Still low batteries, slow crank. Have you addressed the poor battery condition (12.25v) mentioned many times in this thread?
Charge them or replace them. 12.25 does not start a 7.3 well below freezing....

 

I just skimmed back through and didn't see that I mentioned it, but I have a battery charger that has a "recondition battery" mode that I assume just puts a high voltage on the battery in an attempt to reverse some of the plate wear. I haven't actually measured the voltage during this mode though. I did each battery individually. After I finished the batteries were reading just over 12.8V. After letting them sit for a couple hours they settled down to just over 12.5V. I let it sit for a week before I ever started it and they were at 12.25V.

When I've drove it in the last couple weeks the batteries are just over 12.8V after I shut the engine off and over the next hour they will settle at 12.5V. And are usually down to about 12.2 to 12.3V after it's sat for several days to a couple weeks.

 

Those batteries are tired, but you can limp them along with a charger/maintainer like you are doing. I have the same issue with my 5 year old lead acid batteries - same voltages you are seeing. At home, I use a maintainer to keep them up. The 2A version I have does not have the current to get these tired batteries into "equalize" or recondition mode - only gets to about 13V, but it's enough to keep them alive for cold starts.

 

They got tired pretty quickly then... They aren't even 2 years old. I bough them in May of 2020...

 

Darn, that's a good point. Could be one battery pulling the other down? If you are reading 12.2-12.3 at the battery posts after sitting a day or three, and the truck has a normal shut-down current draw of 20mA or so (keep alive memory and such), those batteries should stay up near 12.4-12.5V. Maybe you have a larger current draw when the truck is off? Might be worth a check.

 

I decided to check my batteries just for reference. 1 is 2 years old, the other 3 years old.
My truck has been sitting for 2 days, temps 20-30.
I didn't isolate the batteries, just checked with a voltmeter before touching the keys this morning.

12.55 volts.

 

Yeah I should go get them load tested. Maybe I'll have time to do that this weekend.

Can I ask what batteries you have? It's looking like my batteries are going to fail prematurely, but I'll see how long I can get by with them for now.

 

I have Interstate batteries (not the costco knockoffs). I usually get 5-6 years out of them.
I think they do fine, but if I were subjecting them to more extreme conditions (extended periods below zero) I'd probably get some Odyssey AGMs.

 

I lost all faith in flooded lead acid batteries a few years ago when I had about 4 of them on various vehicles we own fail in quick succession. I started converting all of my vehicles (including the riding lawn mower which got a motorcycle lithium battery) over to pure lead AGM batteries like NorthStar and Odyssey Extreme offer.

They are pricey, but I have had no problems with batteries since on any of the vehicles.

Good, clean and solid wiring between the batteries and the ground points are key as well.

 

I've typically had really good luck with batteries. I have historically bought the cheap everstart batteries from Walmart and would get 7 to 8 years out of them. Granted this has been on the cars I daily drive and not a diesel that sits more days than it's drove.

Tomorrow morning is supposed to be down around 0 and I'll have the day off. I'm going to go take a voltage measurement and then try to start it with just letting the glowplugs run for a minute or so. It's been sitting since Sunday. I'll use that as a gauge on how soon I should buy new batteries. Usually we only see these near-zero/sub-zero temps in January so if I can limp them through February and March it should be smooth sailing through Summer and I'll replace them in October. If it starts up fine tomorrow then I'll like try to run them through next winter.

 

Yeah, it's odd that you have battery issues and like Brady, I have good luck with batteries usually lasting over five years and up to nine. But as he said, that's on vehicles that are driven daily. My truck has four year old batteries that are getting weak but it's not driven often. The battery on the front end loader, which gets used rarely but has no electronics or parasitic drain is older than I can remember.

 

I didn't start having an issue until a few years ago and had at least 3 flooded LA batteries fail on me in a relatively short amount of time. They were replaced under warranty with no charge to me they failed so quickly. They were from the usual suspect parts stores and I was frustrated with them and the process of dealing with the exchange. Also, we were lucky they failed while we were at home and I could exchange them easily. We go to some very remote places in our beautiful nation, so going to something more "reliable" was the right call for our application.

Your proposed course of action seems solid and well thought out.

Maybe it was a stroke of bad luck, I don't know know. As described above I was tired of being let down by them, so I made a change. Again, this change suits our travel and boondocking lifestyle. Since making the change, I have had no issues with batteries and only have 1 flooded lead acid to replace that is in the Escape. It has really slowed down this winter and I suspect will need to be replaced this summer even though it is a daily driver and I replaced it about 3 years ago, maybe 3.5 years now, I forget.

An AGM will go in it's place. The JD lawn mower was an easy call. The flooded LA in that (sits on battery maintainer) lasted just over 6 years if I am remembering correctly. I had a lithium motorcycle battery in the garage left over from my riding days, so instead of buying another LA battery, I tossed the lithium in there and it is good to go.

It is definitely a personal choice based on experiences and application. I encourage everyone to do what is right for their situation and ours just happened to be a switch to AGM.

 

do you plug it in when it's that cold?

 

It makes me thing that the quality of batteries has gone significantly down hill in recent years...

I'm not sure who around me carries any of the recommended AGM batteries. I'm seeing that I might be able to order the Odyssey from NAPA or Autozone, but no ones seems to actually any of the other brands on their websites...

No. I don't drive it frequently enough to justify plugging it in. Until this year I've not had a problem with it starting in the winter even in the negative temps. The rough idle that originally started this whole thread started last year, but it sounds like that is related to me putting 15w oil in it when I believe the PO had 5W in it.

 

If I know I'm going to need to start my truck when it's zero I plug it in the night before.
If it's not getting below 20 I use a timer set to turn on 4 hours before I want to start.

Now that I have good batteries and a new, gear reduction starter it's not necessary but I like to think my truck still appreciates it.

You can get odysseys online, the AGM batteries are shippable. I just got one the other day.