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Electric Circus Car vol 2

We are getting close to completing this project.  




I 'm guessing that the multi meter can serve as a charge level indicator for the 36 volt battery pack.  Fully charged, the meter reads 38.4 across the spade terminals on the relay.   It reads 39.1 across the batteries terminal posts.  Is that difference to be expected?  

After running the car, what reading would indicate that it needs to be recharged?  If the reading falls below 36 volts, will the car still operate?

Is the analog golf cart charge meter providing the same information as the digital multi meter?

A multimeter can definitely function as a charge level indicator however if it was used as one on a continuous basis the its battery would wear out a lot faster than normal.

The reason that there is 39.1 Volts at the battery pack terminals and 38.4 volts at the reverse relay's spade terminals is because the wires between the battery pack and relay provide resistance to the flow of electricity that runs through them. This small loss of Voltage due to the wire's resistance is perfectly normal.

The batteries need to be recharged when their Voltage level drops under 32 Volt while they are being used and under load. The controller has a built-in low Voltage protection circuit that turns off the motor when the battery pack Voltage drops under 32 Volts though, so you do not have to worry or think about over discharging the battery pack because the controller will not allow that to happen. Well before that battery pack reaches 32 Volts under load the vehicle will start to travel significantly slower than normal though so there will be ample warning before the controller shuts down the motor due to low battery Voltage.

The 36 Volt analog state of charge meter provides a Voltage reading of the battery pack just like the multimeter does however its range is limited to roughly 30-45 Volts. 30 Volts being when the needle is on the far left side of the meter and 45 Volts when the needle is on the far right side of the meter.

Good info.  

I'd like to add a secret kill switch for security.  Would interrupting the positive wire on the forward side spade terminal of the relay be a good plan?

Interrupting the positive wire on the reverse relay's forward side spade terminal would stop the car from moving forward however it could still be operated in reverse.

If the main (long) black wire that supplies ground to the both sides of the reverse relay's spade terminals was interrupted then the car could not operate in either forward or reverse until the secret kill switch was turned on. Although switches are usually placed in positive wires there is absolutely nothing wrong with placing a switch in a ground wire so that is always an option.

Our project is complete and we have you to thank.  It turned out better than I imagined it could and we could not have done it without your help, so THANKS!



I put a switch in the black ground wire going to the relay, but in either switch position, the original on/off switch still lit up the indicator light and the charge meter.  I took the switch out and reconnected the ground wire which has the green shrink tube.  It did not occur to me to try the throttle to see if the kill switch was effective in keeping the car from moving even though the indicator light and meter were getting power.


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