Battery dropping voltage on first start

Derik_C · Sep 13, 2016

When turning the key to start position, battery light is on (don't remember that being on before) just replaced battery's. After first start, truck cranks flawlessly. first start is very sluggish, seems that it won't start... then it fires... what could be putting that much strain on the battery system at first start? Glow plugs?

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Derik_C · Sep 13, 2016

This truck also eats batteries, 5 year battery will last about 2 years...

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01pwrstkr · Sep 13, 2016

Usually the glow plug relay stays on for 30-45 seconds. Watch the voltage and it will be low and then will jump up.

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Derik_C · Sep 13, 2016

Yea does that mean it would be a bad glow plug or 4...haha never had that issue before....

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79jasper · Sep 13, 2016

01pwrstkr said:
Usually the glow plug relay stays on for 30-45 seconds. Watch the voltage and it will be low and then will jump up.

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Can be on up to 3 minutes. Especially first start of the day.

I bet you have something draining your batteries overnight.
https://youtu.be/KF1gijj03_0

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01pwrstkr · Sep 13, 2016

79jasper said:
Can be on up to 3 minutes. Especially first start of the day.

I bet you have something draining your batteries overnight.
https://youtu.be/KF1gijj03_0

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I did not know that. Lol. I've only ever seen mine stay on for 30 seconds or so.

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Derik_C · Sep 13, 2016

I can let that truck sit for 2 or 3 days.... and it still acts the same.... battery Guage jumps to normal level when key is first turned on... then something comes on and you can watch the meter run down. After 30ish seconds that the meter will return to about 12 but still is hard to turn over

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Derik_C · Sep 13, 2016

If the is a few glow plugs bad, can it have that much of a draw on the system?

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79jasper · Sep 13, 2016

Only if they're a dead short.
Break out a ohmeter and check them.
If they're burnt out (think open short) they won't affect it. It would actually be less draw.
Have both batteries load tested individually.

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Arisley · Sep 13, 2016

No such thing as an open short. An open is two conductors that are supposed to be touching, are not touching. A short is like two wires that are not supposed to be touching are touching.

I would recommend pulling your starter out and having it load tested. If that checks out OK, I would do the same thing to your alternator. If that tests out of, I would test the positive battery cable.

79jasper · Sep 14, 2016

Yeah, bad wording there.

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Derik_C · Sep 15, 2016

Faulty battery was the culprit. Thanks for the input!

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Jomax · Sep 15, 2016

Arisley said:
No such thing as an open short. An open is two conductors that are supposed to be touching, are not touching. A short is like two wires that are not supposed to be touching are touching.

I would recommend pulling your starter out and having it load tested. If that checks out OK, I would do the same thing to your alternator. If that tests out of, I would test the positive battery cable.

How would you test the positive cable?

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