Sat 27 Sep 2008
Peter in the UK has a running Lithium BMS. It uses a slave board on
each cell and a master board. He uses an LCD to communicate with them.
Peter has been doing this awhile.
I’ve ordered slave and master boards that I will populate with parts
and get the software loaded into each board.
This looks very promising. I suspect it could also be used with lead
acid with just code changes.
It’s simple to install.
Thu 11 Sep 2008
Nicads
- 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!
Friday night
- 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,