1991 Honda VFR battery charging issues

**Gareth123** · 13th January 2012, 15:37

My latest acquisition died on me the other night with a flat battery.

The diagnosis at the time was that the battery wasn't being charged and that the reg/rec or stator were buggered.

This afternoon I pulled the fairing off and put a battery from another bike into it and then started checking various readings with my multimeter. I was getting a bit confused with what I was seeing so I rode the bike down to a auto sparky and had him throw his multi-meter across the terminals. He checked the reg/rec and stator for me and pronounced both to be working fine. I did have the headlight fuse out at the time to help save the battery.

Back at home I put the headlight fuse back in and did the same checks the sparky showed me. As I rev'd the bike, instead of going up the readings went down. Light off and the readings go up, light on and the readings go down.

I'm going to check for shorts next, is there anything else I should look for?

I'm also thinking I'll head down to the sparky again on Monday with the headlight going and see what happens. Hopefully it's just my multi-meter being a bit dodgy.

**HenryDorsetCase** · 13th January 2012, 15:43

Five bucks says your reg/rec is stuffed: these bikes are famous for it.

**Gareth123** · 13th January 2012, 17:00

Thats what I reckon it is. But the sparky said it was working. Might try another sparky on Monday.

**vifferman** · 13th January 2012, 19:07

You should get over 12V at idle (can't be bothered going in the cupboard to dig out my Electrex trouble-shooting chart to get the exact figures), and this should rise up to 13.summat volts at 5K rpm, then not get any higher. If you unplug the plug from the stator to the R/R, there should be 65V AC coming from each stator wire, and when the bike is not running, no continuity between any 2 of the three, and none between any one of the three and the frame.
It's a fairly easy thing to check, so if the auto-electrician said the stator's fine, then it probably is, same for the R/R. However (but!) you can have an intermittent fault - the plug is often a point of failure, and the pins or wires in it can crap out or have too high resistance due to corrosion.
It's possible the headlight switch or summat in the headlight circuit is shorting an buggering things up, given the effect that seems to have.
The charging system is pretty simple, and also kinda unreliable, particularly on pre-2001 Hondas. Basically, it just puts out up to 65V AC, this is rectified to DC. The stator always supplies more current than needed, and any excess is bled off through the regulator part of the circuit as heat. Earlier R/Rs were too small and unfinned, probably beacuse Honda wanted to hide them under body work. Despite Shindengen (the manufacturer) having beefier ones available for yonks, Honda ignored the problem and didn't fit them until early this century (sounds weird saying that...)

Because the failure is often caused by connections, wires and earths failing, it can be intermittent. I've had failures on a '90 VFR750, and a '97 VTR1000, and both looked like battery failures, and took weeks to misbehave to the poiint where it was obvious it was the R/R.

If you need more help, PM me - I fixed both bikes myself, and have made my 2001 VFR800 more robust and electrically reliable. HTH...

**Gareth123** · 14th January 2012, 03:05

Originally Posted by vifferman

...If you need more help, PM me - I fixed both bikes myself, and have made my 2001 VFR800 more robust and electrically reliable. HTH...

If it's an intermittent fault caused by the R/R getting too hot that will only show up after a decent ride, right?

The sparky did say I was losing a 1/3 of a volt somewhere and pointed out the 30amp fuse on the starter relay. Not sure how that works out but the plug in there is pretty filthy and gummed up.

**vifferman** · 14th January 2012, 11:06

I was going to post bits from all the stuff I've downloaded over the past 12 years, but went one better:
http://www.electrosport.com/media/pd...ng-diagram.pdf

Originally Posted by Gareth123

If it's an intermittent fault caused by the R/R getting too hot that will only show up after a decent ride, right?

Well... perhaps, but if that is the case, then the R/R is ferkt, and should be ditched anyway. Also, if that was the case, having the headlight on would help by making the R/R have to shunt less excess current to ground, and it's not.

Originally Posted by Gareth123

The sparky did say I was losing a 1/3 of a volt somewhere and pointed out the 30amp fuse on the starter relay. Not sure how that works out but the plug in there is pretty filthy and gummed up.

The battery output runs directly through the starter relay to the rest of the bike, except when you press the starter button, when ALL power goes directly to the starter. So the relay and its fuse are very important.
Regardless of whatever happens now, you need to clean all the connections in the charging circuit (including the starter relay and fuse), the battery connections and earth, and make sure these are all tight.
When I had my '90, I actually remounted the new R/R where the horn goes, removed all wires from the stator to the battery and R/R and replaced them all with fatter wires, no plugs, and all connections twisted together, soldered, and covered with heat shrink. (I subsequently found out that crimped or other physical connections were better as the solder can cause corrosion). I gained over 0.5V from this.
Did a similar thing with the VTR, but not the whole rewire, as I couldn't be bothered, having recentlyish done the VFR. Then on the VFR800 (which has a much better R/R), I just got rid of the plugs and made solid connections, found the connector for all the ground/earth wires for all the wiring loom, cut it off, joined all the wires together, and added a whole new earth to the frame. The R/R was fitted with a PC cooling fan, just because we had several lying around. It runs off a fusebox connected to a relay connected to the wire to the taillight, and is on whenever the key is on. Dunno if it helps, but it certainly doesn't hurt, and draws negligible current. Apart from a tired battery, and an intermittent cutout fault before I rewired the earths and added an extra one to the ECU, I've had no electrical problems.

