I have a 18 3500 desiel ram truck. It is -2 outside I when out to start it and nothing. Put a tester on it only 9.7 needs at least 14. Jumped it got is started took it for a drive. However No sound from the speakers tried the radio Bluetooth and call features it shows connected NO sound. Can the cold affect the speakers? Liked to froze driving around no useful warm air blowing out of the vents. Truck operating at about the 3rd Mork on the temp gage. Heated wheel or seats would not warm up either. I could activate them but would shut off before heating up.
Are these conditions due to the weak batteries or is something else going on??
I'm thinking not enough juice to run the electric accessories but I don't know.

So what do you northern guys say???

Read the fine print in your owners manual. You’ll probably find you should be running synthetic oils in your truck and driveline when operating at those temps.

Cold weather probably shot the battery and the truck is in some kind of "limp mode" to conserve battery/voltage would be my guess

My best guess is your alternator. Cold drained your batteries. if the alternator was working you should have all your stuff working. do you have a gauge? Go to any parts store if you dont and they will check it for you.

When I was on the road in this kind of weather fuel got power service and truck only got shut off long enough to check oil. Diesels dont produce the heat a gas engine does. When its cold the thermostat wont open very much. Before engine clutch fans guys would put a piece of cardboard in front of the radiator.

Low voltage messes with a lot of stuff. I would put battery on charger over night. Disconnect one terminal for a few minutes to reset computer then give her a go.

Hello Rally. Haven't heard from you in a long time, good to see your still kicking.
Now back to the question

This, and your alternator is probably working overtime to try to recover the batteries. Fresh oil for the cold and/or a block heater might help too if it didn't come with one, also a trickle charger mounted on the battery(s) would help it stay topped up and is easy enough to plug in with a quick disconnect when you expect some cold weather. Maybe some cold weather diesel additive wouldn't hurt to throw in a box with your chains and such. A grille blanket is easy enough to sew up out of marine grade vinyl and some grommets.

X2 & 3. As Trapset said. unhook that battery for 15 minutes so the computer will reset. Charge battery.. If it's a gel battery take it inside and let it warm up before trying to charge it.
Also, I agree with the trickle charger idea. I have one on both of my trucks and keep them plugged in until I am ready to start the truck. Block heater is mandatory here but unless you are consistently below 20 degrees you can probably do without. Still nice though because your heater is ready to go a lot sooner too.

If there original batteries it's time for new ones. I had gotten batteries from farm and fleet,walmart and had bad ones from both places.did you have it plugged in.ive got a 2020 and it came with a bra for the front of the grill which helps it stay hotter.we used to put cardboard in front of gas engines to help them stay warmer.like was stated go to a parts store and they can check your batteries and alternator for free

My plow truck ran yesterday am to plow my driveway , now it's drained! Gonna need a few hours to charge.

Its the time of the year where you find out if your batteries are ok or not. I just put a couple new ones in my truck an hour ago

This

Battery's that have 800cca cost a fortune today.

does it not that 2 batteries.... were both checked ?
charges do not do well in frozen batteries, Basic Grade 11 Chemistry lesson
remember that heat of summer also kill battery life as the lead is melted in hot parking lot stays

Batteries last only 5 years ..At the most ..now a days.

So ....it’s not like your throwing money away...by getting a new battery

consider that an alternator is double what your two batteries will cost

my-my a poor cold katush .....no heated seats
and cold hands...what are mitts for