Custom Sport Scooter Project

I stripped down the bike and pulled out all the old GBS cells. I could see the bad one looking slightly puffy.

It was kinda interesting to compare the old and the new as 3kWh for 3kWh. The difference in volume and weight being pretty apparent! The GBS in total were 100lbs, but as 3kWh would be 80lbs. In comparison the Volt module is 60lbs.




I am hoping that the realistic range of the scooter remains the same as even though on paper the 3.8kWh of the GBS is higher. I think there is this potential for several reasons.

1. The additional 40lbs in weight the scooter has to lug up hills with the GBS battery burning additional energy.

2. The higher efficiency losses of the GBS batteries through higher internal resistance. I noticed a 24% loss comparing the Cycle Analyst and the Kill-a-Watt for energy used. I gather when the scooter is run harder the worse this is?

3. Usable range from a charge. Because there is a bit a variability between the GBS cells, the range is dictated by the weakest cell. With the Volt module there will be far less variability so the usable range should be relatively better!

With the old GBS cells removed was time to see how the new one would fit. I had built a stepped carbon base to make the GBS ones fit but as the new Volt battery is shorter this would not be needed.




The moment of truth! The Volt battery fits in just right, though if I want to fit a longer 100V 4kWh one in might be a squeeze with the radii on the front and the rear of the lower engine cradle. So the next thing is to consider how to fix the battery to the cradle and also best option to weatherproof it as I don't believe the upper section of the battery is moisture proof and over time the split lines will allow potential corrosion of the pouches.

Little update. I've been quiet these days, however the bike is still chugging along with total mileage at 27,000 miles. The Chevy Volt modules still working fine, 6 years in from the last post.

Scottydog said:

Little update. I've been quiet these days, however the bike is still chugging along with total mileage at 27,000 miles. The Chevy Volt modules still working fine, 6 years in from the last post.

Click to expand...

Very cool! Do you think you did anything in particular regarding charging and discharging parameters during those 6 years? Perhaps you can estimate number of cycles used. If you have an idea of the total range you could get off 1 full charge, you could do 27000/range per charge to estimate cycle count. Though actual cycle count would differ.

harrisonpatm said:

Very cool! Do you think you did anything in particular regarding charging and discharging parameters during those 6 years? Perhaps you can estimate number of cycles used. If you have an idea of the total range you could get off 1 full charge, you could do 27000/range per charge to estimate cycle count. Though actual cycle count would differ.

Click to expand...

I never used a BMS, instead would occasionally check the cells to see if they drifted. They haven't drifted which is impressive. I charge to 73V max and discharge to 65V min. That would be 4.05V max and 3.6V min per cell, I could probably charge up to 74V max, but always felt safer to be conservative even if I lose some range not having a BMS. I haven't done a range test in years, but riding gently would get me around 28 miles or so. It is slight hilly where I ride and the fat tyres of the bike are probably a bit draggy!

Scottydog said:

I never used a BMS, instead would occasionally check the cells to see if they drifted. They haven't drifted which is impressive. I charge to 73V max and discharge to 65V min. That would be 4.05V max and 3.6V min per cell, I could probably charge up to 74V max, but always felt safer to be conservative even if I lose some range not having a BMS. I haven't done a range test in years, but riding gently would get me around 28 miles or so. It is slight hilly where I ride and the fat tyres of the bike are probably a bit draggy!

Click to expand...

That's great info, thanks. 3.6-4.05v per cell is rather conservative for an e-vehicle, most people want to get max range and don't want to have such a shallow depth of discharge.

Your info suggests 950-1000 cycles. Was the Volt module new when you got it or used? Either way, thanks for the info, helps others with lifespan expectations

harrisonpatm said:

That's great info, thanks. 3.6-4.05v per cell is rather conservative for an e-vehicle, most people want to get max range and don't want to have such a shallow depth of discharge.

