Alternator Questions
according to SGII, the alternator in my 97 civic lx is...well alternating...from 12 to 14 volts while the car is being driven. load is not a factor--it seems to be intermittent.
i've replaced a few alternators in my day, but none that are this difficult to get to. GM alternators(what i'm used to) are generally right on top of the motor, but this one is mounted such that steering and/or suspensions parts have to be moved for access. anyway, i'm debating(if this alternator is on its way out) whether to get an OEM Denso(expensive and 1 year warranty) or a store brand(less expensive and lifetime warranty). in the past, i would go cheap considering it wouldn't take much effort to reinstall another. i will likely require help if this project needs to be done(still need to check the electrical connections and belt), and i do NOT want to do it more than once! thoughts? edit: FYI...battery is new |
Re: Alternator Questions
Take a second look at the alternator. I remember helping my uncle on his old Accord. We thought the alternator was going to be hard, until I suggested taking a wheel off, and doing the alternator through the fenderwell.
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Re: Alternator Questions
Two things-
Check all grounds first. Worth a shot. Find one bad one in a place where it counts and it could show an intermittent voltage issue. I don't think honda is this way, but I know my Volvo uses a separate (replaceable) voltage regulator installed in the alternator. It houses brushes that touch the rotor of the alternator and those wear out. Verify that you can't simply replace the voltage regulator before buying a new alternator. Cheap brand or Denso depends on how long you plan to keep the car. I'm a big fan of the cheapest parts for most applications. An alternator is pretty simple... it only fails in a couple of ways. Bearing failure, voltage regulator/brushes failure, maybe something else. Someone put a cheapo brand alternator in mine before i bought it. It's lasted me 15k with no issues. Sure it's a pain to replace (maybe not with Jay2theresuce's suggestion, which I second) but they typically last many miles. That said, if you plan to keep it for 100k or more consider the expensive one. B |
Re: Alternator Questions
I wanted OEM for my Civic and found a remanufactured Denso on the Denso website for a few bucks more than the reman 'not Denso' brand at the local auto store.
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Re: Alternator Questions
thank you! good info. the denso site was MUCH cheaper than the local part store prices as well!
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Re: Alternator Questions
Is this a recent development?
What I gathered from an HHR site, is that alternator will put out 14+ volts only when in charge mode. Presumably when the computer decides the battery needs to be charged. I know you stated the battery is new, but how long did it sit on a store shelf? Perhaps it didn't have a full charge going into the car. |
Re: Alternator Questions
the battery sticker says 10/10, so i would presume that's a manufacture date? i would consider your HHR site advisement, since i've had no starting issues. maybe actually seeing what the alternator is doing(via digital SGII) is unnerving me for no reason, if it's "supposed" to do that.
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Re: Alternator Questions
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its just a big ol wire from the alternator, thru a fuseable link to the pos post. if its fluctuating id suspect a bad voltage regulator, it goes to 14 when its working right then when it craps out runs off battery voltage. id just take it off and haul it to autozone / advance for free testing. then it will be a clear cut and dry case if its bad or not. |
Re: Alternator Questions
Do you actually have a problem? Or just symptoms? Unless you are killing batteries or being left stranded, things might be fine...
Does SG actually measure voltage or get a voltage output from the computer? In either case, it might not be an issue. I've seen some ECM voltage readings that were annoyingly inaccurate (especially on GM cars). -Bob C. |
Re: Alternator Questions
13.8 tends to be the norm. After a start up it jumps to 14.4, but not always. The scangauge once reported 12.8 for a couple of days over the winter.
