Alternator test is showing it's putting out 13.7 volts to battery but my battery is not getting full charge. Battery will die after 1/2 hours in acc and it is a yellow top. I charged battery last night (it's holding charge) and the tester is telling me that my alternator is not charging battery properly. My alternator is stock and I feel I need a new one but is a stock Dodge alternator capable of properly charging a yellow top and is 13.7 volts low to be charging any battery. The highest alternator I find is 136amp any other option out there. Thank You

2002 Ram 4.7

 

I have an optima yellow top in my truck, along with the stock 136amp alternator. I have not had a problem with either, and I use my battery to operate my emergency lights while at a fire scene. which takes quite a draw. I Also work at Interstate Batteries, and can tell you that you might have a problem with your yellow top. We have them come in quite frequently. Its either a hit or a miss when it comes to those batteries. How did you test your battery? what do you consider a "full charge?" 13.7 volts is a optimal charging status for your alternator. If I was to take a guess, I would say that your battery would fail a load test. which is when it has proper static voltage however when you try to draw from it (such as a starter) The voltage will either immediately, or slowly dip in voltage below 9.6V Hope this helps ya out.

 

I used two different testers and one had a switch to put load on it and it came up weak but not bad around 11 volts. I have an automatic charger that I used last night and did a full charge according to charger and battery is still holding above 12 volts about 20 hrs later. I took my charger and did a test on alternator for voltage and it came up with 13.7 volts and tester also has a percentage rating of output and has a range of 0-199 with 100 being expected output of typical alternator and mine is in the range of 12 to 25 which indicates an output to low to charge a 12 volt battery so I am stumped. Have a good stereo system in truck also and amp gauge takes a nice dump when bass is rockin.

 

Your battery may have a bad cell. On chryslers the alternator is controlled by the pcm and it is either on full or off there is nothing in the middle it switches so fast you never see it unless it's a diesel and those drivers notice it on cold starts 13.7 is a normal charge voltage. Make sure your cables are clean and not swollen with corrosion

 

Your yellow top is no different than any other battery and being quite honest, Ive had several Optima batteries and they just do not last as long as a regular battery. Ive got two 875/1000CCA amp batteries and they both get charged off of my stock 136.

 

You definately do not have a bad cell in your battery. If you did, you would be low about 2 volts on your battery. that is easy to tell. Your load is what still concerns me. Take it to a local battery place, and see if they can do a load test. Note a standard load test takes atleast 15 seconds to perform and monitor for failure. if they just hook up some testor, with no test provided and give you the battieries cca and voltage yadda yadda yadda then thats not what you are looking for.

 

weedahoe where did you put your other battery.

 

I see in your gallery where it is. My air intake goes by there so I can't install another one under the hood.

 

Thats ok, Ive got an extra battery tray that goes on the drivers side but you can use it to place a battery where ever you want. Keep in mind I also upgraded ALL my power and grounds to bigger wire.