Some NiMh battery configurations

[kosliev]

I've decided to shy away from Lithium based batteries, I've had an evercool for more than a year, running two 14500 AW IMR that I treated religiously, and to be honest, I don't need the discharge rate, NiMh are pretty much safer, for the simple reason that no lithium is involved, the 600mAh of IMR leaves a lot to be desired and I'm more than sure I don't want anything to do with lithium cobalt.

Since I'm gonna spend the equivalent of 80$ in batteries+charger(..+shipping), I figured I'd make up my mind on what battery configuration to go for.

Needless to say, I'm heavily biased towards #5, since its "relatively" compact (honestly, its gigantic and will probably weight around 200grams), it can deliver 5V for a very long time, and the wattage is just right for my tastes with a 3~3.5 ohm atom, in other words, the evercool spoiled me.

Figured the image could help someone else, or I could get some insight (maybe theres some mistakes too).

Lastly, I will not make battery packs, I'll still charge batteries one by one in a single channel charger.

edit. Right click on the image and hit "view image".

 

[Stosh]

I've been using version #4 for quite a while now, usually with a 2.8-3.2 ohm coil. Good vape, safe recharging, and I regulate the voltage to the carto with my thumb If it's too much fresh off the charger, let go of the button sooner or pulse it, only hold it long enough to get a good output. For my higher voltage demanding cartos (like the 2.0 ohm dual coils) I use NiZn 1.6v AA batteries, the voltage is fine when the watts are divided over two coils.

 

[johnpencraig]

This is excellent work - I've been mulling over the same questions, but havn't put it down on paper(!) so clearly.
Thanks.

 

[kosliev]

Don't have NiZn and sadly they arent easy to get a hold of.
Anyways, I have a few PTR08060WVD's lying around, so I was checking what Rset to use for a "maxed" 5.5V output, and then I notice this on the pdf:

"The minimum input voltage is 4.5V or (Vout/0.83) V, whichever is greater"

So depending how strict that is, if I wanted to run 5.5V, my Vin would have to be 5.5v/0.83= 6.6V (which is not always the case as the batteries get drained and are barely at 1.2V each, under load).
Ah well, I can stick to safer 4.8V Vout, so that Vin has to be 5.8V, and call it a day.

Anyways, 5V uses a 270ohm resistor (commercial value), 4.8V needs a 280ohm one, these aren't sold commercially, however you can make one by having two 560ohm (commercial value), ones in parallel.

Then again the accuracy rating might be so terrible you're better off buying a bunch of 270 and finding one around 280 with the tester

 

[grantemsley]

I've done 4 nimh batteries with no regulator before. Search my posts for my noma usb charger mod and you should find the pics i posted. It worked quite well and lasted a long time between charges. If you do it make sure the fire switch is high quality and easily replacable. Even the higher quality switches i got eventually (after 3-6mo) wore out and built up a 3-5ohm resistance inside the switch killing performance.

Just make sure you use high quality batteries. Cheap nimh ones either only last a few hours or have too much of a voltage drop under load. With the powerex ones i use i believe it ran at about 4.2-4.5v on a standard atty and fresh batteries.

Sent from my Transformer Prime TF201 using Tapatalk 2 Beta-h6

 

[johnny bobcat]

I've been using version #4 for quite a while now, usually with a 2.8-3.2 ohm coil. Good vape, safe recharging, and I regulate the voltage to the carto with my thumb If it's too much fresh off the charger, let go of the button sooner or pulse it, only hold it long enough to get a good output. For my higher voltage demanding cartos (like the 2.0 ohm dual coils) I use NiZn 1.6v AA batteries, the voltage is fine when the watts are divided over two coils.

That's so funny, I use the same setup and use the exact same method to regulate vaping temperature, I also tried the nizn's but they kept blowing my atties.

 

[Stosh]

Using the NiZn you can use just 3 batteries instead of 4.

Just measured mine after a few hours vaping on them so not fresh off the charger 3.0 ohm Nova, 5.15 V unloaded, 4.55 V loaded, so about 7 watts. With the tops coil Nova its plenty of power....

 

[Lonnie Lepp]

Thanks for publishing this

I have been toying with using more or less than 4 NIMH batts with a PWM like the eGo board.