voltage problem

Hello All, I've got around a .5v voltage difference between the battery voltage and the line that goes to the coil and then on to my voltage reg/rec combo.
This voltage difference seems to be causing my regulator to charge the battery with a little higher voltage than I would like, upto 15v or so depending on rpm. I didn't seem to notice this problem with the higher charging voltage until replacing the old separate rectifier and regulator with this new electronic reg/rec combo.

I connected the switched or sense line from the voltage regulator directly to the battery and the charging voltage measurement on the battery is then around 13-14V depending on rpm, pretty much normal. I can't leave the sense line connected to the battery all the time, as I think it would eventually drain the battery? So should I install a relay kit to power the coil and then the voltage regulator sense line so it will get the full 12v?
Thanks for all suggestions, Tony

You can do what you suggest, or you can try so solve the voltage drop problem (new ignition switch or fuse box assembly), or you can put a really big diode in the output line from reg/rec to the battery.

That diode will drop the voltage about 1 volt or slightly less. The diode needs to be a 50 amp or higher diode. You could also use half of a 25-amp full-wave bridge rectifier available at Radio-Shack.

The diode would probably have to be heat-sinked.

Best way is to solve the actual voltage-drop problem.

Post edited by: loudhvx, at: 2006/01/13 13:55

I have exactly the same problem as you and fixed my problem the same way as you, I ran a line directly from the battery to the RR (brown wire). As you said it charges properly that way and seems to work fine. I did that at the end of the summer and I don't know if leaving it like that would cause a problem. I have a fixed voltage meter on my bike and running the wire directly to the battery didnt seem to cause any drain on the battery. I had about a month of riding before I had to store my bike and didnt notice any ill affects from it after that time. If you find a better solution other than the coil,relay thing (I had a failed attempt at it, left me bitter) please u2u me and let me know

thanks and good luck

It really depends on the design of the solid-state reg/rec. Some "voltage sensor" inputs will have significant current and some will use almost none (when the bike is not running). As Christo points out, some reg/recs may take months to drain a battery (when in storage etc).

Some KZ's (I've seen them on 650's) actually use a design that has no dedicated sense line. The sense-line senses the output line connected directly to the battery (usually via the starter relay) to sense the battery voltage.

However, this is a dangerous design when using an external battery charger. If the sense-line is connected while an external charging system is applied, the external charging system can fry the reg/rec with over-voltage. By having the sense-line switched out, the reg-rec is protected from external chargers. Obviously, if you disconnect the battery from the bike before charging, it is not an issue.

(Mechanical regulators use significant current in their sense-lines.)

LOU,, I have my battery in the house for the winter and will make sure it's charged well before ig goes back in the bike. I'll keep in mind that charging it on the bike with my RR hooked up the way it is might be a problem. As I said I had it hooked up like this for about a month last summer (before I put it into storage) and never saw any drain in the battery over that time, granted I was riding regularly and it would have recharged over that time. I know that this isnt a permanant fix but so far it has worked for me. If you have any other suggestions on fixing it I'd be happy to try them. I have taken apart my ignition and it looked perfect very clean, no loose wires, I have looked at my fuse panel and it also looked fine....

That's about it. Make sure the sense-wire cannot come disconnected while the engine is running and make sure it is not connected if you use an external charger.

You can isolate the voltage drop if you have a volt-meter. If you're bored some day you could measure the voltage on the main fuse while the bike is running. (Maybe you already did this).

It is also possible the .5 v drop is normal (although it does seem a little high) and the reg/rec is defective.

Finally got some time to work on the bike today. I removed the ignition switch, it checked okay, but I disassembled, cleaned and reassembled it anyhow. I then removed the solid-state rec/reg and went back to my original electro-mechanical separate rectifier and regulator system. Problem solved - it charges at 13-14V depending on rpm just like it should. So I guess the voltage drop was more or less normal and the new voltage regulator was faulty. Also after checking the schematic, I was wrong on the wiring, the coil and sense line to the reg are different wires.
Anyhow, thanks for your help/suggestions,
Tony