Friday night was chilly; low around 38. Truck had been sitting unused for 4 days.
Saturday morning (temp in up'r 50s). Truck would not start; the engine would barely turn over, vvvveeerrrrryyy sllooooww...no where near turn-over enough to start.
Volt meter on each battery read about 12.3volts (each).
I hooked up jumpers from a portable battery to the truck battery (the one on driver's side)---started like no problem.
After starting, I volt meter checked each battery; each was reading 13.+ volts.
QUESTION:
What happened?
Why wouldn't the truck start?
If one of the batteries is starting to go bad, how do I determine which one?
(I'm not too "electricity-savvy", so request you speak "simple-minded"... Thankx! --D

 

you need a load tester to find out. best to test after it has sat over night if one is bad replace both. a old one will drag a new one down to its level most auto parts stores will test them for you ,take them down in the morning after they have sat .

 

We just dealt with this in one of the cars. 2 brand new batteries and each had a dead cell, which can only be ID'd by a load test. We finally got a good one and haven't had any problems.

 

Like said above always replace both at the same time.

 

Sorry for your problems, but that statement is just too funny.

 

I think I waxed my truck once at that temperature, -26 and snowing here right now.

I feel your pain though, battery problems are not fun no matter how simple or complex. Batteries are a necessary evil I guess.

38 degrees, where are my shorts Sorry I couldn't help it.

Jeff

 

LOL, im no Canadian, but I know what you guys are talkin abt. i recently moved to VA from n.w. Ohio. It got down to a "bitterly cold" 40 the other morning and everyone broke out the Carhartt bibs, jackets, thermal underwear. I walked into work in jeans and a hoodie and ppl thought I was nuts.

and just to keep it on topic, yeah load test, last time I had a bad battery it was reading good on a voltmeter, but the dial barely moved on my load tester. Its kinda like having tons of HP, but no torque

 

You were measuring alternator out out if the truck was running. You can put 1 lead in cell 1. Reading should be ~2.1 volts. Next move 2nd lead to each of the other 4 cells. Volt reading should go up ~2.1 volts for each cell. Alternatively, measure specific gravity of each cell. Finally, have each battery load tested at a store.

Do not take store's word. Confirm with other data. I had a parts jockey swear that my Mercedes diesel needed an alternator. I unplugged the glow plugs & measured voltage went up. Glow timer will be replaced as soon as I get to a yard.

 

Yeah, figured I'd get a couple nibbles by inserting the "chilly" blurb Grew up in N.Mich so I know what true chilly... Wasn't born Texan, just got here as soon as I could...mid-70's today, so compared to July/August I guess winter will be here for the next month or two...

BTW, she fired up just fine today; thks for the "load test" suggestions.

 

danalex.... You never mentioned how old your batteries were. You indicated Truck would not start; the engine would barely turn over, vvvveeerrrrryyy sllooooww...no where near turn-over enough to start. Volt meter on each battery read about 12.3volts (each).
At 12.3 volts, about 50% of your battery capacity is lost. Normal charged batteries should indicdate 12.6 volts. Both of yours likely tested the same as both are connected together. If your vehicle was not used for 4 days and batteries were down to 12.3V, (assuming they were at about 12.6V when you shut it down because you reported charging voltage is +13V), it appears that there is something in your truckaconsuming power. However, if your batteries are old +5 years or so, perhaps they are not charging up fully any longer. Hopefully you've checked battery acid level to ensure that this is OK. If they are relatively new then you might have some battery drain or bad battery contacts at the terminals. Clean those up. Battery drain can be determined by disconnecting the second batterys and placing an ammeter between the positive terminal and battery cable on the first battery. This will give you an indication of power draw when everything is shut down. Hope some of this helps as well as other suggestions in previous posts.