So I'm after a sanity check rather than showing off my creation for now, hopefully this is the right place.
I'm planning a build for bashing around off road, to keep up with my mates who are 10 yrs younger
What I think I need:
Something relatively low key, that won't upset the UK mountain biking fraternity too much
Future version with larger battery and controller is Version 2 (V2)
150 KG/330lb bike and rider, 20% grade, thinking that adding 150W for 3hours is about right to not be seen as cheating too much. Edit: Probably doubling this +
The plan is to start with a downhill or freeride bike, use a gearless hub so it's quiet and mechanically simple, have enough torque to tackle some pretty steep (20-25%) short hills and enough Wh to just provide some pedalling assistance on a day trip
Bike
Bike shortlist: Orange 5, Scott Nitrous, Transition TR450, Kraftworks FRM125 or Lapierre 718 Froggy, all around the £6-700 mark off ebay. I'm thinking I need a big cog on the front, perhaps a wide range front and back
Edit - Bought the Nitrous
Motor: - already purchased - MXUS 3K V3 Turbo XF-40-45H - 26" wheel, 10 Ga spokes
Controller: Powervelocity 18 FET 7Kw as the sensible pedal assist option
V2 upgrade for hooliganing - 24 FET 15KW but twice the size and 3X the weight so not so good for low key
http://powervelocity.com/home/55-24f-15kw-sinewavesilent-controller-android-ios-bluetooth-programmable.html
Battery - low key - 24S2P
Sony US18650 VTC6 30A 10Wh 3Ah cells seem to be the best spec, new cells cost a bit more but give fewer hassles.
A 24S2P Battery could produce 60A & 100V peak, 84V nominal, maybe around 5.4Ah, 440 Wh at 20A draw
Two of these batteries in parallel could be used for extended range - self built to fit frame with bespoke 3D printed box to look, um, less boxey
Sold out Hmm - may go for VTC5 2.6Ah instead or start looking again
Looking at the Samsung INR21700-40T 4000mAh - 35A it can put out 45A if limited to 80 Deg C,
Optional V2 higher spec battery 34S6P for use with larger 15 KW controller - future expansion of project
BMS - Daly - planning to check it regularly initially and fit a reset button. I have a cheap scope, clamp meters etc so will have an external balancing type cable for checking and perhaps paralleling batteries - maybe through ~30 Ohm resistors
May not need a second BMS for second parallel batt that way either
https://www.aliexpress.com/item/4001359842440.html
Charger
Cheap Current and voltage limiting charger [EDIT} power supply used as charger
2 x https://www.aliexpress.com/item/32953568490.html in serie
powered by one 600W supply, assuming they're floating outputs https://www.aliexpress.com/item/32850123866.html
I should add a spare thermal cutout (sensors in the pack, wired to a relay that is powering the charger)
TODO - proper risk assessment of charging FMEA etc
The result? 61% efficiency at 5MPH up a 10% incline or 50MPH for V2 - seems pretty good
The two configurations on a 10% incline - Grin simulation if the 4504 is the 45mm magnet and 04 winding - any thoughts on better settings for the V3 MXUS motor - can anyone confirm this is correct for this motor?
This shows likely pedalling and max output V2 options I think:
https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_86_0.2_5.4&cont=cust_60_150_0.03_V&grade=10&axis=mph&throt=13.6&hp=200&mass=150&bopen=true&cont_b=cust_150_300_0.03_V&motor_b=MX4504_SA&batt_b=cust_122_0.2_17&mass_b=150&hp_b=50&grade_b=10&autothrot_b=false&autothrot=true&throt_b=100&frame=mountain&frame_b=mountain
So, questions are, what am I missing?
24S seems pretty good for the motor and 7 Kw controller combination. Q. Why don't people like higher voltages?
The motor seems to work well accross the speed and torque range I need with the two battery configurations
For the purists, yes, geared is more efficient but I want silent, I don't even like the click of freewheels.
