Tired of cold hands? These will heat them up!

[BlueValk]

Okay, this is not a great idea, nor is it cheap or easy, and even looks a bit funny.  But, I am thrilled to have warm hands this winter.

I bought some block heaters off of evilbay.  They are 4" x 5" and wrap around the stock grips just right.  Then I used a piece of bicycle inner tubing and rolled that over the heaters to hold them in place.  I positioned the thick part of the heater pad where the lower part of my palm rests.  It is not uncomfortable that way.

These heaters are 120W!  Fortunately they are only 30w each when connected in series (at 12v, ~40w at 14v).  So, you absolutely need a controller for these.  I'll include a simple schematic for one way to do it.

Anyway, I can leave the house with cold hands, turn the control up to about 3/4 and in minutes they are toasty hot.  Once hot, I have to put the control at 1/2 or less.  I use just a cheap medium set of gloves.  If the inside of your hand is hot the back of them seems to be just fine.

If you want to remove them, just roll off the inner tube and peel them off (no glue).  You will want some connectors close to the grips.

I'll include a link to the seller on evilbay.  When I got them, they were a bit cheaper.  No affiliation ....







http://www.ebay.com/itm/Universal-Flexible-Block-Heater-Hot-Pad-12v-120watt-/400274471794?pt=Motors_Car_Truck_Parts_Accessories&hash=item5d3237bb72&vxp=mtr

[RP#62]

Great idea.  Are you using the 555 to pulse the power?
-RP

[BlueValk]

Great idea.  Are you using the 555 to pulse the power?
-RP

Yes & thanks.  The pot I happened to have did not have an on/off switch with it (everyone's should, though).  So I made the circuit adjust from 0% to about 99% duty cycle.  So, it can effectively be turned off, but if that fet ever shorts out, I'll be pulling off to the side and unplugging the grips. 

[csj]

If you're worried about the fet, you could put a 0.2 ohm, or as
high as a 1.0 ohm between 'source' and 'return', to limit pulse current.

[art]

Darn I thought you were going to show a beautiful chic in a bikini

[BonS]

This will warm your hands and your FET too! 

Now, seriously, nice idea!

[The Anvil]

I think it's a pretty great idea...

Just out of curiosity though, could you not just use a rheostat for controlling something like that? I'm not an electrical guru so I don't know.

[BonS]

The downside of a rheostat is that whatever power isn't used by the hand warmer is burned up in the rheostat. The electronic circuit is probably 90+% efficient so most of the power used creates heat in the handgrips not in a rheostat.

The downside of a switching circuit is electronic noise that may interfere with onboard audio circuits. Additional electronic filtering or some circuit modifications may be necessary to minimize this.

[gordonv]

Isn't that what the additional caps are for, just to remove any extra noice?

[alph]

thanks for that ebay listing!!  if you do a search of flexible heaters you'll come across one guy that sells 'em for $25, then charges $20 for shipping!!  what a rip off!!  (the shipping charges that is!)

http://www.ebay.com/itm/Flexible-Silicon-Heaters-PN-211716-Omegalux-SRFG-118-2-/300393788103?pt=LH_DefaultDomain_0&hash=item45f0dd72c7

there are TONS of uses for these things!  exspecially if you live up north!!  my cousins live in Lethebridge, Alberta Canada, and they have a heater on their battery, on the radiator, and engine block!!  truck always starts when it's below zero!!

i'm going to get a strip for my wifes computer keyboard.  she's a transcriptionist and types all day.  most days her hands are freezing, even though she's working in a bright sunny room with a space heater by her feet, her hands will be about room tempurature (73*)!!

[BonS]

Isn't that what the additional caps are for, just to remove any extra noise?

Yes, capacitors, in the right places are usually used and sometimes additonal resistors, inductors, ferrite beads, metal shields and refined circuit and circuit board design all play a part in taming the noise beast.

[RP#62]

Isn't that what the additional caps are for, just to remove any extra noise?

Yes, capacitors, in the right places are usually used and sometimes additonal resistors, inductors, ferrite beads, metal shields and refined circuit and circuit board design all play a part in taming the noise beast.

Yes, but in the diagram, C1 triggers the 555 and the other cap prevents false triggering.  If it IS noisy, you'd probably need to add a cap as close a possible to pin 8 and ground.
-RP

[BonS]

I was more concerned about the sharp triggering of the square wave that's triggering of the FET driver and the subsequent voltage/current edges/spikes running from the controller wiring to the grips.

[Canuck]

I took the lazy way and ordered these earlier this year from Aerostich.
http://www.aerostich.com/a-to-b-utilities/rider-comfort/heated-grips-accessories/aerostich-warm-wrap-grips.html
Work great.

[Smokinjoe-VRCCDS#0005]

Plug and play

[BlueValk]

If you're worried about the fet, you could put a 0.2 ohm, or as
high as a 1.0 ohm between 'source' and 'return', to limit pulse current.

Thanks for the suggestion.  These heaters are resistive, so there is no surge current to worry about.  A 1 ohm resistor would use up about 16 watts!  If the fet goes, I'll just put in a stronger one.  The circuit was originally designed for a set of 20 watt heaters.  They didn't last ....

I took the lazy way and ordered these earlier this year from Aerostich.
http://www.aerostich.com/a-to-b-utilities/rider-comfort/heated-grips-accessories/aerostich-warm-wrap-grips.html
Work great.

Not bad!!  I bookmarked those for future use.  Thank you.

Plug and play

Nice gloves!  But, I liked the idea of not being wired to the bike.  Probably not a big deal once you are used to it.  Still nice, and I'm sure they do a better job.