Will my Efest IMR 2500mah battery work for a 0.25ohm RDA build?

[pbreach]

I bought the above mentioned battery as well as a pack of pre-built kanthal twisted micro coils to put on my new RDA which has yet to arrive. I realized I ordered the coils at 0.5ohm when what I actually wanted was 1ohm each. With a double coil build for the 0.5ohm I'm assuming that I'll be a bit more than 0.25ohm altogether.

I've read that this battery is actually a re-wrapped LG with a 20A max continuous discharge rating, so I think I'm looking at 16.8A draw from this build assuming 4.2V.

Of course I am going to measure the resistance of the RDA when built with a multimeter, but at this resistance I'm not sure how accurate the readings will be. When built I'm sure there will be a slightly higher resistance, and with the voltage drop of the battery/mod maybe I'll be in the clear? This being said I'm still sceptical, and am considering buying some wire and coiling it myself to get a higher resistance (shipping prices to Canada would be hard to justify for another pack of pre-built coils...).

Do you think this set up is reasonably safe?
If not what would you consider safe?
What precautions could I take besides getting / building different coils?
Can you offer any experience with sub ohm builds for this particular battery or similar?

EDIT:

The coils are UD 26 gauge twisted microcoils found here: UD Prebuilt Twisted Micro Coils
but I don't think the twist rate is specified.

RDA will be a doge x v2 with mutation x v2 mech mod

 

[State O' Flux]

I bought the above mentioned battery as well as a pack of pre-built kanthal twisted micro coils to put on my new RDA which has yet to arrive. I realized I ordered the coils at 0.5ohm when I what I actually wanted was 1ohm each. With a double coil build I think for the 0.5ohm I'm assuming that I'll be a bit more than 0.25ohm altogether.

I've read that this battery is actually a rewrapped LG with a 20A max continuous discharge rating, so I think I'm looking at 16.8A draw from this build assuming 4.2V.

Of course I am going to measure the resistance of the RDA when built with a multimeter, but at this resistance I'm not sure how accurate the readings will be. When built I'm sure there will be a slightly higher resistance, and with the voltage drop of the battery/mod maybe I'll be in the clear? This being said I'm still sceptical, and am considering buying some wire and coiling it myself to get a higher resistance.

Do you think this set up is reasonably safe?
If not what would you consider safe?
What precautions could I take besides getting / building different coils?
Can you offer any experience with sub ohm builds for this particular battery or similar?

You should be fine.
With a certain 20A MCCD, you have still a 3.2 amp cushion at 4.2V... and that doesn't take into account a modestly calculated pulse discharge, at a higher amperage value, within 'X' time.

You can increase the resistance slightly by making the legs as long as reasonably possible, within the confines of the RDA. You can also simply run a single, two-strand coil assembly, for a 0.5Ω net resistance.

You don't state the wire gauge or twist rate, so I can't calculate heat flux or heat capacity for a single two-strand twist coil assembly... or a parallel pair of two-strand twist coil assemblies.

 

[IMFire3605]

Yes, should be safe. I'm not a big fan of the purple efest 18650 batteries to begin with, but for this application, still gives you about 3.2amp headroom incase of a short and such.

Try looking at the Orbtronic 30amp cdr, Xtar 30amp cdr (re-wrapped sony vtc4), samsung 25r (20amp cdr), lg he2/he4 (20amp cdr) batteries down the line

 

[pbreach]

You should be fine.
With a certain 20A MCCD, you have still a 3.2 amp cushion at 4.2V... and that doesn't take into account a modestly calculated pulse discharge, at a higher amperage value, within 'X' time.

You can increase the resistance slightly by making the legs as long as reasonably possible, within the confines of the RDA. You can also simply run a single, two-strand coil assembly, for a 0.5Ω net resistance.

You don't state the wire gauge or twist rate, so I can't calculate heat flux or heat capacity for a single two-strand twist coil assembly... or a parallel pair of two-strand twist coil assemblies.

Thanks! Great to hear. I've edited the post to include details of the coils and setup. For some reason I heard the doge x v2 won't work for a single coil setup, but that would definitely be a quick and easy fix if possible.

 

[edyle]

I bought the above mentioned battery as well as a pack of pre-built kanthal twisted micro coils to put on my new RDA which has yet to arrive. I realized I ordered the coils at 0.5ohm when what I actually wanted was 1ohm each. With a double coil build for the 0.5ohm I'm assuming that I'll be a bit more than 0.25ohm altogether.

I've read that this battery is actually a re-wrapped LG with a 20A max continuous discharge rating, so I think I'm looking at 16.8A draw from this build assuming 4.2V.

Of course I am going to measure the resistance of the RDA when built with a multimeter, but at this resistance I'm not sure how accurate the readings will be. When built I'm sure there will be a slightly higher resistance, and with the voltage drop of the battery/mod maybe I'll be in the clear? This being said I'm still sceptical, and am considering buying some wire and coiling it myself to get a higher resistance (shipping prices to Canada would be hard to justify for another pack of pre-built coils...).

