jeffcanada Posted November 24, 2003 Report Share Posted November 24, 2003 Ok, here's the situation before I ask my question: You are driving for a while, engine is up to operating temp. You are in stop and go traffic and you are approaching the point when the fan kicks on. While stopped at a light and in gear (D or OD) your engine temp creeps the rest of the way to where the fan kicks on. The fan kicks on and.... My question: how bad is your voltage drop? while driving around regularly I run at or above the halfway mark on the gauge (13 I think) all of the time. In the above situation my voltage drops to below half, sometimes as low as the quarter slash, and it really feels like the thing is gonna die or something. I don't know, maybe I'm just freaking out and it is supposed to drop that much. Maybe it isn't, and that's why I asked. (For reference I had a brand new alt. installed in March of this year) And related, if it isn't supposed to cause such a voltage drop, is there really a big difference between the crappy reman. battery I have in there now vs. a new good one (I don't mean Optima; more like Canadian Tire top rated CCA's, etc)? If you need to know, I don't have any voltage sucking stereo or anything else. Thanx for any input, Jeff Quote Link to comment Share on other sites More sharing options...
jeremy Posted November 24, 2003 Report Share Posted November 24, 2003 I don't have a voltage guage ...on a side note, it soulds like you alternator is on the way out... Quote Link to comment Share on other sites More sharing options...
TGPilot Posted November 24, 2003 Report Share Posted November 24, 2003 Most any car I have owned you will see a drop in voltage when a cooling fan or major accessory is turned on, but the alternator in good health will regulate the voltage and should go back up to a normal operating range on your gage. Best thing to do is get or use someones Digital Volt Meter (DVM) tied onto the terminals of the battery, see what the actual voltage is at the terminals when the fan kicks on, or you turn your heater fan to full,l or your headlights on...you get the point. Anything less than 12Volts DC and you are discharging (killing) the battery. Your alternator should regulate the draw of volts and return to a good charge. 13-14.7 volts DC is what I have seen on most cars... 8) Quote Link to comment Share on other sites More sharing options...
jeffcanada Posted November 24, 2003 Author Report Share Posted November 24, 2003 Question about the previous reply: How quickly should my voltage gauge come back up in the driving condition? And when measuring at the terminals when the fan kicks in (I'll get a helper to hold the brake while it is in gear) what should the readings be and when (ie. should it be better than 12 V before the fan, less when it kicks in, and how quick should it read above 12 again?). Basically, when I drive off my voltage comes back up. But so long as I sit stopped at that light and in gear it stays down, and the car feels really shaky, like it is just hanging on to running. I forget for sure what the number is, but I think the 1/4 slash is 8V, and though it usually sits above that, once or twice it has gone that low. I haven't let it sit for really long when it does this (I usually throw it into neutral and the voltage comes up a little bit)(also as a note, if the fan comes on when in neutral or park, the voltage does not drop), but I don't think it continues to drop, or if it does, it does it so slowly that I haven't let it go long enough to see it. And, any opinions on the battery issue? Would getting a better one help this go away? Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 24, 2003 Report Share Posted November 24, 2003 Question about the previous reply:How quickly should my voltage gauge come back up in the driving condition? And when measuring at the terminals when the fan kicks in (I'll get a helper to hold the brake while it is in gear) what should the readings be and when (ie. should it be better than 12 V before the fan, less when it kicks in, and how quick should it read above 12 again?). Basically, when I drive off my voltage comes back up. But so long as I sit stopped at that light and in gear it stays down, and the car feels really shaky, like it is just hanging on to running. I forget for sure what the number is, but I think the 1/4 slash is 8V, and though it usually sits above that, once or twice it has gone that low. I haven't let it sit for really long when it does this (I usually throw it into neutral and the voltage comes up a little bit)(also as a note, if the fan comes on when in neutral or park, the voltage does not drop), but I don't think it continues to drop, or if it does, it does it so slowly that I haven't let it go long enough to see it. And, any opinions on the battery issue? Would getting a better one help this go away? My money is on a bad battery.. having a bad battery will require the altinator to run the load for your accesories. When your at a idle the altinator is at its weakest point in operation, so when your engine stutters its starving for all the volts it can for general ignition of the motor. have you ever seen a motor idle with no battery. you get a really shaky idle. Quote Link to comment Share on other sites More sharing options...
jeffcanada Posted November 24, 2003 Author Report Share Posted November 24, 2003 That sounds right on. Thanx a lot. Just one more question: is there any way to test/check the voltage regulator without pulling the alt? A new battery it is I think regardless. I am actually/will actually be really happy if that is the problem, and not the alt. that has been in there for less than a year. I figure I need something better than a remanufactured POS battery to get through the winter anyways. Jeff Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 24, 2003 Report Share Posted November 24, 2003 That sounds right on. Thanx a lot.Just one more question: is there any way to test/check the voltage regulator without pulling the alt? A new battery it is I think regardless. I am actually/will actually be really happy if that is the problem, and not the alt. that has been in there for less than a year. I figure I need something better than a remanufactured POS battery to get through the winter anyways. Jeff i have seen a brand new 1000amp battery die in 3 months. it just happens sometimes. your voltage regulator should be fine after the new battery is installed. Just get the largest battery you can find that will fit. to test it, uhh uhh. i would think its working fine if teh voltage dosnt fluxuate as much when you have a new battery in.. If the cooling fans still pull the battery to near dead again, i would definatly look for a short or a bad fan Quote Link to comment Share on other sites More sharing options...
