bad battery??
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Joined: Apr 2004
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From: Muskegon Mi
bad battery??
I asked a related question a few days ago. My truck will not start without a jump period. The instant I hook the cables to it it cranks right over and fires up.
I went and got a multi-meter to do some more thorough testing and came up with the following:
The battery shows exactly 12v when just sitting there with the key off (it should be something like 13.5 correct?)
When I crank it it rolls very slow... Dead battery style.
The instant I hook my Jeep to it the batt shows 14v, the truck rolls over and fires up fine.
When I unhook the cables with the truck running the battery, charge cable, and solenoid all show 14v indicating my alternator is charging...
After running the truck with the cables hooked up also for about five minutes I shut the truck off, unhooked the Jeep and tested the battery... It showed 12v and would not start the truck.
So does all this add up to a battery not taking a full charge? Between 130 amps on my truck and 160 on the jeep the battery should have charged right? I mean usually you jump a vehicle, unhook it and let it run for a few and its ready to go after that right?
I went and got a multi-meter to do some more thorough testing and came up with the following:
The battery shows exactly 12v when just sitting there with the key off (it should be something like 13.5 correct?)
When I crank it it rolls very slow... Dead battery style.
The instant I hook my Jeep to it the batt shows 14v, the truck rolls over and fires up fine.
When I unhook the cables with the truck running the battery, charge cable, and solenoid all show 14v indicating my alternator is charging...
After running the truck with the cables hooked up also for about five minutes I shut the truck off, unhooked the Jeep and tested the battery... It showed 12v and would not start the truck.
So does all this add up to a battery not taking a full charge? Between 130 amps on my truck and 160 on the jeep the battery should have charged right? I mean usually you jump a vehicle, unhook it and let it run for a few and its ready to go after that right?
Hotshot
Joined: Feb 2004
Posts: 11,697
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From: Marengo, Iowa
If the battery were truly dead, the jumpers would not start it very well, it would not fire easily. The battery is doing its job some, just depends to what level. You should get the battery properly tested, many parts stores will do this for free, no obligation to buy. It will need to show 12.5 to be tested properly, less than that, and it won't test properly. That will give you a definitive answer, anything we give here is largely going to be educated guessing, or speculating. You will need to get proper testing done to be able to give a good answer.
Post Fiend
Joined: Nov 2005
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From: Charles Town, W bygod Va
Battery voltage with engine off should be 12.5 or so, 12 is ok. You need to check the battery voltage while cranking, if it drops below 9.5 then you either have a bad battery (likely) or your starter is drawing too much amperage (unlikely)
Post Fiend
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From: Lost
A 12V battery actually puts out 13.2V (2.2V X 6 cells) when fully charged.
Sounds like either you have a weak battery, or the alt is not charging properly. If the voltage reads 14V-15V when running, without the jumpers hooked up, the alt should be charging good, and the battery needs tested. Low electrolite can cause a battery to become weak. Newer batteries tend to be sealed, so you can't add water, but that doesn't mean it never needs it added.......
Sounds like either you have a weak battery, or the alt is not charging properly. If the voltage reads 14V-15V when running, without the jumpers hooked up, the alt should be charging good, and the battery needs tested. Low electrolite can cause a battery to become weak. Newer batteries tend to be sealed, so you can't add water, but that doesn't mean it never needs it added.......
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From: Muskegon Mi
Well let me fill you guys in a little more.
My starter is new as of August, along with the solenoid, charge cable, battery, and positive cable to the solenoid. I have had the battery tested and its good...
I'm begining to suspect the cable to the starter may be the problem.
I checked my Jeep for giggles and it also shows 12v at rest... So I'm guessing something is drawing too many amps when I try to start it.
My starter is new as of August, along with the solenoid, charge cable, battery, and positive cable to the solenoid. I have had the battery tested and its good...
I'm begining to suspect the cable to the starter may be the problem.
I checked my Jeep for giggles and it also shows 12v at rest... So I'm guessing something is drawing too many amps when I try to start it.
Post Fiend
Joined: Dec 2007
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From: Lost
The starter could very well be drawing more power than the battery and cables can supply. This could be anything from a loose connection on a battery cable, bad starter (new does not mean good) or even a weak battery.
Since it starts good as soon as you hook up jumpers, I'd start with cleaning and tightening the battery cables at the battery. It doesn't take much to create a weak connection.
Since it starts good as soon as you hook up jumpers, I'd start with cleaning and tightening the battery cables at the battery. It doesn't take much to create a weak connection.
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Joined: Jan 2001
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From: Virginia
Most don't seem to understand just reading a battery sitting there will tell you pretty much nothing, unless it has a dead cell. Reading the voltage at the battery, and different spots along the circuit path with a load on the battery and the circuit will tell the story.
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From: Muskegon Mi
My next step is to check it while cranking at the battery, solenoid, and cable down to the starter. Sound like a plan?
I just need a helper since my morning sick wife isn't up to much lately lol.
I just need a helper since my morning sick wife isn't up to much lately lol.
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Post Fiend
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From: Charles Town, W bygod Va
Most don't seem to understand just reading a battery sitting there will tell you pretty much nothing, unless it has a dead cell. Reading the voltage at the battery, and different spots along the circuit path with a load on the battery and the circuit will tell the story.
Post Fiend
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From: Charles Town, W bygod Va
Yes, check for voltage at the battery first, if thats good go down the line
Post Fiend
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From: Charles Town, W bygod Va
Yes, this is a more accurate way of measuring voltage drop. Most people check the voltage at the battery while cranking, say youve got a reading that fluctuates around 11v, then you check between B+ and the engine block and get 9v. That would be 2v drop between B- and the blocck. You can alsso put one lead on B- and one on the block, it should read 0v just like when you touch the voltmeter leads together until you crank. Then it will show the drop between the leads and read 2v.Then you can move the leads up the curcuit to pinpoint where the drop is.
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From: Effort, PA
Sounds like a bad connection to me. I'd clean the battery terminals and cables first. Then clean your main engine ground along with the cables at the solenoid. It doesn't take much corrosion to screw up a connection.
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From: Muskegon Mi
Everything at the battery is new, and the battery. As soon as I get time I intend to check the ground (not new) and the cable to the starter (also not new).
But just for giggles I did remove the terminals and check them for tightness.