Do you think this set up is reasonably safe?
If not what would you consider safe?
What precautions could I take besides getting / building different coils?
Can you offer any experience with sub ohm builds for this particular battery or similar?

EDIT:

The coils are UD 26 gauge twisted microcoils found here: UD Prebuilt Twisted Micro Coils
but I don't think the twist rate is specified.

RDA will be a doge x v2 with mutation x v2 mech mod

The 0.5 ohm dual coil means it has 2 one ohm coils.

How much power you will need to run it depends on the wire type and the gauge.

26 gauge is thick; probably need like 40 to 60 watts for that coil.

 

[pbreach]

Yes, should be safe. I'm not a big fan of the purple efest 18650 batteries to begin with, but for this application, still gives you about 3.2amp headroom incase of a short and such.

Try looking at the Orbtronic 30amp cdr, Xtar 30amp cdr (re-wrapped sony vtc4), samsung 25r (20amp cdr), lg he2/he4 (20amp cdr) batteries down the line

Will do. Glad to hear this should be enough headroom. It's hard to find how close is too close anywhere, but I guess it could be a touchy subject.

 

[dom qp]

The eFest Purple IMR18650 2500MAH batteries are LG HE2s (20A CDR), specifically.

 

[pbreach]

The 0.5 ohm dual coil means it has 2 one ohm coils.

How much power you will need to run it depends on the wire type and the gauge.

26 gauge is thick; probably need like 40 to 60 watts for that coil.

Are you sure? See the link I posted. It's a pack of 10 coils and doesn't mention any specific setup so I'm assuming it's 0.5ohm each.

As for the power, given 4.2V with 0.25ohms comes out to ~70W. Probably lower after its built so I'm hoping it works out.

 

[State O' Flux]

Thanks! Great to hear. I've edited the post to include details of the coils and setup. For some reason I heard the doge x v2 won't work for a single coil setup, but that would definitely be a quick and easy fix if possible.

Unless I've misread your edit info, or am just having a (frequently more and more common) "senior moment"...

If you run a 0.25Ω net resistance, your Ohm's law parity wattage is 71 watts at 4.2 volts. With the coil assemblies as described, and using an estimated 1mm twist pitch, this build will produce a heat flux of a cool 157 mW/mm² +/-, and a not particularly great, but not terrible heat capacity of 74.68 mJ/K +/-.

I'd personally prefer a warmer HF and faster HC... but you got what you got, so there ya' go.

Next time, maybe get some thinner wire so the HF gets warmer... or get a high watt VW APV, so you can "force" wattage on the 26 gauge build beyond Ohm's law parity.

 

[dom qp]

so you can "force" wattage on the 26 gauge build beyond Ohm's law parity.

When I do this I talk dirty to my Sigelei, out of courtesy.

 

[pbreach]

Unless I've misread your edit info, or am just having a (frequently more and more common) "senior moment"...

If you run a 0.25Ω net resistance, your Ohm's law parity wattage is 71 watts at 4.2 volts. With the coil assemblies as described, and using an estimated 1mm twist pitch, this build will produce a heat flux of a cool 157 mW/mm² +/-, and a not particularly great, but not terrible heat capacity of 74.68 mJ/K +/-.

I'd personally prefer a warmer HF and faster HC... but you got what you got, so there ya' go.

Next time, maybe get some thinner wire so the HF gets warmer... or get a high watt VW APV, so you can "force" wattage on the 26 gauge build beyond Ohm's law parity.

Hmm.. honestly never thought about heat flux or capacity for this build (first attempt at buying a rebuildable ever). Out of curiosity, roughly what HF/HC do you go for? I'll test out this build but might take your advice on a higher gauge wire. Anything VW will have to wait a bit (pockets feeling a bit light after this one).

 

[State O' Flux]

Hmm.. honestly never thought about heat flux or capacity for this build (first attempt at buying a rebuildable ever). Out of curiosity, roughly what HF/HC do you go for? I'll test out this build but might take your advice on a higher gauge wire. Anything VW will have to wait a bit (pockets feeling a bit light after this one).

Although I've run hotter in the past - these days, I tend to run in the 220 to 320 range for HF... the low end for RTAs (with the one exception being a Gus Estia... my RTAs are "old fashioned", low air flow, like the R91%, KFL+ and Rose, so I don't run them too hot) and the high end for RDAs with a broad range of AFC adjustments.

HC is simply the fastest ramp up (numerically lower) I can get for my, in order of importance, desired resistance, surface area and HF.

Visit the article at the end of my first sigline hyperlink below. Get on Steam Engine and play with it, while you've got my open to the bit of SE you're looking at... you'll learn a lots of "good stuff". Honest.