correct me if i am wrong....

[Sullie250]

if my batteries are not producing proper cranking amps, my truck will not start that good, right? i have tested my glow plug relay, tested good, worked fine then one day didnt want to start (hard start) after i ran the tests started like it should. did notice my batteries were somewhat low on volts before i ran the tests. do you guys think its time for batteries? not sure how old they are but i have had the truck almost 2 years and know that they were not brand new when i got the truck.

[Stroken7.3]

How many volts did you have? We need strong batteries in these trucks for them to start right. There is a good amount of draw when you start from the GPR, glow plugs and the starter.

[Sullie250]

one battery said 12.6v the other 12.4v. and the gpr when turned on had 10.6v crossing it. not sure on the amp draw though

[chrashd]

Wife's truck was hard to start.I found one of the batt.terminals loose! You have to check the batt voltage while cranking.

[nccatfan]

Cleaning posts and clamps made a world of difference for mine.

[NoRalPh]

As winter, and cold temps, arrive batteries that have worked just fine for the past 6 months will start to be put to the test

THIS is when they need to be up to par. The only to know is to LOAD TEST them (separately). Forget the static voltage, it doesn't mean much unless you're down by 1 cell (2v)

To be done properly, you put like a 200Amp Load on each battery and watch the voltage drop. You can get a kinda heads-up yourself by putting a voltmeter on the system (you can use the "Aux" plug in the cab) and watch the volts drop as the GPs come on and you start cranking (this is using fully charged batteries with clean terminals)

If you've definitely got a problem you'll see it go under say 9v.

If you definitely don't have a problem it will stay above say 10-1/2v.

In between that, go have it checked

This is kinda a half-assed test of course and doesn't take into account the cranking time. If it you cranked even the best batteries for like 15seconds it could lower the voltage to bad levels. BUT, as I said, it would give you some indication.

[dannanw]

Originally Posted by NoRalPh

The only to know is to LOAD TEST them (separately).

most parts stores dont think of this, have each one of them tested and that ill tell you.

[Stroken7.3]

Originally Posted by NoRalPh

As winter, and cold temps, arrive batteries that have worked just fine for the past 6 months will start to be put to the test

THIS is when they need to be up to par. The only to know is to LOAD TEST them (separately). Forget the static voltage, it doesn't mean much unless you're down by 1 cell (2v)

To be done properly, you put like a 200Amp Load on each battery and watch the voltage drop. You can get a kinda heads-up yourself by putting a voltmeter on the system (you can use the "Aux" plug in the cab) and watch the volts drop as the GPs come on and you start cranking (this is using fully charged batteries with clean terminals)

If you've definitely got a problem you'll see it go under say 9v.

If you definitely don't have a problem it will stay above say 10-1/2v.

In between that, go have it checked

This is kinda a half-assed test of course and doesn't take into account the cranking time. If it you cranked even the best batteries for like 15seconds it could lower the voltage to bad levels. BUT, as I said, it would give you some indication.

Nice post.

[2000goshen]

correct me if I'm wrong.

The starter draws upwards of 600 amps

The glow plugs draw approx 180 amps

the 7.3 powerstroke won't start until it hits 100 rpm, this is interesting as unlike a gas motor a powerstroke won't just turn over slightly and fire up, it has to get up to speed before the computer opens the injectors.

This is why 1 battery won't start the truck, well for very long...