Total newbie looking for advice for DC voltmeter/ammeter

Hi everyone!

I'm a total newbie to Arduino and I'm starting my first Arduino project and I figured, meh, why make it easy?

I'm building a electric mini chopper that will be powered be a 48v 12ah battery pack. My controller can draw up to 200 amps max and I want to make a "fuel gauge" that shows both volts and amps.

Just to clarify, a fully charged 48v pack is actually around 57 -58 volts, so I want the voltmeter to read up to 60v. I would like the ammeter to read up to 200a if possible. I do understand that I will need a good quality shunt for something like this.

I've found a couple of post on different website on how to make individual voltmeters and ammeters, but I haven't found any that combine the two.

I'm planning to follow this tutorial to make the speedometer/tachometer:

So I would like to use the same display if possible.

I have "OK" coding skills in a couple of different languages, (I put the OK in parenthesis because my son is a developer for Openstack SDN and he laughs at my code! :wink: ), so I'm not afraid to approach this project as a beginner.

Does anyone have any suggestions?

Thanks

zog

I think you should make it easy and start with a simple project .
The problems you will have are any speed controller will be chopping the power supply and you will not get a steady, easily measured current . There will be a problem with measuring voltage and current - thinking of how you wire it up ( common 0v line ) . Any shunt will limit the motor current in a low voltage hi current circuit and you will need to amplify the signal. All this stuff adds weight- just measure the pack voltage and make do with that ( most controllers include that anyway) .

There are plenty of non-invasive ways of measuring current that don’t require a shunt. Have a look for “non-invasive current sensors”. Since many of them are designed for automotive use 200A DC is not a problem.

But I wouldn’t have anything to do with that “instructables” thing. There are many better ways of making a speedometer.

Steve

Do you have any filter caps or flyback diodes across the motor ?

I've found a couple of post on different website on how to make individual voltmeters and ammeters, but I haven't found any that combine the two.

The Arduino has multiple analog inputs. :wink:

It's actually easier to measure high current. A hall-effect current sensor is probably the way to go. If you use a shunt, it has to go on ground-side, because the Arduino can only measure voltage referenced to (its) ground. And hopefully, you know how to calculate power dissipation in the shunt.

For voltage, the [u]Analog Read Voltage Example[/u] will get you started. You'll need a voltage divider (2 resistors) and you'll have to scale the readings appropriately. And, I'd recommend a couple of [u]over voltage/reverse voltage protection diodes[/u] in case of unexpected spikes from the motor or charger.

Hi,

I'm building a electric mini chopper that will be powered be a 48v 12ah battery pack. My controller can draw up to 200 amps max and I want to make a "fuel gauge" that shows both volts and amps.

Sounds like the OP already has a controller, all that is needed is a battery voltage and load current monitor.

Tom... :slight_smile:

slipstick:
There are plenty of non-invasive ways of measuring current that don't require a shunt. Have a look for "non-invasive current sensors". Since many of them are designed for automotive use 200A DC is not a problem.

Like this?

https://www.ebay.com/itm/50A-100A-150A-200A-Bi-Uni-AC-DC-Current-Sensor-Module-arduino-compatible-/111689533182?_trksid=p2385738.m2548.l4275

slipstick:
But I wouldn't have anything to do with that "instructables" thing. There are many better ways of making a speedometer.

Do you have any links to point me in the right direction?

raschemmel:
Do you have any filter caps or flyback diodes across the motor ?

No, the motor is a DC brushed industrial permanent magnet motor. It connects tho the battery and controller like this:

DVDdoug:
And hopefully, you know how to calculate power dissipation in the shunt.

LOL, not yet, but that's what Google is for! (sigh, What happened to the old days when you could stop learning as soon as you left university? :wink:)

DVDdoug:
For voltage, the [u]Analog Read Voltage Example[/u] will get you started. You'll need a voltage divider (2 resistors) and you'll have to scale the readings appropriately. And, I'd recommend a couple of [u]over voltage/reverse voltage protection diodes[/u] in case of unexpected spikes from the motor or charger.

Thanks for the links and pointing me in the right direction! I'll be sure to post my results when I get everything sorted out.

Thanks everyone!