Slade901 Posted November 24, 2003 Report Share Posted November 24, 2003 I would lean towards a dying battery. BTW, make sure that the battery has electrolyte at the right level. If not, then purchase some distilled water at your local grocery store. Autoparts store will sell you a lead acid battery which you don't really need. All you need to is to topped off the the battery level with a distilled water. Note: Don't overfill the battery. If you want to test your battery yourself, then purchase a $15 battery load tester at your local Harbor Freight store or similar store. Some batteries are shipped out without electrolyte solution in it but majority of batteries sold do have electrolyte solution in the battery. Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 25, 2003 Report Share Posted November 25, 2003 I would lean towards a dying battery. BTW, make sure that the battery has electrolyte at the right level. If not, then purchase some distilled water at your local grocery store. Autoparts store will sell you a lead acid battery which you don't really need. All you need to is to topped off the the battery level with a distilled water. Note: Don't overfill the battery. If you want to test your battery yourself, then purchase a $15 battery load tester at your local Harbor Freight store or similar store. Some batteries are shipped out without electrolyte solution in it but majority of batteries sold do have electrolyte solution in the battery. Autozone had FREE battery and Altinator testing!!!! Quote Link to comment Share on other sites More sharing options...
joey b Posted November 25, 2003 Report Share Posted November 25, 2003 do all of us a favor and stop guessing what the different lines in the voltage guage denote. Go buy a tester and fill us in. Quote Link to comment Share on other sites More sharing options...
TGPilot Posted November 25, 2003 Report Share Posted November 25, 2003 Sorry but the battery is nothing more than a large source of Amperage to start the car. Your alternator is the continued source of voltage for all accessories after the car is started. Now if an alternator is going bad it will cause a severe "deep cycling" of the battery and kill the battery over time. If a car is running like garbage and a battery fixes your problem it is only temporary if the alternator is not charging properly. I have posted this before and will stand by every word said...If a car is started and the battery is disconnected while the car is still running, the car will run indefinitely until it is turned off with a good OEM alternator. Obviously it will not restart without the battery or a jump...but the alternator will continue to keep the car running as it is the source of continued power to the cars electrical system!! I have bought cars and driven them for hundreds of miles without a battery in the car with the headlights on, heater fan running, and opened and closed power windows numerous times during the drive. As someone else said...most auto-part stores will do a free electrical test on your car to isolate your problem. Replacing the battery at the same time as an alternator is recommended by ASE... 8) Buying the highest AMP battery will do nothing more than let you start your car in Bismark, ND in January! Quote Link to comment Share on other sites More sharing options...
ismellrealbad Posted November 25, 2003 Report Share Posted November 25, 2003 go out to your car and pull a battery cable while its running and tell me what happens. MOST of your power comes from the alt while its running but you still depend on the battery too. you need both a good battery and good alternator at the same time for your car to run properly. a dying battery will cause your alternator to be overworked and over time the alt will take a shit. if your alt is dead your battery will soon be shortly also. honestly if i ever have to replace one thing im never going to do it again without just replacing the other (unless i had a TDC, then id just take my chances with the alt :? ) If you just recently replaced the alt, and your fans (or any other electrical device) are causing an abnormal drain, just replace the battery with a decent brand and enough cca's. its what, 60 to 80 bucks at the most? thats just my 2 cents Quote Link to comment Share on other sites More sharing options...
sonyman87 Posted November 25, 2003 Report Share Posted November 25, 2003 once again i will say this to rule out all question. go to Autozone and get your battery and altinator tested. you pull up ask for the test the go in test your battery.. then running the car test the charging system aka altinator Quote Link to comment Share on other sites More sharing options...
jeffcanada Posted November 25, 2003 Author Report Share Posted November 25, 2003 It drops to just under 12 V (11.5 V) when the fan kicks on under the first mentioned circumstances (stopped, in gear). However, if I turn on the climate control fan, defroster, headlights, interior lights, basically anything else at all, it can drop to as low as 10-10.5 V. At 11.5 V it gets shaky, at 10.5 V it feels like it is really ready to quit. Should that be? The battery wasn't replaced when the Alt was earlier this year, so I am going to do that. I think it just may be a case of a crap battery and a good alt. not working well together. Thanx everyone. Quote Link to comment Share on other sites More sharing options...
boostnawd Posted November 25, 2003 Report Share Posted November 25, 2003 what's the voltage with all accessories off? at idle? does it improve when you rev it? maybe you just have a loose alt belt. Quote Link to comment Share on other sites More sharing options...
jeffcanada Posted November 25, 2003 Author Report Share Posted November 25, 2003 With all accessories off, at idle, in gear, driving around town, or stopped and in gear, or stopped and in P or N, it is at 14 V. When I am stopped and the fan kicks on drops it, if I put it in Neutral it usually gives another .25-.5 volt. If I rev it, it is usually so I don't have to sit at the light and feel the car shake. Quote Link to comment Share on other sites More sharing options...
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