Battery doesnt hold a charge overnight!!

[marcoslopez]

I have a 91 ranger 4.0 4x4. i had this problem in the summer and replaced my battery and seemed to be ok. now i have to jumpstart my truck everyday, i dont think its my alternator because if i drive my druck or leave it on it will start right back up. but if i leave it off for 5 hours or more the battery is dead. any suggestions???

thanks
marcos

 

[mossyoak03]

go to autozone and get them to test your battery and your alternator

 

[Chic N Stew]

you may have some type of parasitic drain somewhere

 

[snake]

Disconnect the battery overnight and reconnect in the morning- then see if you have juice in the battery. If so, there is likely a drain on the battery. I would have the battery tested, however. It isn't unusual for a battery to be bad after a few months or even days. Thats why they have a warranty... Testing the battery is the only way to be sure. If the battery tests good check connections, alternator, etc.

 

[Chic N Stew]

i didn't think to say that, lol do what snake said

 

[MAKG]

Also note that you can shorten a battery's life (dramatically) by repeatedly draining it. Lead-acid batteries work best when drained just a little and then recharged (just the opposite of NiMH or NiCd).

 

[shadetree]

Use a common test light. Remove the negative battery cable. Put the test light between the cable and the negative battery post. If the light illuminates with all doors closed, key off, lights off, anything that draws current off, you have a drain somewhere in the system.

Most common is the alternator. Disconnect the large red wire on the back of the alternator and see if the light goes out. If it doesn't, then you can pull fuses for further diagnosis.

If the light doesn't light, the battery may have an internal short. Have it tested. shady

 

[rangertotty]

battery's are highly affected by vibration. the battery could be bad already... i would have it tested. i work in auto part's i have guys bringin battery's back way before the should be bad. you get what you pay for... i had a cheap battery last 4 months wheeling. then i spent the extra and bought a interstate and it has lasted 2 year's. but i just whent to dual optima's...

 

[MAKG]

Use a common test light. Remove the negative battery cable. Put the test light between the cable and the negative battery post. If the light illuminates with all doors closed, key off, lights off, anything that draws current off, you have a drain somewhere in the system.

This certainly works, but I prefer to use an ammeter. Especially a clamp on ammeter, as that doesn't require disassembly.

Anything over 100 mA is a problem. The test light will be rather dim at that level, and depending on what kind of light it is, it may not light at all (no light bulb is linear). Fortunately, however, most drains are quite a lot bigger than that, and yours certainly is if it's draining the battery in 5 hours. It's at least comparable to leaving the parking lights on.

Rangertotty, how many of these batteries weren't secured in the battery tray? It seems common for people to do that, but it's really not good for the battery, especially if it shorts out.

 

[Simple_serf]

Starting batteries don't do well when they are discharged over about 50% more than a few times. The grids aren't meant for deep cycling and just fall apart. I would take the battery down and have it tested (after you charge it and then let it sit overnight). I had a battery on a standby generator crap out just recently like this. It was fine unless I let it sit for a day without the charger on the system (It was continuously floated at 13 volts). I replaced it under warranty and had no problems since. If the battery checks out ok, then get out the clamp on and start looking for parasitic draws.

 

[LearjetMinako]

Starting batteries don't do well when they are discharged over about 50% more than a few times. The grids aren't meant for deep cycling and just fall apart. I would take the battery down and have it tested (after you charge it and then let it sit overnight). I had a battery on a standby generator crap out just recently like this. It was fine unless I let it sit for a day without the charger on the system (It was continuously floated at 13 volts). I replaced it under warranty and had no problems since. If the battery checks out ok, then get out the clamp on and start looking for parasitic draws.

No kidding about the grids. Being cheap about batteries never seem to work in a deep-cycle area.

 

[Simple_serf]

Yeah...We buy good US battery and Trojan batteries at work for the floor scrubbers and we usually get about 1-1.5 years out of them, and these are properly sized batteries and machines.

 

[marcoslopez]

thanks everyone, im getting the battery tested today, thanks for all the great info ill keep everyone posted.

thanks
marcos

 

[bandit]

another thing to look at if all of that checks out is the fuel pump. my b2 started having the same problem of draining the battery at night. i tested the alt. and bought a new battery and found my self have the same problem at night(to the point that i unhooked my battery every night). so over a 3 week span of checking everything for something that could be draining my battery by trucks fuel pump took a crap on my way to work. so i replaced my fuel pump and the battery problem went away. i also had the same problem with my 88 b2. dont know if its just a b2 thing but had it happened twice, and it took a few weeks for both to crap out. just something worth looking at if everything else checks out.

 

[Robin Hood]

This certainly works, but I prefer to use an ammeter. Especially a clamp on ammeter, as that doesn't require disassembly.

Anything over 100 mA is a problem. The test light will be rather dim at that level, and depending on what kind of light it is, it may not light at all (no light bulb is linear). Fortunately, however, most drains are quite a lot bigger than that, and yours certainly is if it's draining the battery in 5 hours. It's at least comparable to leaving the parking lights on.

Rangertotty, how many of these batteries weren't secured in the battery tray? It seems common for people to do that, but it's really not good for the battery, especially if it shorts out.

actually anything over 50mA is a problem. get a DMM. Disconnect one of the battery cables and set it to amps. tell us how much amps your getting with EVERYTHING possible off.


EDIT: if your using a DMM be careful not to blow the fuse. but i doubt your parasitic load will be over 10A.

Also check simple things like glove box light and small things that you don't normally think of. and to the guy that said vibration is bad for batteries- regular vibration is fine but hard hits and blows to the battery really kills it.