Hey guys. I said I’d post about the mods on my surron. For now, I won’t get too detailed. If someone wants more, just ask.
Original bike: from Lunacycle took about 4 weeks (April).
ASI BAC8000 controller: Acquisition of this was long and painful. Originally ordered from ERT, but apparently Alan was sick, so it took forever to receive (3 months). It was DOA. It was taking too long for him to replace or even respond to emails, so I got a CC refund and moved on to Teznic. They supposedly had stock, but were also slow (about 5 weeks to receive), and the loaded parameter set wasn’t right. At least Tom at Teznic responded to emails, and tried helping me. He made progress, but my posts last week described that resolution.
72V Litespeed battery: 200 Sony VTC6 cells give much more power, and better range.
Wheels/Tires: The biggest problem on my early rides (in the Colorado mountains) was traction. My favorite tire type has been the “cheater” – soft Trials rubber with moto style tread pattern. I couldn’t find any for 19” wheels, so I decided to downsize the rear wheel to 16” which gives many more options since that’s the common size for the small dirt bike class. Tires for this class are smaller and lighter than full size dirt bike rear tires (which wouldn’t fit anyway). But because the aspect ratios are much taller, it only lowers the rear end by less than 3/8”, which I actually like since I’m short (5’7”) and prefer a slightly more leaned back geometry. I had a custom 16” wheel built, and mounted a Shinko 525 Cheater tire. Even this was slightly too wide (4”), so I shaved the side knobs somewhat – see pics. I kept the front wheel stock and mounted a Shinko 520 – softest I could find with my preferred balanced tread pattern. Traction was much better, which was especially needed with the extra power. They also helped significantly with the harsh ride because I can run them at 10 lbs (I use Motion Pro Liteloc rim locks).
Seat: The stock one wasn’t as bad as I’d heard, but it definitely needed to be more cushy for my bony butt, so I added 2” of foam covered with tough outdoor fabric I had left over from my pickup “SoftTopper”. See pics.
Suspension: Since I’m less than 140 lbs and don’t do big jumps, the stock suspension is good enough so far… although it’s pretty harsh on the trail, which may eventually force an upgrade.
Brakes: So far the stock ones are working well enough for my light weight, but I’ll eventually upgrade at least the pads.
Allex’s belt drive (52T equivalent gearing): The Gates belt on my Zero FX has lasted 6 years (2500 miles, many of which in the dirt) with no problems. I really like the quiet, clean, efficient operation. The only maintenance is to check the tension from time to time with the very cool audio frequency app.
HDPE bash plate:
Bark busters (hand guards):
https://www.amazon.com/gp/product/B07XB ... UTF8&psc=1
Handlebar control switch:
https://www.amazon.com/gp/product/B0039 ... UTF8&psc=1
Rear Brake/Running/Turn Signal LEDs:
https://www.amazon.com/gp/product/B01GJ ... UTF8&psc=1
Front Running / Turn Signal LEDs:
https://www.amazon.com/gp/product/B01L8 ... UTF8&psc=1
https://www.amazon.com/gp/product/B073J ... UTF8&psc=1
Rear fender: Modified to fit my custom rear bracket assembly. That bracket turned out to be not strong enough to hold the battery, so I ended up removing it on this trip and just strapping it to the seat frame. I'll remake a stronger bracket later.
https://www.amazon.com/gp/product/B075G ... UTF8&psc=1
Tank Bag: This bag is about the perfect size for the surron. The included straps work great.
https://www.amazon.com/gp/product/B084B ... UTF8&psc=1
Extra battery: Since range is such a big problem, I decided to add a pack. I figured since I was a EE in my previous life, I should be able to do it. I read that some people carry “reserve” batteries in a back pack. Others mount one on top of the main pack. Others (e.g. Fechter) use saddle bags. I decided to utilize the available space under the seat to keep the dimensions of the bike tight and the C.G. as low as possible (it also looks better). By designing and printing a plastic enclosure to go there, I was able to fit 140 cells. I printed in PETG since ABS warps too much at this dimension, and PLA won’t hold its shape with the anticipated temperatures. It mounts using longer versions of the two bottom seat mount screws and two screws through a custom rear bracket into heat inserted nuts in the shell. See pics.
I used a kWeld spot welder for the cell interconnects using .15mm nickel strips on top of .2mm copper sheet segments to minimize IR losses. I had to punch slots in the copper to facilitate good welds.
The configuration is 20s7p using Sony VTC5D which I chose because I wanted to have at least as much current capacity at 7p as the LightSpeed pack has at 10p.
For the time being, the two halves of the shell are just taped together with water proof Gaffers tape. Eventually, I’ll glue it together with 3D Gloop for PET, which I’ve tested on this specific PETG. Some PET compounds aren’t compatible with this glue, but this one is – from “IC3D”.
Honeycomb Cell holders:
https://www.ebay.com/itm/18650-Honeycom ... 2749.l2649
kWeld spot welder: Keith shipped it to me very fast. I used a car battery for the supply. Worked great. After experimentation, I ended up setting it to 95 joules.
Nickel Strip: .15mm x 10mm. I actually cut it into 5mm strips on each side of the copper slots, to maximize the weld current going through the battery caps.
https://www.amazon.com/gp/product/B07WB ... UTF8&psc=1
Copper Sheet: .2mm thick. Cut to connect adjacent 7p groups, with slots cut per cell. See pics.
https://www.amazon.com/gp/product/B07ZC ... UTF8&psc=1
BMS: This one has a 400A rating, so it minimizes losses so I can have protection and not bypass the discharge path.
https://www.ebay.com/itm/Smart-Lifepo4- ... SwMYxfD~bt
That’s about it.
Riding this bike is so much easier than my Zero in very rough conditions because I can reach the ground with both heals and it’s so light. Even though my upgrades added a fair amount of weight (25-30 lbs), I can still pick it up over obstacles when necessary. It’s still about half of the Zero weight.
The stock bike was way too wimpy on the street for me (I’m used to the 44HP, 70 ft-lbs, of the Zero), but in the dirt, the stock bike wasn’t too bad. The Zero is way overkill there. With the BAC8000 and 72V high current packs, this surron is now good enough on the street, and can climb anything its tires can manage offroad.
Range is the only real issue now. Even with my extra pack, it’s not enough. What I have to do is ride in the morning to a destination, which sometimes requires some of the extra pack. Meet the wives for lunch at that destination, who drove there with my other main pack (60V stock). After swapping, I can ride back. I could always build another extra pack to swap in the same way if necessary, but it would be much better if we just have one more factor of 2 improvement in battery energy density. Someday…