Cuboid vs RX200
- Thread starter WARMACHINE
- Start date
Can someone please explain what exacly @shaunnaddan meant when he typed below:
"what does this have to do with my battery drain?
if you had a 0.5ohm coil and your pushing 50w on a single 20A battery (Samsung 25R) >
you would be using 11.9A with your battery limit being 20A
the same build on a dual 18650 parallel mod >
you would be using 11.9A of current with a battery limit of 40A
the same build on a dual 18650 series mod (double the battery voltage value) >
you would be using 5.95A of current with a battery limit of 20A
*since the amp draw is less the battery life will be much better than a single 18650 even though the mah is the same"
The two bold parts are what's confusing me. The way I had initially understood it was because your now drawing half the current (A) your using less battery power ie. battery should last longer.
"what does this have to do with my battery drain?
if you had a 0.5ohm coil and your pushing 50w on a single 20A battery (Samsung 25R) >
you would be using 11.9A with your battery limit being 20A
the same build on a dual 18650 parallel mod >
you would be using 11.9A of current with a battery limit of 40A
the same build on a dual 18650 series mod (double the battery voltage value) >
you would be using 5.95A of current with a battery limit of 20A
*since the amp draw is less the battery life will be much better than a single 18650 even though the mah is the same"
The two bold parts are what's confusing me. The way I had initially understood it was because your now drawing half the current (A) your using less battery power ie. battery should last longer.
V=IR
Voltage = Current * Resistance
Power = IV
Power = Current * Voltage
For parallel
50W output = 50W Input = 3.6V * xA
xA = 50W/3.6V = 13.9A (From both batteries together)
For series
50W output = 50W Input = 7.2V * xA
xA = 50W/7.2V = 6.9A (Per battery
Basically, ignore ohms for now. Just think of watts, it's WAY simpler that way due to how our mods work.
Voltage = Current * Resistance
Power = IV
Power = Current * Voltage
For parallel
50W output = 50W Input = 3.6V * xA
xA = 50W/3.6V = 13.9A (From both batteries together)
For series
50W output = 50W Input = 7.2V * xA
xA = 50W/7.2V = 6.9A (Per battery
Basically, ignore ohms for now. Just think of watts, it's WAY simpler that way due to how our mods work.
How does this relate to battery drain though Mike? ie. does it help or not make any difference? I use my RX in wattage mode almost exclusively so I'll stick to your advise.
1x 2500mAH battery = 2500 mAh battery life @ 3.7V
2x 2500mAH batteries in series = 5000mAH battery life @ 3.7V
2x 2500mAH batteries in parallel = 5000mAH battery life @ 3.7V
It's a bit of a misnomer to say that you get better battery life from either series or parallel, as nowadays with very low ohm coils being the norm, most of the time you're running a small buck or a small boost, so there's not too much efficiency loss. Even so, efficiency only accounts for roughly 10%. The temperature of your batteries will probably have more of an effect on "battery drain" than series or parallel. Parallel is also really convenient due to not requiring matched batteries.
2x 2500mAH batteries in series = 5000mAH battery life @ 3.7V
2x 2500mAH batteries in parallel = 5000mAH battery life @ 3.7V
It's a bit of a misnomer to say that you get better battery life from either series or parallel, as nowadays with very low ohm coils being the norm, most of the time you're running a small buck or a small boost, so there's not too much efficiency loss. Even so, efficiency only accounts for roughly 10%. The temperature of your batteries will probably have more of an effect on "battery drain" than series or parallel. Parallel is also really convenient due to not requiring matched batteries.
I am not sure this is correct @Mike. In series you AH should be the same as for 1 battery?
Again, I think you have it wrong. 2 X 2500mAh in series = 2500mAh?
Please look closely, I specifically wrote @ 3.7V which suggests BOTH are regulated to 3.7V. In that scenario, they realistically perform around the same due to the lower current draw required to get 3.7V out of a 7.4V source.
Back to the original question...
I got my Cuboid today, so far, so good. I like the weight and how it feels in my hand. Only downside is I cut the bloody silicone sleeve when cutting open the packaging! Ain't that a b*tch.
I got my Cuboid today, so far, so good. I like the weight and how it feels in my hand. Only downside is I cut the bloody silicone sleeve when cutting open the packaging! Ain't that a b*tch.
Also, I went and worked out what it would cost me to get the rx setup and it was not good news. Mod, 4port charger, 6 new 18650's (3 - 3 married). Not a nice total. I would keep that in mind if I were you...
Nope, not my understanding, but I am no expert. Two batteries in parallel should always give you better battery life than two batteries in series, even @ 3.7V for both sets?
@Andre that shouldn't be the case. A battery has a certain amount of power it puts out per charge = Watt Hours. That doesn't really change that much irrespective of whether you're drawing 0.1A or 10A from them. There is some debate as to efficiency (bucking and boosting etc). I'm fairly sure - and I have studied some electrical modules. We can always check with @johan as he will be able to confirm without a doubt
Here's a bit more discussion after doing a quick google of "series vs parallel regulated mod battery life"
http://discourse.theohmpage.com/t/battery-life-series-vs-parallel-im-confused/939/5
Here's a bit more discussion after doing a quick google of "series vs parallel regulated mod battery life"
http://discourse.theohmpage.com/t/battery-life-series-vs-parallel-im-confused/939/5
@Mike & @Andre, I don't know how the internals operate of the rx200, but irrespective of buck boost, step down or sepic topology (can step and/or down), parallel connected batteries will always deliver longer vape time than series connected.
