A pdib mod :>p

[ChrisEU]

Ok - here's what I got.

I bought the fuses in wrong denominations,
13A at 16V is 203 Watts - takes far too long to trip, I didn't even try this one.
10A at 16V is 160 Watts - it did trip, but the delrin button was melted in the process (I used an old one).

then there are some in the middle that I do not have (yet)

then:
3A at 6V is 18 Watts - and this trips around 0.7-0.8 ohms - A bit too whimpy.

Going to order a couple more "in between" denominations.

But the principle works - I used a full AW IMR 1600 and a 1.2ohm RM2. With standard setup I got around 3.65 Volts at the atomizer (measured with an inline meter), once I put a PTC on the spring (one lead under the spring, one lead touching the battery negative) I got around 3.82V with the same meter and atomizer. A noticable difference.

Now the fuse I used for that is not safe to use, because it is too big, but once I have a smaller one, it will work fine.

PTC under the bottle:

I didn't want to have an unsafe setup, so I put another fuse in the circuit: the little SMD one (3A, 6V). You can see it as the firing pin in this picture. I put a new, unchanged one beside the mod so you can see it.

I could glue or weld that on the firing pin and replace the spring with a no-resistance one.

Now with this setup I have great conductivity - and safety, because the little SMD fuse trips at below 0.8 ohms.

 

[pdib]

Chris! This is looking promising! I'm glad you kept at it! Ideal, I think, would be a fuse that trips at 40 watts. Personally, I'd be good with 30 watts (but, I think 40 is still a safe trigger point and allows for a little elbow room). As I see you are still looking at options to get, and try; I would ask that you keep your eyes peeled for something like: 6A, 6V or 10A, 4V (I don't know how they build, rate them; but of course 10A, 3.7V would be the cat's meow!)

Again, thank you! This is extra-double good stuff!

 

[ChrisEU]

They come at curious ratings: 6V, 15V, 16V, 60V, 600V and a few in between. They are often used in battery pack applications, but we're only talking about single cells here, not packs, so I have to play around with the ratings. The most promising I see so far is the same type as the 3A 6V one, but rated at 2.5A 15V. That would give us 37.5W @ around 0.08Ohm max resistance (Edit: 0.03 rated, normal), if it works as expected.

The contact of the SMD part actually makes a good contact to the battery, even if that's clearly not what it is designed to do =) My Grand feels quite powerful with this setup - and it is still safe.

These things work with heat (the heat changes the internal molecular structure) so I am hoping I can actually go by the power (watts). Before I release this with all the details, I will contact a manufacturer and see what they tell me.

Next stop: Find a good spring replacement with low resistance - without using a dremel and a machine screw, preferrably =)

 

[MamaTried]

They come at curious ratings: 6V, 15V, 16V, 60V, 600V and a few in between. They are often used in battery pack applications, but we're only talking about single cells here, not packs, so I have to play around with the ratings. The most promising I see so far is the same type as the 3A 6V one, but rated at 2.5A 15V. That would give us 37.5W @ around 0.08Ohm max resistance (Edit: 0.03 rated, normal), if it works as expected.

The contact of the SMD part actually makes a good contact to the battery, even if that's clearly not what it is designed to do =) My Grand feels quite powerful with this setup - and it is still safe.

These things work with heat (the heat changes the internal molecular structure) so I am hoping I can actually go by the power (watts). Before I release this with all the details, I will contact a manufacturer and see what they tell me.

Next stop: Find a good spring replacement with low resistance - without using a dremel and a machine screw, preferrably =)

are these the ones or similar to the ones you're testing?

i found some 6V 8A SMDs somewhere but that felt too high

 

[ChrisEU]

Yes, they are similar. The littelfuse ones in that link have their contacts on either side, though. They really are made for SMD soldering. I am using either radial ones, that have legs to use alongside a spring or the type that has the contacts on the top and bottom, so they can be attached to the firing pin.

6V 8A sounds about right - 48 watts, thats ok for a few seconds with a good battery. But I have yet to find one with this rating.

 

[chohan]

Ok - here's what I got.

