Question & Answers For Battery Charging.
Disclaimer: We’ve been asked a lot of questions over the years. I’d like to post some of the answers on this page. (Red is positive. Charge with the caps on. Protect your battery from high temperatures, park in the shade. The negative lead in charger output cables that are bonded together as a wire pair has a rib along its length, small but you can feel it with a finger nail, etc.
“I was recently charging my battery outdoors when it started to rain. I became concerned, because I know that water conducts electricity. Is it very unsafe to connect a charger to a battery in wet conditions? Please don’t tell me to experiment…I’d rather not.”
The rule is: Don’t charge in the rain. Actually water doesn’t conduct electricity very well. If it did, every time it rained all the power lines would short out. Salt water is an exception.
It turns out people are better conductors of electricity than water. So if you reach into or touch water that is covering an electrical appliance, the electricity finds an easy path to ground through you, shocking.
This is why our battery chargers have a grounding conductor, and so should your extension cord and outlet. It is why hair dryers now come with ground fault detectors built in; to turn them off if they fall in a bath tub.
Remember this, if an electrical appliance falls into water do not reach in to get it. Unplug it first. Why you ask, because the electricity will go from the water into your arm and kill you.
So what should you do if during charging it starts to rain? Unplug your extension cord from the outlet. Then don’t use the charger until it’s dried out. By the way, before using an extension cord, check it over for cracks in the insulation. If there are any, don’t use it.
“I enjoyed visiting your Web site. At work, several of people on staff were discussing charging a battery and the effect that placing a fully charged battery on concrete would cause the battery to lose its charge. Their statement is that a battery placed directly on concrete will quickly discharge, while a battery placed on a 2×4 above the concrete will not discharge as quickly.”
There is a newsgroup, sci.chem.electrochem.battery (via Google), (or for News Reader Software). This question has been extensively discussed there. I do not have the old posts to pass along. Perhaps you can find them in news group archives.
My opinion is: The only way to resolve this question among friends, in order to stay friendly, is to take two matched batteries, place one on concrete and one on a board. In other words, use the scientific method. Try to get everyone involved to sign off on the test protocol first to avoid further infighting. It is my experience that this matter cannot be resolved among friends by theoretical discussion alone.:-) Let me know what you find out.
Suggestion for further work, is a board necessary? How about plastic film, wax paper, metal foil, etc. Have fun.
Remember: Theory guides, but experiment decides.
“I wish to know if running vehicle in the daytime with headlights on reduces gas-mileage and the battery life time, and how much.”
If the headlights are on, the dashboard lights and the car’s rear lights are on too. Assume the current drain is 20 amperes, more or less depending on the type of car. That will be about 240 watt-hours for each hour of driving time. That energy has to come from somewhere. Your gas-mileage will decrease. How much, I leave as an exercise for you, dear reader, to figure out for your car.
The effect on battery life should be nil. Two factors most responsible for decreases in battery life are high temperatures, and frequent deep discharges of the battery.
“How can I find out who made my battery charger?”
If your charger was listed by a Nationally Recognized Testing Laboratory, such as Underwriters Laboratories Inc., UL, there should be a control number near the listing mark. UL can identify the manufacturer from the control number.
“Each fall I gather up the batteries from my motorcycle, riding lawnmower and family boat and store them in my basement. I’ve read that it is a good idea to charge them occasionally. I have a variable DC power supply, and I wondered if holding them at somewhere around 13 to 14 volts all winter would keep them charged and healthy, as batteries in vehicles are always at this level when running.”
Keep the voltage below the gassing point of the battery, about 13.8 volts. Check the water level periodically to make sure they aren’t
gassing. If you have to add water, lower the voltage a tenth.
Or – charge the battery, keep it in a cool place, charge again maybe three months later.
Or – use our MLC6012 charger for maintaining a motorcycle, riding lawnmower type battery over winter.
“Can I warm a cold battery (sub-zero) with a 10 minute/10amp boost just before cranking? Would this overcharging cause premature battery failure if done on a regular basis?”
I doubt that you will notice any temperature rise on a sub-zero battery with ten amps for ten minutes, nor do any damage. So many pounds of lead and not enough heat. Invest in a battery warming device instead.
“What are advantages/properties of nickel hydride? Thank you!”
“Your instructions are very detailed, however, I have a deeply discharged battery. It was left in a car in storage. The eye is dark, but not clear or yellow. After about two hours charge time I noticed that the battery sounds like it is boiling lightly. The battery is not warm, about room temperature. Is this normal? I have stopped charging the battery and waiting for a response. If this is normal, it may be a good idea to add it to your instructions. Or at least some idea what might be normal to expect during charging. Thank you for your time.”
Typically a battery left in a discharged state for a long time needs to be replaced. I have an old car with the same problem. Instead of taking a charge, the battery voltage just rises rapidly to the point where the water breaks down into hydrogen and oxygen. That’s the bubbling you hear. Continuing on really does no good. Time for a new battery.Usually when you try to charge a battery like this the current on the ammeter is very low, or maybe starts high and falls rapidly – showing that the battery isn’t charging. This is an example of a worn out battery with sulfated plates mentioned at the end of our instruction manual.
Some Little Battery Tips:
Hot weather is hard on batteries. Park in the shade. I talked to a man who parked his car in the sun on a very hot day in Phoenix, Arizona and found that his battery had exploded. He needed a new hood. His dealer said he wasn’t the only one. He put a thermometer on the new hood to see how hot it could get. He said the thermometer went off scale at 200 degrees F. While only a few batteries will blow up at high temperatures, they all may be damaged by the heat. Their useful life will be shorter and their capacity reduced. Which means the car will be harder to start in cold weather.
Cold weather makes batteries sluggish. The chemical reaction in the battery that produces the electricity slows down in the cold. Cold batteries resist being charged – require a longer than normal charging time. Short trips (less than 30 minutes) in stop and go traffic during cold weather may not give the alternator enough time to put back the electricity used in the trip. If the next morning is going to be unusually cold, charge your battery the night before.
Newer cars have one or more on-board computer systems that use electricity even when the car is not running. If your car is unused for a few weeks the computer can run the battery down (idle batteries also will slowly discharge themselves) to the point where your car won’t start. We make float chargers that will keep up the battery of a seldom used car.
Auto makers are using smaller batteries to save weight to meet government regulations for increased gas mileage. Down sized batteries are made lighter by reducing the amount of lead in the battery plates. They can still start your car, but if your alternator fails, a smaller(lighter) battery will not give the range of a larger(heavier) one.
In cold weather the power available from a fully charged battery is less than half of what is available in warm weather. The engine is harder to start because the oil is stiffer in the cold. Driving in winter means you often are taking more out of your battery that you are putting in: lights on; heater; rear window defroster; wipers running. If your battery isn’t fully charged, it may not be able to start the engine. What to do? Charge the battery once a week. Keep the battery warm. Park in a heated garage. In very cold climates use an engine heater when parked. A battery heater also may make the difference between starting and not.