28Views1Replies

# Super caps to power an automatic putter Answered

Hey guys!
I'm looking to build an automatic putter with a solenoid from a old starter motor and some super capacitors.
I've figured out how to triangulate the distance using a servo and a pair of lasers but I'm at a loss on how to charge them and the math behind it to make sure that the right amount of current goes through.

The basic plan is to either wire up a series of the caps listed above and hopefully charge them in series. OR buy a car booster pack and disassemble it for the bits and pieces. OR use a lipo like this and hope that the discharge is enough to hit the ball down the course.

Any thoughts or suggestions on some reading meterial?

I'll be doing an instructable at some point and will give some cred to the best answer

Tags:

## Discussions

What is the impedance of those caps? Doesnt say in the listing...
The internal resistance (impedance) dictates the absolute max current flowing out of the cap (with a superconducting short applied). This will be lowered even more by the resistance of all your wires and your motor.

So to even start answering, we need:
- Voltage-Rating of the motor
- Internal resistance of the supercaps
- Resistance of the motor
- How long will the motor be active for a single putt
- What will the lowest acceptable voltage be after the single putt (Allowed voltage drop by discharging the Supercap)

Knowing this, we can calculate the needed energy stored in the capbank...

BUT:
I would go with a LiPo. Stuff like https://hobbyking.com/de_de/turnigy-heavy-duty-220... has 120C burst and 60C Constant which gives at around 12V a power of >3kW Burst and about half for constant. Thats 264 Amps Burst and about half constant.
Also, LiPos are easy to source and quite cheap.
They also have good chargers available where the same cannot be said for Supercaps.

For startermotors, i found stuff like 100-200 Amps which would fit the bill perfectly for this pack i linked. I didnt really search for a good pack by the way... First 12V with decent current and capacity. MUCH bigger Packs available like
https://hobbyking.com/de_de/turnigy-jump-starter-t... for 900 Amps for 3 secs (this IS made for exactly this! A external battery to kickstart a car)
https://hobbyking.com/de_de/turnigy-battery-heavy-... for 480 Amps for 3 secs
https://hobbyking.com/de_de/turnigy-heavy-duty-500... for 600 Amps for 3 secs