Finally..

[maccafan]

..part of the stuff I ordered end of Feb arrived from China:











Still waiting for a few more bits..Hope they arrive by Friday and it'll be my Saturday project fingers crossed..

[Deleted]

I see where your going but isnt the control screw for varying the voltage a bit teeny
nice and tidy though
where did you get the board from

[maccafan]

Mar 28, 2012 18:54:16 GMT @colliwobbles said:

I see where your going but isnt the control screw for varying the voltage a bit teeny
nice and tidy though
where did you get the board from

Yeah..I am planning to cut the non-ink end of a ball point pen refill and press it onto the adjuster to get it out through a hole in box and then put a knob on it..

Board is this one.

Clicky

Gonna use 2 x PP3 to give it about 500 mah..May also put a input jack to power it off a mains charger of sufficient amperage.

[warlordxxx - (Mark)]

Nice work similar to the module i've got for a boost circuit by the looks of it - mines a bit smaller than that though lol but then i also have to build my own - by the looks it's not as big as it seems on the photos as those voltage displays are tiny and they look bigger also - let us know how you get on

[domesticextremist]

So for 8V vaping will you be winding some super high res coils?

[Deleted]

You can buy pot (potentiometer) drivers (screwdrivers) that you could adapt and probably firm in position , I used to get issued with them from one place I worked at but I'm sure Maplins would sell them or similar

[warlordxxx - (Mark)]

Mar 28, 2012 22:08:03 GMT @storm said:

You can buy pot (potentiometer) drivers (screwdrivers) that you could adapt and probably firm in position , I used to get issued with them from one place I worked at but I'm sure Maplins would sell them or similar

I was thinking the same thing they do an adjstment tool which you could cut a ppiece off and attach a knob to should you want to - or you could solder on a seperate pot with adjuster on there already if you're handy with the iron

[maccafan]

Good idea gents .It's for my personal use and I'll try press fitting a refill end first. If not I've got a set of jeweller's screwdrivers and it's fairly easy to adjust..

It wil be big Mark because I am using double PP3 NiMh batteries as I really don't like Lithium batteries. I estimate a size of 100 x 50 x 30mm for the mod. I'll have a play with a few layouts but It won't be much smaller.

Mar 28, 2012 21:56:30 GMT domesticextremist said:

So for 8V vaping will you be winding some super high res coils?

I will probably be vaping in the range of 4.2-4.5 volts Dom with SR carts Dom..I just put that piccy up to show how much it can go upto..Under load I suspect the maximum voltage it will go up to is 6.5 volts as they are rechargeable NiMh rated at 8.25 volts. When fully charged and unloaded they read 9.3 volts.

[vereybowring]

Have you checked what the charge/discharge rate (C) is for the batteries ?
Very important one that as they might not be designed to give the required current under load for extended use which might cause failure.
I know you only plan to use standard resistance at lower voltages but its still something you need to consider.
Mods tend to use Li-ion because they have higher C rating than NiMH or NiCd.

[maccafan]

Thanks Verey.

NiMh batteries do not have a C rating as such like Li-Ion as far as I know. They just try to supply the current on demand and discharge rapidly but safely if the rate of demand is too high. I spoke to a few people in the know and they said to look at the datasheet to guesstimate battery life for a 2 amp demand and 7dayshop.com don't do any.

I did consider the amount of amps that I would be demanding from the battery. As an experiment I put a 510 connector on a old torch and which has 3 x NiMh AA in series as shown here.

allaboute-cigarettes.proboards.com/index.cgi?action=gotopost&board=modding&thread=5775&post=135151
It seems to work well even with 1.8 ohm carts.

So won't know unless I try. The last thing I am going to buy is the box so I could always buy a different box and wire it to 4 x NiZn in series to give me 6.4 volts and step down from that.

Freshly charged they are reading 9.25-9.3 volts unloaded and I am going to use 2 of those in parallel . Since I am stepping down to almost half that I am hoping it will meet the demand and give me a decent battery life,

If it nothing works, I've lost about a fiver and I'll just put it down to experience.

[vereybowring]

All batteries of any type should technically have a C rating even alkaline disposables since they all discharge.

Alas knowing they all have such a rating and getting it from the maker are two different stories.
Sadly discharge/recharge graphs are not commonly about for many batteries sold.

As long as you stay safe - hell I make mods with 18650's and have had a couple of hairy moments (nothing worse than seeing that quick plume of smoke telling you there's a short and having to yank the battery fast).

[maccafan]

That's why I prefer to work with NiMh batteries. NiMh overheat only to about 30 degrees C which is very warm before they die.

Mar 29, 2012 12:35:18 GMT vereybowring said:

All batteries of any type should technically have a C rating even alkaline disposables since they all discharge.

C rating is mainly used for safe charging current and also to "rate" the safe discharge current. So high drain Li-Ion has almost 10C without overheating. Does not mean a non-high drain will not supply 10C, it's just that it will overheat and a overheated Li-Ion is very dangerous thing as you are probably aware.

Even with datasheets you cannot tell what the C rating is for NiMh. Here is a table giving you links to many NiMh datasheets. I haven't looked at them all but I don't think you'll find C rating on any of them.

www.rechargeable-battery-review.com/data-sheets/battery-specs/energizer-battery-data-sheets.html

Whereas with a Li-Ion the C ratings are immediately apparent on the datasheet:

www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_CGR18650CG.pdf

[vereybowring]

I know they may consider them safe but to not include charge/discharge graphs seems to be a bit absurd to me (I was a health and safety officer many years ago).
After all a drain at too high a level on any battery will cause thermal overload of some sort (I've had an alkaline battery come close to exploding on me before now).

Oh well, if you can't get the info you just have to experiment and keep a close eye on things yourself I suppose. Just because technically it should be all right doesn't mean it will be with long term usage.

[vereybowring]

I should also say I don't know if you watch VTTV online but Garry Dibley has been trying quite hard to get Lithium batteries to explode in a mod with no explosions thus far.
On his last attempt he even flattened them with a hammer and they still didn't react violently.

I think they were IMR batteries though in the last couple of shows, but earlier experiments were with protected cells.

[maccafan]

Li-Ion batteries are quite safe and rugged. It's only when they are shorted they become volatile. Even safe chemistry Li-Ion batteries overheat to about 185 to 230 degrees centigrade. It is this propensity to overheat when shorted that makes them susceptible to explosions and such.



As for safety on impact, upto 1300 Mah, you can even penetrate them with a nail using a hammer and nothing will happen. Do the same thing with a 2400 mAh and it's a bomb.

A NiMh will melt the insulation on a 7 x 0.2 wire when shorted but that's about it. You can safely hold one in your hand and short them out and they will get very warm. The trade off is battery life and size thereof. It's not the ideal battery for 8 watt vaping, but if you are willing to swap batteries out every 3-4 hours of heavy vaping, they'll be fine.

My 3 x AA in series mod has been going for a week now and still ok. But I use only for an hour or so, mainly during bedtime. I am not saying that NiMh is better than Li-Ion. It most definitely is not. It's just that I feel safer using them, so if anything goes wrong the consequences are less hazardous.