battery wont hold a charge

   / battery wont hold a charge #21  
That is essentially just a volt meter. You'd be better off with a common digital multimeter because it can do a lot more than just measure voltage.
To really test a battery you have to supply a high load to pull current from it, then you measure the voltage to see if it can deliver current to a real load.

For automotive type work I like this DMM from Craftsman. Sears.com It has a very handy DC/AC clamp on for measuring current without disconnecting the circuit. It lives in my truck so it's always handy.
 
   / battery wont hold a charge #22  
You can also check to see if there is a load on the battery when the key is off by putting a small 12v light bulb type tester inline with the positive battery cable and seeing if you have current (light will glow). If you do, pull fuses or plugs until the light stops glowing. The circuit you disconnect that turns the light off is shorted.

To test for really small amounts of parasitic drain like those from ECUs and the like you need to disconnect one of the battery leads and insert an amp meter capable of measuring milliamps. A light bulb will rarely glow with small amounts of current. A common digital multimeter will suffice, just don't turn the headlights on or try to start with it connected this way or you'll blow the meter's fuse out. They usually about a half amp fuse inside for when you forget to switch functions then try to read a voltage with it.
 
   / battery wont hold a charge #23  
Agreed. I have recovered dead batteries before, but the capacity of the battery is not as good.

Agreed but the longer you let it desulphate the more capacity you're likely to recover, if any. Some are so bad they are beyond all hope. Wet or flooded cells like those used in cars are intended mostly just to get the car started. Then there are the deep cycle types intended for marine use that are made to withstand deep discharges, then comes the AGMs, cream of the crop IMHO, that do all that and more very well. They simply pack more punch from a smaller package,are more shock proof and typically last longer too but they do cost more. However nothing, no matter how much you pay for it, is abuse proof. Like anything else if you take care of it, it will take care of you.
 
   / battery wont hold a charge #24  
Get a good voltmeter. A battery at rest should read 12.7, manufactuer may have different values. But for the small bike and ATV gel batteries that is what is listed. Each .1 will tell you what percent of charge you have. With stuff I have worked on you should have 14.4 when revving up the engine.

DC clamp on amp meters have gotten cheaper.
 
   / battery wont hold a charge #25  
A couple years ago I had to replace the battery's in my dump truck and when I seen the age of this one I was very surprised July- 04. I now use it at the saw mill to power my toe board and it was 12.4 V when I used it today to jump my welder. I have had it on a battery maintainer (desulphater)for a wk. or 2 but not since last summer.

Must be one heck of a battery I have all makes included other Interstate but 8-10 yrs. is the most they last.
 
   / battery wont hold a charge #26  
I really liked Interstate for decades... we sold them.

Not so fond anymore... the last 3 were nothing special... don't know if the builder changed or not.

Always had exceptional life with the old "Green Eye" AC Delco batteries... they have also changed.

12 years is exceptional... and the most I have ever gotten...

My OEM Kubota is now 12 years old... it may set a personal best for me as it is still good.
 
   / battery wont hold a charge #27  
A couple years ago I had to replace the battery's in my dump truck and when I seen the age of this one I was very surprised July- 04. I now use it at the saw mill to power my toe board and it was 12.4 V when I used it today to jump my welder. I have had it on a battery maintainer (desulphater)for a wk. or 2 but not since last summer.

Must be one heck of a battery I have all makes included other Interstate but 8-10 yrs. is the most they last.

You must have taken good care of it. It usually pays off in the long run.
 
 
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