I have a standard battery and a 120 amp alternator. I have a cd player, 2 viar compressors and 2 5 gallon tanks for my airbags. As of now my battery drains every week or 2 depending on how much I drive etc..... I have heard people say just get deep cycle battery. Some people say find a 300 amp alternator. Others have mentioned hooking up a second battery for the bags. WHICH SHOULD I DO? If its the second battery option how does that set up work. I have heard so many different ways to set it up...
Is the battery charging like it should? Do you have a volt or ammeter, if so what does it say? Do you just take short trips, and run the compressor every time you drive? How old is the battery?
Battery is brand new. Depending on how often I use bags obviously depends on how long the battery lasts.. I don't have a volt or ammeter. I did call someone to come check it out and I believe with the car running his device was reading 12? Which to him meant the alternator was not working. So we took alternator to autozone where they checked and said it worked perfect and was it putting 120amp. Does the number 12 make sense with the device you were talking about? I'm just getting into working on cars as you can prob tell so bare with me.
You need to get a volt meter, you can use a hand held one to test the alternator when it's on the truck, but having one in the dash will let you see what's going on all the time. A battery just sitting there, if it's fully charged, will have at least 12.5 volts. When the engine is running and the battery is recharging, the voltage will be over 13, less than 15 volts. As the battery charges, the voltage will change, depending on how the regulator is set up to work internally. Once you get a volt meter on it, you can see what's happening, and report back.
you can get a handheld multimeter for cheap...fire it up with the meter connected to the battery and put on the compresors and check the reading , it its not over 13volts then you are taking out more than you're putting in
As said you should be getting around 14v dc at the batt. To truly test the alt. You must full field it or request it to put out full power and monitor the amperage output. It sounds more like you have a parasitic draw. Prepare Your multi-meter on the amperage setting with the leads in the appropriate receptacle. Turn off all devices that use electricity. Disconnect the negative batt. cable. Touch one meter lead to the negative batt. terminal. Touch the other lead to the disconnected cable. You should have no more than .5 amps. DO NOT touch the pos. and neg. Terminal with the meter leads in amps position! It will break the meter.
Anything around 14.4v charging is perfect, i would get the battery load tested properly, depending on the cca of the battery the voltage if load tested correctly should not drop below 10.5v. If that checks out fine, do as mentioned above, a current draw test with everything off, 0.5 amps as mentioned above is too high, your battery would be flat the next morning, it should be no more than 0.05amps draw. Alternator output really needs to be checked on the bench with an appropriate load applied to actually make sure it will produce 120 amps and still maintain 13-14 volts. You need to make sure that with everything running you have more amps going into your battery than whats coming out, id place a dc amps digital clamp meter around the alternator main wire, read the amps, then do the same at the battery positve cable, that will tell you how much is being cranked out by the alternator total, and how much is actually going into the battery. Make sure your battery is the correct cca rating, you may need a dual purpose battery, one that is good for cranking but also acts as a deep cycle. Alot of the newer style lead acid batteries do not like being drained below 12 volts due to the plate construction, they will need a big charge on a good charger to bring them back up on charge correctly. Our battery supplier states that anything below 12.8v standing volts is a flat battery. If all checks out ok, perhaps run a 2nd battery using a voltage sensing relay, or voltage cut-out relay. The alternator will only charge that battery once the voltage reaches about 13.5 and cuts out when it drops to about 12.5-13v. This way it is isolated from your start battery and will not drain it. Hope this helps.
Buy/borrow a meter and test for a drain on the battery. http://www.wikihow.com/Find-a-Parasitic-Battery-Drain
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