I'm thinking about building a 256Wh 16s1p 32650 BatteryHookup LiFePO4 no-weld/no-solder battery for commuting. The idea is:
*$52 cost for the entire battery (plus cost of battery case, springs, etc).
https://batteryhookup.com/products/new-battery-hookup-lifep04-32650-3-2v-5000mah-cells
D-cell cases & springs will probably work, because D-cells have 33 mm diameter & 61.5mm length.
Question: Is LiFePO4 still the best chemistry for pedal-speed commuting, especially if fire safety is important?
*25km/h (15.5mph) average flatland speed, 75W average pedal power, 121W (.47C) average battery drain, 4.8 Wh/km (7.8 Wh/mi).
https://www.ebikes.ca/tools/simulator.html?motor=MG01_STD&batt=B4810_LiF
*Uphill: Double pedal power to 150W, slow down enough to keep battery drain below 1C and keep 250W hub motor from overheating. Ex: 9% grade at 11 km/h (7mph).
Question: Do hub motors usually have temperature sensors? Does it make sense to add oil/Statoraide so that the sensor temperature is closer to the real temperature of the windings?
Question: Is there any problem with using a 48V battery with a 48V controller and 36V 250W motor? Seems like it would work, if controllers reduce battery voltage in order to limit motor speed.
*No BMS, never let SoC get above 80% or below 20%, 154Wh usable battery capacity, 32 km (19.7mi) range, 19.7*2000=39400 mile (63500km) battery lifetime.
Question: What's LiFePO4's calendar life? Does it still have 80% of it's capacity at that point, and would it have 64% of it's original capacity after two calendar lifetimes?
*Easy shipping: In USA, assembled lithium-ion batteries <300Wh, and unassembled cells <20Wh, are easily ground-shippable.
*Intermodal (cars/buses/trains): Most buses & trains allow ebikes, and don't restrict battery chemistry. However, LFP is much more fire-safe than NCA or NMC, and I would guess that in the future, LFP in ground-shippable sizes may be the only allowable battery type, and this battery would meet those anticipated future regulations.
*Spring-loaded batteries can have hotspot/overdischarge/overcharge/balancing problems due to variable electrical connections within P-groups going unnoticed, but 1P design means that a spotty electrical connection would be as obvious as the ebike suddenly losing power.
*No welding/soldering equipment or skills are needed, no cells are damaged by a poor welding/soldering job, and I can get a working DIY ebike far sooner than if I had to buy equipment and practice techniques. Also, the upgrade path remains open-- I can build a big spot-welded battery and add a BMS whenever I'm ready.
What do you think?
*$52 cost for the entire battery (plus cost of battery case, springs, etc).
https://batteryhookup.com/products/new-battery-hookup-lifep04-32650-3-2v-5000mah-cells
D-cell cases & springs will probably work, because D-cells have 33 mm diameter & 61.5mm length.
Question: Is LiFePO4 still the best chemistry for pedal-speed commuting, especially if fire safety is important?
*25km/h (15.5mph) average flatland speed, 75W average pedal power, 121W (.47C) average battery drain, 4.8 Wh/km (7.8 Wh/mi).
https://www.ebikes.ca/tools/simulator.html?motor=MG01_STD&batt=B4810_LiF
*Uphill: Double pedal power to 150W, slow down enough to keep battery drain below 1C and keep 250W hub motor from overheating. Ex: 9% grade at 11 km/h (7mph).
Question: Do hub motors usually have temperature sensors? Does it make sense to add oil/Statoraide so that the sensor temperature is closer to the real temperature of the windings?
Question: Is there any problem with using a 48V battery with a 48V controller and 36V 250W motor? Seems like it would work, if controllers reduce battery voltage in order to limit motor speed.
*No BMS, never let SoC get above 80% or below 20%, 154Wh usable battery capacity, 32 km (19.7mi) range, 19.7*2000=39400 mile (63500km) battery lifetime.
Question: What's LiFePO4's calendar life? Does it still have 80% of it's capacity at that point, and would it have 64% of it's original capacity after two calendar lifetimes?
*Easy shipping: In USA, assembled lithium-ion batteries <300Wh, and unassembled cells <20Wh, are easily ground-shippable.
*Intermodal (cars/buses/trains): Most buses & trains allow ebikes, and don't restrict battery chemistry. However, LFP is much more fire-safe than NCA or NMC, and I would guess that in the future, LFP in ground-shippable sizes may be the only allowable battery type, and this battery would meet those anticipated future regulations.
*Spring-loaded batteries can have hotspot/overdischarge/overcharge/balancing problems due to variable electrical connections within P-groups going unnoticed, but 1P design means that a spotty electrical connection would be as obvious as the ebike suddenly losing power.
*No welding/soldering equipment or skills are needed, no cells are damaged by a poor welding/soldering job, and I can get a working DIY ebike far sooner than if I had to buy equipment and practice techniques. Also, the upgrade path remains open-- I can build a big spot-welded battery and add a BMS whenever I'm ready.
What do you think?