Regulator/Rectifier Test

When all the smoke has escaped from inside the wires...

Regulator/Rectifier Test

Postby hugojose » 21 Jan 2019, 17:56

Some years ago had the alternator connector melted by corrosion. Charging voltage dropped below 14VDC. Changed the connector and afterwards I installed a digital voltmeter on the bars to keep track. Factory manual says charging voltage should be between 14VDC and 15VDC....well, it really swings that much as revs change, and is not consistent either, it seems to be all over the place. Over the years tried another stock R/R with same results.

New lithium batteries coming in the market are much smaller and lighter than stock, but lithium will not stand up to this kind of wild charging fluctuation, thus decided to try a Shindengen SH775 voltage Regulator/Rectifier.

The SH775 is series type R/R, not shunt as the stock. This means it regulates by cutting load to the alternator. The shunt type simply routes(wastes) the extra energy to ground, leaving the alternator fully loaded not matter what. The theory is with a series R/R, the alternator has an easier life, lasts longer, and it runs, let's see how well it regulates.

For the records; the stock R/R in the Zephyr 750 (mine at least) is also Shindengen, just not the series type.

Installed the SH775 under the rear fender (mudguard ..) This is what it looks like.

I routed the yellow wires straight to the alternator using 14 AWG (1.62mm) wires, zip-tying them to the left frame tube. I did same with the black/red wires straight to battery terminals on the right. Positive red through a 30 amps in-line circuit breaker.

I did not do anything irreversible. I could revert to stock R/R any time. The stock alternator/RR harness is still there, simply disconnected and not used....except; in the US a dictat mandates Headlamp always on, there is no switch, and one of the alternator phases(stock harness)triggers a self latching relay in the fuse box, turning headlamp on after engine catches. I did not want to tap on my new connections, so I mounted a separate switch on the handle bar to turn the headlamp on, and this is the only connection used on the stock harness,...………... and here is my switch on the left mirror/clutch lever base..
Head Lamp Switch

The result; the SH775 maintains charging voltage very steady at 14.2VDC (+/- 0.1V) at any revs from 1200 rpm (my idle..tick-over) to 5000 rpm (never go beyond, so don't ask)… Waoooohhh... like a modern car. With this kind of regulation, I could consider trying a lithium battery if I so decide.

Digital voltmeter

I post this only as information and AM NOT suggesting anybody to do this. I just wanted better regulation than what the crude regulators provided 30 years ago. The SH775 is much larger than stock, and it won't fit under the tank. It also uses two big connectors instead of one, even though only requires 5 wires instead of 6. It is all easy, but it requires a bit of understanding of what the R/R does and what the input/output is. I also know where to get factory connectors, and have the crimping tool to do a 'factory' job. Not that is expensive, the crimping tool is about $35 USD and connectors are very inexpensive.

Another factor is the SH775 has a reputation of being so good that in the US, seemingly, the whole Shindengen lot has been monopolized by Polaris (Off road 4-wheeler, huge Indian and Victory motorcycles)..and is not longer available new, unless bought using a Polaris part number. ....and of course; Polaris is charging more than twice (about $160 USD) of what Shindengen used to charge a few years back (....God bless capitalism).

Shindengen offers also a newer R/R; the SH847 but is even larger and more expensive.....Also, the Internet is full of counterfeit cheap "SH775s.... replacements" but they are same shunt type as the stock, so you gain nothing.
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Re: Regulator/Rectifier Test

Postby Zaddict » 14 Feb 2019, 07:59

Good to know, thanks for the detailed write up. I’m not sure how sensitive lithium batteries really are to voltage changes. I’ve been running a Shorei fot several years with a stock rectefier and no probs so far.
1990 Zephyr 550 B1 (Phoebe)
Factory Pro Stage 1 jet kit
Kerker stainless steel race exhaust with 1.5" competition baffle
zx550 cams
Progressive fork springs with adjustable preloaders
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58 rwhp (stock is ~46)
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