I bought the fuses in wrong denominations,
13A at 16V is 203 Watts - takes far too long to trip, I didn't even try this one.
10A at 16V is 160 Watts - it did trip, but the delrin button was melted in the process (I used an old one).

then there are some in the middle that I do not have (yet)

then:
3A at 6V is 18 Watts - and this trips around 0.7-0.8 ohms - A bit too whimpy.

Going to order a couple more "in between" denominations.

But the principle works - I used a full AW IMR 1600 and a 1.2ohm RM2. With standard setup I got around 3.65 Volts at the atomizer (measured with an inline meter), once I put a PTC on the spring (one lead under the spring, one lead touching the battery negative) I got around 3.82V with the same meter and atomizer. A noticable difference.


PTC under the bottle:

Which PTC is this?

Is it the RGEF1000?

RGEF1000 TE Connectivity / Raychem | Mouser

That one is 10A at 16V (unless I'm reading that wrong?) so what is the part number for the 3A at 6V PTC?

 

[ChrisEU]

Update: This proves to be a bit more complicated. I was told by a manufacturer that I can not use the power (in Watts) to determine the correct PTC - the original idea of using the Ihold value (in Amps) and the nearest voltage value was correct.

I used my modded Grand for a while and changed the coil on the RM2 to a 1.0 ohm one. I noticed the small PTC (3A 6V) tripping and shutting down the power on long drags at around 3.8 amps. The 1.2 ohm coil wasn't tripping the PTC in my draw time.

That is consistent with what I learned from the manufacturer. Well, of course it is, they know their products =)

Unfortunately our application needs (short time-to-trip, low resistance, high currents, low voltage, small form factor) don't meet their stock products - they rarely deal with high currents from a single Li-Ion cell - for high power everyone uses what we call "stacking".

For single cells they provide circular "strap-on-top-of-battery"-type PTCs - these go up to our needs in amperage, but they are custom products for cell manufacturers - and won't be sold to the general public for undisclosed reasons - I suspect legal ones.

These are my options:

1: Live with the ~1.1 ohm limit and keep the PTC on the firing pin. The fuse I used is the biggest one in this form factor. This is the end of this road.

2: Use two of the 3A 6V PTCs in parallel - unfortunately there isn't enough room on the firing pin to fit them there.

3: Use the PTC on the negative, bypassing or replacing the spring - A value of 5 to 7 amps would be about right for my personal vaping, but I would need to alter the firing button/pin assembly to something that doesn't melt as fast. In an error condition just barely over the current limit it takes the PTCs a couple of seconds to trip and in this time the firing pin gets hot (because of the miniature contact point) and the delrin of the button melts. I don't want that to happen everytime I have a short.

4: Use a user changeable one-time fast blowing fuse instead of a PTC.

We need to keep in mind that this mod would then basically replace the whole mechanism of the Grand (Spring, firing pin, firing button) and it may be best to leave that to Robert for a next generation high performance REO. The REO has been designed in a time where no one would use currents that have the potential to melt the button in normal use. But that is what we are doing now.

Personally, I will go with option 1 - I will continue to use my current setup, use 1.2+ ohm coils and enjoy great clouds. But I'll order the in-between PTCs and try them.

@redeyedancer - if you ever plan on building a hypothetical "high performance REO" or an upgrade to the current one, please contact me and I can set you up with samples and ideas. These PTCs and fuses aren't electronics, just safety devices, and integrating one in a mechanical mod would be great.

 

[ChrisEU]

Which PTC is this?

Is it the RGEF1000?

RGEF1000 TE Connectivity / Raychem | Mouser

That one is 10A at 16V (unless I'm reading that wrong?) so what is the part number for the 3A at 6V PTC?

The one under the bottle is the RAYCHEM RGEF1000, yes - but it is too big at 10amps, should use a 5 or 7 amp one.
The SMD part in the firing pin is a BOURNS MF-SM300-2, which is fine for "standard resistance".

 

[pdib]

So, I noticed something interesting this evening. My V-drop scores had suffered a bit today and yesterday (wasn't keeping track of which mod; but it was mostly Tinterille). It was looking like 0.3V. I took the time to clean the brass shim today, and make sure everything was clean and tight. Still, same problem. At some point (about 5 minutes ago), I had an inkling. I removed my RM2 and the o-rings that help "seat" it, and then screwed it back in without o-rings. Pow! Right back to a perfect 0.2V drop! Same everything, just the o-rings.

