What EXACTLY does the Battery light mean?
Nose
New Wagonist
Might seem like a dumb question...but what, exactly, is the car trying to tell us when the battery light comes on?
Here's why I ask: My batt light comes on when all the dash lights come on as you start the vehicle. It goes off when they all go off. This tells me the bulb isn't burnt out, so if I begin having a charging or battery problem, the light should let me know, right?
Yesterday after being parked for only a few minutes it was very slow to start, but while driving there was no battery light. After a while all the normal dying-battery things began to happen...lights faded, radio started going in and out, clock dimmed to nothingness, and by the time I made it to a parts store and turned it off, even the beeper wouldn't beep when I attempted to restart the car. A voltage test showed a whopping ZERO volts in the battery.
I'm rather under the impression that the battery light SHOULD have come on to let me know there was a problem with the charging system, the battery, or something. Why did it not come on? Isn't that what the battery light is FOR?
Any thoughts on this one? I've done an hour long search and haven't found a perfect match for this question...although obviously I'm thinking about grounds, alternators, brushes, wiring and the like. I just want my battery light to come on BEFORE the battery has zero volts...am I asking too much? ;-)
Thanks all. :-)
Here's why I ask: My batt light comes on when all the dash lights come on as you start the vehicle. It goes off when they all go off. This tells me the bulb isn't burnt out, so if I begin having a charging or battery problem, the light should let me know, right?
Yesterday after being parked for only a few minutes it was very slow to start, but while driving there was no battery light. After a while all the normal dying-battery things began to happen...lights faded, radio started going in and out, clock dimmed to nothingness, and by the time I made it to a parts store and turned it off, even the beeper wouldn't beep when I attempted to restart the car. A voltage test showed a whopping ZERO volts in the battery.
I'm rather under the impression that the battery light SHOULD have come on to let me know there was a problem with the charging system, the battery, or something. Why did it not come on? Isn't that what the battery light is FOR?
Any thoughts on this one? I've done an hour long search and haven't found a perfect match for this question...although obviously I'm thinking about grounds, alternators, brushes, wiring and the like. I just want my battery light to come on BEFORE the battery has zero volts...am I asking too much? ;-)
Thanks all. :-)
Comments
hope it helps
If you want the battery to last is to check the water level every 6 months(use distilled water).Don't buy cap less batteries .If you CAN"T see the water...DON'T buy it.I'm currently on my 13th year on the same battery.
also makes my engine stutter ...
:roll:
Concerning the alternator light. I've had two factory alternators die without ever turning on the idiot light. Just because the warning light never comes on doesn't mean your alternator is fine. I think the battery light's purpose is to indicate alternator failure and/or possibly ELD (elctronic load detector) failure. This light seems to only be good for telling you your alternator belt fell off. Although with some reman alternator units, I've had the light blip while driving; later found out the alternator was border line good.
I'm not sure if the ECU or the voltage regulator reports if the alternator is working properly (possibly a combination of both). The ECU tells the alternator when to turn on, so it might compare alternator on voltage to some reference voltage (this is just speculation).
I'm not sure if I answered your question, but if your battery read zero volts there is probably a short somewhere. Usually your alternator doesn't completely fail meaning your battery should still have some life.
3rd4ce, sounds like there is a large load on the alternator; could be a short in the headlight circuit. Probably those crazy HID lights
SiWagon: ***13th YEAR???*** Good lord man, that's awesome! What brand did you buy? Was considering going for one of those mini-batteries next but if I can get that kind of results (with a lil maintenance) out of a regular one then Wow!!
abnormal: Much Thanks for the assistance. Sounds like you've got a lot more experience with this than I do. So...I double checked and the belt IS still on the alt. ;-) But, now I'm off to do some trouble shooting. Sincere thanks for the info! :-)
While I was out, I landed a factory service manual on ebay for a meager $4. If anyone has anything they'd like looked up, feel free to shoot me a msg! I'll be combing it for the electrical and alternator diagrams and see what we can get figured out. Don't know if there'll be an exact description of exactly why the light comes on, but it'd be nice to know...and nice to fix my charging issue too! For the record, I replaced the brushes about 2 yrs ago, the voltage regulator about 2.5 yrs ago. Chances are plausible that either of those aftermarket parts may have gone bad, but last time they went out I did get the idiot light on the dash...so, we'll see and I'll report back.
