I’m looking for a battery holder for 4 x 18650 cells in series like this

and be nice and small so it fits in a little battery pouch like this

Some basic over current protection would be nice, I would solder on an XD battery balance connector so I don’t have to take all the batteries out each time I charge them.

Currently I solder/heatshrink together packs, the reason I am looking for a battery holder is so that I can switch out cells easily when they start to die/mismatch the pack, rather than having to pull the whole pack apart each time.

I’ve tried out a Solarstorm battery holder which works ok, but it is a bit bulky and is 2s2p whereas I really need a 4s configuration.

Best I can think of right now is to use two of these back to back http://www.dx.com/p/diy-2-slot-series-18650-battery-holder-w-4-leads-black-359556#.V_SZ3OB952Q but this will probably end up a bit to bulky to fit inside one of those little velcro pouches.

isnt this something turboferret produced with a 3d printer?

EDIT: Indeed. http://singletrackworld.com/forum/topic/fantastic-mr-turboferret-18650-holders

I should have mentioned that http://www.turboferret.co.uk/ broken = very yes. I did nonetheless ping the turboferret an email just now to see if they can help.

I’ve always gone down your last option route with protected cells and abandoned the balance connector after I found it wasn’t really necessary with 4 matched, decent cells (Xtar usually) to start with. I’ve never had a problem with current protection or cells getting out of balance but you could split the pack maybe once a year or so and check each cell individually if you were concerned about that.

I use a different battery pouch to the one that you link to so have no idea if the pack would fit but I’ll try and find a link to the one I do use (eBay somewhere I think)

I’m after something like that too but I’m pretty clueless about these things so I’ll be watching this thread closely.

I’ve got one of the turbo ferret holders, it works well and has the bonus that the cells can be removed and placed into a charger so the need to balance has gone. Mine did suffer from a corrosion problem though as the pouch wasn’t water proof so the cells inevitability got wet and if you didn’t strip it down straight after a ride rust could form

However I’ve stopped using it for the time being as I’ve built a battery using a lipo RC helicopter battery stored in my old lumicycle battery bag. It’s lighter and higher capacity than the 18650 cells.

I’m using scavenged cells so the balance connection is useful to identify when the cells are failing. They are also generally seem to be unprotected cells, I am not quite sure how foolish it is to run packs with no protection, my charger is intelligent with so the main risk would be the cable shorting during use and the batteries catching fire before the cable burns out.

Thinking about it more I should probably define my problem more generally – the issue is finding a combination of battery holder and pouch which fits 4 cells in series and mounts nicely. As per below it seems that a 4 square config is best overall. I already have a couple of basic canvas bags which fit 4 cells in square configuration although I would probably benefit from better neoprene ones which would keep the weather out.

4 square configuration
Good for strapping to toptube, stem, bars, helmet.
Ok fit in toptube bags
Tricky finding suitable battery holder – use two 2xflat holders as compromise.
Easy to find pouch

4 flat configuration
Good fit for toptube bags
OK for strapping helmet, or to toptube if there was a suitable pouch, might swing a bit though.
Poor shape for strapping too stem, or bars.
Easy to find basic battery holders
Hard to find pouch

2 sticks of 2 configuration
Good for strapping to toptube if there was a suitable pouch.
Poor shape for toptube bag, stem, bars, helmet.
Hard to find battery holder – use two 2xflat holders as compromise.
Hard to find pouch

Yes, sorry the photos don’t show up on my website any more as the server software changed the way it handled code and I couldn’t be bothered to change it.

I’m afraid my days of moulding battery holders are way behind me, but I’m sure there are lots of cheap Chinese options these days.

Cheers, Rich

This is the type of battery pouch I use but I didn’t buy it with the battery pack. I can’t find the pouch for sale on it’s own but I’m sure I bought two separately from somewhere.

http://www.dx.com/p/4400mah-external-battery-pack-with-pouch-for-sku-29489-30864-4-18650-32756#.V_TATcktqpo

Why not try making one like this

http://forums.mtbr.com/lights-diy-do-yourself/yet-another-18650-battery-holder-545583.html

This one is turned but a similar result could be achieved with a pillar drill

twisty – Member

I’m using scavenged cells so the balance connection is useful to identify when the cells are failing. They are also generally seem to be unprotected cells, I am not quite sure how foolish it is to run packs with no protection, my charger is intelligent with so the main risk would be the cable shorting during use and the batteries catching fire before the cable burns out.