**Gareth123** · 15th January 2012, 09:08

Originally Posted by vifferman

The battery output runs directly through the starter relay to the rest of the bike, except when you press the starter button, when ALL power goes directly to the starter. So the relay and its fuse are very important.
Regardless of whatever happens now, you need to clean all the connections in the charging circuit (including the starter relay and fuse), the battery connections and earth, and make sure these are all tight.
When I had my '90, I actually remounted the new R/R where the horn goes, removed all wires from the stator to the battery and R/R and replaced them all with fatter wires, no plugs, and all connections twisted together, soldered, and covered with heat shrink. (I subsequently found out that crimped or other physical connections were better as the solder can cause corrosion). I gained over 0.5V from this.
Did a similar thing with the VTR, but not the whole rewire, as I couldn't be bothered, having recentlyish done the VFR. Then on the VFR800 (which has a much better R/R), I just got rid of the plugs and made solid connections, found the connector for all the ground/earth wires for all the wiring loom, cut it off, joined all the wires together, and added a whole new earth to the frame. The R/R was fitted with a PC cooling fan, just because we had several lying around. It runs off a fusebox connected to a relay connected to the wire to the taillight, and is on whenever the key is on. Dunno if it helps, but it certainly doesn't hurt, and draws negligible current. Apart from a tired battery, and an intermittent cutout fault before I rewired the earths and added an extra one to the ECU, I've had no electrical problems.

There goes my day of riding tomorrow. Thanks for the advice vifferman.

**sil3nt** · 15th January 2012, 09:45

My reg/rec died the other month. It took the battery out as well. The battery was actually showing full charge but we still had no electrics after replacing the reg/rec. New battery to go with the R6 reg/rec and no problems since.

Worst case scenario is your alternator has gone as well.

**Gareth123** · 15th January 2012, 12:03

Well after checking the stator and the reg/rec again I'm thinking the reg/rec has definitely done it's dash.

The local Honda shop can sell me one for $205. Are there any cheaper alternatives?

**ducatilover** · 15th January 2012, 12:41

Is it a five or six wire reg? Buy one off eBay, I pad $20 for a new one on my ZZR600D (Little Honda rip off reg/rec) and have done 2000km on it without a problem.

**ducatilover** · 15th January 2012, 12:42

Also, have you checked your stator isn't grounding out or shorted?

**sil3nt** · 15th January 2012, 19:43

Originally Posted by Gareth123

Well after checking the stator and the reg/rec again I'm thinking the reg/rec has definitely done it's dash.

The local Honda shop can sell me one for $205. Are there any cheaper alternatives?

R6 reg/rec. SH713AA. I got mine from ebay. Was around $100 shipped. You can probably find one cheaper just depends on when you look.

**vifferman** · 15th January 2012, 20:51

Originally Posted by sil3nt

My reg/rec died the other month. It took the battery out as well.

That's not uncommon. The R/R can fail in one of two ways: the rectifier failing, which means the battery will get A/C volts and get cooked, or the regulator failing, which means the battery gets insufficient charge (most common), or too much (gets cooked).

As for buying a secondhand one - it's a gamble. It might last nearly forever, or die in a few hours.

**spanner spinner** · 16th January 2012, 20:57

It will be the reg/rec, I have replaced plenty of reg/rec on all brands of bikes, they like dropping one phase (there are three on your bike). if one phase drops out there is enought charge to run the bike if there is no extra load ie lights cooling fan etc. That is why you got good readings with the lights disconnected but bad readings when you reconnected the lights. Your local bike shop can supply a aftermarket reg/rec eurobike sell them you need the 35 amp option if you want it to survive any lenght of time.

**Gareth123** · 16th January 2012, 21:13

Originally Posted by spanner spinner

It will be the reg/rec, I have replaced plenty of reg/rec on all brands of bikes, they like dropping one phase (there are three on your bike). if one phase drops out there is enought charge to run the bike if there is no extra load ie lights cooling fan etc. That is why you got good readings with the lights disconnected but bad readings when you reconnected the lights. Your local bike shop can supply a aftermarket reg/rec eurobike sell them you need the 35 amp option if you want it to survive any lenght of time.

Eurobike? Are they an internet company or are they a local company?