I ran across this message from our engineering team as to why we recommend using high drain batteries.
Yes, this is a technical explaination and my head almost exploded trying to understand it fully. However, I wanted to share it with everyone out there.
Shoot. I'm sure there are many out there that can 'grok' this better than me... and perhaps put it into easier to understand terms?
Why does the Provari need to use HD (High Drain) batteries?
The Provari uses an internal dc/dc converter that continuously monitors the output to the atty load and maintains a constant voltage with
an output current limit of 3.5 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 4.0 volts at 3.5 amps into an atty load, that calculates to be 14 watts.
That means the battery has to supply 14 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 14 watts / 3.7 volts or 3.78 amps minimum. Because nothing is 100% efficient, lets add that in. Most Provari devices
are 90% to 95% efficient. Picking the worst case, 90%, the battery current must now need to be 3.78 amps/ .9 = 4.20 amps. That is a more realistic current draw,
But wait, it could be even higher. WHY? Look at what happens when the battery voltage droops lower than 3.7 volts. At 3.5 volts the battery current goes up to 4.44 amps.
But wait, 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 4.86 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. REALLY, the battery needs to supply pulsed currents of over 9 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. Next time you look at the battery specification you are buying, see what it says its internal
impedance is. Do the math. Better yet we have done the math AND we have tested what is available. If it won't match up to the demands of the converter in the Provari
we won't sell it.
But wait, 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 due to the higher internal resistance causes them to shut down early. So if you think you are getting 2500 maH out of a battery with that rating you would be wrong.
Just remember, the Provari, when adjusted to full power out, can supply 6.0 volts at 2.42 amps. That is 14.5 watts. What happens to all these calculations when the output power is now
14.5 watts? This exercise is left for those inclined to want to know.
Provape Engineering
Yes, this is a technical explaination and my head almost exploded trying to understand it fully. However, I wanted to share it with everyone out there.
Shoot. I'm sure there are many out there that can 'grok' this better than me... and perhaps put it into easier to understand terms?
Why does the Provari need to use HD (High Drain) batteries?
The Provari uses an internal dc/dc converter that continuously monitors the output to the atty load and maintains a constant voltage with
an output current limit of 3.5 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 4.0 volts at 3.5 amps into an atty load, that calculates to be 14 watts.
That means the battery has to supply 14 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 14 watts / 3.7 volts or 3.78 amps minimum. Because nothing is 100% efficient, lets add that in. Most Provari devices
are 90% to 95% efficient. Picking the worst case, 90%, the battery current must now need to be 3.78 amps/ .9 = 4.20 amps. That is a more realistic current draw,
But wait, it could be even higher. WHY? Look at what happens when the battery voltage droops lower than 3.7 volts. At 3.5 volts the battery current goes up to 4.44 amps.
But wait, 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 4.86 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. REALLY, the battery needs to supply pulsed currents of over 9 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. Next time you look at the battery specification you are buying, see what it says its internal
impedance is. Do the math. Better yet we have done the math AND we have tested what is available. If it won't match up to the demands of the converter in the Provari
we won't sell it.
But wait, 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 due to the higher internal resistance causes them to shut down early. So if you think you are getting 2500 maH out of a battery with that rating you would be wrong.
Just remember, the Provari, when adjusted to full power out, can supply 6.0 volts at 2.42 amps. That is 14.5 watts. What happens to all these calculations when the output power is now
14.5 watts? This exercise is left for those inclined to want to know.
Provape Engineering
