battery knowledge
 

I recently learned that, without modification, there is no possibility of ever FULLY charging the battery BY DRIVING.
Thus our batteries are not lasting as long as they might, especially if the charge gets low e.g. if allowed to stand for a few days.

This is probably because software control is aimed at reducing alternator load to produce better fuel economy figures in government testing.

In our cars, if the battery is low, on startup "it will deliver about 20A at 14.45V for a minute, then reduce to about 4A for a couple of minutes then taper off to NIL
with the voltage across the battery falling below 13V."

In prior decades the alternator would supply a constant 14.4V.
If anyone knows how to change our software to make that happen then let us know.

Meanwhile, using a charger regularly to top up the battery is a solution.

Are you having electrical issues? Battery discharging? No start or slow start condition?

Well, I don't know about all of that, all I know is that the alternator in my 2013 FR-S produced enough electricity to run the car and has kept the battery charged for the past 5 years, with many short trips.


:iono:


humfrz

Just changed my 2013 original battery last month. Got a solid 5 years of daily driving everyday.
So I don't know what you are smoking but pass that stuff over here.

If you don't have any problems, you are way overthinking this.

I used to commute one mile, with the stereo on, the lights on, and the defrost going too. This is not long enough to charge my car. And after a week of quick 1 mile trips, my car would die.


Now that I drive 50+ miles each way, my battery stays FULLY charged. I have tested its voltage; it's good to go now.


I have also upgraded from, IMO, the crappy Panasonic battery.

I know less than the battery engineers at work, and probably much less than the battery engineers at Toyobaru.

I ran my OE flat two or three times (dome light left on, trunk open) and it lasted just shy of 5 years, the Panasonic is a tank as long as you don't drive too little. 1 year on a lightweight PC680 battery with no issues on a <5 mile commute (~15 minutes in traffic).

So what's the problem again?

People don't think chemisty be like it is, but it do.

I disagree.

:popcorn:


humfrz

Service manual says Alternator voltage output should be between 11-14v.

What if I do drive very little and also ran it flat(trunk open) a couple times? Should I then do a trickle charge for a couple hours every couple months in that case?

Re-read the part where I'm not a battery engineer
:bonk:

The new systems are smart.
The old voltage regulators were slow to react and were not very accurate.
After starting you should get 14.2 or 14.4 depending on where you measure. that is full charge voltage the amps depend on the state of the battery. After the battery approaches full charge the voltage will drop to about 13.6, this is a maintain voltage for the battery. If it stayed at 14.4 it would over charge and convert the water in electrolyte to gas. A comin problem with old cars. The new cars often have a voltage and charge sensor connected to the battery terminal.
I might suggest that you check the battery terminals to make sure there is a good connection, then do a load test on the battery. A lead acid battery that has been fully discharged will have a loss of load capacity each time it is fully discharged. (The exception are deep cycle type.)
It is possible you have a bad regulator. Excluding the sensor type most are "one wire" type and are built into the alternator.
Even if you put a battery on a new smart charger, out of the car, you will see the same kind of a voltage drop.

All this ^

There is zero need to have 14 volts all the time.Old cars just did it because they were dumb and didn't know any better.