Simple example:
1. Series connected 3.7Vnominal // 2500mAh // 20A constant current
Simple example:
1. Series connected 3.7Vnominal // 2500mAh // 20A constant current
- Total voltage output (from batteries): 7.4Vnominal
- Total constant current (from batteries: 20A
- Total capacity (from batteries): 2500mAh
- Total voltage output (from batteries): 3.7Vnominal
- Total constant current (from batteries: 40A
- Total capacity (from batteries): 5000mAh
@johan what we're discussing is series vs parallel in regulated mods.
Let's say we're using an output of 5V. That way the parallel needs to boost and the series needs to buck.
The parallel will give us 5000mAh at 3.7V. Or 18.5WH
The series will give us 2500mAh at 7.4V. Or 18.5WH
In the parallel mod at 50W, we'll need the set to give us (50W/3.7V=) 13.5A
Or an input of 13.5A at 3.7V
In the series mod at 50W, we'll need the set to give us (50W/7.4=) 6.75A
Or an input of 6.75A at 7.4v
So from this we can tell that the series combo will only draw half the current. In this way, the 2500mAH is only drained half as quickly as the 5000mAH. So realistically, the 96% vs 93% efficiency of bucking vs boosting can be ignored and we see that parallel and series in a regulated mod is mostly equal.
Let's say we're using an output of 5V. That way the parallel needs to boost and the series needs to buck.
The parallel will give us 5000mAh at 3.7V. Or 18.5WH
The series will give us 2500mAh at 7.4V. Or 18.5WH
In the parallel mod at 50W, we'll need the set to give us (50W/3.7V=) 13.5A
Or an input of 13.5A at 3.7V
In the series mod at 50W, we'll need the set to give us (50W/7.4=) 6.75A
Or an input of 6.75A at 7.4v
So from this we can tell that the series combo will only draw half the current. In this way, the 2500mAH is only drained half as quickly as the 5000mAH. So realistically, the 96% vs 93% efficiency of bucking vs boosting can be ignored and we see that parallel and series in a regulated mod is mostly equal.
I agree 99% with your explanation Mike, the 1% is totally topology and efficiency related
.
Thanks guys. I feel a glimmer of understanding. Let me digest that and try to apply it to my own situation vis a vis an iStick 100W (parallel) vs the Cuboid (series), vaping at between 15 and 25 W.I agree 99% with your explanation Mike, the 1% is totally topology and efficiency related
So let's see if I got this correct this time. 2x 2500mah batteries connected in parallel (5000mah) will last about the same time as the same batteries connected in series. So even though the series has only 2500mah, the series batteries draw half the current that parallel draws at the same wattage.
I hope I got it right this time
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I hope I got it right this time
Sent from my SM-G920F using Tapatalk
Hahahahaha
So much maths going on here, feels like I'm in school again.
I don't really worry too much about how long a battery will last at certain watts.
When your battery is flat swop it out and charge ☺.
But that's just me.
So much maths going on here, feels like I'm in school again.
I don't really worry too much about how long a battery will last at certain watts.
When your battery is flat swop it out and charge ☺.
But that's just me.
The water analogy for electricity works for explaining the mysteries thereof most of the time...
Imagine your 18650 is a cubic metre of water.
Parallel scenario: A tank is one metre tall and holds 2m³ of water
Series scenario: This tank also holds 2m³ of water but is 2m tall - hence thinner than the parallel tank
A hose with a valve is attached to a hole at the bottom of each tank. The parallel tank's hose will squirt a certain distance when the valve is fully opened. The series tank, when the valve is opened will squirt further because the head of water is twice that of the parallel tank. In order for the series tank to squirt the same distance as the parallel tank you need to close the valve somewhat - that's the regulator. (pressure equates to voltage, volume equates to current)
Both tanks will run empty at about the same time, just like your REGULATED mod with either series or parallel cells for the same wattage output.
Imagine your 18650 is a cubic metre of water.
Parallel scenario: A tank is one metre tall and holds 2m³ of water
Series scenario: This tank also holds 2m³ of water but is 2m tall - hence thinner than the parallel tank
A hose with a valve is attached to a hole at the bottom of each tank. The parallel tank's hose will squirt a certain distance when the valve is fully opened. The series tank, when the valve is opened will squirt further because the head of water is twice that of the parallel tank. In order for the series tank to squirt the same distance as the parallel tank you need to close the valve somewhat - that's the regulator. (pressure equates to voltage, volume equates to current)
Both tanks will run empty at about the same time, just like your REGULATED mod with either series or parallel cells for the same wattage output.
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Im basing this on my knowledge of auto electrics. 24 volt is much better for cranking than 12 volt as its cranks faster. So if u need to crank an engine fast use 24v. I have a digger that is a pain to start when hot. If i connect a battery parallel to it 12v then it doesnt have the cranking speed to start but if i conect it in series then it starts. So series is better for higher wattages and parallel is better for lower wattages. Batteries charge better in parallel as well. I might be wrong i hope not i forgot the pinch of salt
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Sent from my SM-N9005 using Tapatalk
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