Where to connect the backup battery charger

[Never_Fade]

We have a question about the backup battery charger (Found here).

We are curious if we are supposed to connect the 12v in(of the charger) before the master breaker, or after the master breaker.

http://picasaweb.google.com/KE7CKI/Robotics/photo#5156166962017891010
We have it hooked up on this side. Can we hook it up here?

We currently have the 12v in connected after the master breaker (on the 20/30 fuse panel), the 'backup battery input on RC unit' connected to the battery input on the RC, and 'backup battery' label on the diagram connected to the backup battery.

Our situation occurs here. When we do not have the main 12v battery powered up, the 7.5v backup powers the system, through its connection on the 20/30 fuse panel.

If we were to connect the battery charger in the line before the master breaker, the 12v battery could be in -charging our 7.5 backup- while the breaker was restricting power to the rest of the robot. We are under the impression that this is illegal because that means that there is power running while the breaker is off (which defeats it's purpose, in a sense).

[kE7JLM]

I don't know that is a good question....!?

[popo308]

Why not just throw some spaid connectors on there and run it through the fuse panel?

[Jim E]

We have used the IFI circuit for 2 years now and have noticed the partial feedback issue. No inspector or referee has complained yet. It isn't an optimal design. but it will drain your backup battery if allowed to continue.

This year FIRST alloes custom charging ckts. If 'not happy, Draw

[falconmaster]

Originally Posted by Jim E

We have used the IFI circuit for 2 years now and have noticed the partial feedback issue. No inspector or referee has complained yet. It isn't an optimal design. but it will drain your backup battery if allowed to continue.

This year FIRST alloes custom charging ckts. If 'not happy, Draw

Are you sure that this year we can use our own charging circuit?!!!! Where do you see that?

[jgannon]

Originally Posted by falconmaster

Are you sure that this year we can use our own charging circuit?!!!! Where do you see that?

Sounds like it... check this out.

<R49> The 7.2v backup battery may be charged on or off the ROBOT. When off the ROBOT, the battery is to be charged with a 7.2V backup battery charger. When mounted on the ROBOT, the backup battery may be charged from the 12VDC primary battery by using the custom charging circuit available from Innovation First Inc. or any similar charging circuit (note: IFI will provide the design for this circuit on the IFI website, however teams must obtain the parts for this circuit and assemble it themselves). The use of this circuit is strongly encouraged.

[Alan Anderson]

It's a custom circuit. It has to be powered from a 20A circuit breaker.

To address the problem with back-feeding the rest of the robot, just add another 1N5820TR diode in series with the power input. You might still see a small issue with the backup battery draining (slowly) through the charger circuit itself when the robot is powered off, but it will no longer try to run all the Victors.