Never see right voltage charging #'s with sh775 and Lithium

[GabrielGoes]

So I've been using these sh775 (confirmed oem/good used) before on these GS and lithium batteries, I never see the voltage go above 13v even at like 4500 rpm. Ive tried swapping out stators with known good ones and even new RICKS stators put in' and no matter what i do I can never see the golden 14.5v charging numbers.

Wiring method: The 3 stator leg wires into the 3 grey plugs spots' the power to the main fuse box and black to ground as simple as it gets. I also tried the positive directly to the battery no difference.

I currently have a lithium 12v battery with an sh775'... I've tried with lead acid as well and the gauges and lights get brighter when you rev, and even if you drive with the highbeam on all day the battery starts right up and the battery doesn't dip below 12.4v or so- I sort of just been "trusting" it.

Is there something "smart" that these regulators know like if the battery is at full charge to back off the charging a bit?

this has been driving me crazy thank you in advance foe any tips

[bonanzadave]

Id commit to the stator papers and thoroughly check off each step. Make sure your meter is set and reading correctly. You are correct trying to achieve that golden 14.5 number. It aint right until you do. Make your connections 100%

TGSR-Stator Papers (thegsresources.com)

[Grimly]

I'd really suspect a dodgy volt meter.

[pdqford]

Not clear on just which model you are working on,
nor just where you are measuring that voltage.

I was measuring the voltage at the coil’s on my 1980 GS 750E,
and was dropping nearly 2 volts between the battery and the coils.

I cleaned many of the connectors on the bike picking up about 0.75 volts.
(Most of that improvement-was in the ignition’s glass fuse in the fuse box.)

Follow the red wire coming out of the 15 amp main fuse in the fuse box on its way up to the ignition switch.
After it disappears into the main harness, unwrap the harness covering for about a foot.
That is where I found the output of the R/R is crimped to that red wire,
and was turning green!

Night and day difference of how the bike runs with near 14 volts to the coil’s.

[GabrielGoes]

I'd really suspect a dodgy volt meter.

I was thinking perhaps I just bought another one in case

[Nessism]

The SH775 is made for lead acid batteries. If the charge is low, the SH775 will charge at less than 14V. You need a good strong battery, with decent charge level, in order to see 14.5V. Could this have something to do with the problems you are seeing?

SH775 Install by nessism, on Flickr

[unfocused]

77 GS750 w/750cc and a 1000cc engine installed during diagnosis. Currently running the GS1000 engine with the results below.


My issue: low voltage after installing electronic ignition. Extremely low like idling at 11.9/12V with lights on - 2 different brands of ignition, stock charging system at first, then installed SH775 wired direct, switched to LED bulbs except dash, ignition wired direct through relay. I even suspected wiring/voltage drop issues but testing ruled this out.

Replaced everything except stator - why - exact same symptoms with x2 engines rules out stator as well as tests on both came up with the same numbers.

I purchased a AGM battery with 250 CCA. This solved most of the problem. With my lights on I can still drop to 13.4/5 volts at idle but this is more than static battery voltage so I am good with this. With the lights on in cruise mode, I average about 13.8V over 3500 RPM... FYI - this isn't a high end AGM battery

I've installed a digital volt meter in dash wired in with the dash lights and verified it's accuracy with my DVOM at the battery.

The only difference between my wiring and the above wiring diagram - I don't have my VR tied to the main wiring harness or factory fuse box - my GS doesnt have a fuse box.

I've even talked to an after-market supplier of stators and the costs associated with a replacement compared to the increase in amperage wasn't worth it for testing. Knowing what I've learned from all of the above I'm glad I tried everything else...

[GabrielGoes]

The SH775 is made for lead acid batteries. If the charge is low, the SH775 will charge at less than 14V. You need a good strong battery, with decent charge level, in order to see 14.5V. Could this have something to do with the problems you are seeing?

