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Ohms law in regulated mod?
Brighty Offline
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Post: #1
Ohms law in regulated mod?
Hi all

Any ohms law regulated mod experts answer a question?

Conversation on another non vape related forum.
Guy is running a smok alien at 160W with a 0.15ohm coil

Mod screen is reading 160w, 0.15ohm, 5.12v, 32.8 A

He thought he was drawing 32A from each battery

My thought was, no, that's numbers at the coil, so current is being shared by 2 batts, so 16A each. Which would make sense if they were in parallel delivering 3.7v., but this is 5.12v.

But this is a regulated mod with batts in series yes? So batteries are actually giving out 7.4v, so at 160W 7.4v, current is 21.6A, the regulated mod then converts 7.4V/21.6A to 5.12V/32.8A

Is that right? What current is each batt drawing?

Cheers

Brighty
18/05/17 11:01 PM
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Uncle Dave Offline
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Post: #2
RE: Ohms law in regulated mod?
With a little bit of electronics a 3.7V battery can produce a higher voltage at the coil, so the fact that the mod screen is reading 5.12V doesn't mean that the batteries have to be in series. (This can be illustrated by a single battery mod, which can, for example, have a mod screen voltage reading in excess of 6V, despite the battery voltage being approx. 3.7V).

If the batts are in parallel they would share the coil output current (plus losses) approximately equally. i.e. the total current halved.
If the batts are in series they would both be subjected to the full current (plus losses).
18/05/17 11:58 PM
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Barnweld (19/05/17), Ken (19/05/17)
MDC Offline
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Post: #3
RE: Ohms law in regulated mod?
(18/05/17 11:01 PM)Brighty Wrote:  Hi all

Any ohms law regulated mod experts answer a question?

Conversation on another non vape related forum.
Guy is running a smok alien at 160W with a 0.15ohm coil

Mod screen is reading 160w, 0.15ohm, 5.12v, 32.8 A

He thought he was drawing 32A from each battery

My thought was, no, that's numbers at the coil, so current is being shared by 2 batts, so 16A each. Which would make sense if they were in parallel delivering 3.7v., but this is 5.12v.

But this is a regulated mod with batts in series yes? So batteries are actually giving out 7.4v, so at 160W 7.4v, current is 21.6A, the regulated mod then converts 7.4V/21.6A to 5.12V/32.8A

Is that right? What current is each batt drawing?

Cheers

Brighty
Works the same either way - in parallel, twice the current is required, but is split between 2 batteries. As you say, 32.8A is the output current, that drawn by the batteries is not the same, and will go up as the battery voltages drop. Also you should add maybe 10% to the battery current for efficiency losses in the converter and wiring.
19/05/17 07:28 AM
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Barnweld (19/05/17)
Ken Offline
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Post: #4
RE: Ohms law in regulated mod?
I'm an expert but not telling electrical secrets Smiling it's magic really Big Grin

21/05/17 10:41 PM
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