I had to buy some speed controllers and other EV parts for my yard machine, so I took a chance and got what was supposed to be a 36 Volt system battery SOC gauge. kelly controller SOC gauge
I took out a variable voltage power supply, and checked the led display's SOC against a Trojan battery company equivalent voltage chart, and found that it was not even close. I could not use it as it was, and the thing was glued together with no way to get inside.I took my band saw and cut the outer tube so the back could be removed. The circuit looks like a series of resistors that make up a voltage divider and some op amp comparators to turn on the leds when the voltage rises over the voltage divider taps. This type of comparator can be quite accurate, but it depends on voltage references and precision resistors,which this unit does not use. What was most interesting was that there is a potentiometer on the circuit that can adjust the divider current to make the whole scale move up or down. I set the power supply to the 100% SOC voltage according to the trojan chart, and then adjusted the pot so the 100% led just came on. I then adjusted the power supply down until each led went out, and noted where the 50% SOC was so I knew when to get to a charger. While this setting may be a bit temperature sensitive, it at least made the gauge usable. To gain access to the pot, without cutting open the whole case, drill a hole in the indicated place on the back cover and you should be able to adjust the gauge without cutting it open. Of course one could calculate the precision resistor values required for accurate SOC throughout the range, and replace the 10% resistors that they used, but relative SOC is all I need so simply getting the 100% and 50% points will be sufficient accuracy for me.
About 12 years ago, I decided to build a powered bicycle, so I dismantled my seldom used weed whacker and built a three speed drive system that attached to the motor. I put it on the front wheel of a bike, with a hand shifter so I could move it through the gears. It worked pretty well as far as pushing the bike, with top speed being faster than I felt comfortable going. I could not stand the noise and fumes, so I removed it. I just ran into the motor/drive when looking for something else, so I figured I would snap a few photos in case someone else wants to play with a similar concept.
With the many projects I hope to work on, some extra hands are always welcome. Check here to see if their will be a workshop if you want to come up and lend a hand. Present project: Design, build, and test an IMA-EV mod to give full electric mode to the gen 1 Insight
As any owner will tell you, when you are pumping charge in and out of the pack with MIMA, it can get hot, especially in summer. The battery is cooled with a two speed fan that draws air into the battery pack from behind the passenger seat inlet vent.MIMA will force the two fans on at full speed when the temperature of the battery gets over 95F. I made a Turbo Cooler for my pack by ducting the passenger foot AC outlet to the battery pack input duct. I set the fan on high, and the duct to foot only. The driver side vent is ducttaped over, so that all the air comes out of the passenger side. The increased air flow helps a lot, with mild MIMA use, but if you are really pushing the hybrid ratio to the electric side, the pack can still get into the 100 F range. Because of the large thermal mass of the heavy batteries, it takes a lot to cool them even a few degrees. To Turbo Cool the pack, I wait till I am going down hill, so the power is nearly free, and turn on the AC to full, set to 60 F. A long hill and you can cool the pack several degrees.
Genesis One, LLC
If you would like to get involved or support any of these projects, please contact me at (860)935-5569.