Mid drive is better on steep hills and for unsprung weight, but I want simple and quiet and snapped chains seem a pain (putting 3KW through a system designed for 10% of that would seem to need more engineering consideration)
The battery is pushed to its limit, I expect to outgrow it quickly so it may have a 100 recharge life. Anyway, I have to find more projects for my modified £20 welder a 3P version may fit easily in the frame (CAD TODO) which would be more sensible
Debating using a battery box and removable battery for charging versus a battery box that clips round the bike or just wrap in fibreglass fire blanket or rig a smoke alarm to a hose for a hillbilly fire suppression system or something... TBC
Security
I've a couple of USB drive sized GPS trackers which I could dismantle to embed in the electronics then encapsulate in epoxy or something. Parasitic back up power from the controller or direct from battery should be ok, might need a buck converter from a couple of cells from the batt but expect a 5V rail on the controller so may run from a big Capacitor to make it difficult to find or remove. Once localised with GPS, the Bluetooth from the BMS should allow me to find it again
No photos yet because I haven't bought much or built anything but if anyone spots has any thoughts and suggestions please shout out. I'll edit this if I get questions to make it more readable / explain
I'm planning a build for bashing around off road, to keep up with my mates who are 10 yrs younger
What I think I need:
Something relatively low key, that won't upset the UK mountain biking fraternity too much
Future version with larger battery and controller is Version 2 (V2)
150 KG/330lb bike and rider, 20% grade, thinking that adding 150W for 3hours is about right to not be seen as cheating too much. Edit: Probably doubling this +
The plan is to start with a downhill or freeride bike, use a gearless hub so it's quiet and mechanically simple, have enough torque to tackle some pretty steep (20-25%) short hills and enough Wh to just provide some pedalling assistance on a day trip
Bike
Bike shortlist: Orange 5, Scott Nitrous, Transition TR450, Kraftworks FRM125 or Lapierre 718 Froggy, all around the £6-700 mark off ebay. I'm thinking I need a big cog on the front, perhaps a wide range front and back
Edit - Bought the Nitrous
Motor: - already purchased - MXUS 3K V3 Turbo XF-40-45H - 26" wheel, 10 Ga spokes
Controller: Powervelocity 18 FET 7Kw as the sensible pedal assist option
V2 upgrade for hooliganing - 24 FET 15KW but twice the size and 3X the weight so not so good for low key
http://powervelocity.com/home/55-24f-15kw-sinewavesilent-controller-android-ios-bluetooth-programmable.html
Battery - low key - 24S2P
Sony US18650 VTC6 30A 10Wh 3Ah cells seem to be the best spec, new cells cost a bit more but give fewer hassles.
A 24S2P Battery could produce 60A & 100V peak, 84V nominal, maybe around 5.4Ah, 440 Wh at 20A draw
Two of these batteries in parallel could be used for extended range - self built to fit frame with bespoke 3D printed box to look, um, less boxey
Sold out Hmm - may go for VTC5 2.6Ah instead or start looking again
Looking at the Samsung INR21700-40T 4000mAh - 35A it can put out 45A if limited to 80 Deg C,
Optional V2 higher spec battery 34S6P for use with larger 15 KW controller - future expansion of project
BMS - Daly - planning to check it regularly initially and fit a reset button. I have a cheap scope, clamp meters etc so will have an external balancing type cable for checking and perhaps paralleling batteries - maybe through ~30 Ohm resistors
May not need a second BMS for second parallel batt that way either
https://www.aliexpress.com/item/4001359842440.html
Charger
Cheap Current and voltage limiting charger [EDIT} power supply used as charger
2 x https://www.aliexpress.com/item/32953568490.html in serie
powered by one 600W supply, assuming they're floating outputs https://www.aliexpress.com/item/32850123866.html
I should add a spare thermal cutout (sensors in the pack, wired to a relay that is powering the charger)
TODO - proper risk assessment of charging FMEA etc
The result? 61% efficiency at 5MPH up a 10% incline or 50MPH for V2 - seems pretty good
The two configurations on a 10% incline - Grin simulation if the 4504 is the 45mm magnet and 04 winding - any thoughts on better settings for the V3 MXUS motor - can anyone confirm this is correct for this motor?
This shows likely pedalling and max output V2 options I think:
https://ebikes.ca/tools/simulator.html?motor=MX4504_SA&batt=cust_86_0.2_5.4&cont=cust_60_150_0.03_V&grade=10&axis=mph&throt=13.6&hp=200&mass=150&bopen=true&cont_b=cust_150_300_0.03_V&motor_b=MX4504_SA&batt_b=cust_122_0.2_17&mass_b=150&hp_b=50&grade_b=10&autothrot_b=false&autothrot=true&throt_b=100&frame=mountain&frame_b=mountain
So, questions are, what am I missing?
24S seems pretty good for the motor and 7 Kw controller combination. Q. Why don't people like higher voltages?
The motor seems to work well accross the speed and torque range I need with the two battery configurations
For the purists, yes, geared is more efficient but I want silent, I don't even like the click of freewheels.
Mid drive is better on steep hills and for unsprung weight, but I want simple and quiet and snapped chains seem a pain (putting 3KW through a system designed for 10% of that would seem to need more engineering consideration)
The battery is pushed to its limit, I expect to outgrow it quickly so it may have a 100 recharge life. Anyway, I have to find more projects for my modified £20 welder a 3P version may fit easily in the frame (CAD TODO) which would be more sensible
Debating using a battery box and removable battery for charging versus a battery box that clips round the bike or just wrap in fibreglass fire blanket or rig a smoke alarm to a hose for a hillbilly fire suppression system or something... TBC
Security
I've a couple of USB drive sized GPS trackers which I could dismantle to embed in the electronics then encapsulate in epoxy or something. Parasitic back up power from the controller or direct from battery should be ok, might need a buck converter from a couple of cells from the batt but expect a 5V rail on the controller so may run from a big Capacitor to make it difficult to find or remove. Once localised with GPS, the Bluetooth from the BMS should allow me to find it again
No photos yet because I haven't bought much or built anything but if anyone spots has any thoughts and suggestions please shout out. I'll edit this if I get questions to make it more readable / explain