Hot answers tagged

17

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% charge in about two hours (assuming the battery and alternator are in good condition; the battery may be damaged by being uncharged for so long, but I've never ...


12

I can't give you numbers or calculations without some work, but I can tell you than energy is never free. Cars have an A/C compressor that is mechanically driven by the engine because this is the easiest way to get the job done in a typical consumer car. An A/C compressor actually takes a huge amount of energy to operate. In fact a central A/C unit for a ...


12

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 slowly if time allows. This type battery has its worst damage happen when it is stored discharged. The chemistry in this state is more acidic. This acid ...


10

This battery pack is rated for 4A at 12V. But a really empty car battery can easily draw much more that 5A when connected to 12V, which is definitely too much for your battery pack. The LiPo battery itself can deliver lots of, but not unlimited current. At high currents, it can get really hot and even start a fire. The battery pack contains a protection ...


9

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 make a battery work, also breaks down the battery. During this period, the battery goes through a sulfating period, where sulfur crystals grow on the lead ...


9

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 attached to the car and it will keep the battery topped up and stop it going flat in the first place. If possible, I'd also recommend finding someone you trust ...


9

Well, Teslas (and presumably other all-electric cars) have A/C so it's not impossible, but A/C takes a fair amount of power. On the other hand, Teslas store a lot of energy. The A/C is something like 2.4kW which is about 8,000 BTU/h or about 3HP. So using an electric motor on a conventional car might give you a few more HP briefly, but the alternator has ...


8

The short answer to your question is no. As @JPhi1618 noted, the compressor is mechanically driven. Without the compressor you don't have any cooling. The AC runs by changing the state and pressure of a liquid, and compressing the liquid is a big part of that cycle. If you bolted an electric compressor onto the car you would have to find a way to switch ...


7

This is a body ground. This is not the main ground, but will affect how anything attached to the ground will work. This might mean your radio or your lights might not work. It might mean the computer in your car (if it has one) won't work. There are any of a hundred things which could go wrong, but you should still be able to jump your vehicle. With this ...


6

Yes, this is possible. Several companies (VAG, BMW) have switched to AC units that are driven by electric motors. For BMW, this is part of their Efficient Dynamics strategy, where they'll switch the compressor on/off depending on engine load to optimize fuel consumption. When the weather's not too hot, you can run the compressor intermittently without the ...


6

Fair warning, this is a guess. Vote appropriately... General accepted order: Dead + Good + Good - (directly to the terminal) Bad - (to a good engine ground, but not the terminal) Avoiding the last connection directly to the dead negative is to avoid sparks near the dead battery, but this also avoids sparks near both batteries since the good one is ...


5

Absolutely yes. I sell alternators all day every day - and a poor battery is often the root cause of alternator failure. A battery with a short in it will cause the alternator to run at full output for extended periods of time, if not continuously - and they are not built to do this. Alternators the world over are built to supply an initial high current, ...


4

To summarize the various comments into an answer... You can connect an ammeter (or a voltmeter in current mode) in series between the charger and the battery - this will tell you if a current is flowing through the circuit - and so whether the charger is at least attempting to charge the battery. Make sure that the meter you are using can take the maximum ...


3

A lead acid battery, as used in motor vehicles has a very low internal resistance, this means that when directly connected across the terminals of the li-po battery pack, it does act very similarly to a dead short. Most li-po packs are not designed for very high current draws, and have short circuit protection built in. This is likely tripping. Really, the ...


3

When you purchase a lighter plug extension that adds three extra plugs, you're not changing the voltage because the plugs are in parallel with each other so that each plug can deliver 12V to the accessory connected. How much current each accessory draws, however will be added together, and can't exceed the current capacity, usually dictated by the fuse. ...


3

Do I need to concern myself with being shocked while trying to change the battery? 12V is too low to present any significant electric shock hazard. The biggest hazard when working on batteries is shorting the thing out. This leads to a massive release of energy which can lead to severe burns. Some precautions that can be taken to reduce the risk. If ...


2

When disconnecting a battery always remove the negative terminal first. This breaks the circuit and neutralizes the possibility of a short circuit. When reconnecting the battery always connect positive terminal first. Never underestimate 12 volts : Under normal conditions the outer skin resistance is high enough not be an issue. However if you have open ...


2

When the alternator fails, the copper windings melt and become shorted. This will cause an electrical fire smell and will cause several indicators to come on. As others have stated, burnt fuses and failed regulators can cause the same smell. When a regulator stops... regulating, your voltage can spike to excessive levels causing equipment to burn out and ...


2

There is NO free lunch, you will need many batteries and a much better alternator. You could in fact attach a window mounted air conditioner like @Spehro Pefhany suggests. OR TEC Thermo Electric Cooling There are peltier elements that also generate a cooling effect compressor free. They are essentially a plate of ceramic postively charged, and one ...


1

Fuse box is good on a Honda, choose the terminal where the source cable is connected directly to the battery, be sure to use an in line fuse (30A) on your wire. Use #10 wire to connect your accessory to the terminal.


1

Is the field coil connection connected? If not the alternator will not produce any output at all. The field coil supplies the magnetic field needed to induce current in the alternator coil winding. There are 2 connections on a alternator. B+ Output of regulator Field Field coil connection The ground is the casing of the alternator. The plug ...


1

I've seen electronic toys with very weak batteries do what you're describing. They try to come on, but as everything starts to power up, the little remaining battery current can't keep up, and the toy goes dark, just to start the process over again. If your battery is very weak, I could see how the key less entry system might be starting to "boot up" and ...


1

Usually the car is charging the 12V battery with over 14V to get it up to something over 13V, so a charger with 12V will do no good. It should work while the battery is lower, but it won't get you anywhere where you can use the battery to start a car. The next problem might be the way the charger detects a short circuit, probably by measuring the flow. The ...


1

In order for an an alternator to function it requires a functional battery. The battery current is required to required to energize the field coil which produces the magnetic field required for the alternator to produce energy. The alternator sends 5 amp-hours at about 3000 RPM to the battery and the balance of its output goes all the other systems in the ...


1

The recommended battery for a 2000* Jaguar S-type 3.0 is a 019, which has 800CCA and a capacity of 100Ah. *Randomly chosen as you didn't specify a year.


1

Starter Solenoid If you can turn the starter over when your skip the solenoid then I the logical next step would be to replace your solenoid. It's a very simple procedure and the solenoid is a relatively inexpensive component I suggest you swap out your solenoid and see if that resolves your issue.


1

Lots of good answers, but will clarify something for what it is worth: All hybrid cars do have a 12V and a high voltage system. In my Prius (2009, 2003-2009 model), the 12v battery is in the boot. The standard car electrics like computers (all 13 of them) and screens and headlight and indicators and everything runs off the 12v battery. The 12v battery is ...


1

In addition to the other answers: if the tools you use are exposed metal, wrap some tape around the handle to insulate it. After you've removed one battery cable, cover the exposed terminal. This prevents the cable end from contacting the terminal again.


1

Try this, key on engine off unplug the alternator connector. If the battery light goes off that tells you if the battery light circuit is OK and that the problem exists with the alternator or the circuit on the S terminal.


1

If the car drives for about half an hour and switches off or parked off and within 10mins or so of trying to restart the vehicle, suspect the crank sensor. The reason is that the crank sensor is impaired by dust or dirt. Remove, clean and replace. It controls timing (spark) so if the tank is full and you hear the engine fuel pump buzzing sound in the ...



Only top voted, non community-wiki answers of a minimum length are eligible