Battery sleds

[awsum140]

OK, I'll kick off this category.

The DNA75, by virtue of being a 3.7 volt chip, is a good candidate for a single 18650, high drain, battery.  I recently built a DNA75 into an ERM enclosure and it does make a nice, compact, mod.  The problem is the battery sled.  I'm using a Keystone 1044, single, 18650 sled and the are a couple of weak points with it.

The contacts are, at best, marginal given the current draw of the DNA75 even at "lower" power, like 30 or 40 watts.  They are kind of flimsy and I've already had to re-bend them, twice, to maintain good contact.  I've thought about modifying the sled with more substantial contacts but find a suitable spring gets to be a problem as well.

The next problem is mounting it so that it is semi-permanent.  The sled does need a little "massage", on one end, with some sandpaper or a file to fit into the enclosure.  The enclosure I have, from Proto Vapor, has a nice little ledge inside the front half of the enclosure that keeps the sled from pressing on the board, but keeping it in there tight enough to allow easy battery changes is a challenge.  I've got it "wedged" in place, which works, but I'm leaning toward hot melt glue to keep it a lot more solid.  Given the "tightness" of the sled, and the sled inside the enclosure, screws just don't seem to be an option to me.

Any suggestions out there?

[VapingBad]

Here is what I did, it could be better, but as I just worked it out as I was doing it using what was to hand. 

I used a 4 mm brass screw, some circuit board fibre glass, a spring, a copper contact from an old flash light and some epoxy. Could be better especially the spring, but a lot better than the standard contacts.  The positive sits at the bottom and it is important to insulate any bits that you can accidental touch with the enclosure when fitting or removing it, I used epoxy for this.

[awsum140]

I was hoping for something commercially available.  It's amazing that 18650s can put out 20 to 30 amps and the holders offered don't look safe at 10 amps.  I did look around and ordered a few with springs for the negative terminals.  My plan being to use a brass plate and braided cable on the negative, spring, end and a brass button style on the positive end.  Both will be 14 or 16 gauge wire depending on what will actually work.

[Spector NS5 RD]

awsum140 said:

I was hoping for something commercially available.  It's amazing that 18650s can put out 20 to 30 amps and the holders offered don't look safe at 10 amps.  I did look around and ordered a few with springs for the negative terminals.  My plan being to use a brass plate and braided cable on the negative, spring, end and a brass button style on the positive end.  Both will be 14 or 16 gauge wire depending on what will actually work.

here's how i would build a sled......because i doubt you'll find one that u would consider a good candidate. have as much surface area contact on each of the battery contacts to utilize all of the neg and pos surface area on the battery. and have a very taught spring for either the negative or positive contact. maybe cut some round circles out of some 22 gauge copper sheeting, use that for the actual contacts...solder a spring on one etc. etc. my two cents.

[VapingBad]

As Chunky said I don't think there is a commercially available battery holder that is fit for > 30 W e-cigs they are made for other applications.  That only impacts on performance so nothing to worry about.  It's funny lots of us think nothing of fabricating an enclosure but far fewer making battery contacts.

You could solder a XT30 socket on the battery and a plug on the board & a charger/charger adepter.

[Nick]

Most sleds are inherently pretty poor sadly just based on how they work and the contact force.

I got a DNA75 mod the other day with a very good battery tube and I can say the performance is a good deal better thanks to the stronger contact.

[awsum140]

I'm working, sort of, on some low tank DNA75 mods and have FD battery tubes for them.  Those are nice and secure but way too big to fit into an ERM.

[BillW50]

awsum140 said:

... and have FD battery tubes for them.  Those are nice and secure but way too big to fit into an ERM.

Battery tubes? Where? I have been looking for those.

[VapingBad]

You only need to make more substantial contacts and add some pressure, spring or threaded and you can reuse the plastic chassis.

[awsum140]

Fat Daddy has battery tubes in brass or stainless for both 18650 and 26650.  Fixed positive post and the bottom post is actually the bottom cap and be screwed in to make a nice, tight, connection.  Scroll bout a third of the way down the page -

http://fatdaddyvapes.com/shop.html

[BillW50]

Oh thanks awsum. I never even thought about using mech parts for battery tubes. Love it!

[Wayneo]

Gents, what about doing what some of those high end mechs do, like reomods. He's got replacement battery connectors, and copper springs, each about $5.

[BillW50]

Wayneo said:

Gents, what about doing what some of those high end mechs do, like reomods. He's got replacement battery connectors, and copper springs, each about $5.

[VapingBad]

BillW50 said:

Those are still not great for high power mods, those mods do not have the current requirement we have. I have been using springs from other mods for a year or two, last one was ProVari latest version cut down so probably half the resistance and it is still not as good as the set up I posted above.

