.Why does the ProVari need to use high drain
batteries (the full technical answer)?
The ProVari uses an internal DC/DC converter that continuously monitors the output to the atomizer load and maintains a constant voltage with an output current limit of 2.5 amps ( each unit is tested to this limit in production, most exceed this limit by .1 to .2 amps). This output voltage is usually higher than the input battery voltage, depending on what the ProVari is adjusted to.
Battery output current is NOT the same as ProVari output current.
Here is an example that shows why. When the ProVari is putting out 5.0 volts at 2.5 amps into an atomizer load, that calculates to be 12.5 watts.
That means the battery has to supply 12.5 watts to the ProVari, at a minimum. In reality it is more because nothing is 100% efficient.
If the battery voltage is 3.7 volts it will need to supply 12.5 watts / 3.7 volts or 3.378 amps minimum. Because nothing is 100% efficient, let's add that in. Most ProVari devices are 90% to 95% efficient. Picking the worst case, 90%, the battery current must now need to be 3.378 amps/ .9 = 3.75 amps. That is a more realistic current draw, but it could be even higher.
WHY?
Let's take a look at what happens when the battery voltage droops lower than 3.7 volts. At 3.5 volts the battery current goes up to 3.968 amps.
But it can be even higher still when the battery droops to near end of charge, say 3.2 volts. The battery output current now goes to 4.34 amps. And we have to keep in mind that this is ONLY the average current. Because the ProVari converter is a pulsing device, the pulsed battery current can be a factor of 2 higher than the average current.
The battery needs to supply pulsed currents of over 8 amps. These engineering calculations show why you need a high quality, Low Internal resistance battery to supply what the ProVari converter needs.
Where does the internal resistance come into play? According to ohms law, when you are drawing 1 amp out of the battery , the battery voltage will droop .1 volts for every .1 ohms of battery internal resistance.
At 4 amps this means the battery voltage is no longer 3.7 volts but 3.3 volts.
If it won't match up to the demands of the converter in the ProVari , We won't sell it. This is why we recommend using AW red high drain
batteries only!.
They have passed all our tests and are rated to work with the full range of voltages that the ProVari can offer.
Why do the cheap
batteries work at all?
They work when the output is not adjusted to supply high power. They 'get by' running at low power but the full capacity of the battery is never available because of the voltage droop. This is due to the higher internal resistance causing them to shut down early. To avoid problems, only use the approved batteries that we recommend.
Are Li-ion Batteries Safe and which ones should I use?
The amount of power required to run an eCig requires a battery that can store a large amount of energy and deliver that energy on demand rapidly. Because of this requirement lithium ion batteries are the best choice. We all need to respect the amount of energy in these batteries.
But are they safe?
We all hear about the occasional incident where a battery fails in a violent way. This is caused by a short circuit within the cell or if stacked cells are used, one cell can discharge into the other with high discharge rates when one cell depletes its energy before the other.
A mild short will only cause an elevated self-discharge. Little heat is generated because the discharging energy is very low.
If, however, for whatever reason any of the following conditions happens;
1. Internal short circuit
2. Excess external charge current
3. Excess external discharge current
4. Environment conditions
The temperature can rise to the point where thermal runaway can happen that results in 'venting with flame.'
There are two basic types of lithium-ion chemistries: cobalt and manganese (spinel). Typical battery chemistry mixes are cobalt, nickel, manganese and iron phosphate.
Lithium-ion cells with cobalt cathodes should never rise above 130°C (265°F). At 150°C (302°F) the cell becomes thermally unstable, a condition that can lead to a thermal runaway in which flaming gases are vented. To achieve maximum runtime, cell phones, digital cameras and laptops use cobalt-based lithium-ion. Because of the lower temperature whereby the cell becomes thermally unstable, electronic protection circuits are added.
Manganese is the newer of the two chemistries and offers superior thermal stability. It can sustain temperatures of up to 250°C (482°F) before becoming unstable. In addition, manganese has a very low internal resistance and can deliver high current on demand. It is these two features that make this battery the best choice for use in the ProVari. The drawback of spinel is lower energy density. Typically, a cell made of a pure manganese cathode provides only about half the capacity of cobalt. The higher inherent safety of the spinel system permits the exclusion of the electric circuit in the battery. In the ProVape eCigs we incorporate the protection circuit into the eCig thus providing an added layer of safety. We know of NO safer combination then to use the manganese lithium ion battery with the ProVape eCig.
The AW IMR type cells that we carry use the manganese chemistry and are the safest of the lithium chemistry types.
The higher capacity cells use the cobalt chemistry with the electronic protection circuit.
The ultimate in safety is to have multiple redundant safety layers whereby if one layer of safety fails the other layer prevents an unsafe condition. This is what we strive for at ProVape, even if it means more internal components with its associated higher cost.
Asia produces many non-brand replacement batteries that are popular with users because of low price. Many of these batteries don't provide the same high safety standard as the main brand equivalent. A wise shopper spends a little more and buys a higher quality battery with its higher level of safety.
It is NOT recommended you use an unidentified lithium-ion battery from an Asian source.
As a consumer, you are in a position to select the highest quality and safest equipment. With each purchase, ask yourself,Are a few pennies or dollars saved worth the safety risk? Ultimately, your personal safety is in your hands with the equipment you buy.
Today, lithium-ion is one of the most successful and safe battery chemistries available. Two billion cells are produced every year. But be aware that there are several lithium ion battery chemistries being sold in the market. Some are safer than others.
Considering the number of lithium-ion batteries used on the market, this energy storage system has caused little harm in terms of damage and personal injury. In spite of the good record, its safety is a hot topic that gets high media attention whenever an incident occurs.