The other problem with using unprotected cells is that you can run them down in use below a safe level and damage one or more cells. Personally I don’t bother with unprotected cells and have had no problem other than in the past using cheap xxxFire brands which always seem to fail prematurely.

Actually, it just occurred to me, if you’re using scavenged cells why not just glue them together in the right configuration and solder them in series with the protection circuit in? Then you can just add the connection lead you need and shrink wrap the whole pack.

I’ve done that in the past with 4 protected cells in series and the pack is still going strong after 3 years.

Hmm, unless anybody has any further inspiration it looks like I am creating 4square packs using 2x2stick holders.

If somebody comes forward with PCB/plastic manufacturing abilitys I could design something a bit better, inspired by dvatcmarks post, it should be quite easy to have 3d-printed top/bottom parts, with PCB’s sitting inside to do the battery connections/protection and threaded bar through the centre or elastic round the outside to hold everything together.

if you’re using scavenged cells why not just glue them together in the right configuration and solder them in series with the protection circuit in?

I’ve done this, and cut out nice bits of plastic for the front and back so it is nice and sealed. The problem is that when one cell goes I have to cut off the heatshrink and do a bunch of soldering – I’m trying to do something that is easier to maintain.

I’ve done this, and cut out nice bits of plastic for the front and back so it is nice and sealed. The problem is that when one cell goes I have to cut off the heatshrink and do a bunch of soldering – I’m trying to do something that is easier to maintain.

I would guess it’s because you are using crappy scavenged cells of unknown quality and/or use/age. If you are going to all the trouble to try and create a decent battery pack then why not use new, quality cells? Torchy sells decent ones at a budget price.

You are spending money on a pack that you can easily dismantle just so you can use cheap cells that you suspect are going to fail? What you are trying to achieve smacks of false economy to my way of thinking.

I usually offer my own 3D printing services but I’m snowed under with proper work.

If you can design something then take a look at 3D Hubs, they list loads of people with printers close to you and are generally well priced.

I would guess it’s because you are using crappy scavenged cells of unknown quality and/or use/age. If you are going to all the trouble to try and create a decent battery pack then why not use new, quality cells? Torchy sells decent ones at a budget price.

You are spending money on a pack that you can easily dismantle just so you can use cheap cells that you suspect are going to fail? What you are trying to achieve smacks of false economy to my way of thinking.

You are right, but I’ve got a big box of Li-ion cells and I don’t like the idea of throwing away a cell until I know it is borked. It does save a small amount of money because the battery cell holders etc cost peanuts.

I usually offer my own 3D printing services but I’m snowed under with proper work.

If you can design something then take a look at 3D Hubs, they list loads of people with printers close to you and are generally well priced.
I think I was overthinking things 😉 Going to buy some 2x cell holders now.

I made the first pack.
I got some cell holders but eventually deciding they’d add too much bulk so I just taped and soldered the cells together.
I did find some silicone pack covers though which is good because I think it will be fully waterproof but not-so-good in that the pack is now slightly too large for my velcro battery pack holders…
I used a battery protection board, wiring it all together was fairly fiddly but the pack seem to be working at least for now.

Where did you get the silicone pack covers? I’m considering refurbishing some of my packs and they look much better than what I was considering

Just out of interest, why do you want a 14.8v battery for a bike light?
I assume that’s the reason you wanted 4s rather than 2s2p?

The silicone cover is “18650 Battery Colorful Waterproof Soft Silicon Rubber Case 1PCS (1065147) ” from banggood.com

I want the 4s pack as I’m running Luxeon-M 12W leds in my lights, run at about 10V so would need a boost regulator if running from a 7.2V pack, buck regulators are easier to get off the shelf and a bit more efficient. There are also some advantages to running higher voltage (less current = less resistive losses) although I have to admit it has been more hassle than I originally thought getting everything to work.

Thanks for that