SH775 Install by nessism, on Flickr

SO to conclude this thread, the issue is I discovered that Lithium Batteries have this LiPo4 feature built into the circuit boards that sit on top of the battery cells= when the charge is full, it blocks or stops further charging of the batteries. So i guess you REALLY need to make sure you have a series R/R that will eliminate the heat issues with shunt.

i dont know how technical it gets but a R/R putting out full 14.5v into the battery and the battery has a safety feature built in to make it stop charging is not a good idea if you dont have the right r/r.
I know theres series vs shunt vs mosfet. out of all of them i assume the series is the best for dissipating heat

[Nessism]

I know theres series vs shunt vs mosfet. out of all of them i assume the series is the best for dissipating heat

Those Shindengin MOSFET units are shunt type.

[GabrielGoes]

Those Shindengin MOSFET units are shunt type.

Good to know!!! do you know if SH775BA and other variants are series as well? are we still having to hunt these down via used polaris parts? or are they available on other platforms.

I believe the SH775BA comes on 883 and 1200 sportsters. this would be good to know for availability

[Nessism]

All SH775's are SERIES type.

Search eBay for "710001103", and toggle "used". Just make sure you can see SH775 printed on the top fin. Some seller don't provide good photos, so message them, or just look for an ad with the proper photo. Also, make sure to look at the plastic connector for broken tabs, or smashed plastic connectors overall.

BTW, I have several good used SH775's if you cant find one. PM me if interested.

[GabrielGoes]

All SH775's are SERIES type.

Search eBay for "710001103", and toggle "used". Just make sure you can see SH775 printed on the top fin. Some seller don't provide good photos, so message them, or just look for an ad with the proper photo. Also, make sure to look at the plastic connector for broken tabs, or smashed plastic connectors overall.

BTW, I have several good used SH775's if you cant find one. PM me if interested.

Thanks!!

Also p.s.

I think it's important to mention that with an sh775 and probably along with other Mosfet rr's have built in feature to detect a charged battery and so will back off on voltage. So you won't see the 14.5v if the battery is fully charged.

[pdqford]

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SO to conclude this thread, the issue is I discovered that Lithium Batteries have this LiPo4 feature built into the circuit boards that sit on top of the battery cells= when the charge is full, it blocks or stops further charging of the batteries. So i guess you REALLY need to make sure you have a series R/R that will eliminate the heat issues with shunt.

i dont know how technical it gets but a R/R putting out full 14.5v into the battery and the battery has a safety feature built in to make it stop charging is not a good idea if you dont have the right r/r.

Nessism, I have a question with respect to your SH775 install picture and the above quote:

If say the R/R was cranking out 14V would the R/R know the battery is full and to cut back the charge rate?
It seems to me the LiPo4 function of the battery would NOT ALLOW any more voltage into the battery once it is fully charged.
Mean while, the way I read your SH775 wiring diagram, the 14V would be blocked from going through the fuse block and into the battery, BUT, the 14V would continue on into the main wiring harness.. Once the main harness draw was met (i.e. you turned of the heated grips) THEN the R/R would reduce its output to match the load.

And if you put a meter on the battery you would see 13.6V at the battery and 14 V, say at the coils.

Ed, Thank You for your thoughts..
(This electrical stuff is what strains my brain.)

[Nessism]

Sorry, I'm not an electrical guy either. In my experience, the SH775 will put 14.5 V to the battery just about all the time, assuming the battery is properly charged. Voltage is potential, it's not a measure of flowing electricity, current is.

[Grimly]

I think it's important to mention that with an sh775 and probably along with other Mosfet rr's have built in feature to detect a charged battery and so will back off on voltage. So you won't see the 14.5v if the battery is fully charged.

The SH775 isn't a smart charger - the charging regulation is a property of the combination of the set-point voltage the regulator is at and the battery coming up on voltage as it charges. When the battery voltage reaches the same as the reg output, charging effectively ceases. Current won't flow when the voltage points are equal.
That's all there is to it.
However, on modern ECU-controlled engines and charging systems incorporated, all that above doesn't necessarily apply, as cunning design can make the regulation do stuff that is far more clever than older setups.