# Why no simple gauge on a car battery to measure charge? **URL:** \ **Category:** Factual Questions\ **Created:** [July 21, 2017, 8:24pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832 "2017-07-21T20:24:06Z")\ **Posts on this page:** 10\ **Page:** 3
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [April 23, 2020, 10:08am UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/42 "2020-04-23T10:08:57Z")
I am surprised at all the negative answers. My 2015 car has an on-board computer sophisticated enough to progressively cut down demand if the voltage drops. The first indication is that the stop/start stops working. In cold weather, the heated front screen stops working. I one does nothing about it, I am told that other things like the in-car heater and the radio also stop. A car that is clever enough to do all this could surely send me a message, just as it tells me that a door is open or the oil needs changing, that the battery voltage is low. I do understand that this may not be a sign of imminent failure, but it would tell me to dig my smart charger out and if that fails to cure the problem, to start researching battery suppliers. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 23, 2020, 12:02pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/43 "2020-04-23T12:02:35Z")
[Moderating] **Yakamaniac** was not the one who bumped this thread; that was a spammer who has now been deleted. So no zombie jokes, please. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [April 23, 2020, 1:23pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/44 "2020-04-23T13:23:34Z")
> [@bob\_2](#): > > I am surprised at all the negative answers. My 2015 car has an on-board computer sophisticated enough to progressively cut down demand if the voltage drops. The first indication is that the stop/start stops working. In cold weather, the heated front screen stops working. I one does nothing about it, I am told that other things like the in-car heater and the radio also stop. that is called “load shed,” non-essential accessories are put to sleep to minimize the power draw from the storage battery to keep the car running as long as possible. > [@](#): > > A car that is clever enough to do all this could surely send me a message, just as it tells me that a door is open or the oil needs changing, that the battery voltage is low. if your car is in load shedding mode, it should very well be giving you all sorts of warnings. but here’s the thing: > [@](#): > > I do understand that this may not be a sign of imminent failure, but it would tell me to dig my smart charger out and if that fails to cure the problem, to start researching battery suppliers. Load shedding while running is an indicator of _charging system failure_ or electrical system overload, not battery failure. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [April 23, 2020, 1:42pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/45 "2020-04-23T13:42:54Z")
> [@mixdenny](#): > > Us golf cart enthusiasts live and die by the battery. I have a NOCO Genius Mini 3 charger that analyzes and charges a battery in 8 stages: > > 1. Analysis. Can detect any kind of lead acid battery, regular, deep cycle, AGM, gel, etc > > 2. Diagnostics > > 3. Recovery. When detected, it applies a high-voltage low-current pulse charge causing battery sulfation to convert back to the active material, regaining lost battery capacity. > > 4. Initialize > > 5. Bulk charge > > 6. Absorption charge > > 7. Optimization and finish charge > > 8. Maintenance > > [NOCO - 3-Bank 30A On-Board Battery Charger - GEN3](https://no.co/gen3) > > My vintage Melex golf cart came with an extraordinary set of batteries, (6) 6 volt Trojan Gel Cells that cost $315 each. When I bought it, they were in dire shape. The previous owner used the old fashioned buzz box charger, not suitable for gel cells. Cables were poorly connected to the point that one battery \*\*\*melted \*\*\* around the terminal. Another battery only read 4 1/2 volts, a sure sign of death. I charged it, after sitting a week it was back to almost nothing. > > I bought the Mini 3 Genius. After only a few charge cycles (which originally took 2 days each!!) all batteries are back in action. > > I dare say NOCO could build an on-car analyzer. > > Dennis Just wanted to thank you for this post. I had to use my 10A buzz box charger the other day because one of my cars hadn’t been driven in a while. It’s a Hybrid and the drive batteries were fine, but the 12V that fires up the electronics was about 5V. I did get it going after an hour or two of charge. But have ordered the NOCO Genius 10. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [April 23, 2020, 2:39pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/46 "2020-04-23T14:39:53Z")
I would say that some indication that a battery is going should be easy to build into a car’s computer. Cranking time, speed along with engine and outside temperature is one way I could think that the car might say that the battery should be checked out. As for other methods, I got a tester that places a load on the battery, IIRC it was not very expensive, but gives a indication of how good the battery does. I normally do that test 2x per year, once going into winter and some other time. If it appears weak I will replace it especially with winter coming. If at another time of the year I may just let it go and check it again down the road. ---
**Author:** ![Deereman](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@Deereman](https://boards.straightdope.com/u/Deereman)\ **Post date:** [April 23, 2020, 6:11pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/47 "2020-04-23T18:11:47Z")
> [@Gary\_T](#): > > Not necessarily more than enough, but a significant amount. These are as basic and simple as gauges get, and decades ago were not uncommon. Unfortunately, hardly any drivers really understood them. I can’t remember the last time I saw a car with an ammeter (it was decades ago), and it seems only few cars nowadays that aren’t electric or hybrid have voltmeters. The demise of ammeters so to speak is also due to the higher and higher amperage systems and vulnerability for bad connections. For the ammeter to show the system power flow properly ALL the power for all the various subsytems in the car has to go to it and then be distributed to it. On my old stuff it would go to one post, through the gauge, and then to the rest of the system Other brands used a capacitance ammeter that just had the main power wire routed to a clip on the gauge but it didn’t actually flow through it. So all the power had to be routed to go through a gauge that can burn out, or you get a bad wiring harness and kill everything because of one bad spot. Mind you, all my toys can’t even put out 30 amps. New stuff has 120amp alternators or more, and the wiring to handle that amount of power would not be cheap. Putting a voltmeter in a system is pretty simple, just wire it up and you can measure the system voltage from pretty much anywhere ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [April 23, 2020, 7:01pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/48 "2020-04-23T19:01:55Z")
To the OP The reason car batteries die unexpectedly nowadays is because (as engcompgeek suggests) they are built to a lesser standard of performance concerning longevity vs short-term performance. Short term, one can construct a battery with the requisite cold crank ampacity much cheaper (and lighter) than a more robust (long term) battery of the same ampacity… Less lead, (thinner plates), less acid, less body thickness. Hence more margin of error upon failure. The old battery design gave a longer heads up in their indication of failure due to their heavy construction compared to the more modern lightweight batteries. Old batteries took awhile to croak (due to heavy construction) and gave more of a heads-up of their demise, compared to the newer, lighter, more cheaply manufactured batteries that tend to die in a heartbeat. ---
**Author:** ![Mangosteen](https://avatars.discourse-cdn.com/v4/letter/m/6a8cbe/32.png) [@Mangosteen](https://boards.straightdope.com/u/Mangosteen)\ **Post date:** [April 23, 2020, 7:07pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/49 "2020-04-23T19:07:25Z")
My 1994 Toyoda T-100 has a battery charge gauge just to the left of the steering wheel on the dash board. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [April 23, 2020, 7:23pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/50 "2020-04-23T19:23:52Z")
My 1972 VW Beetle has a charge indicator in the dash-As do nearly all automobiles since the '50’s So what? ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [April 23, 2020, 7:40pm UTC](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832/51 "2020-04-23T19:40:47Z")
To the OP: Based upon the simplicity of analyzing battery health via auto parts suppliers… If auto manufacturers felt it necessary to provide battery health information to the consumer, they would do it @ $5 USD per unit upon new purchase. [Previous page](https://boards.straightdope.com/t/why-no-simple-gauge-on-a-car-battery-to-measure-charge/791832.md?page=2)