tempting at this point, but that'd be a 150lb pack instead of 20. The extra range I'd get would be nice, though. What would you all do? Think entry-level pack to wait for the next round of tech to show up in a year or two.

  3. #13
    Moderator Nuts & Volts's Avatar
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    That weird throttle circuit could explain some of the issues that Chef was having with the bike before he sold it to you. I would replace it with a Magura throttle (here is a cheap one http://www.ebay.com/itm/like/360735571315?lpid=82) and then reprogram the Alltrax for a 0-5K throttle. You'll need a serial to usb cable for that most likely. That will give you a smoother throttle, but then you don't have to spend $100 for a new throttle.

    You can also find some cheap 0-5k throttles, but I really dislike the plastic feel of them.

    i got my magura from here http://holmeshobbies.com/Magura-Twis...-throttle.html
    also http://www.ebay.com/itm/Qty-1-Magura...3D151237865847

    I say just install the Lead Acid cells at 48V and ride that for a week. If you like that you then have two options. Keep that for awhile and save up for LiPo or some other Lithium battery when you find a deal. Or if can fit more, buy 2-3 more Lead batteries and call it a day.

    Above all I think you should try to ride for a few weeks with what you already have on hand. It will help you get an idea of what you want out of the bike a little bit more than just tinkering.

    -Kyle
    Whats under my tank may shock you!!! R6 Build, Blog/, [/URL] OSU Current webpage

  4. #14
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    Do you think the Alltrax 7234 will run happily at 48v? Somebody wrote 'programmed 60v' on it and I wonder if that is an LVC. I did get a serial/USB cable in anticipation of programming changes, so I can surely change that if that is what it is.

    The bike will be pretty slow on 48v I am sure, but I think that tinkering with what I have is a good idea.

  5. #15
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    I now recall that EMS had created a fail-safe system for the GPR-S that required you to first turn off the kill switch and then turn it back on, after the ignition switch was turned on, before the bike could be started - and the throttle would work. It was something that I sometimes forgot about when trying to get the bike running in the morning.

    EMS sold a "low-power" version of the GPR-S powered by 12-volt AGM batteries for about half the price of the LiFePo4 version. It didn't seem to sell well and reports were that it didn't take very long before you were traveling at 30 mph and needing to push the bike up hills.
    Richard - Current bikes: 2014 14.2 kWh Zero S, 2016 BMW R1200RS, 2011 Royal Enfield 500, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior.

  6. #16
    Moderator Nuts & Volts's Avatar
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    Quote Originally Posted by nedfunnell View Post
    Do you think the Alltrax 7234 will run happily at 48v? Somebody wrote 'programmed 60v' on it and I wonder if that is an LVC. I did get a serial/USB cable in anticipation of programming changes, so I can surely change that if that is what it is.

    The bike will be pretty slow on 48v I am sure, but I think that tinkering with what I have is a good idea.
    No the undervoltage only goes up to 30V on the Alltrax and it works with 24-90V battery input

    http://www.alltraxinc.com/Products_AXE.html

    So I don't even think you'll need to reprogram it. Thou it's good to go in and tweak some things so that you understand what things effect different aspects of the bike. Maybe you'll need to change the full speed to 100% if it's not set there.
    Last edited by Nuts & Volts; 01 April 2014 at 0758.
    Whats under my tank may shock you!!! R6 Build, Blog/, [/URL] OSU Current webpage

  7. #17
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    It would be correct to assume that 2/3rds voltage would result in 2/3rds speed, right? Theoretically/generally/steady state.

  8. #18
    Moderator Nuts & Volts's Avatar
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    Quote Originally Posted by nedfunnell View Post
    It would be correct to assume that 2/3rds voltage would result in 2/3rds speed, right? Theoretically/generally/steady state.
    Yes for DC motors and simple AC systems it is accurate to assume that battery voltage is proportional to speed.

    Your motor is roughly 40RPM/V. So 48V will give about 1920RPM top speed. Using this with gearing to understand what your wheel RPM and then vehicle speed will be.
    Whats under my tank may shock you!!! R6 Build, Blog/, [/URL] OSU Current webpage

  9. #19
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    After looking at this spreadsheet:
    http://www.chromebattery.com/media/specs/S00016.pdf

    I am now much more hesitant about lead acid. Only 22ah out of a 35ah battery when discharged at 22A is not good for elmoto use, I don't think! Who knows how little energy they would give with 100-200A draws.

  10. #20
    Moderator Nuts & Volts's Avatar
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    Quote Originally Posted by nedfunnell View Post
    After looking at this spreadsheet:
    http://www.chromebattery.com/media/specs/S00016.pdf

    I am now much more hesitant about lead acid. Only 22ah out of a 35ah battery when discharged at 22A is not good for elmoto use, I don't think! Who knows how little energy they would give with 100-200A draws.
    While this is true, I think you're missing an oppurtunity with using the Lead cells. Basically I think they are best for testing and getting to know the bike better. They provide you a cheap, immediate, simple battery. You can figure out all the tricky and interesting things going on with the bike, before you actually spend anymore money on it. That way when you get your LiPo or whatever you can solely focus on paying attention to and safely using them.
    Whats under my tank may shock you!!! R6 Build, Blog/, [/URL] OSU Current webpage

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