Heated grip controller, DIY

Towards the end of last winter my heated grip controller died.  It didn't really matter as it was getting warmer and I didn't need the heated grips.  The heated grip controller did pretty well, I think I've had it for over 7 years.

As you might have noticed the weather starts to get a bit worse at this time of year so I thought I should do something about it.  I really didn't want to buy a new controller (I'm cheap!) given the heated grips are fine.

I could design a new controller - it's not that difficult - it's just slow PWM, but I couldn't be bothered so I went for the ultimate low-fi solution: a switch.

To be more specific an on-off-on DPDT switch from Maplins:

http://www.maplin.co.uk/p/10a-toggle-switch-dpdt-f-jk30h

I then wired it up so I could choose between the grips being wired in series, wired in parallel and switched off:



The diagram above shows the bottom of the switch - the wires marked plus and minus go off to a switched supply (don't want to leave them on accidently!).  The green wire is just wired between the two switch contacts (it's just green to make it obvious). The orange resistors are the grips.

When wired in series you get about 1/4 of the maximum heat output, when wired in parallel you get the maximum output.

Here are some pictures of how amazing they look on the bike:







I mounted them by using the old controller bracket and the back of the old controller unit - I drilled  hole in it for the switch.

The full power setting is great for heating it up quick but too hot for this (relatively) warm time of year - 1/4 is fine. The settings are not ideal - there is no 1/2 or 3/4 settings - but they are a lot better than the broken heated grips I had before.

I'm not sure 'amazing' is the right word...

All that electrical tape is playing havoc with my OCD, but I appreciate its the warm hands that matter.

sullivj wrote:I'm not sure 'amazing' is the right word...

All that electrical tape is playing havoc with my OCD, but I appreciate its the warm hands that matter.

'Amazing' is the right word if you're not being too serious :)

I know it is a bit of a bodge; I suspect that after a while I will get bored of switching between high and low and either concoct a more sophisticated solution or buy a new controller but until then it doesn't look out of place on my bike.  I could take some other photos of my bike that would make your hair stand on end...

A reostat with the grips wired parralel should give you an infinate amount of adjustability.

ashcroc wrote:A rheostat with the grips wired parallel should give you an infinite amount of adjustability.

Yes, but you would need one with sufficient power handling, this might do (for example):

http://www.ebay.co.uk/itm/25-Watts-High-Power-Wirewound-Potentiometer-Rheostat-25W-Variable-Resistor-/162114302102

I fear that this might not be too waterproof, but they are fairly chunky so might stand up to the weather for a bit - if you were going to put it in a box it would have to have a little ventilation as it might get a little hot when on certain settings.

A quick note (I did some calculations):

If you wire up the rheostat (RV) and the parallel grips (RL) like this:



Assuming your heated grips have a combined (parallel) resistance of about 3.5 Ohms if you manage to find a 2 Ohm rheostat/potentiometer that has a power rating of *at least* 10 W - this should give you control from 100% down to 40% of full power.

If you can only find a 5 Ohm rheostat you will get 100% down to 16% but, given the power control is non-linear, it will be quite difficult to set it correctly near the 100% end of the scale.

This 2 Ohm one from ebay would fit the bill:

http://www.ebay.co.uk/itm/25W-2-Ohm-Ceramic-Wirewound-Potentiometer-Variable-Resistor-Rheostat-/400790904651?hash=item5d50ffdf4b:g:tkoAAOSwcu5UQig2