Slash 5 key and battery drain

[Duane Ausherman]

If your ride was above 3500 rpm, then you should have returned home with a fully charged battery. It sounds like you have a charge issue.

Once again, measure the charge voltage. I have a website with some info on BMw motorcycles. Try that, or Google for the information.

Those nearly useless voltmeters that are BMw accessories won't do the job. They aren't accurate and are connected to the wrong place. They are almost only bike bling.

Get a multimeter from Radio Shack, or similar. They usually cost only $20-$40.

[vespajg]

Assuming the bike has charging issues, could someone please list the possible problems/failures? I know that's an unknown at this point, but what failures could lead to the bike not charging properly? I'll buy a multimeter at Radioshack this afternoon, but what exactly does the measurement at the battery terminals tell me at 3k rpm? Does it tell me the rate of charge being generated? I'm quite familiar with your website, Duane...just never tackled an electic problem.

Thx in advance everyone...

[Kurt in S.A.]

A healthy charging system should put out close to 14v at over 3K RPM...that's what the battery readings will tell you. The possible causes for that? Could be corrosion in the contacts along the wiring harness, corrosion build up in the positive cable underneath the insulation, failed diode on the diode board, poor grounding, internal wire separation on the rotor or stator, voltage regulator, bad battery...yada, yada... This is not a trivial thing to pinpoint this over the internet...and you don't really want to start throwing money at it either.

It might be helpful to get the book on Airhead charging systems from Motorrad Elektrik...it takes you through steps to isolate where the problem is; top of the page here:

http://www.motoelekt.com/goodstuff.htm

Kurt in S.A.

[vespajg]

Picked up the Radio Shack multimeter and the reading is a bit low...13.30, varying a bit above and a bit below. i think it maxed at 13.39. Now, need to find the cause...

[Duane Ausherman]

So much info is available online that you need to read. Why should we type up bits here and there for you, go read it and get the full story faster.

[vespajg]

There's a lot of crap, misinformation, and poorly written guidance on the Internet. I came here, as I have in the past, and as I believe many (but not all) do, for some guidance on an issue I have no experience with, to learn from my board mates, and to avoid damaging my bike (as I have learned from this board can happen when messing with the electric system). No need for you to type anything, Duane.

Thanks to all who responded with helpful comments. Your posts are appreciated.

[Garnet]

This is a good place to start. http://robfrankham.co.uk/bike/earthing_article.htm

New, modern battery cables are another big plus. Wirerkr who is a member here sells them on Ebay as does http://www.euromotoelectrics.com/Batter ... s_s/74.htm . Poor connections are the probable reason that you are not getting close to 14V at the battery. (Stock V/reg is set at 13.8 and most aftermarket ones are 14.2 ish.)

Unplug and clean the heavy red wire connectors on the diode board and starter relay. It's not a bad idea to run another 10 gauge wire form the diode board to the positive battery cable at the starter or right to the battery.

If you still read low voltage after all the cleaning then you may have to spend some money on a new voltage regulator or alternator brushes or something, but do the free stuff first, it is probably all that is needed.

[Duane Ausherman]

Before the solid state regulators we would adjust the stock regulators to whatever would fit the riding style of the owner. The charge voltage should never be under 14 for any reason. We never set them below 14.2 and for short distance rides we would set them at 14.3-14.4 v.

[vespajg]

Thanks to all for the advice, tips, knowledge. I'm going to start with removing the battery cables, a thorough cleaning and reinstallation with a healthy dab of dielectric grease, and see where that gets me. My guess is that my cables are the stock ones installed in 1971 at the factory so it may be that new, more modern cables are in order.