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iStick 100W - series or parallel?
MDC Offline
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Post: #11
RE: iStick 100W - series or parallel?
(07/09/15 08:29 AM)VapeOff Wrote:  
(07/09/15 12:11 AM)JoBo Wrote:  She. Smiling

It's parallel. Uses a boost circuit to get to 10v. Not as efficient as series but perfectly possible. All the iSticks go to 10v and they all have 4.2v batteries.

You don't need to worry about resistance with a regulated mod, as long as it's within the useable range. The coil isn't directly connected to the battery, the chip is demanding the power it needs. The batteries need to supply the power from whatever voltage they have left, with efficiency losses, so a reasonable rule of thumb is:

max amps = max watts/2.5v

and then divide that by the number of batteries. So you need 20a batteries for 100w and the 25Rs are perfect.

I'll admit, I always assumed that you were male JoBo. I stand corrected Smiling

So should the 0.18 coils be safe to use then? I always thought that with a parallel configuration where both batteries are the same, the individual amp limit is doubled, so that two 20A batteries like the 25Rs would effectively be able to provide approx 40A?

No, the regulation (boost/drop) changes that. Basically it's power in = power out minus about 10% for conversion and heat losses.

So, if the converter drop volts the mod can supply more current to the tank than it takes from the batteries and vice versa.

Minimum coil resistance is more a function of how much current the device can supply safely and where the protection circuits kick in.


To allow for worst-case cut out, flat batteries, and a bit of safety margin, multiply the batteries rated amperage by 2.5 to find the maximum power they can supply - here, 2 * 20A *2.5 = 100w. 25r batteries are conservatively rated, so there is plenty of safety margin.


So, as the mod is rated for 0.15 ohms the batteries will be fine. Not sure why you want to go that low, since TC isn't involved.
07/09/15 08:44 AM
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VapeOff Offline
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Post: #12
RE: iStick 100W - series or parallel?
(07/09/15 08:44 AM)MDC Wrote:  
(07/09/15 08:29 AM)VapeOff Wrote:  
(07/09/15 12:11 AM)JoBo Wrote:  She. Smiling

It's parallel. Uses a boost circuit to get to 10v. Not as efficient as series but perfectly possible. All the iSticks go to 10v and they all have 4.2v batteries.

You don't need to worry about resistance with a regulated mod, as long as it's within the useable range. The coil isn't directly connected to the battery, the chip is demanding the power it needs. The batteries need to supply the power from whatever voltage they have left, with efficiency losses, so a reasonable rule of thumb is:

max amps = max watts/2.5v

and then divide that by the number of batteries. So you need 20a batteries for 100w and the 25Rs are perfect.

I'll admit, I always assumed that you were male JoBo. I stand corrected Smiling

So should the 0.18 coils be safe to use then? I always thought that with a parallel configuration where both batteries are the same, the individual amp limit is doubled, so that two 20A batteries like the 25Rs would effectively be able to provide approx 40A?

No, the regulation (boost/drop) changes that. Basically it's power in = power out minus about 10% for conversion and heat losses.

So, if the converter drop volts the mod can supply more current to the tank than it takes from the batteries and vice versa.

Minimum coil resistance is more a function of how much current the device can supply safely and where the protection circuits kick in.


To allow for worst-case cut out, flat batteries, and a bit of safety margin, multiply the batteries rated amperage by 2.5 to find the maximum power they can supply - here, 2 * 20A *2.5 = 100w. 25r batteries are conservatively rated, so there is plenty of safety margin.


So, as the mod is rated for 0.15 ohms the batteries will be fine. Not sure why you want to go that low, since TC isn't involved.

Cheers MDC - between you and JoBo, I can always get the answer that I need Smiling
As for why I'm building coils this low, it's more incidental than anything else... I've run out of 28G wire and other than super thin wire, 24G is all I have right now... I tried using twisted coils for the first time in the velocity when I first got it and the flavour was phenomenal. But I was concerned that 0.18 was damned low and without the proper knowledge, I didn't want to risk it (safety first!)

I took a while deciding that 24G would probably be best for what I needed, but I'm starting to wonder if 26G would actually be a better middleground.

I also want to try out some proper twisted coils and Clapton etc, but I don't own a drill and manual methods don't seem to produce anything near the consistency and quality of a machine-generated coil.
07/09/15 08:51 AM
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MDC Offline
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Post: #13
RE: iStick 100W - series or parallel?
(07/09/15 08:51 AM)VapeOff Wrote:  
(07/09/15 08:44 AM)MDC Wrote:  
(07/09/15 08:29 AM)VapeOff Wrote:  
(07/09/15 12:11 AM)JoBo Wrote:  She. Smiling

It's parallel. Uses a boost circuit to get to 10v. Not as efficient as series but perfectly possible. All the iSticks go to 10v and they all have 4.2v batteries.

You don't need to worry about resistance with a regulated mod, as long as it's within the useable range. The coil isn't directly connected to the battery, the chip is demanding the power it needs. The batteries need to supply the power from whatever voltage they have left, with efficiency losses, so a reasonable rule of thumb is:

max amps = max watts/2.5v

and then divide that by the number of batteries. So you need 20a batteries for 100w and the 25Rs are perfect.

I'll admit, I always assumed that you were male JoBo. I stand corrected Smiling

So should the 0.18 coils be safe to use then? I always thought that with a parallel configuration where both batteries are the same, the individual amp limit is doubled, so that two 20A batteries like the 25Rs would effectively be able to provide approx 40A?

