ArduPilot users Eohan George and Stefan Posey have launched a Kickstarter for a project they call BatMon. BatMon adds Smart Battery capability to a regular battery by monitoring the battery and using the SMBus interface to the autopilot to allow ArduPilot to monitor any battery on your craft. Various attempts at creating this device have been around for a few years but this is the first to make it out of the prototype phase and be made available to the general community. Well done guys! Check it out.
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I assume this would work with DIY 18650 battery packs.
Yes. This would work with 18650 batteries.
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It’s better to make this work with uavcan.
There are many of the existing systems using SMBUS. We will eventually get support for UAVCAN too.
Standard battery monitoring uses SMBus https://en.wikipedia.org/wiki/System_Management_Bus
and we don’t use UAVCAN for batteries. Why would you want to?
Great project, one thing i do not understand is how batteries can be charged, do i still have to use balance connector to the charger?
Battmon would be more suitable for DIY home power wal projects where a BMS is required. On a drone, we already have real time battery (voltage, current) monitoring systems that make battmon not really needed and balacing cells is dealt with battery chargers. The introduction video on the kickstarter page showing two kids having trouble to measure the battery state of charge is a non existing problem.
Where is the SMBUS port on a pixhawk. I have never heard of such a port…is this new or am i just missing something.
SMBus is a variant of I2C specifically for monitoring batteries. You can connect an SMBus device to the I2C port
Really…oh now the brain is clicking. I have a drone build that I keep messing with and I want to build an 18650 pack and this would be a great addition. To make it more interesting to me is I believe the battery connector would be an XT90-I which has the SCL and SDA pins. My drone just so happens to have I2C in the vicinity of the battery connector…so this is now starting to sound promising.
Sponsored. Wa hooooo exciting stuff
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Anyone know where you can get an stl (3d file) or something for a batmon case. I would love to start designing it into my battery pack.
Great idea but there are flaws…
- Drop the OLED it is just for vanity. Four leds are more than enough for onsite charge check, all other data should go to the flight controller via smbus.
- It is not clear, does this also acts as a charge controller ? Does it do balancing during charge ? (tipp: it Should!)
- Get rid of the connectors, a BMS module is must be integrated with the battery pack, any unneccessary connectors poses a possible point of failure. Solder,solder, solder.
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Looks like a good project to me. ArduPilot supports smart batteries which normally means the old 3DR Solo battery or the Maxell smart battery. There are some other smart batteries out there but they don’t seem to be readily available and so very few people use them.
Knowing the remaining capacity in the battery is really important for getting your vehicle home but also making sure the battery isn’t used below 10% or left charged at over 100% for long periods of time should improve battery life significantly (which saves expense and is better for the environment as well).
I hope the project is successful and I really hope that one way or another more people move to smart batteries.
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Does it act as a charge controller?
I agree a smaller version without monitor would be great.
The batteries can be charged using the “regular” charger. Our balancing circuit keeps the battery cells at same voltage. So, you wouldn’t need to use the balance connector. HOWEVER, depending on how different the cells are, the balancing circuit might not be able to balance it enough. The best way to check this is to monitor the min-max voltage of the pack and make sure its pretty low.
We’ll be putting the CAD up online after the kickstarter. Also see the latest update. If you are lazy to build your own pack, Titan has agreed to install it on their packs for free. They also make custom packs.
@Eosbandi @Corrado_Steri
Few customers have tens of battery packs and require deciding the right battery to use for the fleet. OLED help make some of this information easily visible.
OLED will be optional for further designs.
It does balancing of around 100ma. So if you charge it too high of a current, will not keep up with balancing a “badly” balanced pack.
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Why are you using a shunt instead of a hall sensor?
I cannot see a big advantage of this as a hobbyist when I have invested in decent sensors like Mauch. The smart discharge is nice extra feature though. The ability to adjust remaining capacity according to temperature is a big extra advantage for winter fliers but you do not have that feature now.
I do hope you are successful with the Kickstarter but working directly with battery manufacturers seems the way to go. I will probably get one just so I can do my bit to encourage innovation. I would like to see a simpler, smaller unit with no OLED or connectors, costing $30.
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Let me know when the cad goes up. I want to get some batteries ordered for the build and want to include this in the design.
Will be uploaded after the Kickstarter campaign