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#1
10-02-2021, 01:01 PM
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10SI undercharging
well, it charges but not as well as it should.
Voltage when engine is stated cold is a happy 14.5 and stays there until the alternator starts to heat up then voltage drops down slowly a full volt to 13.5-13.7 Toss on the headlights and it drops a little more........by this time the dash volt gauge is well into the yellow. Raising the idle a bit helps but still under 14 volts. Belt is tight and I rebuilt the alt with all new NOS parts......voltage reg, rectifier bridge, diode trio, everything except the rotor and stator as they ohmed out ok and visually they didn't have obvious probs. I see they sell 100 amp upgrade kits for the 63 amp 10SI alts for around 80 bux but since everything inside is already new I don't want to buy if not needed. Would a new stator help? This company has an upgrade one for a reasonable price: https://store.alternatorparts.com/partno27104.aspx My alt is definitely not putting out as much as it should (just like my ex) and would like to get it back where it should be. also when I full field the alt when it's at idle around 13.7 it immediately jumps to max output of almost 16 volts. Is this a sign of a bad regulator or at least an iffy one? |
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#2
10-02-2021, 01:29 PM
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The voltage regulator has a built-in temperature compensation, at cold temps it will charge a a higher voltage, hi temps at a lower voltage.
That said, yours seems to be over-compensated (drops too low at higher temps), or you are not getting enuf airflow thru the alt. Check for belt slippage, fan too far away from the front housing, hot air entering the rear housing. An alt gets cooled by sucking air into the rear housing and out the fan. If you have a one-wire, change to the 3-wire connection that has the voltage sense point at the battery. If all that is good, I'd say the regulator is over compensated. Case in point, I had a Caddy Northstar in which I replaced the alt with with an AC Delco. Now it performs exactly as you describe......the issue is worse with the Northstar, the exhaust manifold is right next to the rear housing of the alt. If you can, see if you can get a regulator from a different manufacturer, maybe even and old OEM part. In my case I just left it because the alt is such a b!tch to change... george
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"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#3
10-02-2021, 01:50 PM
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Quote:
Belt is tight and pulley is good. The regulator and all other internal parts I swapped out are all NOS Delco items bought off ebay, no offshore junk as I didn't want problems but unfortunately I have one although quality parts were used.......but then again new doesn't always mean good. Maybe the regulator was dropped at some point who knows. Only original parts reused are the stator and rotor that's why I thought either/or may be the issue. I just don't want to swap parts unless bad. Is there supposed to be heat sink grease on back of the regulator? I don't remember doing it if so. |
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#4
10-02-2021, 01:54 PM
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A lot of could be''s. Could be the reg, but I doubt it. OE Delco has regs with a set point voltage of 13.6 up to 14.7 without the OE number I don't know which reg you have. Could be the trio has one bad diode, most probable from your description. Could be the rectifier. Could be the stator has a burnt connection where the eyelets attach to the stator wire, or a burnt wye connection, another good possibility. Before you take the alt back off, take some voltage readings while it is connected and running at the alt + post andbat ground, and from the bat+ to the alt case. Also take a reading at both of the wires in the plug in while it is connected. Compare these readings to the battery voltage and let us know.
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#5
10-02-2021, 02:01 PM
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No heat sink grease on the rect. George, I don't think the 10SI alts had temp compensation.
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#6
10-02-2021, 02:05 PM
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Have you checked the actual amp load that you're asking it to supply? Maybe it's too small, or borderline under cold conditions and insufficient when hot?
__________________
'65 Tempest 467 3650# 11.30@120.31 |
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#7
10-02-2021, 02:06 PM
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Quote:
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#8
10-02-2021, 02:18 PM
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what is the reaading on the reg plug #1 R compared to battery volts
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#9
10-02-2021, 02:25 PM
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Got to cut some grass. If the reg #1 reading is a lower than the bat reading it may be the trio. If not then take a good look at the stator crimp and wye connections when you take it apart.
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#10
10-02-2021, 02:46 PM
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May need to start from ground zero: exactly what did you replace (brushes, diode trio, regulator) ? Did you polish the rotor contact area ? Was common to twist/damage the connections when removing the nutz.
What happens when you short the contact in back to ground ? Does it jump to full charge ? YWTK. |
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#11
10-02-2021, 03:11 PM
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Quote:
everything replaced except rotor and stator. Slip rings were polished. Nothing was twisted when disassembled I was very cautious. |
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#12
12-17-2021, 07:50 PM
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So, did the battery get swapped out? What was the fix? I have built many 10si, and would like some closure...Always Learning!
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"The Future Belongs to those who are STILL Willing to get their Hands Dirty" .. my Grandfather |
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