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24 votes
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Can one slightly charge a dead car battery with a portable battery jump kit?

As Miracle Max would say, there's two kinds of dead batteries, and there's a big difference between them. Mostly Dead This is the most common kind of dead battery. Let's say your battery is rated for ...
Machavity's user avatar
  • 366
23 votes
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Charging battery with battery charger vs jump starting and running the car

Got a 1998 Toyota Camry that has an empty battery and am wondering what the best course of action is. Why is it empty? Is it empty because the battery is old and dying and won't hold capacity? Or is ...
juhist's user avatar
  • 14.6k
18 votes

What is more cost effective: re-charging a car battery or replacing it new when it dies?

The cost has been addressed, but there's an underlying question: is the battery dead (i.e. it cannot hold enough charge anymore to start the car), or has it just been discharged? If it's just been ...
Hobbes's user avatar
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18 votes
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Is charging my engine battery like this bad?

Use the jumper battery to start the engine, then disconnect it and leave the engine running (with no current drain such as lights, heater fan, radio, etc). The car should charge its own battery to 80% ...
PeteCon's user avatar
  • 8,712
13 votes

Factors Limiting EV Battery Acceptance Rate on DC Fast Chargers

Generically speaking, higher charge rates will heat a pack more quickly than the lower rates. Tesla models are designed and constructed with active cooling as well as appropriate monitoring and charge ...
fred_dot_u's user avatar
  • 4,580
12 votes

Is charging my engine battery like this bad?

Lead acid type batteries, such as this, like to be charged very slowly. Under 5 amps for many hours would be best. During fast charging the internals overheat and electrolyte can boil. Best to charge ...
Fred Wilson's user avatar
  • 11.6k
11 votes

Can one slightly charge a dead car battery with a portable battery jump kit?

Those types of chargers are designed to provide short bursts of power to start a car, most do not have a battery charging mode. Once the car is started the alternator will complete charging the ...
GdD's user avatar
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10 votes
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12V Battery change

IIRC, the Prius has a step down voltage regulator which charges the 12v battery from the main power. I'd bet this system is having an issue and is not charging the battery. As for the 12v battery. I'...
Pᴀᴜʟsᴛᴇʀ2's user avatar
10 votes
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How do I keep an idle/unused battery ready for immediate use?

Similar batteries are used for motorcycles, and many people don't use those very often at all. They sit in the garage for months at a time until the weather is just perfect for that 20 minute ride. ...
JPhi1618's user avatar
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10 votes

Is my car battery charger not working?

12.45 to 11.94 in 6 days seems like a significant discharge. You should be able to leave your car for a month or longer and still have enough power to start. At your current discharge rate, I wouldn'...
rpmerf's user avatar
  • 8,403
10 votes

Solar Charging Car Battery through Cigarette Lighter Outlet?

Why don't you connect it to the battery directly? Do you know, that mechanical contact with metal springs inside lighter plugs is not very reliable? It has relatively big resistance and will be ...
cyclone125's user avatar
9 votes
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Is there any advantage to keeping the battery "topped up"?

As long as it is not overcharging your battery, it will increase the useful life of the battery. The reason behind this is, as a battery sits, it loses power. Some of the electrolysis which goes on to ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
9 votes

Is charging my engine battery like this bad?

A @FredWilson says, you need to charge it slowly - either by driving it around or by using a trickle charger. If you can get a trickle charger with a 'maintenance mode', you can leave it permanently ...
Nick C's user avatar
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9 votes
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Have I fried my alternator through frequent use of an external charger?

It's very unlikely your charger had anything to do with your alternator failure, unless you were running the charger and your engine at the same time, even then I'd expect a charger to cut out as it ...
GdD's user avatar
  • 17k
8 votes

Car battery dead for a while... now it won't charge?

