Topic: 7 lead Solid state regulator/ rectifier wires?

[Geoff Hastings]

I fitted one of the 7 lead solid state reg/ rectifier units to my sons 78 cb550 and immediately found the battery was not charging. Swopping over the black and white lead connections black to white and white to black cured the problem. I assumed the unit had been wired internally incorrectly as all was well for about six months but it did randomly end up with a flat battery. I went though the wiring and replaced any iffy connectors or suspect wiring right back to the windings. Eventually I thought I’d found why it was intermittent, the windings were loose in the casing, the screws were tight but they just did not clamp the windings firmly in the case. When I checked the voltage at the new fully charged battery it read up to 16volts when revved hard. I bought another unit on the assumption that the loose windings had caused spikes which had damaged the unit. This one also needed the black and white wires reversed to produce a charge, has anyone else bought one of these units? The bike is now charging at 12.8volts with the lights on, do you think this enough to maintain the charge.

[TwoTired]

A good fully charged and rested lead acid battery should have a no load voltage of 12.6 to 12.7 Volts.  Technically any voltage over that is replenishing the charge, albeit slowly.  It matters if the alternator is revved up, as the alternator makes only 1/3 of rated power at idle rotation speed.

Revved, depending on battery charge state, you'd like to see 13.8 Volts.  But, battery charge state is dominant.  A depleted battery won't have attractive voltage even if the charging system is going full blast.  Depleted batteries can almost appear to be dead short and at the very least severely depress voltage level, even on the best charging systems.

[bryanj]

What you are saying about swapping leads suggests to me the the unit you have is not compatible with our old style charging systems as the field coil is fully insilated and it should not matter which wire goes to which end of coil as all it does is produce a magnetic field from dc current, the stator produces ac.
No 12.8 is not high enough, with a good battery and charging system cut off should be about 14.2

[PeWe]

Blinkers and brake light need some extra. City riding need a good battery and charging system.
I have volt meters attached between my speedo and tacho so I see what happen with voltage when riding.

[Geoff Hastings]

Thanks for the responses guys, both the solid state units I bought were advertised as being for the CB550, that’s why I was surprised that the black lead and the white lead from the regulator needed to be reversed to make it work. Unfortunately neither unit came with a wiring diagram and as five of the wires go straight to the multi pin plug and that just leaves the black and the white leads there would not really much you could get wrong, or so I thought. I might just take the casing back off and check the field windings are not also loose like the stator was.

[Geoff Hastings]

Hi there,
I managed to find a circuit diagram for the seven wire reg/rectifier. I realised straight away why swopping the black to white and white to black wires allowed the bike to charge. I’d basically bypassed the unit and was feeding 12 volts straight to the field coil. Everything else checked out ok although to be honest I’ve not checked the ac output but assume as it charges when the field coils are energised they are ok. It would appear that both units are faulty and have read that there are some hooky ones on eBay. I did buy both these units there so looks like I’ve wasted my money!

[TwoTired]

I'm not so sure you didn't destroy the vreg when you swapped wires.  From the Vreg perspective (assuming it mimics the stock regulator) the black input is both a sense point for what the battery voltage is, as well as a supply of power to be distributed to the white wire as needed to power the field coil.  If you placed 12v on the output white wires connection of the vreg, it likely blew the output distribution control device internal to the vreg from the forced backfeed into an output.  While the vreg circuitry can be designed to protect itself from random miswires, it adds cost to the unit, which many buyers refuse to pay for, as the lowest price point is the dominating factor by purchasers.

[Geoff Hastings]

I agree that swopping the wires over probably did knacker the unit but as the battery did not charge with either unit when wired correctly and, no diagram, I was groping in the dark. There was no power to the field winding and obviously once I’d swopped the wires it was charging. I had the 12 volts going to the unit via the red wire but nothing coming out of the white wire whether the bike was running or not.

[TwoTired]

The white wire voltage should be dependent on the battery charge state. A full battery does not need charging, and the voltage on the white wire should be reduced or nonexistent if the battery voltage being sensed as too high.  So, no voltage on the white wire is only a concern if the battery is depleted or if the system load is known high. 

Without knowing the system conditions, I really can’t say if your measurements were truly indicative of a bad unit as received.  Better luck with your next device, I hope.

Also, without knowing the internal design, it is not known whether the red wire is routed to the regulator section or only to the internal rectifier, which can be separate functions.  The stock bike had two separate devices for these functions.  Who knows whether the units you bought made common use of those connections.  In the future, make sure the black switched power reports full battery voltage the the vreg, or it will never provide proper charging function. As you know, the black wire distribution routes through several  connectors, switch and fuse contacts all known to develop resistance and voltage drops, leading to false operation of the charging system.

[Geoff Hastings]

Thanks twotired, I had not considered that the white wire would not have 12volts on it if the battery is fully charged, it is a new, fully charged battery so common sense would say that the control voltage would be cut to the white wire. The simple test of holding a metal object close to the alternator casing and turning the ignition on to test the field windings are energised perhaps doesn’t work with these solid state units, does anyone know if that’s true? however, with the headlight on and having cranked it over a few times I would have expected the battery voltage to increase with rpm, it did not vary at all. My next attempt will be to refit the mechanical regulator and use the solid state rectifier.

[TwoTired]

The field coil of the alternator is a component of an electromagnet.  The 550 doesn’t have as strong an alternator as the 750, but it should draw a thin steel feeler gauge blade closer to it when energized.  I would first check the resistance of the coil and wires going to the coil from the perspective of the vreg. The white to green ought to be pretty close to 5 ohms.  I don’t know how long the field coil will survive when driven with a constant 12 v.  The winding insulation is quite old now, and extra heat just might compromise the thin wire insulation.  But, if the resistance is still correct, it should be fine.

FYI all my 550s still employ the stock regulator.   Work fine, though I did have to readjust two of them, as the PO had errantly adjusted them without understanding how it was supposed to work.  They really behave as a voltage limiter, rather than a regulator. The battery charge state rules the system voltage. The regulator mostly just keeps the battery from being overcharged when it’s full and highway cruising.

[Geoff Hastings]

Right, finally making some progress. I checked the field winding resistance again just in case as TWOTYRED suggested a constant 12volts might have fried the windings. They read 4.5 ohms at the multi plug behind the side cover so that was ok but, I flexed the wires along their length and where they enter the alternator casing the reading fluctuated between 4.5 and open circuit. First job tomorrow will be to remove the casing again and find the break.

[TwoTired]

I hate intermittents.  Hopefully, you'll find the break outside the actual field coil windings.  Good job so far...

[Geoff Hastings]

Finally sorted, the socket connector on the white wire where it goes into the alternator was the problem, the joint was nice and clean but the crimp to the wire was faulty. The clear plastic sleeve over the connector was all that was keeping the connector in place. It now charges at a nice steady 14.5 volts. By the way, I’ve used the new solid state rectifier as it worked fine but bypassed the regulator part and I’ve used an original mechanical regulator.

[TwoTired]

That's good news!

Do make sure no one has messed with the VReg adjustment.    Have a fully charged battery, remove lighting fuses, and rev the bike while monitoring battery voltage.  If it never goes above 14.5V, your battery is safe from overcharging.  Put fuses back in and have fun riding!