"Range gauge" for an electric mobility scooter
Discussion
My father-in-law has an elecric mobility scooter which has a notional range of about 10 miles.
However, the only indicator of how much power's left in the batteries is an uncalibrated (no V markings) voltmeter, which essentially shows a voltage on the far right of the scale until the batteries are almost depleted. As such it's no use for determining whether there's 10 miles or half a mile of range left.
What we need is a better way of indicating the remaining power and therefore range in the batteries.
I'm aware that a more accurate voltmeter would indicate the state of charge of the battery but we'd then need to translate (e.g.) 12.67V to 10 miles, 12.5V to 5 miles and so on.
Does anyone have any practical and inexpensive solutions other than inferring power remaining from exact battery voltage, or any refinements on that idea?
However, the only indicator of how much power's left in the batteries is an uncalibrated (no V markings) voltmeter, which essentially shows a voltage on the far right of the scale until the batteries are almost depleted. As such it's no use for determining whether there's 10 miles or half a mile of range left.
What we need is a better way of indicating the remaining power and therefore range in the batteries.
I'm aware that a more accurate voltmeter would indicate the state of charge of the battery but we'd then need to translate (e.g.) 12.67V to 10 miles, 12.5V to 5 miles and so on.
Does anyone have any practical and inexpensive solutions other than inferring power remaining from exact battery voltage, or any refinements on that idea?
Any idea how much current the motor pulls? In addition to voltage the Arduino could use an appropriately rated current sensor to calculate how many Watt Hours have been drained from the battery since the last full recharge (and have some reset button on your measuring widget to indicate that you've recharged the system).
You could also rig up an optical or Hall-effect sensor on one of the wheels or some other part of the drivetrain to calculate distance covered since the last reset, and calibrate appropriately, although lighting the tyres up in burn-outs or excessive drifting might skew the results. If you wanted to go completely over the top, add in a cheap GPS module which you could also use to deduce distance travelled.
Arduinos are great, but getting to be a bit old school. Nowadays I'd use something like a Pi Pico and some embedded Python.
You could also rig up an optical or Hall-effect sensor on one of the wheels or some other part of the drivetrain to calculate distance covered since the last reset, and calibrate appropriately, although lighting the tyres up in burn-outs or excessive drifting might skew the results. If you wanted to go completely over the top, add in a cheap GPS module which you could also use to deduce distance travelled.
Arduinos are great, but getting to be a bit old school. Nowadays I'd use something like a Pi Pico and some embedded Python.
Edited by eharding on Tuesday 16th March 17:12
eharding said:
Arduinos are great, but getting to be a bit old school. Nowadays I'd use something like a Pi Pico and some embedded Python.
Wasn't aware of the Pico. Provided all the modules are available for the job in hand it looks like a great alternative.Edited by eharding on Tuesday 16th March 17:12
Evanivitch said:
eharding said:
Arduinos are great, but getting to be a bit old school. Nowadays I'd use something like a Pi Pico and some embedded Python.
Wasn't aware of the Pico. Provided all the modules are available for the job in hand it looks like a great alternative.Edited by eharding on Tuesday 16th March 17:12
https://www.amazon.co.uk/MakerHawk-Development-0-9...
You need to coulomb count, ie to add up all the amp seconds (amps for each second) that go into the pack when charging, and then do the opposite during use.
Say the pack charges at 10 amps for an hour, that's 10 Amp.hr of charge, and if your motor pulls 10 amps, then you can do that for an hour until you reach the inital state of charge.
Basically, you need a current sensor and a microcontroller of some sort, although i suspect you can buy such a device i suspect
Say the pack charges at 10 amps for an hour, that's 10 Amp.hr of charge, and if your motor pulls 10 amps, then you can do that for an hour until you reach the inital state of charge.
Basically, you need a current sensor and a microcontroller of some sort, although i suspect you can buy such a device i suspect
Here you go!
https://www.ebay.co.uk/itm/DC8-80V-50A-100A-350A-B...
Check the scooter is 12V
The 50 Amp shunt (which is cheaper) would most likely be fine and a tad more accurate.
I recently fitted one in my caravan - works fine and arrived in a couple of weeks
https://www.ebay.co.uk/itm/DC8-80V-50A-100A-350A-B...
Check the scooter is 12V
The 50 Amp shunt (which is cheaper) would most likely be fine and a tad more accurate.
I recently fitted one in my caravan - works fine and arrived in a couple of weeks
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