Using 7.2v charger as BackupBattery

[MacFlightSierra]

We have been experimenting with the camera for some time now, and among other problems, we noticed that the little 7.2v backup battery runs out very fast. We can only get 3-4 mins of operational time out of it, before the BackupBatt LED on the OI turns red and the camera stops working.
My idea was to use the IFI supplied charger for that battery, instead of the battery itself (hook up the charger output to the BackupBatt RC Input). I measured the charger outputs- 8.0v @ 750mA -just like the backup battery itself.
My question - is that idea safe (for experimental use of course)? Any chance it might screw up the camera or the RC itself?

any feedback would be greatly appreciated
thanks

[Eldarion]

We have been experimenting with the camera for some time now, and among other problems, we noticed that the little 7.2v backup battery runs out very fast. We can only get 3-4 mins of operational time out of it, before the BackupBatt LED on the OI turns red and the camera stops working.
My idea was to use the IFI supplied charger for that battery, instead of the battery itself (hook up the charger output to the BackupBatt RC Input). I measured the charger outputs- 8.0v @ 750mA -just like the backup battery itself.
My question - is that idea safe (for experimental use of course)? Any chance it might screw up the camera or the RC itself?

any feedback would be greatly appreciated
thanks

I was able to apply 12v to the backup battery input with no ill effects.
I used that setup for quite a while before we had the robot together... :)

[Jared Russell]

I was able to apply 12v to the backup battery input with no ill effects.
I used that setup for quite a while before we had the robot together... :)

And I've been running it at 5V without problems as well. Seems those little cameras have pretty good voltage regulating capabilities ;)

[Al Skierkiewicz]

My idea was to use the IFI supplied charger for that battery, instead of the battery itself (hook up the charger output to the BackupBatt RC Input). I measured the charger outputs- 8.0v @ 750mA -just like the backup battery itself.

Mac,
It is never a good idea to use a battery charger as a power supply. Frequently chargers use a pulsed DC output that is well above what you might be measuring. If your backup battery runs down in 3-4 minutes there is something wrong. Either the charger isn't fully charging the battery, or it has a defective cell or there is a short in the wiring to camera or the camera has a defect and is drawing too much current. You need to find the reason and correct it.

[ForgottenSalad]

As far as the backup battery dying in 3-4 minutes, we had the same problem until we realized why it was happening, and it was beacuse we were powering the servos off of the camera board instead of off the rc. Is that possibly what you're doing?

[Rick TYler]

The CMUCAM2 spec sheet says it will run on 6 to 15VDC. Why not use the 12V main power on the 'bot? The camera is not much drain on the big battery, and then the backup battery can go back to its life of neglect and apathy.

Even if it didn't like 12VDC, I'd be tempted to get a voltage regulator and run it off the 12VDC main battery anyway.

[Al Skierkiewicz]

The CMUCAM2 spec sheet says it will run on 6 to 15VDC. Why not use the 12V main power on the 'bot? The camera is not much drain on the big battery, and then the backup battery can go back to its life of neglect and apathy.

Rick,
The IFI website lists the camera power as "7.2 VDC nominal @ 235mA. 5.2V - 8.6V range max, up to 20 V if internal servo jumper removed." A blanket statement that the camera can run on 12 volts is not entirely true. If you are depending on your camera to help in competition, know that it will fail if the power falls below the range stated. Robot main power for many teams will regularly drop below 5 volts during high current demands and the 7.2 volt backup supply is not tied to the main power. Want to keep the camera operating, use the recommended connections to the backup battery.

[MacFlightSierra]

thank you all for your advice

[never actually connected the charger as I thought]

We disconnected everything from the controlller [all victors and spikes], and got 20 mins if playing time with the camera [and the backupBatt LED never came on].. I guess there were some problems with our initial setup - we'll be more careful next time we wire it


thanks again and good luck

[devicenull]

thank you all for your advice

[never actually connected the charger as I thought]

We disconnected everything from the controlller [all victors and spikes], and got 20 mins if playing time with the camera [and the backupBatt LED never came on].. I guess there were some problems with our initial setup - we'll be more careful next time we wire it


thanks again and good luck

20mins is still far too short. As a reference, ours will last for 2-3 hours before we have to change it (The RC doesn't register it as dead, but the camera has problems locking on). Something is defineitly up with either your camera or wiring.

[Bharat Nain]

Do you have more servos or anything that will eat up your backup battery?

[MacFlightSierra]

2 -3 hours? wow... we dont have any other servos connected, so nothing else is eating the battery's power. I will conduct a full test tomorrow and see what we get.
What could be wrong in this case [except for a faulty battery/camera]? It just a simple battery <-> controller connection.. weird.

[devicenull]

2 -3 hours? wow... we dont have any other servos connected, so nothing else is eating the battery's power. I will conduct a full test tomorrow and see what we get.
What could be wrong in this case [except for a faulty battery/camera]? It just a simple battery <-> controller connection.. weird.

Short on the back of the camera? Take it off the pan/tilt mount and see what kind of battery life you get. Do you have another backup battery? If not you may want to get another for a couple reasons: You will discharge it during a competiton, and you will need one for the robot while the other charges. It will also assit you here, as you can rule out the battery being bad.

For now, you may want to see if anyone on your team has one, as the connector/battery is common in RC cars. Someone said in this thread, they gave the backup battery connector 12v, and it worked. You may want to try a 9v battery connected to it, but there's the chance of frying the RC (I take no responsibility)

[Eldarion]

Someone said in this thread, they gave the backup battery connector 12v, and it worked. You may want to try a 9v battery connected to it, but there's the chance of frying the RC (I take no responsibility)

I don't think a 9v battery will work; the RC draws a lot of current from the backup battery terminals!

[Donut]

3-4 mins is too short a life for the backup battery, but it is long enough for competition. We plan on bringing 3 backup batteries and switching them between every match just like we do the 12v batteries, especially with how important it will be to not lose camera power mid-match.

[bhsrobotics1671]

We have been experimenting with the camera for some time now, and among other problems, we noticed that the little 7.2v backup battery runs out very fast. We can only get 3-4 mins of operational time out of it, before the BackupBatt LED on the OI turns red and the camera stops working.
My idea was to use the IFI supplied charger for that battery, instead of the battery itself (hook up the charger output to the BackupBatt RC Input). I measured the charger outputs- 8.0v @ 750mA -just like the backup battery itself.
My question - is that idea safe (for experimental use of course)? Any chance it might screw up the camera or the RC itself?

any feedback would be greatly appreciated
thanks


we did that on our team, and found out the camera didnt work properly, we couldnt do anything in labview, it kept shorting out i guess you could say. at first we didnt know what the problem was, so we called the guy who invented the camera because we thought they sent us a defective one, but it was just that we needed to use the battery, and couldnt use the charger

[X-Istence]

In the rule book there is a rule about using a different backup battery as long as it was a 7.2 volt, that means you can if possible, grab a Vex battery, which is 7.2, but has 2000 mAh, instead of the measly 600 mAh that comes in the standard battery pack supplied by FIRST.

There are also standard RC car batteries that run at 7.2 Volts, which would allow you to do the same thing.

Another option is looking for the chart to make a backup charger from the 12 volt battery, however so far my team has decided not do this as we are already abusing our 12 volt battery.