 

[ChrisEU]

You can use a piece of thick copper foil in the catch cup in place of the oring, plumbers used to use that to seal valves. It is quite malleable. I know them as "Kupferdichtring" - copper sealing ring. But you'd need to cut away a bit. The ones I tried were too big (and too thick) for the catch cup.

 

[pdib]

Thanks, Chris . .. great idea (rather, Brillantenkopfenshein)








totally made that up, of course

 

[pdib]

Although, copper? I think the juice I get in the catchcup is not gonna end up vaped; but still, it might? Maybe I could make a bit of a donut out of the brass shim. The atty happens to seat w/ good enough orientation on Tiniterille. So, I think I'll just fly naked with that one, and see about the other two.

 

[SeaNap]

I thank that turned out great Chris! What are you using for your spring?

If interested in alternative springs this article has some good information

 

[Jeremy Evans]

I thank that turned out great Chris! What are you using for your spring?

If interested in alternative springs this article has some good information

After reading that and then going back to see how much they were, it seems they have already figured out a re-settable fuse idea that looks pretty spiffy, might I add. Also you use this in place of the spring itself

Bug | atmizoo vaping modware | shop

 

[ChrisEU]

After reading that and then going back to see how much they were, it seems they have already figured out a re-settable fuse idea that looks pretty spiffy, might I add. Also you use this in place of the spring itself

Bug | atmizoo vaping modware | shop

Ah, thank you! Yes, looks like basically the same thing - but it appears to be not very springy, so it won't even out differences in battery length.

At the moment I am using a redneckish solution - 4 small pieces of Bierdeckel ( I don't even know if there IS a word for this in English? Thick pieces of cardboard to put your glass or stein on) stacked where the spring was, one leg of the PTC in the screw hole, fixed with a screw, the other one on top of the stack touching the battery.

I use a 5Amp PTC now (they just arrived today).

Result @1 Ohm: 3.89 Volts from an AW IMR 1600 with stock firing pin. 3.68 without the PTC.

But a hard short in the atomizer will still melt the button - I don't see a way around this because the firing pin gets hot. If only we could get a button out of a more stable material, even wood. Well, at least the battery won't go ballistic - I can live with a melted button as the only result of a disaster.

I also received "strap on" type PTCs which are very flat and have the exact length of the firing pin of a Grand. But they are too wide in the middle section to fit into the delrin insert - that would have to be modded to use a PTC as a firing pin, and I don't really want to do that for a test.

 

[pdib]

After reading that and then going back to see how much they were, it seems they have already figured out a re-settable fuse idea that looks pretty spiffy, might I add. Also you use this in place of the spring itself

Bug | atmizoo vaping modware | shop

Jeremy, reading this, I feel that a hot spring may really work solely on heat! Not on current passing through it. Which HYPOTHETICALLY would mean that my shim does not circumvent the existing spring's effectiveness! Must look into this some more.

 

[jcalis1394]

Jeremy, reading this, I feel that a hot spring may really work solely on heat! Not on current passing through it. Which HYPOTHETICALLY would mean that my shim does not circumvent the existing spring's effectiveness! Must look into this some more.

Would make sense. "Hot" spring . On a serious note it does make sense. My springs collapse when I pull too much current through them with a .4 ohm coil. They don't read the amperage, so it can only be that at a certain temperature they collapse.

 

[pdib]

Well, the idea put forth by the smart people (serious), was that the spring has electrical resistance, and the current passing through it was what heated it up enough to collapse it. (as opposed to just transfer from abutting heat source, battery)

 

[pdib]

Ok. So, back to the safety of this particular mod I've done. Just rebuilt an old Phoenix knockoff that I've had laying around for some time. (haven't used it in months) Screwed it onto Blackie, did what I ALWAYS DO: I BRUSHED THE BRASS SHIM ASIDE AND PUT THE BATTERY DIRECTLY ON THE SPRING TO TEST THE BUILD. Fired it up . . . .




All's good. Spring did it's job.


BTW: Rob, I need some more springs!

 

[pdib]

Just in case someone missed the picture near the beginning of the thread. This is how I've got the mod DIS-engaged when firing a new build, or changing atties. Every time.