My first mod 5.26 Volt

and I reckon my estimated 1.1v per cell is pretty close then..


this

makes noooo sense to me..

 

You could try just using 3 cells and shorting out the last slot.
To do a load test you would need to measure it on the switch output and ground ..

The graph noe posted shows a good quality cell has an internal resistance of about 40mΩ .. so 0.16Ω total for the 4 batts, (if they are new and good quality) then add all the contact resistances, wires,switch and connector resistances in and you get the real series mod resistance. A cheaper cell is going to be 3 or more times that though.
The internal cell resistance on older batterys is nowhere near linear either, drawing a larger current will drop off the voltage a lot more than just internal resistance would indicate.

 

What I meant was, you are still going to run into ohms law, so if you have a given resistance and make the voltage variable, then you will need to also vary the amps to make ohms law true for the new voltage. This means if you lower the voltage you increase the amps to supply the needed power.

 

ok, that makes even less sense ...

I think, you are working backwards from the wattage ? ..
you can't do it that way, ohms law sorts itself out, you CAN'T alter the amps up while lowering the voltage for a constant resistance. Thats impossible.

In this case resistance is a constant (at least it is outside the cells), drop the voltage and the current drops. always.

So ignore the 17W that was mentioned earlier, it exists nowhere but in text form.
i suggested that all going well, you would get maybe 4.4v on a 2ohm atty and the numbers in my head that I don't actively think about said 10W .. just ran em on a calculator and its 9.68W .. damn,I'm good

there was another number chucked out working on my voltage and an atty closer to 1.2Ω ..

now it gets very dependant on cell quality and contacts etc .. so considering ebay batterys, thin wires, average contacts and an unknown switch .. I would chuck out 0.9v now per cell.
3.6v total .. running that in a calculator .. 10.8W

I stand by my estimation of around 10W whether its 2Ω or 1.2Ω.

judging by the cell life mentioned now of 75 to 100 puffs, these are not good cells and likely worse than the above.

personally I find the syringe mod more interesting and likely to outperform this in voltage even though its only a single cell of 3.6v.

each to his own though and modding is always fun and worthwhile as an exercise.

 

Gah yeah I got it mixed up in my head... back to ohms law school for me

Anyway using the ohms law calculator here: PV Web Apps
It appears that if this mod is getting 3.6v under load, then on a 1.1ohm coil, the amp draw is 3.3A, watts 11.8W.
So those batts could only be 500mah -1000mah capacity & will run constantly for less than 10 minutes before needing to recharge, .comging by it lasting 75-100 puffs, using 4secs for an average puff.

 

its all just guesswork without under load tests. pointless speculating really.

one cell could be 0.3v under load for eg .. thats the other problem with using 4 cells, only need one crap one for mostly fail.
the oft quoted 'memory effect' is just that IMO, just the pack getting out of balance. The manufacturers run with it since it makes it sound like the users .comlt, when in reality even nicad packs could do with a balance charger. The theory is they attempt to overcharge every cell in the pack as unlike lithiums its not an explosion, it just happens to reduce lifespan and hey presto they sell more cells.

 

Or like I did with some NiMH batts once. Put them on to charge, forget about them & they overheat, burst their casing & leak acids/alkalines into the charger corroding the terminals on the charger & make you have to buy a new charger & batts.
Stupid charger was supposed to cut out but continued to "trickle charge", now I am much more careful with lithium cells.