Weird charging circuit values

Hi all,

I have just bought a new battery this weekend and decided to check the charging circuit before I put the new battery in and I am getting some weird(in my opinion) values!

When the bike is idleing I am getting 13.7V DC across the battery terminals. When increasing to 5000rpm the value decreases to 12.88V. Both of these values are when the battery is under load with all lights on. The battery voltage is 12V before the bike was started as I dont want to put the new battery in and knacker that one too, could this be the problem?

I was about to check the alternator voltages just before it pi**ed it down, would this help?

Any ideas guys?

Thanks,
Andy

[johnnyrod]

Seems a bit low, definitely check the AC output from the alternator (with it disconnected) - 75V at 5000rpm I think should be a minimum across each pair of wires.

[timwilky]

Having just changed my 6 year old battery I am still getting lousy voltage accross the new battery as well. In my case about 12.7v at 5000rpm rising to about 13.3v if I turn the lights off.

I have checked my altenator output and it is about 85V accross the 3 pairs. So I guess I have a knackered RR. Any recommendations

I tested the alternator last night and got 86V AC across each pair, so it doesnt look like it can be the alternator.

Come on guys, any ideas why the voltage should drop when engine speed increases?Is this normal?

[johnnyrod]

Try this:

http://www.electrosport.com/electros...t_finding.html

it's a bit long but quite comprehensive. Or Sid the Squidmeister always seems to know something, if he's along soon.

Your alternators sound okay, could be the RRs or some grotty wiring. Voltage doesn't usually drop as speed increases, unless the charging system basically isn't working - should be maintained about 13-15V.

Forgot to post this earlier but I put a new batt in last night too. The voltage is now 13.3V @5000rpm but it is still dropping from 14.0V at idle.The alternator is increasing from about 70V AC at idle to 86V AC @5000rpm.

Any help appreciated!

Originally Posted by johnnyrod

Your alternators sound okay, could be the RRs or some grotty wiring. Voltage doesn't usually drop as speed increases, unless the charging system basically isn't working - should be maintained about 13-15V.

Also happens when the input to the reg/rec increases from higher revs, loading the reg/rec causing heat build up (cos its faulty) increasing resistance, reducing power to the battery

Originally Posted by andyb

When the bike is idleing I am getting 13.7V DC across the battery terminals. When increasing to 5000rpm the value decreases to 12.88V. Both of these values are when the battery is under load with all lights on. The battery voltage is 12V before the bike was started as I dont want to put the new battery in and knacker that one too, could this be the problem?

This happens on my '99 as well. I had some charging problems a couple of years ago, and when I measured the charging voltage I concluded that the RR was to blame. Bought a new one and got the same result. Checked the AC-voltages and regulator/rectifier as specified by the manual, everything checked out OK. I tracked down several bad connections and corroded terminals in the wiring loom and sorted those out. The battery would now hold a charge, but charging voltage is still the same.

At idle it's around 14V, which decreases to about 12.8 when I rev the engine. I can actually see the lights dim a bit when I rev it. Maybe it's supposed to be like this, but it's a bit annoying to have to hook my "new" bike up to a charger every week just to keep the battery happy. When I got everything else sorted out I'll look for a better quality RR.

mine is the same too. I have no 'issues' so I don't think it being regulated like that is a problem.

Originally Posted by Blue_SV650S

mine is the same too. I have no 'issues' so I don't think it being regulated like that is a problem.

What kind of values do you get Blue_Sv650S?

Cheers for all the help guys, think I may have been worrying unnecessarily! Will still check out the alternator and rec/reg though just to be 100% sure.