Power bank with replaceable 18650 batteries

Before I do a cursory Google search and end up ordering something completely unsuitable from China, does anyone have any suggestions for power banks with USB charging ports that utilise 1 or more 18650 batteries that can be replaced? I'm thinking about using one to charge PDAs/phones on long trips underground, but using what is quickly becoming the currency for underground power; 18650 batteries.

If anyone has one they can recommend that would be suitable for use underground (I.E. houses the 18650s inside a reasonably water-tight and shock-proof case) please let me know. Otherwise it's going to be trial-and-error buying multiple ones, and testing them by recharging the Bluetooth speaker in my dig!
 

Benfool

Member
That would be very easy to build....

1x Small Peli Case
1x https://www.ebay.co.uk/itm/222429896066?hash=item33c9dadd82:g:XggAAOSwXY5ZWNT2 (4x Parallel)
1x https://www.ebay.co.uk/itm/373723265394?hash=item5703a47972:g:hTYAAOSwuJZdXKiG

Difficult bit would be working out how to waterproof the cable coming out of it....

B
 

ZombieCake

Active member
Are you looking at something like these (other shops available)?

https://www.torchdirect.co.uk/battery-chargers/nitecore-f2-flexbank-dual-bay-li-ion-battery-charger.html

https://www.torchdirect.co.uk/battery-chargers/fenix-are-x1-charger-and-18650-2600-mah-li-ion-battery-set.html


 
Benfool said:
That would be very easy to build....

1x Small Peli Case
1x https://www.ebay.co.uk/itm/222429896066?hash=item33c9dadd82:g:XggAAOSwXY5ZWNT2 (4x Parallel)
1x https://www.ebay.co.uk/itm/373723265394?hash=item5703a47972:g:hTYAAOSwuJZdXKiG

Difficult bit would be working out how to waterproof the cable coming out of it....

B

In theory, this is what I'm looking for - but I don't have the skills or energy to make it myself!

ZombieCake said:
Are you looking at something like these (other shops available)?

https://www.torchdirect.co.uk/battery-chargers/nitecore-f2-flexbank-dual-bay-li-ion-battery-charger.html

https://www.torchdirect.co.uk/battery-chargers/fenix-are-x1-charger-and-18650-2600-mah-li-ion-battery-set.html

Yes, except in both of those the battery is quite exposed, meaning a light shock will knock it out of place. I'd like something where the battery is enclosed, like it is in a torch, but with USB outputs as well.
 
If it serves a useful purpose for you, you could also consider the Fenix LR40R monster torch.

https://www.torchdirect.co.uk/fenix-professional-torches/fenix-lr40r-rechargeable-led-searchlight.html

This has a massive pack inside, but also takes 1-4 18650 batteries. You can charge it by proper negotiated USB-C, plus it will output USB to other devices.

Claims to be IP68, but like all fenix stuff this is dependant on you actually shutting the rubber flaps and them staying closed.

Caverkeith did a review on youtube.
 

IanWalker

Member
i use this battery charger and it works well as a power bank.

https://www.inglesport.com/product/fenix-battery-charger-set/

put one in a tupperware box?
 

ali_mac

Member
Benfool said:
That would be very easy to build....

1x Small Peli Case
1x https://www.ebay.co.uk/itm/222429896066?hash=item33c9dadd82:g:XggAAOSwXY5ZWNT2 (4x Parallel)
1x https://www.ebay.co.uk/itm/373723265394?hash=item5703a47972:g:hTYAAOSwuJZdXKiG

Difficult bit would be working out how to waterproof the cable coming out of it....

B

Cut your USB charging cable, thread through this, drilled into the Pelicase: https://www.ebay.co.uk/itm/383254402870
Then solder it back together and insulate with heat shrink inside the case.
 

Ian Ball

Active member
If you want to go ultimate lightweight have a look at the nitecore LC10 single cell unit. Max output is 1A with a fully charged cell.  It's essentially two magnets that slot onto the ends of the cell and you plug into what you want to charge.  If you're trying to charge a phone from flat it''ll take a couple cells and a fair while. 

This site might be of interest to you

https://lygte-info.dk/

 
OMG this is another nightmare in the making, straight after that other thread concerning soldering wires directly on to the bodies of 18650 Li-Ion cells.

