"Vent with flames" / fireball / pyrotechnics may well eventuate. A battery that may not start a car may happily deliver 10 x as much current as the laptop battery can safely handle. Max safe charging voltage for your laptop battery is probably about 8.4A (A = Ah rate). If the laptop battery was rather flat (around 9V) and the car battery had modest life in it (eg starter relay goes click-click-click but starter will not turn, headlights light dimly) then the car-battery voltage may be usefully greater than the laptop-battery voltage and the charging may occur in the opposite direction. This will probably not usually be what happens. The laptop battery open circuit voltage may be lower than the car-battery voltage and no energy transfer may occur. If the car battery is very high impedance due to eg major internal sulphation the voltage may be around 12V when open circuit. The laptop-battery can be damaged and lose cycle capacity and worst case can "vent with flame" - spectacular high energy melt down. If car battery is very flat its terminal voltage may be low enough that the laptop-battery provides more current than is wise. At 9V if it does actually charge you are in the area where it is doing damage to the battery to use it. Actual cell voltages will be about 4.2V fully charged and 3V dead dead, so the battery = 9V to 12.6V. Even when the car-battery has been run flat by lights left on or whatever, it has the ability to accept energy from the external source and then to return it to the starter motor.Ī 11.1 V LiIon battery probably has 3 cells in series.ġ1.1/3 = 3.7V/cell. The starter motor draws hundreds of amps - probably 100-200 Amps in a very good situation and 400-600-800 Amps in various other cases. What is often not generally appreciated is that energy to turn the starter motor during a jump start does NOT come directly from jump-battery to starter but is first transferred from jump-battery to car-battery and then from car-battery to starter motor. Getting it to do so safely and effectively is "the trick".
#Lithium car battery jump starters portable
They are portable and provide the required amperage to jump start an empty battery.The laptop battery described could typically provide quite a few jump starts. Jump boxes consist of a maintenance-free battery attached to cables in a pack. If you want a plug-in unit, you should consider features such as the float-charge option, multiple-amperage settings and the various charging modes. Plug-in units are battery chargers that deliver enough amperage to help turn your engine on. Jump boxes are maintenance-free jump starters with jumper cables attached to them. There are two types of car jump starters: plug-in units and jump boxes. The outlets eliminate the concerns that come with incorrect connections and the creation of arcs near battery terminals. Vehicles with six- to eight-cylinder engines need 200 to 300 amps.Ĭan jump starters be powered from cigarette lighters?Ĭigarette lighter outlets can be used in place of jumper cables to interconnect the 12-volt power outlets of two vehicles. A rough estimate of petrol/gas engines shows that a four-cylinder car engine requires a jump starter with 150 to 200 amps. Auto jump starters do not have a power on and off switch they transfer current as soon as the clamps are connected to the terminals.Ĭars have various kinds of engines that require different cranking currents. Turn on the power on the jump starter to transfer the current to the dead battery. The black clamp is for negative and the red clamp is for positive. Be sure to match the coloured alligator clamps. You hook the jumper pack to the auto battery. High-discharge lithium-ion batteries are also available.
Jump-starter batteries are made out of lithium, which makes them small and compact. What type of battery is in a jump starter? Simply put, it should match the starting amps of your car battery. Be sure to look for a battery with 225 or more amps and 900 or more peak amps. Batteries with high peak amps generate more power for your car battery. The device should have sufficient cranking amps and peak amps to start a car during an emergency.
What strength of battery should be in a jump starter?
Here are some frequently asked questions about these devices. They operate as jumper cables but they don't need an extra vehicle to generate the power required to boost the low or dead battery. Jump starters are portable battery devices used to start a vehicle when the car battery is low.
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