Ford Power Stroke Nation banner

1 - 11 of 11 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Hey everyone, had a question regarding my voltage at startup. For the past two months, I've noticed that when I turn the key, the voltage reads approximately 8 volts. The starter cranks a little slower but otherwise starts up mostly fine. After the engine runs for twenty or thirty seconds, the battery indicator jumps back up to the normal range of about 13V. It makes this jump at precisely the same time the heater begins to crank with more power.

The batteries are 2 years old, and I just installed a new alternator about a year ago. I have this issue every time I startup, even after driving and making a quick stop and the engine being warm.

Any ideas? Thank you for your help!
 

·
Registered
Joined
·
5,465 Posts
It's normal.

The glow plugs can stay on for up to 2 minutes after starting and will draw the voltage down until they shut off.

If you want to cure it you need to go with a high amperage alternator and upgrade the wiring from the battery to the alternator to handle the higher current.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
I guess my question would be why did this suddenly start? My truck does start, but I'm worried about letting it sit for a day or two in the snow and having it not start. I keep an extra GPR, so I was thinking of switching it out and seeing if it's just drawing too much juice suddenly.
 

·
don't play well w others
Joined
·
3,657 Posts
Check battery connections and grounds. Check both batteries fully charged 1 at a time for load test, you could have a weak battery.
I just replaced 2 year old batteries in my Pete, 2 out of 3 didn't pass a load test.
 

·
Moderator
Joined
·
7,971 Posts
and you could also have a weak starter.
my 02 was like that. 2 new batteries, all new cables, and a new starter and it now wings rite over.
 

·
Registered
Joined
·
4 Posts
The alternator does not switch on until G.plugs shut off. Charging voltage could zap G. plugs
Measure battery volts with a DMM, IIRC computer needs 10 Volts to operate.
 

·
Registered
Joined
·
1 Posts
I wouldn't rule out the Glow Plug Relay either. Every time mine has starting issues, it's the GPR. I need to upgrade to the White & Roger's but, haven't yet.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #9
Bought new batteries and changed the glow plug relay, still the same issue. The battery indicator also l stays prior to cranking the engine. After about thirty seconds of running, the voltage indicator bumps up to the normal range at exactly the same time as the cab and dash lights getting brighter as well as the heater fans increasing flow. Could this maybe be the starter just being old?
 

·
Registered
Joined
·
5,465 Posts
Bought new batteries and changed the glow plug relay, still the same issue. The battery indicator also l stays prior to cranking the engine. After about thirty seconds of running, the voltage indicator bumps up to the normal range at exactly the same time as the cab and dash lights getting brighter as well as the heater fans increasing flow. Could this maybe be the starter just being old?
Everything is normal. The glow plugs draw so many amps when they are on that the alternator can not keep up with the draw from the battery. Then when the relay shuts off it is normal. The glow plugs can stay on for up to 2 minutes after you turn the key on

Sent from my SM-J737V using Tapatalk
 

·
Registered
Joined
·
286 Posts
The alternator does not switch on until G.plugs shut off. Charging voltage could zap G. plugs
.
That's is the case only on the dual alternator setup. On the single alternator trucks Ford used a puny 110 amp alternator to protect the glow plugs and on the duals it used the same 110 amp alternator for the initial one since it runs while the GPs are energized, only the second alternator is switched off when the GPs are energized. The dual alternator setup was a work around for vehicles that needed more charging power since they knew if they simply put a bigger alternator in the single system it would shorten the life of the glow plugs.
 
1 - 11 of 11 Posts
Top