Magnets

[Malta]

As regarding sealed electric (21 turn) motors ...

 

How can I increase the strength of the magnet and thus power of the motor?

[YT2095]

You can`t really, you`de have to replace them with either NIB or Samarium Cobalt types, that will give you a greater flux density.

the other way would have been to decrease the amount of windings and use a thicker wire to rewind the armature.

[Malta]

I need to find a solution ... without opening the sealed can (motor)!

 

- If I use the electronic freezer ... will it help?

- If I put metal surronding the can outside?

 

- Any comments or suggestions?

 

Thanks everyone .......

[YT2095]

electronic freezer?

do you mean a heatsink? or a peltier device?

neither would work in all honesty, I think you`de have to freeze it significantly! as in a few 10`s of degrees above 0 Kelvin. liquid nitrogen sort of temperatures, and then you risk shattering your magnets. I can`t see anyway to do it effectively without opening it, or getting a better motor? sorry.

[Malta]

Thanks YT2095 for your comments.

 

We are using the motor for rc racing and it has to be standard for eveyone in the same class. I am trying to see if I can improve the power in some way.

 

I already have a heatsink ... there is really nothing I can do?

 

If I put another magnet on top of the motor ... will it effect anything?

[YT2095]

Yes it will, and not in a good way, they are already optimised when they were designed, you wont increase the flux density that way, the motor housing will block the majority of the flux and the uniform magnetic pattern that already exists will become corrupted.

you COULD try adding another Ni-Cad cell, the extra 1.25V wont burn your motor out in a single run, but will eventualy shorten it`s life span. you`ll get a few hundred good runs out of it 1`st though

also, keep your batteries cool!, the internal resistance in Ni-Cads changes with heat. so the cooler you keep them, the more even the current delivery curve will be

 

Good luck

[Malta]

Thanks for the info ... are you in rc racing too?

 

- However I cannot add another cell since it is also againts the rules

 

- As regarding the batteries ... they do tend to heat up when I charge them ... and then peak them again before the race!

 

I usually charge them with 4 or 5 V .... if I charge with 6 or 7 V ... will it give more power?

 

Also, shall I charge the batteries ... say in the morning ... let them get cold (few hours) ... and than just peak them before the race ? OR I make the full charge before the race and race with them still bit hot?

 

- Another thing ... there is a freezer for electronics that will drop the temperature below 0 ... never heard of it?

[YT2095]

no, not RC racing, I do race rocket cars though.

 

charge them at half a volt above their power output. always make sure you never store them charged for long periods, the M.O.D. Ni-Cads actualy have a "shourt out" spring across the terminals for long term storage, so if it`s good enough for the Military

charge them slowly, 10 hours charged properly is better than the 2 hour or 30 min fast charge. fast charging is a great way to destroy your batts.

never boost charge them, it`ll damage the plates and you`ll get something "battery memory" whereby it`ll never fully charge past a certain point, and the powerout will diminish quickly too.

unplug them an hour before the race and let them cool right down.

the freezer device you mentioned are called Pelteir (or something like that) it`s a semicondutor device a bit like a diode, that works for heat, they consume a heck of alot of power! I wouldn`t bother with them to be honest.

[Malta]

It is great to find someone so responsive like you

 

As regarding the "freezer" it is a spray can that actually freezes the can from outside, so it makes the magnet cooler ... do you think it helps?

[YT2095]

aha! yeah, Freon gas (quite expensive), well lets just say it wouldn`t hurt anything

be carefull that you don`t get any "frost" in the workings though!, as it`ll conduct elec and also corrode your contacts!

but if it`s an air tight sealed unit, that shouldn`t present a problem, you`ll find lots of little sprays, giving the heat time to escape will cool it better too, say 3 secs spray, wait 30 secs and do it again, do that about 5 times.

make sure you read the aerosol can 1`st though, make sure it isn`t flamable, because the motor sparks may ignite any remaining gas trapped in the windings (it would look impressive but wouldn`t win you the race).

it would help keep the windings cooler (Important as it effects resistance), but it wouldn`t have any significant effect on the magnets though.

as for responsive, that`s what the Forums are for