Also re tubes: the tube is not important, necessary or even useful unless you wanted to build a mod with a tube, IMO it would just take up room with no real benefit, but oversized mods are a pet hate of mine.  It's the contact area, pressure and resistance of the contacts that matter.  IMO it is easier to make good contacts rather than cram a tube into a mod that is not a tube mod.

[awsum140]

VB, you don't think that tube would work for a 75 watt, max, mod?  The contacts look very substantial to me, especially compared to a typical battery sled.  The fact that the bottom provides pressure when screwed in almost guarantees a good connection every time.  As far as size, there is space inside what I am building due to the diameter of RTAs like an Aromamizer.  A few extra mils in overall width aren't really all that important to me and is being dictated by the extrusion I'm using.

[VapingBad]

awsum140 said:

VB, you don't think that tube would work for a 75 watt, max, mod?  The contacts look very substantial to me, especially compared to a typical battery sled.  The fact that the bottom provides pressure when screwed in almost guarantees a good connection every time.  As far as size, there is space inside what I am building due to the diameter of RTAs like an Aromamizer.  A few extra mils in overall width aren't really all that important to me and is being dictated by the extrusion I'm using.

Not saying there is anything wrong with the tube at all, just that it is unnecessary unless you want to design around a tube. If you took the tube and ground the body so it only had a 2 or 3 mm strip of metal each side lengthwise between the two terminals the performance would likely be the same. Or you could cut both ends off the tube and fit those in your box.

[dwcraig1]

Here's my thinking of how to do it. This is the negative contact of an IPV2.
The negative wire is soldered to the brass plate at the battery end of the spring essentially removing the spring as part of the electrical path. I think a bit stronger spring should be used than the one pictured though.

[Spector NS5 RD]

this is from the FDV site. this looks good. no springs, you crank down on the batt - threaded cap till it's tight against the posi post. solid brass as well easy to solder than the SS version. kinda big but i like the idea....... only a little over 3 inches long when assembled.

[BillW50]

[awsum140]

I'm actually designing around the available enclosure I found, FleaBay item.  I want a low tank, or side by side, form factor.  The end result is needing some way of holding the battery in position and supplying a way to change the battery conveniently.  Cutting a round hole for a battery is no problem, but with limited tooling and skills, cutting and threading a cap is a whole other problem.  The tube solves all three problems and there is more than enough room inside the case.  Size is not my biggest design factor, the low tank is the governing factor and I'll sacrifice a little bigger enclosure to get to that goal.

[awsum140]

So, I bought some different battery sleds with the idea of modifying them  They came with 24 gauge wire on them.  What are manufacturers thinking?



I drilled out the rivets from both ends to get everything out.  I replaced the positive contact with a 3/8" brass disk with 14 gauge silicon wired soldered directly to it.  I added a 3/8 brass disk to the negative spring and soldered a short piece of braid, from a piece of RG6, to it and soldered the disk to the spring.  The shield was trimmed to length and soldered to another piece of 14 gauge silicon wire.  The spring can conduct, of course, but the rel path is the braid.  Everything was placed back in using JB Weld.  I also added a pull ribbon to get the battery out because the sled has a death grip on the battery.



I've still got to find the time to swap out the Keystone sled with this one and build at least two more like this..

[dwcraig1]

^^^excellent

[awsum140]

I finally got the new sled into the ERM-DNA75 this morning and it makes a BIG difference.  I'm using LG HD2 batteries and at 1/2 charge showing on the battery meter I only get a  "weak battery" warning once in a while.  The Keystone sled was giving them after five hits on a fresh battery.

I did some modifications to the sled.  The positive terminal is a laminated piece of brass with the brass center disk soldered in place.  I also found a "deep well" socket that was a little bigger in diameter than an 18650.  I put that into the sled and heated the whole thing with a heat gun.  Now the battery fits normally and comes out with no difficulty while still being held firmly. 

The sled is almost a force fit into the Proto ERM enclosure so no wedging to get a tight fit.  Overall, well worth the added effort.

[dwcraig1]

dwcraig1 said:

^^^excellent

I was waiting to hear about it, very good

[dwcraig1]

I have not seen this "weak battery" message on mine as yet and I tried to make it happen. It got down to 3.4 volts twice but it was time to go to work so I changed the battery. The first time was with an HD2, second time HE4 @ 40/50 watts. It appears to not be the board as some are saying.
I would imagine that if I were to be vaping @ 75 watts things would be working out different but I'm using it just as I use my 200 (one of them anyway)