Thu 11 Sep 2008
– 2 weeks before Rally truck only had a 12 mile range.
– Drained pack, shorted only lowest 70 cells. Did it twice. Helped some.
– Finally read the nicad manual and found that it said drain and short the whole pack, so I did.
– Made shorting clips with bailing wire as a load resistor.
– It helped a lot!!! Pack finally has a 20-27 mile range.
– Rally was 20.5 miles.
– Used 4.4 kwh to get to Rally.
– Fantastic efficiency 200 wh/mi at 45 mph! Loaded with scooter and tools!
Took scooter to Rally. It worked great.
– Had to machine a new hub until 3AM! Shattered into 4 pieces.
– Titanium return spring bent!
– Steering out of trim.
– Standing long sure makes the feet sting!
Made a panel that automates some of the charge/discharge testing.
– Designed in Rhino3D
– CNC Machined
– Mounted Emeter and other parts.
– Still needs to be wired to load tester and charger.
Thundersky 40ah cells from Green E motors.
– Tested at 103-105% at 40 amp load.
– Next test is 60 amp load, then it goes into the truck!
– Plastic insulators need to be machined to keep screw heads from poking nicads.
– Also have K2 cylindrical cells from Allen to test.
Found a voltage monitor IC for a Lithium BMS.
– LTC2912 from Linear.
– Has over undervoltage and undervoltage outputs.
– OV and UV will trigger a buzzer or external LED with an opto.
– Will try to get samples from Linear and test.
Found a BMS that is like my design, but is for sale at Black-sheep.us.
– Ordered 3 of them.
– $34 each.
– Designed to fit 90ah cell. Will use cables to adapt to 40ah cells.
– May modify Black-sheep’s design with LTC 2912 so it can be used on any battery voltage.
– Simple analog interface to an LED or buzzer for under or over voltage notification.
Wednesday night drained pack.
– Shorted cells Thursday afternoon thru Friday morning.
– Pack took on 41.5 ah’s (14 kwh).
– Biggest recharge so far!
– Found that low volume cells were very low on water. At least one is damaged.
– Lots of overcharging without checking water levels.
– 6 Replacements were installed so low water cells can be tested.
– Driver’s side of pack is watered.
Labview classes all of next week
– COuld help in making an automated multi cell battery tester.
Bring: Markers, shorting clips, orange hammer, Emeter panel, picture of Blacksheep BMS,
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