Thanks again everyone! :-)
If you pull the "alternator connector" (the plastic piece with four wires inside it, mine's green) off of the althernator, the book tells us how to do some testing to see what's what. According to the tests, my alternator is GOOD. That seemed wrong to me, so I pulled the alternator off and had it load tested at the shop. Sure enough, it's GOOD.
SO...my battery is good and my alternator is good...but I'm draining the battery of its power and the battery is not receiving any of the charge from the alternator, and yet the idiot light on the dash still does NOT come on, until the battery is literally down to about 1 volt. Sounds crazy, right?
The good news is that this is telling us that the idiot light isn't necessarily SUPPOSED to turn on when we're about to die of a dead battery...riiiiiight? And this is good news because...umm...uhhhh.......
...hmm...ok so maybe it's not good news after all.
Now I'm headed to the shop, because now the official service manual is asking me to hook up the SUN VAT-40 and compare the results to the graph in the book. And wouldn't ya know it, I sold my last SUN VAT-40 at a garage sale last summer. Or maybe I'm thinking of the old donut frying machine. Either way, I don't have one and wouldn't know what to do with it if I did, so I'm headed back to the shop. :-)
Lucky bugger
It's a Kirkland(Costco) 72 month(6yrs) battery.These batteries are highly rated in Consumer Reports.Costco must think it's good 'cuz now it's a 1OO month(8.3 yrs) battery(I think).I just kept swapping it to the next Civic 'cuz I know my battery is good. :arrow: You may not find it listed at Costco 'cuz the poles might be reversed.Just look for the same size battery with the poles reversed.When you install the battery fill it with distilled water.These batteries come from the factory with the water low(to prevent spillage & save on shipping).The Civic cables will reach.Don't trust the garages.Several have told me you don't need to fill them.FYI: Marketing scam so your battery dies & you buy another battery from them.
Warning:Don't buy sealed top batteries("maintence Free").If you can't pop the top don't buy it.Sealed top are only good for racing or show.They don't last long 'cuz you can NOT fill it with water.Even my 5 yr. Delco Maintence Free sealed top battery only lasted 4 years.When I forced off the top(sonic welded)...low water.
Why do think Optima & Miata batteries only come with a 3 year warranty. :shock:
:arrow: Battery Tips:
1)Reason to buy at Costco:a)Batteries are fresh (high turnover).Do you want to buy a 5yr. battery that's been sitting on the shelf for 2 yrs.b)Low cost.
2)Just fill the battery water when low with distilled water every 3-6 months.If you're running high powered stereos you need to check it more often.Check on the web on how full to fill it. :!: Never let the water get so low as to expose the lead plates.If you do the battery's days maybe numbered.
funny signature...
hopefully bad wiretuck
gl
: )
Hey, guess what. All this time I'd been thinking my alternator was good. Cause the shop down the street bench tested it and said it was good. The name of the shop is D/C Starter & Electrical Service. They've been there for years, and with a name like that and a counter full of generators, starters, and alternators, you'd think they'd know a good alternator from a bad alternator.
In this case, they didn't.
They tested my alt and said it was good. I retested it at two other stores and both stores gave me a big fat FAIL result. I'm gonna try putting in a new voltage regulator, cause I did a rectifier and brushes about 2 yrs ago and both still look ok. The volt.reg. is kinda cheap, compared to buying a new unit, so I'ma gonna see what happens.
I'ma also gonna learn never to bench test anything at only one shop. Always try it again somewheres else to make sure. Lesson learned...the hard way...after I went thru and tested the ELD, every wire I could find, even pulled the cluster to see if all my bulbs were good in the dash. Sheesh whatta waste of time...heh...ahh wells...heh...
Big hassle though. I'd be pissed. That's just me though.
Short story: I had a bad voltage regulator. Put a new one in (inside the alternator body) and I'm back on the road.
Longer story, with food for thought: With the bad voltage regulator, the car DID warn me that something was going wrong...I just failed to notice. Ordinarily when you turn the key "on", all the lights on the dash light up, including the batt. light. In my case, it did not. It wasn't something I failed to notice was missing until AFTER I'd done the fix. Now with the good volt.reg., I again have a batt. light on my dash.
SO...what EXCACTLY does the battery light do? It appears to tell us that we have a bad voltage regulator by simply NOT coming on with the rest of the lights on the dash during start up.
:-)
I think that sums it up pretty well. The regulator has to tell you that it is bad, but the bad regulator may not be able to tell you this. The battery light not illuminating when the ignition is switched on is a subtle, easily overlooked clue. I had a similar issue with the oil sending unit.