No, the regulation (boost/drop) changes that. Basically it's power in = power out minus about 10% for conversion and heat losses.

So, if the converter drop volts the mod can supply more current to the tank than it takes from the batteries and vice versa.

Minimum coil resistance is more a function of how much current the device can supply safely and where the protection circuits kick in.


To allow for worst-case cut out, flat batteries, and a bit of safety margin, multiply the batteries rated amperage by 2.5 to find the maximum power they can supply - here, 2 * 20A *2.5 = 100w. 25r batteries are conservatively rated, so there is plenty of safety margin.


So, as the mod is rated for 0.15 ohms the batteries will be fine. Not sure why you want to go that low, since TC isn't involved.

Cheers MDC - between you and JoBo, I can always get the answer that I need Smiling
As for why I'm building coils this low, it's more incidental than anything else... I've run out of 28G wire and other than super thin wire, 24G is all I have right now... I tried using twisted coils for the first time in the velocity when I first got it and the flavour was phenomenal. But I was concerned that 0.18 was damned low and without the proper knowledge, I didn't want to risk it (safety first!)

I took a while deciding that 24G would probably be best for what I needed, but I'm starting to wonder if 26G would actually be a better middleground.

I also want to try out some proper twisted coils and Clapton etc, but I don't own a drill and manual methods don't seem to produce anything near the consistency and quality of a machine-generated coil.
I'd invest in some thinner wire. Although the mod is rated for it, you are quite near the limit. As JoBo and others have said, it's preferable to run higher volts and higher resistances if it works for you, as you are reducing heat losses and stress in the mod electronics. It also makes the coil more tolerant of less than perfect contacts.

If you want a drill, take a look around ASDA - my local store always seems to have cheap (< £20) variable speed battery powered drills in the miscellaneous section. They probably aren't brilliant for hard use, but should be great for coil winding.
07/09/15 09:15 AM
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VapeOff Offline
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Post: #14
RE: iStick 100W - series or parallel?
Weird... The 25r pair in my istick 100w were running low, so I put them on the XTAR to charge. Bear in mind that these batteries have only ever been used together, charged together and I often swap which terminals they're in in the istick as recommended for parallels... Both batteries were connected to the charger at exactly the same time.

The charger is showing one battery after about 20 mins as having charged 778mah and being at 3.9v, whereas the second battery only charged by 384mah and is already fully charged at 4.2v...

If the istick is using the batteries in parallel, shouldn't they be sharing the load between them, in which case both batteries would have near identical charges? :/
10/10/15 11:19 AM
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JoBo Offline
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Post: #15
RE: iStick 100W - series or parallel?
Yes. Did you check their voltages coming out of the mod?

Pairing is no guarantee of well matched batteries, so it could be that one is weaker, but if it hasn't happened before it might be summat else. Cllean all contacts and batteries and keep an eye on them. Could also be a charger issue.
10/10/15 11:25 AM
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AlmostAMyth Offline
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Post: #16
RE: iStick 100W - series or parallel?
I know this is an old thread but I just got an iStick 100w and I was wondering the same thing. I'm no battery or electronic techie but I do know of a couple of very easy ways to tell whether your dual battery mod is running in series or parallel.

First look for a physical connection between the two battery terminals on the same side. If you can see that the bottom two posts (for example) are connected to each other then your battery orientation will tell you which way it's set up. Both batteries facing the same direction means parallel. Batteries facing opposite directions means series. This method doesn't work with the iStick 100w because the battery terminals protrude from the casing.

Another easy way to tell is to first remove the tank. Then remove one of the batteries. Press the fire button. If the display lights up then your mod is running in parallel. I personally wouldn't vape using only one battery on a mod designed for two, but it can be done if your mod is set up in parallel. Not sure if it's unsafe because like I said earlier, I'm no techie on this stuff. If your display doesn't light up then it's running in series.

Both batteries need to be installed for a series unit otherwise the connection is incomplete. In parallel the connection is complete with just one battery but the power output would be reduced by 1/2.
02/01/17 04:09 AM
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MDC Offline
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Post: #17
RE: iStick 100W - series or parallel?
(02/01/17 04:09 AM)AlmostAMyth Wrote:  In parallel the connection is complete with just one battery but the power output would be reduced by 1/2.
Not necessarily so. The mod will still try to put out the same power, but thrash the battery harder.

One high drain fully charged 18650 doing 100w will very quickly go into low voltage protection, due to the volt drop across the battery internal resistance.
02/01/17 11:25 AM
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AlmostAMyth Offline
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Post: #18
RE: iStick 100W - series or parallel?
(02/01/17 11:25 AM)MDC Wrote:  
(02/01/17 04:09 AM)AlmostAMyth Wrote:  In parallel the connection is complete with just one battery but the power output would be reduced by 1/2.
Not necessarily so. The mod will still try to put out the same power, but thrash the battery harder.

One high drain fully charged 18650 doing 100w will very quickly go into low voltage protection, due to the volt drop across the battery internal resistance.

Ok, the power input would be reduced by half. Like I said, I'm not a whiz with the technical end of this stuff. The examples I gave were meant only to determine a series or parallel setup. I don't recommend anyone vape with a single battery in a mod designed for two. That's why I said to first remove the tank before running the power up test.
(This post was last modified: 02/01/17 02:47 PM by AlmostAMyth.)
02/01/17 02:39 PM
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