I've got a new problem. I'll throw it out here to get some ideas for when I get a chance to look at it.

We had a really nasty storm roll through last night. I prepped the car to getting started easier afterward. A little brushing of snow and I fired it up to warm up. I don't normally warm the car up, but at -6 degrees, I thought I'd be easier on the car to let things at least warm a little bit. While it was running, I cleaned the outside. When I got in, I got the beeping warning when I shut the door. It doesn't usually do that with me in the car. The light on the dash to show the brake pedal and key is usually green when I'm in the car. It was red like I didn't have my fob with me. I shut the car off and tried to restart it. Nothing. Thinking the fob in my pocket might have an issue with the sub zero temperature, I went inside and got the other one. Still nothing. The batteries were replaced last summer in the fobs.

The car isn't completely dead, the door ajar indicator works so it's getting power. It started fine, although it cranked a little slow. Well, it was -6 degrees F. It was warming up fine. Any ideas on why it would work fine, then not? Like I said, it's below zero and the car will sit for a bit. The battery is 3 years old.

 

Well the first thought is you have a battery problem. Charge it....... Then as soon as you can get it load tested. Keep in mind that wherever you go to get it charged it must have at least 12.5 stabilized voltage for a load test to be accurate.

The purchase date of your battery as well that sticker is not the true age of the battery. Batteries will not always indicate signs of starting to fail. So frequently at least every season change to get them load tested is in your best interest.

 

My batteries always gave advanced warning of failure until the vehicles manufactured in the later 90's and subsequent. Since then, it seems the failure is total and unexpected. I'm assuming that it's the advanced computerization that results in sudden, total failure.

When the battery failed in my Jeep several years ago, it was dramatic, with the dash looking like a Christmas tree and the windshield wipers taking off on their own with no way to stop them except to pull the fuse. Even after hooking up the charger and bringing the system up to voltage, there were a number of things that wouldn't work, including cruise (both regular and adaptive), the blind spot monitor, parking sensors and several other little things. Even after a new battery was installed, I had to go to the dealer to have the codes reset to get things back to normal. Luckily, they didn't charge me for that, but it was nerve wracking as I thought I had burned something out.

The failure on my CX5 was just as sudden, but without the drama. A new battery brought everything back to life.

 

Pre say 1990's or the starting draw was greater and the overall conditions of the engine compartments were not protected as well. This meant that if you understood the load of current draw during starting it was that slow engine turiining oiver that gave the signs a bttery was not long for this world.

Vehicles from about say 2000 and newer the starter do not demand as much during cold starts and the ECU on many now control the charging rate. Batteries also are IMHO POS with recycled material instead of 100% new. This all means that most of the time batteries will start to degrade long before they leave you with a no start engine. Unless you frequently and I often suggest that DIY load test their batteries every new season and most assuredly before summer and before winter begins. You would be surprised how many batteries will fail the load test indicating they are starting the slow rate of failure!
A couple of years ago I did a oad test on my own battery to show how to do it and was surprised to find my Optima battery failed the load test but gave no trouble yet starting. Naturally I ordered a new battery, and it was replaced that day!

07-30-2021, 09:10 AM
POST # 273
Mazda3 Things I like to do - Page 28 - Mazda Forum - Mazda Enthusiast Forums

 

Got the hood open and checked the battery. 12.4 volts. Load tested it and it looked good. Previously, it was running but wasn't reading the fob. Restarting, it didn't start. After checking the battery, I tried to start the car. It fired right up. I let it run a bit then shut it off to eat lunch. Afterward, I tried to move it into the garage and it wouldn't start. It's either/or it either starts or not.

 

If it's not reading the fob, the vehicle battery may be fine, but either there is a problem with the fob or the sensor in the starting button. I would check those out first. First thing to try would be using the fob to push the starter button to make sure that it isn't the fob batteries or a bad connection to the batteries.

 

I'll second changing out the FOB battery.
When the battery gets low they can do weird things and it's the cheapest and easiest thing to try first.
Mine only lasted a year as did the cheap *** starting/power battery under the hood.

 

One fob battery died last September. I put new batteries in both fobs. It's supposed to be up around freezing tomorrow. I can handle that. The -3 degrees was a bit cool to be holding metal tools.

 

The batteries are probably ok, but check them anyway. Even those lithium batteries have a shelf life and it wouldn't be the first time that bad ones were sold.

 

Good on both accounts. One other thing when a battery is not moved in its position there can be a resistance built up and loss of continuity. The simple act of removing them and reinstalling them can often cure a thought to be bad battery.
There are countless times looking for a problem that has a device that is controlled by a battery powered remote and having checked voltage in many batteries and finding that the voltage was almost as new. The most common for this are 76,2016 and 2032 . When they are mine, I just replace them even after checking them.