karinvail Posted October 15, 2005 Share Posted October 15, 2005 well, my voltmeter is reading low lately - just around 11 to just under the 12 mark. It's got a new belt and it's proper tension. Is there a way to test whether it's the battery or the alternator? Also, when I put my fan on the highest setting, the voltage drops even more. Like down to 10. Quote Link to comment Share on other sites More sharing options...
85Sub4WD Posted October 15, 2005 Share Posted October 15, 2005 I usually take a suspect alternator to a general parts store - they will usually test yours for free - yours does sound suspect - two 12mm bolts to remove (easy) - that will allow you to eliminate the alternator as suspect check you dash grounding too (check voltage with an external voltmeter at the battery car running and off) - a bad ground could cause the voltmeter to read low Quote Link to comment Share on other sites More sharing options...
Phizinza Posted October 15, 2005 Share Posted October 15, 2005 if you want to get surius with checking the battery, get a SG messurer. There long glass tubes with a float inside. What you do is leave the car off, take one of the caps off the battery, use the SG thingamabob to suck some of the acid out and if it reads higher then 1200 then your usaly ok, but make sure you test all 6 cells... Quote Link to comment Share on other sites More sharing options...
edrach Posted October 15, 2005 Share Posted October 15, 2005 All the autoparts stores in this area offer free testing of the battery and alternator. Of course, the object is to sell you a new battery or alternator. If you have a digital voltmeter, an easy test that works 95% of the time is to measure the voltage across the battery at idle...it should be around 12.5 to 13 volts. As you increase the engine rpm it should climb to around 14 to 14.5 volts at 2000 rpm. Lower voltages than that usually indicates a bad alternator. A good battery will normally charge up to the alternator output; if the battery voltage drops significantly below 12.5 volts at idle, it usually means it's time for a new battery. This test isn't 100% because it doesn't test the battery under full load conditions but is a pretty good indicator of how well the battery/alternator combination work. If that combination seems okay and the voltage guage in the dash is still significantly low, I'd think about looking for a bad ground. Quote Link to comment Share on other sites More sharing options...
karinvail Posted October 15, 2005 Author Share Posted October 15, 2005 so a bad battery ground could also cause this? I forgot to mention that sometimes in the morning when I first start it, the voltage reads even lower - like around 10. Is the voltage meter reading the battery power or the alternator output? (If that makes any sense?) I have my stereo hooked up to full-time power so I don't have to turn the key on to have the stereo on. It does have a little bit of a draw because of the clock back-light on the stereo. If I leave it not started for a week or more, then it has to be jump started (dead battery). I found this out after coming home from vacation this summer. Normally it's started at least every other day, and occasionally the battery is low if I haven't started it for a couple days. I'm personally leaning toward a battery, but either battery or alternator is not a cheap fix! Quote Link to comment Share on other sites More sharing options...
edrach Posted October 15, 2005 Share Posted October 15, 2005 Karin, both items are cheap at Pull a Part; Alternator is $12.50 plus small core charge and tax; battery is $14.50 plus core charge and tax. I have three batteries here from PAP which I buy because they are cheap and I have an easy way to test them and if they don't test out, I just take them back for a full refund (receipt and marking needed and within 30 days). Alternators I pick up when I find a good one; I install it on my car to make sure it works and the working one I took off my car goes onto my "spare parts" shelf in case the other one fails after the 30 day grace period. Last alternator I bought is still in my car after 2 years of use. As to the stereo discharging your battery, pick up a "trickle charger" from Harbor Freight (or Radio Shack) and put your battery on a small charge when you're not going to use the car for a week or more; this will prevent the dead battery syndrome that you've already experienced. so a bad battery ground could also cause this? I forgot to mention that sometimes in the morning when I first start it, the voltage reads even lower - like around 10. Is the voltage meter reading the battery power or the alternator output? (If that makes any sense?) I have my stereo hooked up to full-time power so I don't have to turn the key on to have the stereo on. It does have a little bit of a draw because of the clock back-light on the stereo. If I leave it not started for a week or more, then it has to be jump started (dead battery). I found this out after coming home from vacation this summer. Normally it's started at least every other day, and occasionally the battery is low if I haven't started it for a couple days. I'm personally leaning toward a battery, but either battery or alternator is not a cheap fix! Quote Link to comment Share on other sites More sharing options...
HooptyGL Posted October 15, 2005 Share Posted October 15, 2005 hey karinvail thanks for the tip on the rally rims in mt vernon my hoopty is running a LOT smoother now neal Quote Link to comment Share on other sites More sharing options...
Cougar Posted October 16, 2005 Share Posted October 16, 2005 I would hookup the radio back the way it is supposed to be. You could then add a switch to direct power and turn on the switch when you want the radio on but not the accessories. Not sure why you want to do it this way but I guess you have your reasons. You may need to replace both the alternator and the battery. If the battery is fairly old it not a good idea to put in a new alternator and not replace the battery also. This can save your new alternator from working harder than it should. Always charge a weak battery with a charger first before placing it in service. Quote Link to comment Share on other sites More sharing options...
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