Battery charging question

2014 Toyota Camry 4-cyl

Because most of my driving is short distance, often with stops at several locations, I typically have made a point for years of taking an uninterrupted drive of about 35 miles each week to keep the battery charged.

During the past ten months I’ve done very little driving but still have gone for a good long drive every two weeks at farthest apart, averaging 35+ miles and several times a good 60 miles. It keeps the battery charged and the scenic drives maintain my sanity while otherwise mostly isolated at home.

About ten days ago I discovered I had left an interior map light on inside the car since having last driven it several days earlier. I only managed to drive about 15 to 20 miles in response to that error but had to quit because I didn’t feel well once I began driving. Turns out I was quite ill within a few hours later with either flu or covid from which I am finally beginning to improve.

It’s going to be later this week at soonest and likely next week I’ll be safely ready to go for an extended drive. So by then most likely a full three weeks or more the car will have sat after only a short drive following leaving that interior light on for several days.

The battery is two years old so hopefully the car will start without problem. If it doesn’t I’ll call AAA. And, yes, now I’m thinking that I really should spend the money to get a trickle charger to maintain the battery charge. I’ve been hoping not to have to spend the money for one.

My immediate question is this, about how far a distance, how long a time should I drive the car when I can manage to in coming days so that I ensure the battery is deep charged??? I don’t want to ruin an only two year old battery by letting it get too depleted.

(And, yes, I feel sheepish needing to ask but right now I have brain freeze.)

Just put a charger on it and monitor your battery with this:

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Glad you’re feeling better :slight_smile:

If it was one of my cars (the Focus or the Odyssey) I would probably pick a restaurant doing take out a 3-4 towns over, order dinner, bring my thermal lined bag that keeps hot food hot, then take the scenic route drive over and back. It’s not as good as a battery charger, but that should give the alternator time to get it back to a good level.

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We had something similar a couple of years ago. Mrs. Triedaq broke her left foot and hadn’t been driving her 4Runner. I was busy writing grants and didn’t really think about the 4Runner, as I normally drive the Sienna. At any rate, when she was ready to drive, the battery was too low to start the engine on the 4Runner. I put the small 8 ampere charger on the battery for a couple of hours and the engine started right up. The battery was three years old, so I took the 4Runner to the Toyota dealership to check the battery and charging system. The service department said all was fine and just take the 4Runner for a 20 mile drive. The dealer didn’t charge me and I even ate a couple of their cookies and drank two cups of coffee in the waiting room.

If everyone was doing this just for the sake of recharging a low battery our planet will suffer.I agree that the best way to do it is with a battery charger.

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I don’t think everyone is… @Marnet is asking for herself specifically. It stimulates the local economy some, Marnet doesn’t need to cook dinner one night, and her Corolla gets some charge (and it would get the oil hot to get excessive moisture out too). I doubt in the long term that that would make a massive difference to our planet.

Frankly my Focus is a PZEV and only ever once threw a CEL, and I replaced the O2 sensor quickly, which resolved the issue. And while my Odyssey burns more fuel and creates more emissions simply because of that, it’s still not causing excessive emissions (never had the CEL come on during operation). So I’m not really concerned that I’m drastically affecting the planet doing this. It’s not like I’m driving my old neighbor’s 60s era Chevelle doing this :wink:

Unless your power is provided by solar or wind, your battery charger is still causing emissions, they’re just not in your immediate area.


I really like the PZEV designation. Just like vodka is partially alcohol free, after all vodka is 60% water.


OP really wants to know the state of charge of the battery, and how that changes with down time, drain, and driving. If the battery caps come off, the way to test each cell’s condition is with a battery tester that draws out some fluid and measures its specific gravity.

The cheap simple tool has several small colored balls of different densities in its chamber - the more that float, the higher the SG and the state of charge. A color chart gives the SG reading.

The more professional tool has a floating closed tube inside, marked like a ruler but with with SG gradations.

For actual information about the state of charge of a battery, and the condition of each of its cells, this simple tool does it best.

I appreciate all the replies. Thank you.

