Been having probelms with battery power latley. One day I was outside cleaning my truck and had the stereo running the whole time, when I went to move it the battery was dead and it wouldnt crank.. So I go to Pep Boys and they say the only carry 1 battery for my truck so I get it. Get home go to put it in and notice its alot smaller then my old battery and the battery mounts dont fit it good. I end up putting it in anyway and it cranks up fine but when I have my truck off and play my stereo it drains easy and my amp cuts out from lack of power. With the truck turned on and my stereo playing loud my amp doesnt cut out at all but my stock battery meter in the truck bounces pretty good like its sucking alot of power up. Do I need to get a better battery? anyone else have a battery that is smaller then the battery mounts?

I was thinking I needed a capacitor for my stereo but someone else told me I needed to run a dual battery setup.. I think its just that I didnt get a good enough battery.
I can tell you the #s on the battery if you need them. IT was 30* when I took these pics so I didnt want to stay out long lol.

 

Get the biggest battery you can afford I like to aim for 1000 amp but I just got one

that was 850 and haven't had a problem from it. You may need to start it up every
now and then while jamming out!! A dual battery set up would ensure it doesn't do
it again say when you are out in the woods, fishing etc. If your daily commute is
not long enough to recharge your battery and it will shorten your listening time, Say
you use up 300 amps while listening to the stereo for a few hours, your alt let's say
takes 1 hour to recharge 100 amps to regain the 300 amps would be 3 hours now
your daily commute is 45 minutes it will take 4 days to recharge the battery BUT you
still are cranking the motor so you also have to rebuild up those amps to that are getting pulled everyday. A capacitor will help the charging situation since when the
music is at a low db the cap can charge up and store some juice for a loud section
instead of pulling it from the battery/alt. When I had a big system (2000 watts, 2 10"
2 12" and somewhere around 12 other speakers, I had a house EQ, black lights, inverter for 110volts, could hook a microphone into the head unit, a guitar amp to the
110v, and enough room for a drum set, the bass guitar through the woofers) We would drive around jamming and making all kinds of noise, we would go to big bonfire
parties and play out in the woods with black lights and strobes everyone knew that
van it was some crazy times. I just carried an extra battery and jumper cables.

 

You might consider finding a 75-100 amp alternator for your truck, along with a 2nd battery.

Sounds like your amp is really thumpin. Get along with your neighbors?

 

If the charging system is set up properly all of the power comes from the alternator while the engine is on. The exception is short demands (seconds) from something like a stereo which draws a lot of power. Anytime the use is needed for when the engine is off for long periods a deep cycle is the way to go. Deep cycles can take may cycles of very deep draining and charge back up and still last a long time. A regular battery will not take more than thirty or so discharges at a deep rate and come back to normal.

Deep cycles are expensive and not designed for heavy currents like a starter though. The best way to use a deep cycle is to use an isolator and just run those devices off it that you need when the car is off and let it charge up when the car starts.

If you do not use an isolator then one good battery is best. If you want to have more than one make sure they are exactly the same type and age. The problem with connecting two batteries together is if one goes bad it will discharge the other.



This may help some with their problems and tells a great deal.

Voltage test first:

Measure the voltage at the alternator output post and case with heavy electrical loads on (lights, fan, etc.) after five minutes at idle, note.

Measure the voltage right at the battery posts not the connections at the same time, note.

The difference between the two should be less than .3 volts. If the voltage difference is greater than check the charging circuit wiring and connections, you might need to upgrade wire size if that is the problem. Getting the voltage close to zero is the goal here.

The older alternators will have a output voltage around 13.8 volts, the newer alternators greater than 14 volts. The newer lower maintenance batteries of the last twenty years require the higher 14+ volts to insure there long life.

The above test will tell you more in ten minutes than anything else you can do. It is better to test first then attack the problem to prevent wasted time and parts. Once you touch anything with wiring you do not know if you fixed the problem or made it worse.

This test will tell you if the alternator is producing the correct output voltage or if the wiring is at fault for poor connections in the charging circuit. This is very quick to do and should always be the first test when having electrical charging issues with voltage problems on any system.

If the voltage is low in the entire charging system check these:

alternator/regulator
alternator light/gauge and wiring
belt slipping
shorted battery

To test for current drain with the key off a test light or current meter inserted in series with the battery at the battery connection. Just remember some devices use current all the time, a clock for example. Pull one fuse at a time to find the circuit leaking.

There is a misconception that a larger alternator rating will charge more but this is not really true. The maximum output rating of an alternator is only produced at very high RPM's. Most of the time the engine is at lower RPM's and many alternators of lower rated maximum outputs will produce more power at lower RPM's. The output of a alternator is greatly reduced at the lower RPM's. There are spec sheets for alternator output to fit the best condition. If most of the driving is at lower RPM and there is a lot of non-stock electrical devices to power you can slightly decrease the alternator pulley size to increase it's RPM and produce much more power. Most alternators are rated for 10 to 12 thousand RPM maximum. Remember that increasing the RPM though will lower the life of the alternator somewhat.

The only way to fully test the output of any alternator is to run a proper test to look for shorted windings, open or leaking diodes, bad brushes, etc. and this can only be done at a good shop. For the most part though if the voltage is proper than the system is most likely ok.

Hope this helps someone, I see at great deal of info on charging systems going around that is not correct.<!-- / message --><!-- one sig per page -->

 

Here is a quick video I did to show the gauge and stuff.
My amp is nothing special its only putting out 486rms I have no AC and only run my stereo so I dont see why its draining it like that.

http://www.youtube.com/watch?v=GnkWW9evbrs

I guess Ill take this battery back and get a better one and see how that helps.

 

Do the test above with a voltmeter and post.

 

i dont have a voltmeter