At least in the case of AGM batteries, a flat 14 volt continuous current will shorten the battery's life. I've read a sitting lead acid battery needs a maintenance charge about every six months to replenish loss from self discharge. If a charger is readily available, I'd try topping off the battery first. At most, you'll have to disconnect the battery. So start with the least effort fixes first. But I suspect it's nothing. The SG is giving you real time reports from the car's computer. Taking voltage multiple voltage readings, while the car is in motion, is likely something you haven't done before. I'd start worrying when the voltage is regularly going under 12 while the engine is running. Currently, I just check the volt reading to see if it's below 14 before EOC/FAS. Presumably, this means the battery is fully charged for the restart. And I watch it while the engine is off to not let it drop below 11.6 before restarting. |
Re: Alternator Questions
I'm 99% sure that the SG measures voltage itself. I seem to remember it displaying voltage properly when I was using a 9v battery to power it while I input long XGauge codes.
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Re: Alternator Questions
thanks guys...all posts appreciated.
think i'll keep an eye on it and see if any symptoms(none yet) occur. makes me wonder tho, why the previous owner bought a new battery. |
Re: Alternator Questions
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Re: Alternator Questions
easiest way to test to see wtf its doing is get even a cheapo multimeter and set to DC volts and measure at the battery terminals.
my s10's volt gauge would spike down to under 9 for no reason and i was thinking the alt was taking a crap. hooked up a multimeter and layed it on the windshield, when the gauge fluctuated the meter stayed constant 14v |
Re: Alternator Questions
new observation: it seems to run consistently at 14 volts when the engine is cold. as it warms (near full warm-up), the fluctuation begins; again never dropping below 12.
is there a possible heat soak issue? |
Re: Alternator Questions
There is some intentional thermal effect, yes. The design theory is that the battery needs the most recharging when the engine has just been started (and therefore the regulator is cold).
However, cheap aftermarket voltage regulators don't have good control of temp vs. voltage and might drop too low. On my Buick, I spent the money for a GM voltage regulator (internal to the alternator) because it has proper temperature circuitry. When I replace the alternator every 3-4 years, I disassemble the alternators (old and new) and keep my GM voltage regulator, because it works correctly. The GM regulator cost like $35, and a cheap rebuilt alternator (using ultra-cheap parts, including an ultra-cheap/poorly designed regulator) will typically cost $40-$50. Therefore they are probably buying some $3 imported regulator... Having said that, as long as you are maintaining a minimum of 13.3V, even when hot, things should be just fine. A more normal range is 13.6 - 13.9, and some cars will maintain 14.2 (which is really higher than you need) when hot. But if you are seeing voltage below 12.6 while running, then you have a problem. -BC |
Re: Alternator Questions
thanks Bob. i'll have to watch where in the 12 volt range it drops to more closely. the alternator has a honda label, so it COULD be the original. the car has nearly 200k miles, but the previous owner bought OEM replacement parts so...
def would look to use OEM denso to replace it if necessary. made up my mind, the location dictates that i do not wish to do this more than once! |
Re: Alternator Questions
yea some parts on any car can be goofy, my s10's was charging fine but had bearing failure at 140 somehtingK styarted that growl then a high pitched squeal haha yea time to swap it out...
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Re: Alternator Questions
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Re: Alternator Questions
There's a chance you just need new brushes. My '88 Escort with nearly 515K miles still has the original alternator, all I've done to it is replace the brushes once since the car was new. I'd suggest looking to see if the brushes can be removed and changed if needed without removing the alternator. A new set of brushes would probably set you back about $5.
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Re: Alternator Questions
i doubt it, modern alternators aren't people friendly like the early 90's and older
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Re: Alternator Questions
found this to be interesting concerning my alternator issue... https://www.gassavers.org/showthread.php?t=783
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Re: Alternator Questions
hmm weird...i guess u learn something everyday haha
i dunno id just keep driving it and see what happens haha |
Re: Alternator Questions
The HHR system seems to spend some time in the 12.5 to 12.8 range. I've been paying more attention to the volts recently, so I don't know if it's normal of a change. Perhaps it's like the Honda system, and I don't have to worry as much.
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Re: Alternator Questions
Hey check the voltage when you turn your headlights on and off and see what happens then. It should drop for a second the come back up to voltage maybe even a little higher when you turn on the lights. That will tell you if the alternator is working or not.
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