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Tempo 11-15-2007 09:11 PM

KTM 640a Voltmeter
I installed a voltmeter from DigitalMeter to monitor my KTM's [sucky] power output. So far it works well. :thumb

R.Markus 11-15-2007 09:43 PM


That's a good clean install. I like it. I may have to get one of those myself so I don't let my Gerbing jacket kill the battery.

ChrisC 11-16-2007 06:48 AM

Looks nice... just wondering how weatherproof it is?

Tempo 11-16-2007 07:01 AM

Me thinks I'll find out today. I am riding 90-min south (to get a custom seat!) and the forecast is:

Today: Periods of rain. High near 55. South southwest wind 17 to 20 mph decreasing to between 5 and 8 mph. Winds could gust as high as 26 mph. Chance of precipitation is 100%.

It's still pretty dark here but I can tell that it's quite stormy right now. This could be a rough ride!

disconnected 11-16-2007 07:46 AM

dangola... its 32 here with snow flurries... :nod

very good looking install.. keep us posted..

thanks for the link..


Tempo 11-16-2007 11:51 AM

Well I rode 90 min in pissing rain this morning to Mr Eds Moto, where I am now, and the meter still works. :thumb

Wish I could say the same about the KTM... riding down the Interstate it started acting like it was gas starved. WTF? After coasting to the shoulder it sputtered along for a mile or two then went away. Not feeling real good about the ride home.

Back to working on my new seat...

Tempo 11-16-2007 08:37 PM

I rode +/- 4.5 hours in more or less steady rain today. Yeah the voltmeter seems OK to use in the wet stuff. :nod

/end of thread

bmwktmbill 11-16-2007 09:55 PM

Nice job.
What circuit did you wire into?
Were the readings more or less steady underway or were the numbers rolling up and down?
BTW nice seat too.

Tempo 11-16-2007 10:31 PM

There are two switched 12v circuits under the fairing, right? Just use one of them. You can find male Molex connectors for about $0.25 or less at a good electronics store (not Radio Shack). Crimp some wires and plug right in.

So far I've noted that readings are pretty steady given a constant RPM. Here's some very UN-scientific data after all of 5 hours in the saddle with the voltmeter going:
  • I see 14.0v - 14.1v on avg. with no accessories running at 4k+ RPM
  • When idling it drops under 14.0v but is still is more than 13.0v
  • Sometimes idling it goes below 13v (yet above 12.0v)
  • Heated grips on low take 0.3v - 0.4v off the top
  • Heated grips on high take 0.7v
  • GPS doesn't seem to draw much, if any, maybe 0.1v (?)
  • Sorry I can't remember what the high beam draws (0.3v?)
  • Haven't tried it with the heated vest yet
It's a worthy accessory. Tonight while I was idling in traffic (!!!) in the rain (!!!) I saw it dip below 12.0v so I shut off my grips.

Seth S 11-17-2007 04:20 AM

The voltmeter is easy to wire in. You will get your most reliable results if you connect it directly across the in one lead to battery + and one lead to battery -. it wouldnt hurt to throw in a small amperage fuse as well...something like a 5 amp or less would suffice. The voltmeter is not a load but if one of your wires wears through and grounds out you will have a fuse to blow before the wiring burns up.

on2wheels52 11-17-2007 05:18 AM

Wouldn't a voltmeter be a (constant) load if wired direct to the battery? Or does the one pictured have a third wire to power the display?
Minuscule power draw, no doubt.

Tempo 11-17-2007 07:08 AM

If it was wired directly to the battery it would never turn off. :rofl

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