Cold weather and high charging voltage, any cause for concern?

[Markous]

Took this picture the other day when the temperature was around the -30 Celsius (around -20f i think) neighborhood.

Supposed to be in that temperature range for the next few days until the new year.

I'd like to hear some thoughts on this from anyone in the Mechman crew.

This is the voltage as seen at my 2K inputs at idle (725-ish rpm) with a cold engine, system isn't running in this image, gotta let everything warm up in the cab of the truck for 10-15 minutes before i let it wang.

It will spike briefly into the 15.5- 15.8v range for maybe a 1/4 second (just a quick red blink on the VM-1) when i listening to tunes at 2/3-3/4 volume and above.

My 2k hasn't had any high voltage protection issue's (supposed to engage at 15.5v give or take 0.2-0.3v AFAIK) but i'm curious if anyone else has this (non?) issue?

Not sure if this will have a long term negative effect on my three NSB AGM batteries?

 

 

 

 

Edited December 29, 2017 by Markous

[Markous]

DERP

Edited December 29, 2017 by Markous
meant to edit OP

[alex912005]

I got the same batteries, same cold weather voltage. To be fair, you only get that high voltage at startup, it doesn't stay like that all day.

Here is what Northstar says in the user manual about this:

Thermal Compensation

The optimum level for float charging the NSB

automotive and marine batteries is 2.27 volts/cell

at +25°C (+77°F) (which is 13.62 v). If the battery temperature

increases above this level, a thermal

compensation of -4 mV/cell/°C is recommended.

Conversely, if the temperature decreases below

25°C, the voltage should be increased by 4

mV/cell/°C.

-> So at minus 30 degrees C you should give it an extra 220 mV per cell, which is 2.49 V per cell, which is 14.94 V total. And that's Float charging which is the voltage at which a battery is maintained after being fully charged, to maintain that capacity by compensating for self-discharge.

 

I think 15.2 V for a short period in the cold weather is fine, but let's see what others say.

 

Edited December 29, 2017 by alex912005

[Markous]

Thank you Alex for dropping some knowledge here, it is seriously appreciated ☺️?

I'll be honest, i haven't bothered to check the VM-1 after i've been running for awhile, just want to GTFO when i get home after being out and about for a while.

Luckily it's only supposed to get up to a balmy high of -29c here in the city today and i've got some running around to do so i will report beck with an image of a "hot" voltage after it's been running for an hour or two.

I've got a Fluke 325 dc clamp meter i'm curious what kind of draw my system creates with these conditions, i'll throw it on for giggles and shits too.

[ShadeTreeMechanic]

Although I don't have much to add, I am curious as to what your resting voltage is when sitting overnight at low temperature with the truck off? As long as the batteries are charged, they shouldn't freeze. But with the high initial voltage, it makes me think that the amperage is near zero until the electrolyte "gets going". Almost like the higher voltage is the alternators unloaded voltage. As long as the battery cases don't start to bulge from excessive electrolyte outlasting, then I would say you are ok. Block heater on a gasoline motor? Yeah that's cold. I am not sure at what point a battery heater is needed.

[Markous]

My batteries are a re-branded Northstar sold under the Motomaster brand name at Canadian Tire stores up here in Canuckistan they even add an extra year to the warranty for 5 years of coverage.

They have two CCA ratings, the regular one at 0F and another at -20f which was the biggest selling point for me. Having approx. 1500 amps of cold cranking current on tap in this kind of weather we are experiencing is very re-assuring that the little 3.0L in my truck will spin over with ease, even if spends the night outside.

Not really worried about them freezing but i have briefly given the battery blanket idea some thought, but i park underground in an unheated underground (but easily 10-20c above outside ambient) garage and do not have access to a plug in for such a thing.

I do not know anyone personally but i've heard of folks knocking out another frost plug and running two block heaters.

Edited December 29, 2017 by Markous

[Markous]

derped again

Edited December 29, 2017 by Markous
2nd time in as many days i've gone to edit and accidently quote my post

[rocking.that.eclipse]

How long does it say that high? I'll bet you after letting your engine bay warm up it drops back to a reasonable voltage?..

 

[Markous]

I'll be checking that today, when i usually get home i just want to get out and get inside.

Gonna compare the VM-1 to my Fluke 325 and see what we get.

I'll be sure to get some shots to share in this thread.

[alex912005]

Steve Meade is also getting 15.2 V at startup now in his Lexus IS-F according to the new video he posted, thanks to Mike Singer.