First off, if you want a 5.0 volt output delivering reasonable current (like a USB socket on a PC does) then you won?t get it from 18650 cells either singly or arranged in parallel or series.

Li-Ion cells are 4.1 volts each when fully charged (so 4.1 for any number parallel linked or 8.2 for two in series, 12.3 for three in series etc).  These numbers are not 5.0, so you?d need a buck or boost power supply controller to drop 8.2 (or some other bigger number) to 5.0 or to raise 4.1 to 5.0 efficiently.  As the batteries are run down their voltage will droop from 4.1 to say 3.5 where you might consider them to be exhausted.  So wired in parallel your 8.2 becomes 7.0 as the battery runs down.  The raw battery voltage isn?t anywhere near constant.  The only way to do voltage level shift and regulation efficiently is a good switch-mode power supply that was not designed by either you or some random online seller.

Second, it isn?t going to be waterproof for two reasons.  A USB inline plug or a panel mounted USB socket by its very nature isn?t waterproof.  Cases tend not to be completely waterproof either, or to some extend develop condensation inside over time.  ?IP? ratings are meaningless too if you read the small print as they allow ?reasonable ingress? of damp or liquid and the item still passes the IP test.




 

aricooperdavis

Moderator
Stuart France said:
The only way to do voltage level shift and regulation efficiently is a good switch-mode power supply that was not designed by either you or some random online seller.

It depends what you mean by efficiently, but I have tested eBay voltage regulation chips much like the one Ben posted and found them to be completely satisfactory for powering small projects over USB. What do you think most USB battery banks use?
 
I have a small adapter for bosch 18v battery to give 2 usb and a 12v.
This is very handy for running a fridge when camping and charging stuff.
A fast charger for the 18V batteries at 8A
Not what your asking for but handy to think about.
 

JoshW

Member
For some reason in my head i thought little monkey made an adapter for 187650 batteries to provide output to usb, but can?t seem to find anything now.
 

Shapatti

New member
JoshW said:
For some reason in my head i thought little monkey made an adapter for 187650 batteries to provide output to usb, but can?t seem to find anything now.
I think he made a very short run of them, mainly based on something he made for himself to charge phones and lights whilst out cycling...
 

royfellows

Active member
Without going into the question of why anyone would want to take, and be able to recharge, a PDA or a phone underground, I agree with previous comments that the "waterproof" bit is the main issue.

The problem with any one off build is that components of quality have to be sourced from suppliers such as Farnell or RS Online who have a minimum spend to get free postage.

The way i would go about it would be to test the electronics from a cheap, off the shelf, USB power bank, and then enclose in an aluminium case rated at IP68, manufactured by Deltron or similar. They probably best. The case would be drilled and tapped to accept a threaded sleeve sealed with FT 101, and would take an IP 68 plug by someone like Hummel. I use this in some of my lamps, but its M16 not large enough for a USB plug, else I would give you the part numbers.

If you wanted to be able to see the charging - charge completed - low power level etc LEDs then there is a fresh challenge.

One can spend many hours sifting through different components, and then when in the lab find them unsuitable for purpose. There is quite a lot to this sort of thing.

Not particularly robust, but fairly waterproof and with a transparent lid, how about just sticking an ebay power bank into a transparent lidded  Appleby Box?
I used to put network cameras into them many years ago for outside use.
 

Mr Mike

Member
An expensive solution for a waterproof USB, but will do the job at IP68, the Bulgin USB range:

https://www.bulgin.com/en/products/range/circular-data-connectors/standard-usb.html

https://uk.farnell.com/bulgin/px0842-a/usb-adaptor-2-0-type-a-type-b/dp/9667741?ost=9667741

https://uk.farnell.com/bulgin/px0733/sealing-cap-for-px0847-connector/dp/314390?ost=314390
 

PeteHall

Moderator
royfellows said:
Without going into the question of why anyone would want to take, and be able to recharge, a PDA or a phone underground...
To answer the question you didn't ask, for surveying.  :sneaky:
 

royfellows

Active member
PeteHall said:
royfellows said:
Without going into the question of why anyone would want to take, and be able to recharge, a PDA or a phone underground...
To answer the question you didn't ask, for surveying.  :sneaky:

Of course!
All you need now then is a waterproof phone to go with the waterproof power bank
:LOL:
 
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