Your info suggests 950-1000 cycles. Was the Volt module new when you got it or used? Either way, thanks for the info, helps others with lifespan expectations

Click to expand...

Thanks, I have thought to charge a bit higher when needed. I use a Grin battery charger so have a few profiles with 72V being the default setting and 73V and 73.6V being selectable options. Thinking about it on the range test I would ride down to 65V unloaded, basically when I get down that low I'd be more ginger on the throttle.

The module I got was a 2013 one from Hybrid Auto Center in LA I think it was back in 2015 or so. It was a 1st gen second hand one. I have a second pair of modules Gen 2 or 3 not sure. The plastic is a darker colour, would make for a 96V pack. I really need to build a second bike around them, I got a bit enthusiastic 5 years or so ago and bought them without really thinking things through!

I haven't kept track of the battery choices now, but I really swear by pouch cell format by LG, would be nice to know if there are more options these days that are similar. If I was doing it now, would be tempted to build my own pack using LG or similar pouches and shed the volume and weight the Chevy modules have.

The last few weeks I did some machining to shorten up the wheelbase to match the OEM position. The bike gets used almost every day so looks a bit rough now as compared to when it was first built.

A well-traveled EV is the coolest kind of EV in my book. Congrats on making it through 6 years / 27,000 miles!

Nice looking thing. Never seen one of this scooters befor. I hope it drives like it looks, the aluminium frame should make it feel like a real motorcycle.
Looking through the classifieds , there is one near me with an actual KTM SX350 4-Stroke motor in it with 56hp, but it is based on the 50ccm scooter.
Was yours a 50ccm engine ? The one with 125ccm I have found have a complete different swingarm.

From-A-To-B said:

A well-traveled EV is the coolest kind of EV in my book. Congrats on making it through 6 years / 27,000 miles!

Click to expand...

Thanks! Agree well traveled makes sense, no point in paying for an expensive battery to be sitting around. My gas powered bikes get very little mileage now. It would be 8 years now in total for the bike as a whole, if it keeps going to 2025 will be 10!

dominik h said:

Nice looking thing. Never seen one of this scooters befor. I hope it drives like it looks, the aluminium frame should make it feel like a real motorcycle.
Looking through the classifieds , there is one near me with an actual KTM SX350 4-Stroke motor in it with 56hp, but it is based on the 50ccm scooter.
Was yours a 50ccm engine ? The one with 125ccm I have found have a complete different swingarm.

Click to expand...

Hey thanks! They are very cool looking, I also have the sportbike version also as a 2T 100cc kitted version. They do handle very well but being Spanish have their idiosyncrasies! The shortening of the wheelbase has improved the cornering ability noticeably, but also as I found wear in the pivots etc.

I would love to see the link to the KTM converted one, that sounds cool! There were 4 versions of the bike, 50cc 2T, 125 4T, 250 4T with motors mounted in the rear as normal scooters do. Then there was a race edition with a normal swingarm, with the motor centrally mounted with a chain drive. This was the version I decided upon back in 2008/2009 as it suited fitting a mid drive motor (this was before good hub options existed). In 2013 when I decided to go for it I discovered the 13" hub motor option so went that route. It does compromise the handling a little, but is very quiet and allows for a large battery pack. I have a second bike so plan to build some point a "Sunday ride" version which looks pretty!

I think the 125 / 250 versions would work well for conversion also. Either a new swingarm is fitted, or you can machine out the crankshaft section to fit a motor and then use the belt transmission, converting to a direct drive with the ratio you prefer. I am sure I have seen this on a scooter. I attached a YT link, but isn't the one I am thinking of.

dominik h said:

KTM 350 GP1

Click to expand...

Oh man someone had fun thinking up that idea! Must be a rocket with 54ps! I attached a photo of the streetbike version I have. It is pretty cool, I have a dry clutch conversion and other tuning parts, along with a redesigned carbon airbox I had to come up with so it could actually breathe on the OEM setup. I probably ride it 2 or 3 times a year! lol