battery voltage ?

strokin6L · Jun 23, 2012

Alright, maybe got a little something going on with my battery voltage, but don't know if it's normal or not. To start off...batteries, alternator and starter are new. The ground cables are also new. Now when i cycle the glow plugs and start the truck...voltage is 11.5-11.9v usually. Then after like a minute or less voltage will be high 13's...around 13.5-13.8v. This is all at an idle. Then when i start to drive....voltage will constantly stay in the 13.8-14.2v range until the truck gets up to temp. Now after it gets up to temp voltage averages around 13.6-14.0. I hardly ever use A/C, but since my wifey is pregnant she needs the A/C alot. So when i turn the A/C on to the normal setting and fan on high... voltage wont drop too much, but will stay in the 13.3-13.8 range. Now, when i turn it on max A/C with the fan on high...voltage will drop to 12.9-13.3ish. And if i got all accessories on(headlights, fog lights, A/C on max with fan on high, radio and wipers)...voltage will be in the 12.3-12.7v range at idle. With all the accessories on and driving voltage will average high12-low13 volts. If i keep all accessories on except the A/C...voltage will raise to 13.5-13.8v. Does the A/C really draw that much to drop the voltage that much? Just seems like turning the A/C system on sucks voltage down and not sure if that's normal or not.

Snake · Jun 23, 2012

Yep, sounds pretty normal if you don't have a high output alternator. How many amps is yours?

strokin6L · Jun 23, 2012

IDK...whatever stock is. Isn't stock like 130amp or something?

FX4 F2-Fifty · Jun 23, 2012

Not much help, my voltages are very similar. But I have found that there is a poetry big jump from level 3 and 4 on the fan. Level 4 drops voltage significantly.

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strokin6L · Jun 23, 2012

FX4 F2-Fifty said:
Not much help, my voltages are very similar. But I have found that there is a poetry big jump from level 3 and 4 on the fan. Level 4 drops voltage significantly.

Sent from my DROID BIONIC using Tapatalk 2

yeah i notices the same thing. I guess my readings seem to be normal. Just never would've thought cause i hardly ever use the A/C.

redracer62 · Jun 24, 2012

Mine does the same, voltage is at high 11's at idle and high 12's low 13's when driving only when the a/c is on. I noticed it and then never did anything about it cause I thought it was normal.

Snake · Jun 24, 2012

strokin6L said:
IDK...whatever stock is. Isn't stock like 130amp or something?

I can't remember exactly, but it's around there. Remember, that's also the max output and it puts out 50-75% of that at idle. One of the reasons I went with a 200a alternator a few years ago.

2wd-fire · Jun 25, 2012

Where are you reading volts from cause if I use my scan tool it will read lower than if I hold the odometer button then turn the truck on and read it from there

strokin6L · Jun 25, 2012

reading it from OBDII with edge insight CS. Yeah i noticed that also. The multimeter will display a few tenths of a volt higher than the reading from the OBDII port.