TheWizard
1 mW
Preface:
Last week I salvaged a Chinese AOWA 36V pedal-elec. After stripping off the cheezy plastic panelling, I found a very solid bike that was fun to "drive" (the cranks are just above the ground and are 155mm long with a 1:1 gear ratio, making "riding" a bit of a joke) but the SLA batteries are holding it back - as well the wimpy 18A controller and thin phase wires on the 9C motor, but those are the easy things to fix.
I'm gonna cut off the SLA bracketry, bend and weld a rack to hold a 7s3p A123 EV pack just forward of the cranks.
That will get the heavy weight nice and low. And it will make room for welding in a top-tube that will run from the seat-stay junction to the far edge of the front wheel, turning this moped into a 72V 20Ah cycle-truck!
But first I need to assemble a charger for my A123 7s3p packs. I bought 3 of them, betting that e-biking will be a serial addiction! The plan is to cut the bus bars and rewire them from 24V (7s3p) to 72V (21s).
I trolled the junkyard today and took a second look at a well-aged heap of telecom wreckage. I removed 3 of these 24V 15A power supplies from some 19" racks:
http://www.ebay.com/itm/SOLA-CVDC-POWER-SUPPLY-28-1203-2-24VDC-4-5A-15A-OUT-NICE-USED-TAKEOUT-M-O-/160756813551
The item pictured is in much nicer shape than what I recovered, but it was a fair wager at scrap price. They weigh about 25 lbs a piece! All american
My phone is being a goon so I'll have to upload pics of the under-side later. The only hidden pieces down there are 2 pots in-line with the transformer and an inductor/shunt/wire-wrapped-rod thingy. No protection of any kind (maybe inside the big rectifier unit?), I'll be adding some fuses
Am I wrong in assuming that I could wire the outputs in series like people do to make HV chargers out of multiple SMPS's?
I'm reading through this but I haven't really groked the circuit yet
http://www.google.com/patents/US2804588
http://www.google.com/patents/US2806199
http://www.ieeta.pt/~alex/docs/ApplicationNotes/DC%20Power%20Supply%20Handbook.pdf
Looking at those big ole caps, they are rated 30Vdc & 40Vdc. If I tweak the windings on the inductor/wire-thingy, do you all think there's enough headroom to get an additional 6V out of each supply to get a 86V charge voltage?
1.21 Jiggawatts! err, 1.2Kw charger....time to string a new power-run in the garage.
What kind of charge times could I expect? Is that a just a math problem or is there some LiFe/A123 chemistry-voodoo there?
Last week I salvaged a Chinese AOWA 36V pedal-elec. After stripping off the cheezy plastic panelling, I found a very solid bike that was fun to "drive" (the cranks are just above the ground and are 155mm long with a 1:1 gear ratio, making "riding" a bit of a joke) but the SLA batteries are holding it back - as well the wimpy 18A controller and thin phase wires on the 9C motor, but those are the easy things to fix.
I'm gonna cut off the SLA bracketry, bend and weld a rack to hold a 7s3p A123 EV pack just forward of the cranks.
That will get the heavy weight nice and low. And it will make room for welding in a top-tube that will run from the seat-stay junction to the far edge of the front wheel, turning this moped into a 72V 20Ah cycle-truck!
But first I need to assemble a charger for my A123 7s3p packs. I bought 3 of them, betting that e-biking will be a serial addiction! The plan is to cut the bus bars and rewire them from 24V (7s3p) to 72V (21s).
I trolled the junkyard today and took a second look at a well-aged heap of telecom wreckage. I removed 3 of these 24V 15A power supplies from some 19" racks:
http://www.ebay.com/itm/SOLA-CVDC-POWER-SUPPLY-28-1203-2-24VDC-4-5A-15A-OUT-NICE-USED-TAKEOUT-M-O-/160756813551
The item pictured is in much nicer shape than what I recovered, but it was a fair wager at scrap price. They weigh about 25 lbs a piece! All american
My phone is being a goon so I'll have to upload pics of the under-side later. The only hidden pieces down there are 2 pots in-line with the transformer and an inductor/shunt/wire-wrapped-rod thingy. No protection of any kind (maybe inside the big rectifier unit?), I'll be adding some fuses
Am I wrong in assuming that I could wire the outputs in series like people do to make HV chargers out of multiple SMPS's?
I'm reading through this but I haven't really groked the circuit yet
http://www.google.com/patents/US2804588
http://www.google.com/patents/US2806199
http://www.ieeta.pt/~alex/docs/ApplicationNotes/DC%20Power%20Supply%20Handbook.pdf
Looking at those big ole caps, they are rated 30Vdc & 40Vdc. If I tweak the windings on the inductor/wire-thingy, do you all think there's enough headroom to get an additional 6V out of each supply to get a 86V charge voltage?
1.21 Jiggawatts! err, 1.2Kw charger....time to string a new power-run in the garage.
What kind of charge times could I expect? Is that a just a math problem or is there some LiFe/A123 chemistry-voodoo there?