Battery advice needed please

[daisystar]

Hi All,

Probably, about 9 or 10 years ago I given a violet / purple laser pointer (around 750mw) without a battery. I was told at the time to get two 16340 3.7v Li-ion batteries for it which I did. The problem has always been that the host battery holder isn't large enough to accommodate both batteries.

Today I bought a 18650 battery which fits nicely but unfortunately lacks the voltage needed.

Can anyone advise of a suitable c. 7.2v battery with roughly the same dimensions as a 18650?

Cheers
Daz

 

[Encap]

No such battery exists unfortunately.

If you have protected button tops 16340 batteries try using unprotected one button top and one flat top should be a better fit.

 

[daisystar]

oh...thanks. Do you think I was given the pointer on the basis that the host was the wrong size then? If that's the case, is it a simple matter of getting a new host to accept the two 16340 batteries?

 

[daisystar]

No such battery exists unfortunately.

If you have protected button tops 16340 batteries try using unprotected one button top and one flat top should be a better fit.

Thanks again. I'd need around 10mm less height in total for the screw cap to go on nicely. The 16340's I have are around 35mm in length each.

 

[CurtisOliver]

Tip, the first two numbers (16)340 is the diameter (16mm) and the last three is the length. 16(340) is (34.0mm)
So 2x 16340's are 68mm long. 18650 are 65mm. As you are measuring ~70mm (2x35mm) I am presuming you are using button top cells.
Are two 16340's close to fitting, if so then maybe you need flat top cells.

I'm not recommending you get these specific batteries, just giving an example.

Imren 16340 700mAh Flat Top | Shade E-Vaping

shade-e-vaping.co.uk

Note, the dimensions given from that source are actually under 34mm. Stated ~32.9 which would put you only ~0.8mm over the length of a 18650 which fitted.

 

[Encap]

You have to make sure using 2X flat top batteries that the + side of one protudes enough to make contact with the underside/- side of the other battery, which is why I suggested 1 button top and one flat top.
If push comes to shove you can use a small 1mm X 6mm magnet to make the conncetion between the two.

 

[CurtisOliver]

Yes, I have seen the magnet option mentioned before. I have actually used two flat top 18650's before now with no problem of contact.

 

[Encap]

I have as well but in both cases there was enough + to make contact.

The reported 10mm discrepancy is odd/unusual--- 2 X 16340 even with a ful 34mm length should be 3mm or less difference from 18650 68mm vs 65mm?

 

[CurtisOliver]

Yes, that is a huge difference.
If assuming they are 35mm then 5mm difference is present. However the OP lists a 18650 fits? Now I have never come across a 18650 that is only 60mm long.

I did wonder for a second that the laser might of been a 2x CR2 host @6V but then even those dimensions don't add up.

 

[Encap]

Same here but as you say even that doesn't add up.
Have never seen a 18650 that is 18600 either

Maybe the module position in the host off for whatever reason or tailcap switch retainer is not screwed down all the way, maybe both need adjustment if possible---no way to know.

 

[daisystar]

Tip, the first two numbers (16)340 is the diameter (16mm) and the last three is the length. 16(340) is (34.0mm)
So 2x 16340's are 68mm long. 18650 are 65mm. As you are measuring ~70mm (2x35mm) I am presuming you are using button top cells.
Are two 16340's close to fitting, if so then maybe you need flat top cells.

I'm not recommending you get these specific batteries, just giving an example.

Note, the dimensions given from that source are actually under 34mm. Stated ~32.9 which would put you only ~0.8mm over the length of a 18650 which fitted.

thanks very much.

 

[CurtisOliver]

You're welcome. How well does a 18650 fit Daisystar? And is the 18650 a flat top or button top?

 

[daisystar]

the 18650 fits perfectly and is a flat top. Just not the right voltage!

 

[CurtisOliver]

That is odd. It's like the host was intended for a 18650 but the driver used doesn't suit that battery configuration. Based on the fact it is so old, I thought of CR2's. But they are 27mm long typically so would fall 11mm short of this host. The closest 7-7.4V fit is to use flat top 16340's. As long as the thread is enough to catch an additional <3mm length then you should be fine.

 

[daisystar]

Thanks so much. Do you have any UK recommended sites for flat top 16340?

 

[CurtisOliver]

Imren 16340 700mAh Flat Top | Shade E-Vaping

shade-e-vaping.co.uk

This is all I found on a quick search within the UK.
Just don't over drain them and they should be fine.