Using Spark Core to sense and cut circuit on Battery Charger

Would like to share my thoughts and get feedback on an idea I have for a possible shield for spark core.

Charging a battery for the most part has similar limit characteristics as Maximum Voltage and Maximum Current applied to a battery regardless of the type of battery. The frequency is controlled by the charging circuit but, a lot of battery chargers do not provide any more user interface other than a “Red” and “Green” light.

I want to design (or try) to build a Spark Core Shield that will sense both voltate and current being applied to a battery with the option of multiple monitoring points for multiple batteries charged in series such as LiPo batteries for added safety and battery condition monitoring.

I would suggest this Charger Monitoring shield should have three connectors.

CN1 - Red Wire = Voltage +

CN2 - Black Wire = Voltage -

CN3 - Yellow Wire = In Series with Red Wire to measure Current being applied to battery (Batteries)

? Would using a Voltage Comparator Circuit or Zener Diode Circuit or LM377 circuit (those I know about) work ? Or, what esle could I use that is more efficent to accomplish both voltage & current monitoring ?

Any help pointing me in the right direction will be very much appreciated.
Thanks, Bobby

@spydrop, what voltage and current range are you looking to monitor?

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@peekay123, I would like to monitor from 6v to 24v at a minimum up to 7 Amp but, going all the way to 72vdc at 10 Amp would cover just about all chargers for bikes, cars, and solar.

I can live with the lower limit of 6v to 24v / 1 - 7 Amp as I want it to be a 1" x 3" form (like @kennethlimcp SD Card) if at all possible.

What do you suggest is best way ?

Thanks, Bobby

@spydrop, I have been working on a Spark powered current/voltage monitor for some time. I will be creating a shield that does pretty well exactly what you are looking for. I am just finalizing the electronics design. :smile:


@peekay123 - Awesome to here. Will it incorporate multiple contact points as in between batteries or between multiple battery packs ?

Most solar and bicycle electric battery systems employee multiple batteries in series or multiple parallel banks of batteries in series (I bet you already know that too) I just mention here for those who might not have that info.

Having multiple contact points / monitoring would be awesome ! (but absolutely a must - I know).

@spydrop, to do multiple contact point would require a larger shield. One of my prototypes is setup to monitor the charger side of the battery and the load side of the battery. That requires two current sensor circuits. However, it is completely possible.

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@peekay123 - Very Nice. Possible sounds good :smile:

Can’t wait to see your proto-type. Even with only one contact point would be a blessing to most people to assure their charger and the battery managment for that matter is working properly.

To tell you the truth, I am building a multi-voltage / multi-current Alkaline Battery Charger and I am in the final design stage. Next version is final proto-type.

Any chance your using @kennethlimcp MicroSD Card Size & Core location parameters or is your shield bigger than that ? Having a set Shield Make-up (or even Eagle Files) would be a blessing to me and I am sure others (Sorry, if I seem pushie about what people should do, I just would love to do “Plug & Play” with all the new shields coming our way :smile:

Thanks for helping and letting me know this shield is in the works. It is a repeat of @kennethlimcp shield too - I started one and got shot down by a few because my work is not the best; and I’m absolutely okay with people telling me to step aside, got it covered as it makes me Very Happy ! I can concentrate more on my other projects.


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@spydrop, the challenge with 30+ volts and 7+ amps is the isolation required. You also need larger wires and and connectors. So there are compromises. There may need to be a board extension like what @kennethlimcp was doing with his prototyping board.

One other possibility is to use “remote” sensors that use I2C and could be daisy chained or on a hub to connect multiple units. This provide simple expansion and isolation.

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@peekay123, Yes ! High Volts / High Current thicker traces adejuate componet sizing - I understand. and Daisy Chaining (our dog is named Daisy :))

Hmm. Most 24v chargers put out 27-29 volts… Okay ! Is 24 volts at 2 amp max doable for your current design ? If so, that woud be great ! Covers what I need for my project.

And ---------> :slight_smile: Okay, What to build that will mate up with your shield (I really do like @kennethlimcp size and cor location but, not locked in yet.

Thanks, Bobby

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@spydrop, the current design handles 32V and 3.2A. I originally wanted 60V at 50A but the wires get really big and connections become a problem. I will have to think about what I can put on that size board.



Sounds Great ! Please do let me know what you decide for size and the core location on your shield as I will want to use that info on my Battery Charger.

Many Thanks for taking the time to help me - it helps me a lot and saves me lots of frustration as I move ahead; lots to learn.

@peekay123 have you gotten further with your design? I have a project where I want to measure water flow through a sensor that generates power. I want to use that power also to charge a battery so the spark is self powered.

Seems like if I could just track that incoming voltage, I would have what I need with a simple battery charging shield.

Make sense? I’m a rookie at this stuff, sorry if I overly simplified the concept.

Here are some specs on the flow sensor/generator I have:

Test pressure: 1.2MPa
Temperature range:0-120 degrees

Built-in regulated voltage circuit
Maximum working pressure: 1.75MPa

Water flow rate: 2L/min
Built-in 520mA LI-battery.for energy-saving
Shell material: nylon
Net weight:165g
Working pressure: 0-1.75Mpa
Flow range: 1.5-20L/min (press 0.05-0.2MPa)
Output voltage: 3.6±0.3V VDC

@ScottZ, slow but sure. I decided on a sensor that will sense up to 3A/32V but I am trying to see how I can accommodate multiple channels versus just one while still keeping the shield small.

You could measure voltage from your generator by using a simple voltage divider (assuming it is DC) and protect the input with a 3.3V zener. What is the current produced by the generator? Is this an off-the-shelf product with a built-in battery? :smile:

No problem - glad you are around!

It is off the shelf -

Not sure the current - it has to be small. I want to measure household water flow.

I thought I might be able to use this with an external battery, but I don’t think it does what I need.

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@ScottZ, this is a generator, not a water flow sensor. So it will charge its internal battery when water flows. It can be used to powerr the Spark but it may not be the best choice if water flow is intermittent. If water flow is somewhat regular, you could use it as a power source. What you need for flow sensing is something like this hall-effect flow sensor:

For battery power, the adafruit unit is fine though I am not sure what kind of runtime you expect while on battery power. Can you elaborate?

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