A flat battery can show 12 volts , but not be good enough to start a car . 11.9v indicates the battery is completely discharged. Anything under 12.2v means the battery is in a state of discharge, and a healthy battery should show 12.6v in a static state.
In answer to your question, the six amp charger will charge your battery three times faster than the two amp charger. Six amps is stil a relatively slow charge and should be fine to use for a deep cycle battery. If your charger is telling you the battery is full, place a load on the battery before charging it.
If you're trying to charge a 12V battery with a 6V charger, it won't explode but it won't charge either. A 12V lead-acid battery is considered completely discharged at somewhere around 10. x volts. A 6V charger won't do a thing for you.
Normally, a car battery holds 48 Amps. In that case, if you charge it at 1 Amp, it will take you 48 hours. Again, if you charge your car battery at 6 amps, the total time to fully charge the battery is about 8 hours.
This will run your battery dry and create a thermal runaway scenario, which is very dangerous. Again, some people use a 12V charger to get their 6V battery jump started, but it is never advisable to use a 12V charger to try to fully charge your 6V battery.
A 12v battery is a 12 volt battery, you can't use it at 6v. It doesn't work that way. Each of the 3 cells in a 6v battery produces a bit over 2 volts, just like each of the 6 cells in a 12v battery produces a bit over 2 volts. Because that's what a lead-acid battery cell does.
Most battery manufacturers recommend sizing the charger at about 25% of the battery capacity (ah = amp hour capacity). Thus, a 100 ah 12 volt battery would take about a 25 amp 12 volt charger (or less).
A healthy 12 volt motorcycle battery should maintain a range from 9.5 - 10.5 volts under the load, for a good 30 seconds straight. If the battery begins to hold and then steadily declines, there is a problem. If the voltage drops to 0 volts, there is a problem.
All batteries, including the lithium-ion batteries powering everything from electric vehicles to drones to computers, operate with direct current (DC). A majority of appliances rely on AC, or alternating-current, power sources.
This is called the “open-cell” or “resting” voltage of the battery. Resting fully charged 12-volt batteries are around 12.8-12.9 volts, and flat dead ones are at 12.0 volts, so 12.4 volts on a resting battery means it's about 50% charged.
Generally, a 3.7V lithium battery needs an overcharge and overdischarge protection circuit board. Lithium battery with protection circuit board can be charged with 5V voltage(4.8V to 5.2V can be used). For 3.7V lithium batteries, the charge cut-off voltage is 4.2V and the discharge cut-off voltage is 3.0V.
12.2v is enough to start the car. It's a 12v battery after all, it's just voltage settling after being at ~14v when driving.
Voltage on a fully charged battery will read 2.12 to 2.15 volts per cell, or 12.7 volts for a 12 volt battery. At 50% the reading will be 2.03 VPC (Volts Per Cell), and at 0% will be 1.75 VPC or less. Specific gravity will be about 1.265 for a fully charged cell, and 1.13 or less for a totally discharged cell.
How to Test Your Battery Voltage with a Voltmeter
- Make sure your vehicle is turned off.
- Remove the battery's positive terminal cover.
- Check the reading.
- Any voltage above 12.9 volts is a good indicator that your battery has excessive voltage.
- Charge your battery if the voltmeter display a voltage below 12.4.
A 12V lead-acid battery will not be damaged by overcharge if the voltage is kept low enough to avoid electrolysis, and the charging current is kept below 0.2C (5 times less than the Ah capacity). If it can put out more current than the battery can take then the battery may overheat.
When the probes touch the terminals while the car is off and the battery is resting, the multimeter display should show a reading of 12.2 to 12.6 volts (full charge). This voltage range means the battery is in good condition for starting the vehicle.
Each cell in a deep-cycle battery can produce about 2 volts. A 6V battery has 3 cells, making a total of 6 volts, and a 12V battery has 6 cells, making a total of 12 volts! In order to really understand how this comes into play, you have to understand voltage and what it does.
Troubleshooting 12 Volt Auto Battery Chargers
- Set the dial on the voltmeter to "Ohms" and test the voltmeter. Touch the leads of the voltmeter together.
- Touch the lead wires on the voltmeter to the lead wires on the 12-volt auto battery charger.
- Check the resistance.
- Set the dial to the highest volt setting on the voltmeter.
- Turn the battery charger on.
Look at the digital or meter display on the multimeter or voltmeter. It should read 6 volts if the battery is in good condition and is at least 20 percent charged. If it reads less than 5 volts, recharge the battery.
