Top or Bottom Loading Battery - Any Ideas?

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Ned
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Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Top or Bottom Loading Battery - Any Ideas?

Post by Ned »

I’m designing a new chassis to convert very small 1/32 scale slot cars into magnetically guided magracers using 2.4ghz radio components. It will use the standard magracing motor (which has an uncommon 1.5mm output shaft), one 10440 (AAA) 3.7 volt li-ion rechargeable battery, and an HK-5320 servo for steering.

I’m trying to figure out how to make a bottom loading battery “box” that does not require magnets to hold the battery in place. The magnets take up too much space. In the case of top loading battery boxes on my LMP chassis, gravity and the flexibility of the plastic hold the battery in place. In this new short narrow chassis, top loading doesn’t work so well.

The battery will be located transversely very close to the motor. Thus the length of the battery determines the minimum width of the chassis, at least back near the motor. If the battery is loaded from the top, then the wires connecting the motor to the electronics board in front, have to go underneath the battery or around the ends of the battery. Neither is desirable.

Do you have any ideas on how to hold a battery in place when it is loaded from the bottom? Cannot use disc magnets like those used in typical magracers. Perhaps some kind of temporary adhesive could be applied to the surfaces of a tight fitting box. Any ideas would be appreciated.
kiklo
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Re: Top or Bottom Loading Battery - Any Ideas?

Post by kiklo »

Hi Ned.

Stay on the bottom loaded !

Make a partly (1/4-1/3) closed compartment at the negative pole - just enough tho be able to slide it inn. Then a hole in the + connecting end wall to let the +pole hang onto. At the - negative pole make a plastic spring arrangement to push the battery towards the +.
Racing Regards

Kim K.
Ned
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Location: Sedona, AZ USA

Re: Top or Bottom Loading Battery - Any Ideas?

Post by Ned »

kiklo wrote:Hi Ned.

Stay on the bottom loaded !

Make a partly (1/4-1/3) closed compartment at the negative pole - just enough tho be able to slide it inn. Then a hole in the + connecting end wall to let the +pole hang onto. At the - negative pole make a plastic spring arrangement to push the battery towards the +.
An interesting idea. I will definitely give it some thought. Thank you very much Kim.
WesR
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Re: Top or Bottom Loading Battery - Any Ideas?

Post by WesR »

I would always stay with underneath Ned. When building a track or experimenting as I am doing everyday, I can some times take the battery in and out half a doz. times an hour. Not a problem if you are running chassis only but a nuisance if the body is fitted.
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HeliumFrog
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Re: Top or Bottom Loading Battery - Any Ideas?

Post by HeliumFrog »

Also remember if you insert the battery in reverse by accident it will blow the PCB. It certainly does on the new radio boards. Mounting the -ve on the side prevents this.
Ned
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Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: Top or Bottom Loading Battery - Any Ideas?

Post by Ned »

Kim, Wes, & Martin, thanks for the feedback. I have decided to make it a bottom loading battery compartment to avoid removal of the body. I have incorporated a variation of Kim’s idea for holding the negative end in place. Have also incorporated a spring at the (-) end to push the battery toward the (+) end. Also modified the design to prohibit inadvertently installing battery the wrong way and blowing the PCB, per Martin’s comment.

Still having problems with the (+) end. If the nipple of the battery at the (+) end is pushed through a small hole at the end of the compartment to hold it in place, I suspect it will be hard to get the battery out.

The nipple protrudes about 0.055” beyond the end of the battery. It is about .015” in diameter compared to the the body which is .400”, with insulation.

Pulling the battery straight up might break the piece of plastic containing the hole, but maybe not. That piece would likely be 0.030” thick leaving only 0.025” (0.635mm) to extend beyond, to make contact with the metallic electrical conductor.

Any more ideas? All ideas and comments are welcome.
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