Back-up Battery question

[Oumonkey]

Hello,
I've been told that new yellow back-up battery is all we are allowed to use for the regionals. I want to know if that is true, but I have been searching for a place to buy them and I can't seem to find anyplace. Ifirobotics only has the blue ones, and I am unsure which kind we are allowed to use. I went throught the manuals and didn't see anything. I looked though CD and I didn't find anything either. So I guess my question is are we allowed to use the blue back-up battery? And if not where can I purchase the yellow ones. I'm sorry if this is somewhere obvious, but I just can't seem to find any information.

Thanks
Josh

[Vikesrock]

According to rule R73:

<R73> The 7.2V Robot Control backup battery must be connected to the Robot Controller as described in the Robot Controller manual. The 7.2v battery should be charged to at least 7.0v before entering a match. As a replacement for the FIRST supplied battery, any other commercially available 7.2V NiCad battery pack may be used.

So you can use any 7.2V NiCad battery including the blue one available for purchase from IFI.

[Mike Betts]

You received a blue backup battery in your KOP. The intended purpose is so that you can use it on your robot.

Also:

<R73> The 7.2V Robot Control backup battery must be connected to the Robot Controller as described in the Robot Controller manual. The 7.2v battery should be charged to at least 7.0v before entering a match. As a replacement for the FIRST supplied battery, any other commercially available 7.2V NiCad battery pack may be used.

[Vikesrock]

Originally Posted by Mike Betts

You received a blue backup battery in your KOP. The intended purpose is so that you can use it on your robot.

Some teams (such as mine) received a yellow backup battery in their kits. I believe this is what led to the confusion.

[RyanN]

But!!!! you must use the supplied charger in the Kit of Parts! None of you guys included that, so I thought I should. And yes, I do recommend getting a larger capacity battery, and using it the whole day, and charging it overnight at competition.

[Danny Diaz]

Originally Posted by RyanN

But!!!! you must use the supplied charger in the Kit of Parts! None of you guys included that, so I thought I should.

Now that I do not believe is true. It is completely true that you must use the supplied charger in the kit of parts for the main 12v battery, but you do not have to use the supplied charger for the backup battery so long as your backup battery charger is still safe. The reason being that the backup battery you might have may not have a compatible adaptor for the [supplied] charger, and it would be extremely silly to require you to create an adaptor to fit just for charging.

-Danny

[Mike Betts]

Originally Posted by Danny Diaz

...but you do not have to use the supplied charger for the backup battery so long as your backup battery charger is still safe...

Danny,

Your point is well taken but is not supported by exact interpretation of the rules.

<R56> The 7.2v backup battery may be charged on or off the ROBOT. When off the ROBOT, the battery is to be charged with the provided 7.2V backup battery charger.

This is one of the FIRST rules which is largely non-enforceable. I also agree that, from an engineering standpoint, there are many better solutions than the provided charger. This is particularly true of "smart" chargers which monitor the state of charge of the battery (they utilize an embedded microcontroller and look for the minus dv/dt "bump") and adjust the charging current accordingly.

As it stands right now, few inspectors will walk the pits looking at your NiCad chargers. However, if pressed, they would have little choice than to quote <R56>.

I invite you to air your concerns on the FIRST Q&A. Only by airing these concerns to FIRST will we get the rules changed.

That's JMHO...

Mike

[Danny Diaz]

Originally Posted by Mike Betts

Danny,

Your point is well taken but is not supported by exact interpretation of the rules ... I invite you to air your concerns on the FIRST Q&A. Only by airing these concerns to FIRST will we get the rules changed.

Concern aired. Hopefully I'll get an answer.

-Danny

[Al Skierkiewicz]

Danny,
Mike gave you the answer, I am afraid. The robot rules are very specific. I prefer to inspect robots in their pit as do many other inspectors. This prevents a pile up at the weighin and size stations and it gives us a chance to make students feel a little more comfortable. I like to check out the pit and see chargers, extra compressors and safety violations that may have been missed by the safety people. It's all part of the full service.

[Danny Diaz]

Originally Posted by Al Skierkiewicz

Mike gave you the answer, I am afraid. The robot rules are very specific.

Yeah, I understand why the rule is there, but now I have to run out and find one of those funky connectors for the charger so I can charge our COTS NiCad battery as well as the provided NiCad battery. The Q&A gave a definitive answer for me - after reading Mike's response I knew what the answer would be, but I had to ask anyway.

Thanks!
-Danny

[Mike Betts]

Originally Posted by Mike Betts

...from an engineering standpoint, there are many better solutions than the provided charger. This is particularly true of "smart" chargers which monitor the state of charge of the battery (they utilize an embedded microcontroller and look for the minus dv/dt "bump") and adjust the charging current accordingly...

I invite you to air your concerns on the FIRST Q&A. Only by airing these concerns to FIRST will we get the rules changed...

Please read Team Update #13...

Your posts to the FIRST Q&A have had a positive effect...

Regards,

Mike

[dcbrown]

We'll also be pulling the breaker supplying it when the robot is not in use

.

It is also best to disconnect the backup battery from the on-board charging circuit. Without an attached RC or connection on the 12V supply end the circuit still discharges through the charging circuit to ground. Granted we only measured 6-8ma, but why start off with a partially discharged battery. With supply side connected but without the main battery the discharge rate will be much higher (assuming things like victor fans, etc. are directly connected to breakers and not via spikes).

[pheadxdll]

Originally Posted by dcbrown

.

It is also best to disconnect the backup battery from the on-board charging circuit. Without an attached RC or connection on the 12V supply end the circuit still discharges through the charging circuit to ground. Granted we only measured 6-8ma, but why start off with a partially discharged battery. With supply side connected but without the main battery the discharge rate will be much higher (assuming things like victor fans, etc. are directly connected to breakers and not via spikes).

That's why we added a diode to avoid back feeding the spikes and victors. Too bad we'll have to take it off at competetion.

[RyanN]

Originally Posted by Mike Betts

Please read Team Update #13...

Your posts to the FIRST Q&A have had a positive effect...

Regards,

Mike

This will make many MANY teams happy because the KOP charger is very very slow and is also dangerous. I'll quote the update so other teams can directly view the change:

THE GDC MEMBERS AND FIRST STAFF HAVE JUST BEEN MADE AWARE THAT THE
7.2V BATTERY CHARGER PROVIDED IN THE KIT OF PARTS IS A DC POWER
SUPPLY AND DOES NOT DROP BACK TO TRICKLE CHARGE WHEN THE BATTERY
REACHES FULL CHARGE. THIS CAN LEAD TO AN UNSAFE SITUATION. THIS
BATTERY CHARGER WILL CHARGE THE BATTERIES, BUT IT IS OUR
RECOMMENDATION THAT THE BATTERIES NOT BE LEFT UNATTENDED WHILE
BEING CHARGED. WE ARE CHANGING RULE <R56> TO ALLOW ANY 7.2 VOLT
BATTERY CHARGER TO BE USED.
Section 8 – The Robot, Rev G has been modified to include the following changes:
Rule <R56> has been updated to state that:
When off the ROBOT, the battery is to be charged with a 7.2V backup battery charger.
Robot Inspection Checklist, Rev C has been updated.

[Billfred]

Originally Posted by Danny Diaz

Now that I do not believe is true. It is completely true that you must use the supplied charger in the kit of parts for the main 12v battery (snip)

Not quite, but close. (Emphasis in rule my own.)

<R54> The ES17-12 can only be charged between matches by a 6-ampere rated automatic battery
charger. When recharging the Kit Of Parts batteries, either the charger provided by FIRST
or an automatic charger with an equivalent charging current rating may be used.