Show me your "18650 on a PCB" solutions

[dusan]

I just found out that if I get rid of the battery holder and mount battery directly on PCB I can fit my project into 30% smaller box. I'm looking for an inspiration how to mount 18650 directly on PCB. Please post even if you think your solution is inferior to others, it may work better for me as every project is different. Thanks.

[Doctorandus_P]

The most common solution is to spot weld tabs to your batteries. You can even buy batteries that already have these tabs and can be soldered directly into the PCB.

Some people claim to have success with soldering wires directly to the battery by using a hot iron, keeping the heating time to an absolute minimum, and cool with water (wet cloth) directly after soldering. But I'm not sure what that does to battery internals and it's probably a bad idea.

You can also buy batteries (or battery packs) with wires and a plug on them.

For the rest, I'm quite happy you can buy decent battery holders for 18650. For AA for example the battery holders are usually so bad that they become very unreliable.

[Psi]

You can get sort of "curved L" shape SMT spring metal battery contacts.
What about a battery sized internal routed cutout in the PCB for the battery to sink into.
Then the top and bottom battery contracts are SMT.
Since the battery is sitting in the middle of the PCB they will align to the center of the battery.

Then you only need something to restrain the battery, which could be a velcro strap that threads through two long slots in the PCB either side of the bigger cutout where the battery sits.

[ArdWar]

soldering wires directly to the battery by using a hot iron

Don't do that please.

Either do a proper spot welding, or use one of those naked terminal instead. Less plastic while still replaceable.

Beware of its tendency to damage battery insulator sleeve and potentially causing short circuit however.

[voltsandjolts]

I recently purchased a FNIRSI SWM-10 battery tab spot welder, £45 delivered to UK from FNIRSI store on aliexpress.
https://www.aliexpress.com/store/2939001
It's near it's limits doing 0.1 nickel tab to 18650, but does a good job of it. Might be OK for 0.15 at max settings.

If saving space is critical for you, then tab welding is the only way to get shorter than a spring clip type fitment.

[RoGeorge]

if I get rid of the battery holder and mount battery directly on PCB I can fit my project into 30% smaller box

Depends what do you mean by 30% smaller.

18650 is one of the most common type, but that is only one of the standardized sizes for cylindrical Li-Ion batteries (18x650 mm is diameter x length).  If that is too big, maybe choose a smaller cylindrical battery, or maybe a flat format one.

[voltsandjolts]

(18x650 mm is diameter x length).  If that is too big...

Hmm, yeh, I think 650mm long would be too big 

18mm x 65mm, format 0, which means cylindrical.

[DimitriP]

How about this clip from digikey ?

DigiKey Part Number  36-54-ND
Manufacturer Keystone Electronics
Manufacturer Product Number  54
Description  BATT CONT CLIP 18650 1CEL PC PIN

https://mm.digikey.com/Volume0/opasdata/d220001/medias/images/1124/MFG_54.jpg

[tszaboo]

I buy it as a 1S1P pack, with protection circuit and NTC, with JST 2.5mm connector. Cable tie to PCB.
Not for my ATEX stuff obviously.

[Doctorandus_P]

18mm x 65mm, format 0, which means cylindrical.

Euhm, no.
Length is in 100um instead of whole mm.

CR2032 is for example 3.2mm thick.

https://en.wikipedia.org/wiki/Button_cell#Package_size

[voltsandjolts]

18mm x 65mm, format 0, which means cylindrical.

Euhm, no.
Length is in 100um instead of whole mm.

CR2032 is for example 3.2mm thick.

https://en.wikipedia.org/wiki/Button_cell#Package_size

IEC standard 60086-1 describes the naming convention for cylindrical primary cells, which works as you described.
IEC standard 61960-3 describes the naming convention for lithium secondary cells, but the 18650 designation precedes this and doesn't conform.
There is conflicting information out there for 18650, a term which was coined back in the early 1990's. Some say 0=cylindrical, some say 0=65.0mm. I don't see a definitive explanation from Sony or Panasonic, one of whom likely instigated it.

https://en.wikipedia.org/wiki/List_of_battery_sizes

Commonly-used designation numbers indicate the physical dimensions of the cylindrical cell, as given in IEC standard 60086-1 for cylindrical primary cells. The first two digits are the nominal diameter of the cell in millimetres, and the two following digits are generally the height in millimeters, with the fifth digit indicating cylindrical shape. Alternately, the last three digits can refer to the height in tenths of a millimeter. Manufacturers may use non-IEC designations for their products.

[voltsandjolts]

OP: there is also 17500 lithium ion cells, shorter with reduced capacity of course.