Lil' CousinCommutator after 1000 KMJackscrews make opening the case easyA Simple gear puller frees the other sidThe stolen "Buttercup."
OwnerMark Fisher
Owner's Other EV2009 X-Treme Sooters XB-600
LocationTakoma Park, Maryland United States map
Email email image
Vehicle2004 Yonkang Crown SEC-R700
Custom "clad" electric scooter.
Motor Permanent Magnet DC
700 Watt nominal, 1200 Watt measured consumption. Pronounced cogging at low RPM coast after re-bonding 3 of 10 magnets, thus the name "Hummer."

The cogging went away after a year, and, after 2 1/2 years, so did the brushes. I replaced them, but neither ran the motor in at low power to bed them nor faced the comm; the entire commutator area became a molten plastic mess as the arcing melted the brush holders.
Controller OEM
labeled capacity: 500 Watt, 48 V
Batteries4, 12.00 Volt, Lead-Acid, AGM
17AH x 4: "Werker" tried, but did not last.

Pack wiring was 14GA, which other posts have deemed adequate for a max 20A draw.

As of 9-2-08, I just rewired the pack to implement parallel wiring to the charging jack, with a series jumper plug for normal operation, and a parallel plug for charging.

The new pack wiring is all 10GA, and the charging/jumper plug is Anderson PowerPole 40A.

Each battery has a pair of 10GA wires running to the eight-contact jack in the seat. I made up a jumper plug that "wires" the batteries into a 48V series string. The main circuit breaker is also part of the jumper plug, so potential can be removed before inserting or removing the plug, reducing arcing. Total wire length is probably around five feet, up from ~3 feet of 14GA. Of course, now full pack amps go through six Anderson connectors as well (the most negative and most-positive battery posts are permanently wired into the scoot).

Charge gets to the batteries via two four-contact Anderson connectors. Since my old charging system had four parallel Vector 2.5/6/10 chargers, I was able to use two of the chargers, allowing faster charge times. Since each charger is on a completely separate cable/plug, they will be plugged into either charger "A" or "B" randomly. For charging, I now have two 12V parallel strings.

First day's ride seems to show less pack sag than before, and equal or better power. I still have 3' of 14GA wire from the controller to the motor, but I don't want to upgrade that in case that was helping to avoid overheating the motor.
System Voltage48 Volts
ChargerVector 2.5/6/10
2 @ 24V 1.5A capacity Soneil2404 bricks:
After ~500KM, these "cooked" one pair of batteries.

Switched to four Vector 2-6-10 12V chargers. Aside from bulk and noise, they have been satisfactory. Just bought four Chicago Freight float chargers (constant current, tested 14.06V cutoff) for an onboard setup. We'll see. ChiFreight chargers were hot and noisy. Sent to scrap bin.
DC/DC ConverterErickkson PKG 4625
(Hey, guys, it's "Ericsson"!) Isolated ~12V output.

Required re-wiring ground system, as the original scoot came with a common ground for both the 12 and 48V system (!!!).
InstrumentationSpeed, volts; sometimes WattsUp & GPS.
Top Speed30 MPH (48 KPH)
Equivalent to an energetic bicycle rider.
Range15 Miles (24 Kilometers)
Old, mismatched batteries. Building Lee Hart's shunt balancers - will it help?
Answer: no. For a system with buried batteries, the separate zeners cannot be monitored. When the zeners are collected together, they require a large heatsink, and even then, they interfere with the voltage sensing of 3-stage chargers.
Watt Hours/Mile100 Wh/Mile
EV Miles
Start:125 Miles (201 Kilometers)
Current:3,124 Miles (5,026 Kilometers)
Total:2,999 Miles (4,825 Kilometers)
Seating Capacity1 (+1/2)
Curb Weight150 Pounds (68 Kilograms)
Tires10" x 3"
Conversion Time3 months of occasional evenings.
Conversion Cost$200.00 All the little bits add up... A new battery pack will be another 2-400, depending on quality.
Like all free puppies, lots of little bits. I started with a complete non-working scooter with no body. Reworked motor, DC/DC, separated 12V and 48V ground, and fabricated body (rear wheel blisters are cut from Nissan minivan bumper).

To do: +12V "turbo boost" controller bypass, safety contactor, and regulator shunts.

After 1000KM, none of the "to do" items has appeared, but I'm still happily riding to work.

On 3-14-07, "Buttercup" (the cute one) was stolen. After presumably breaking the ignition/steering lock, the dweebs woke us up by pressing the horn, thinking it was the starter, but they got away.

In Sept. 08, I rebuilt the speedometer crown gear. It was nylon, and had not correctly meshed with the pinion. I potted the entire gear in filled epoxy and hand filed new teeth to increase its diameter. About 1 hour's work, and the speedo works again!

In June 09, it had its "never get overs." see "Motor" section above for details. Pack wiring detailed in "Batteries" section was a success, allowing a mis-matched pack to deliver its full capacity to the end. I'll re-use the batteries - my new scoot uses the same form factor.

code by jerry