For now, please understand I do not have a charger or battery measuring tools. Nor available money to buy such. I’m an older woman with very limited finances and severe arthritis.

I simply need to drive the car when I can, hopefully by next week, far enough to thoroughly recharge the battery.

Normally letting the car sit two or even three weeks isn’t a concern. But because I carelessly left that map light on inside the car for several days and drove only 15 or so miles after finding I had, I’ve worried how much that drew down the battery versus the short drive restoring that much charge or not.

Perhaps I’m worrying too much.

Maybe check with friends or family to borrow a charger?
It takes several hours to thoroughly fill a partially discharged battery.
Except for road trips I drive once or twice a week, mostly short trips 10 miles or less.
Even less with COVID.
Before I got a solar panel (that sits on the dashboard) I would charge the battery overnight every 3 months.

You don’t want to use a trickle charger.


@Marnet. Since the car started after you left the map light on, I don’t think you have anything to worry about. My guess is that the map light has an LED bulb which draws very little current.
I do have a battery charger, but I didn’t buy it to recharge car batteries. When I had 5 acres in the country and had a horse, the horse liked the grass better on the other side of the fence. So that the horse wouldn’t mash the fence down, I put up an electric fence and charged it with a battery operated fence charger. The “hot shot” ignition battery to operate the charger was expensive, and after I bought a couple of these batteries, I got an old 6 volt car battery and recharged it periodically. I’ve long since moved out of the country, but I still have the battery charger. I’ll bet I haven’t used any more than 5 times since I moved to town 43 years ago. Since you have AAA, don’t buy a battery maintainer you would rarely have occasion to use.


Again, thank you everyone. I appreciate the help.

And thanks for having continued to welcome me as part of the “regulars” these many years despite my being so un-mechanical. I keep learning by hanging out here and doing lots of reading. Besides, you are interesting folks. :+1:


Okay, please explain. I realize there is a difference between a trickle charger and a charger to recharge a battery, if I’ve understood many previous discussion threads on batteries. A battery maintainer trickle charger has often been recommended to posters who do limited driving.

So although the more I think about it the more I think I’ll rely on AAA for the rare event I run into trouble, I would like to understand why you say not to use a trickle charger.

I’m not challenging your advice, simply wishing to understand, please.

If an interior light is left on it will be turned off after 20 minutes, from the owners manual;

P 295

"To prevent battery discharge

Vehicles without a smart key system

If the interior lights, personal lights and/or door courtesy lights are left on when the engine switch is turned to the “LOCK” position, the lights will go off automatically after 20 minutes."

My 1996 Dodge will switch off the interior lights after 10 minutes if a light switch is on or a door is left open. This is one of the features of the body computer.

A trickle charger can over-charge a battery and damage a battery.

A battery maintainer charges a battery, but once the battery is charged, it maintains the charge on the battery but doesn’t over-charge it.


@Nevada_545 You remind me I should double check my manual about all the settings and normal function of internal lights. I know for a fact the light was on at least almost 24 hours. I remember turning it on after I had garaged the car and turned off the engine. I couldn’t find my house key by feel so turned on the map light to see but absent mindedly neglected to turn it back off afterwards.

Late the next day I went in the garage and noticed the light was on so went for the drive I had to cut short when I realized how rapidly I was getting sick.

I’m wondering if that automatic shut off after 20 minutes of such interior lights applies even when a light is turned on after the engine has been turned off.

Time to reread the manual.

You illustrated one of the disadvantages of Toyotas . . .

Unlike some other manufacturers, they’re not set up to turn off accessories, dome lights, etc. 20 minutes or so after turning off the ignition

We’ve owned many Toyotas over the years, and unless things drastically changed within the last few years, that’s one of the weaknesses, as I see it

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@Tester Oh, I hadn’t understood that a trickle charger is not the same as a battery maintainer! Thank you for explaining. I very much appreciate it.

@db4690 I’ll keep it in mind. Normally it’s not an issue given my habits with any car. But as in this case, doing something different than normal habit can easily lead to oversight.