I'm not going to tell you to try and utilize a battery charger to fix the issue as @MoveMoreCommentsLinkToTop has suggested in the comments, but it has been my experience when a battery has sat for an ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
8 votes
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Battery maintainer vs trickle charger

The difference is smarts. A trickle charger provides a constant current all the time. It does not know whether the battery is charged or discharged. A battery tender is smart. It will charge the ...
vini_i's user avatar
  • 16k
8 votes

What is more cost effective: re-charging a car battery or replacing it new when it dies?

It is nice that some people put complicated math here (which is mostly correct also) but IMHO there was no reason to complicate it so much. As a rule of thumb: IF battery can be recharged then it is ...
Evren Yurtesen's user avatar
8 votes
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Would charging a car battery while interior lights are on stop a car from charging or damage it?

It didn't damage your battery or the charging at all. Because: All batteries in automotive created for simultaneously charging and discharging otherwise your car will not have an alternator in the ...
Cubic273.15's user avatar
8 votes

Factors Limiting EV Battery Acceptance Rate on DC Fast Chargers

One of the issues you face is that the battery capacity is itself one of the limiting factors for the power a battery can take. This is typically referred to as C-rating. That means you can charge a ...
Arsenal's user avatar
  • 181
7 votes

Is it better to hook up a Battery Maintainer for 2 months outside, or take our chances with the battery?

I don't know the exact model of the trickle charger, but would suggest against using it and getting an actual battery tender instead. The difference is, the trickle charger will continue to charge, ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
7 votes

Drained battery; imminent explosion?

In a word: nothing. If a battery is completely dry, or has a lack of electrolyte which doesn't contact the bottom of the charge plates, then nothing will happen. Even if one cell of a 6-cell battery (...
Pᴀᴜʟsᴛᴇʀ2's user avatar
7 votes

Solar Charging Car Battery through Cigarette Lighter Outlet?

On my car, the lighter (power) outlet is switched with the ignition, so it is not directly connected to the battery, so you would not be able to charge the battery through that connector if the ...
Peter Bennett's user avatar
7 votes

Charging battery with battery charger vs jump starting and running the car

If the battery is completely flat, then it will have been severely degraded in capacity. Lead acid batteries don’t hold their full charge after going completely flat, so it would be best to replace ...
HandyHowie's user avatar
  • 25.4k
6 votes

battery fully discharged, got a jump-start, but what do I do now?

It is very important to charge back the battery as soon as possible. As per how fast does the alternator charge the battery?, it may take as much as 10 hours or more for the battery to be re-charged ...
cnst's user avatar
  • 1,515
5 votes

Start a dead battery car with a power/USB charger

Any car jump starter device will do, such as http://www.walmart.com/ip/Schumacher-Instant-Power-500-Peak-Amp-Jump-Starter/13005748 Cheaper, simpler, and more reliable than playing with stuff you find ...
PeteCon's user avatar
  • 8,712
5 votes

Multiple Batteries Charging

When you put two batteries in parallel they will share the charge among themselves. For example, if you connect two batteries together, one fully charged and one dead the resultant combination gives ...
vini_i's user avatar
  • 16k
5 votes
Accepted

How to prepare a car for one year of storage

As you have already said, place the battery on a tender. Fill the gas tank completely. This prevents moisture from accumulating in the tank. They also make fuel stabilizer (Sta-bil is a common one) ...
Sherman418's user avatar
5 votes

Solar Charging Car Battery through Cigarette Lighter Outlet?

If the outlet is directly connected to the battery then it should be possible. Make sure to connect the solar panel through a charge controller configured for the chemistry of you car battery, so the ...
Manu3l0us's user avatar
  • 151
5 votes

Battery only charges with parallel load - why? recoverable, or replace?

Given how complicated this seems from both posts, I would suggest that you fit a known good battery and run the complete set of tests on the charging system. I would include the tests for voltage ...
Solar Mike's user avatar
  • 34.6k
5 votes

How can I evaluate a used automotive manual battery charger?

You shouldn't be shopping for a battery charger but for a power supply. A properly designed battery charger will have protection circuits that stop it frying batteries (and on a bad day, starting ...
alephzero's user avatar
  • 2,954

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