Dead Battery Can Affect Fuel Gauge Reading?

[Pitter]

Well CX-5 wouldn't start this morning, lots of messages flashing on the screen including low fuel. I jumped it with a portable starter and while it was running I looked at the fuel gauge and it said there was only a range of 44 kilometers. I didn't use the car yesterday and I could swear I filled it the day before. My parking area isn't full of leaked gas and I'm pretty sure they didn't bamboozle me at the gas station.

I haven't driven the car to run up the battery yet and will have to jump it again tomorrow to go to town for a new battery but my question is could the failed battery cause the fuel gauge to read inaccurately low? I hope I don't have to coast down my mountain tomorrow with the car in neutral and riding the brakes to make it to a gas station.

 

[N7turbo]

I would not be surprised. The computer seems to freak out about many things when the battery is not providing enough voltage.

But you don't want to ride the brakes down hills in neutral. They can't handle it. They will overheat against the weight of the car. If you can't stay in 1st gear to provide engine braking, leave the car at home.

 

[Jmaz]

After disconnecting the battery I have to reset the clock and programmed radio stations. It also resets the tip odometer(s) and average fuel usage to zero. Probably resets the range also. If you know there's gas in the tank I'd just drive it. Who are you going to believe? Yourself who knows they got gas or the display which got spastic because of low voltage.

 

[Pitter]

Thank you both. I should be ok then on gas to get to the dealer tomorrow. No I won't go down in neutral riding the brakes.

 

[Pitter]

Well I made it to the dealer twenty kilometers away ok after jumping the battery but just barely. I learned just how much this car depends on electricity and the effects of a really flat battery on the drive. Starting out I lost manual shift and when I got to the city and traffic lights the car often wouldn't downshift and I'd be starting up probably in third gear. Just as I made it to the dealer the power steering went south and the steering started locking rather violently. Barely made it in the door. I was anticipating some serious effects from all this but as soon as they popped in a new battery everything was mellow yellow.

One thing that bugs me though is I had no warning. The day before the battery died (like completely) the car cranked perfectly normally. In the old days cranking would typically be slow before the battery gave out. I've also experienced short battery life for the six year life of the car. Last battery (Willard) lasted just seventeen months and no cold weather. I remember back in the states Sears Die Hards being guerenteed for five years. Of course they may not have lasted that long in real life.

 

[cz5gt]

Glad all is ok.
In future see if you can get a deep cycle AGM. Those would last much more than a regular battery.

About the warning, the problem is all these new cars with so much electronics have a fail safe. Under certain voltage and you are toast. Old cars could start slowly even on lower voltage but not anymore.

 

[HyFlyer]

My guess is your rough roads cracks plates in your battery

 

[Pitter]

HyFlyer interesting idea. I should ask my neighbors about their battery life.

 

[HyFlyer]

" ...The day before the battery died (like completely) the car cranked perfectly normally. ..."

Leads me to believe a structural failure of the battery internally

 

[madar]

Well I made it to the dealer twenty kilometers away ok after jumping the battery but just barely. I learned just how much this car depends on electricity and the effects of a really flat battery on the drive. Starting out I lost manual shift and when I got to the city and traffic lights the car often wouldn't downshift and I'd be starting up probably in third gear. Just as I made it to the dealer the power steering went south and the steering started locking rather violently. Barely made it in the door. I was anticipating some serious effects from all this but as soon as they popped in a new battery everything was mellow yellow. One thing that bugs me though is I had no warning. The day before the battery died (like completely) the car cranked perfectly normally. In the old days cranking would typically be slow before the battery gave out. I've also experienced short battery life for the six year life of the car. Last battery (Willard) lasted just seventeen months and no cold weather. I remember back in the states Sears Die Hards being guerenteed for five years. Of course they may not have lasted that long in real life.

It's exactly why I change my battery every 4 years regardless. Newer vehicles are very fussy with voltage.

 

[Lazy2.5]

I wonder why you're experiencing manual mode lockout. never heard of that before.

I had an old CAA battery in my Mazda 6 from 2021 to end of 2024. It lasted 120,000KM. Here in Canada, we get cold winters and hot summers. The battery was holding normal voltage unloaded, but I eventually got a P0600 code and CEL, so I knew it was time to change the battery. I noticed no symptoms of a weak battery whatsoever, but the engine did start to crank over a little weak, because it was cold here. I do keep the battery plugged in on a tender though.

 

[Jmaz]

HyFlyer interesting idea. I should ask my neighbors about their battery life.

Definitely want to make sure the battery is clamped down securely. Battery bouncing around will shorten the life for sure.

 

[SparkYellow]

Glad that everything is back to normal! I thought there'd be warning signs before fuses, relay, or batteries go out. In my case, things got gradually worse over time until I got stuck.