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Charging Clyde Space Batteries on the Development Board

Discussions pertaining to the electrical issues (e.g. circuitry, power, etc.) of Pumpkin's CubeSat kit.

Charging Clyde Space Batteries on the Development Board

Postby aek » Wed Jun 25, 2008 4:02 am

We have not yet had a chance to try the Clyde Space EPS in-house, but here are some thoughts:

1) D10: +5V_SYS from the CSK Bus
2) D11: VCC (+3.3V) generated locally from +5V_SYS OR +5V_USB
3) D:13: VCC_SYS (+3.3V) from the CSK Bus

+5V_SYS and VCC_SYS are both generated by the CS EPS and are fed to the CSK bus.

D11 will be lit all the time because it's fed from +5V_USB.

D13 being lit means that the VCC_SYS (+3.3V) output of the CS EPS appears to be fine.

D10 blinking suggests that the EPS' +5V output is starting up, then shutting down, then restarting, etc. I know this happened to one other EPS customer (KYSat) and it's my understanding that their EPS had an inrush current problem that CS was able to solve.

I do _not_ think it has to do with the CUbeSat Kit's 500mA current limit from USB, as you would also see the +3.3V output of the EPS shutting down as well ...

So it sounds to me that the +5V(_SYS) output of the CS EPS doesn't like what it's seeing on the bus and is shutting down via its protection circuit.


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Re: Charging Clyde Space Batteries on the Development Board

Postby applewood » Wed Jun 25, 2008 10:50 am

We are attempting to charge our Clyde Space batteries on a Rev. C CubeSat Kit Development Board.

We have connected a Rev C. Linear EPS with 4 AAA batteries to the board and it functions perfectly, including the R-B-F and Launch Switches.

However, when attempting to charge the Clyde Space batteries through a USB from a PC we run into a problem. With both the R-B-F and Launch Switches positioned as they would be after P-POD deployment, LED D10 flashes once when the USB is first plugged in and then goes off while D11 and D13 continually lit. We get no apparent charging (although the Clyde Space board does make a regular and repeated high pitch sound and the batteries feel slightly warm to the touch).

If we open both switches (R-B-F Pin inserted and Launch Switch pin inserted) only D11 and D13 are on. Removing the R-B-F pin (closing the switch) does not change anything on the LEDs. Reinserting the R-B-F pin while closing the Launch Switch results in a situation where D10 flashes continually while D11 and D13 are solid on.

We have asked Clyde Space for help, but do not know how familiar they are with the Development Board.

Any thought you might have on this would be appreciated.

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Re: Charging Clyde Space Batteries on the Development Board

Postby aek » Fri Jun 27, 2008 2:08 am

I had another thought ... you mention that you have a Rev C Linear EPS. That one has the older, 80-pin CubeSat Kit Bus.

The Clyde EPS has the newer, 104-pin CubeSat Kit Bus.

The newer, 104-pin bus has the RBF and Deployment switches pinned out differently from the earlier, 80-pin bus.

So, make sure that the Clyde EPS is seeing the corrct pins for the RBF and Deployment switches.

(We're now calling the erstwhile Launch Switch the Deployment Switch, to be in keeping with Cal Poly's nomenclature).


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Re: Charging Clyde Space Batteries on the Development Board

Postby Kevin@ClydeSpace » Tue Aug 05, 2008 12:57 am


This does sound similar to another issue we heard of. Basically the overcurrent protection was seeing a large inrush current to one of the boards it was connected to. The solution to this is a simple change to slow the overcurrent protection down slightly. It requires changing one capacitor.

If this problem has not been resolved please contact William Fletcher here at Clyde Space for more details on this.

Sorry for not responding sooner but we have just come across your post on this forum.



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