I want a rechargeable power bank that will supply USB, and a 12V car "cigarette lighter" accessory output.  Power poles would be awesome but I can make adapters.  It should have the option to charge from USB, 12V, or solar.  Preferably with a good OLED display that tells you charge status, etc.

Every one of these I can find is sealed up and designed to be disposable.  The thing is, the vast majority of these power banks use common 18650 lithium cells inside.  


Does anyone make a power bank that allows you to easily access the insides and replace the cells?  I am not opposed to soldering in new cells myself, and I don't mind if it's screwed together.


But most of these are assembled in such a way that you would damage or destroy the case trying to open them up to replace the batteries.


This will be for a specific emergency power use (backup for other devices, and for portable ham use) and if I am unable to periodically cycle the cells through some charge/discharge cycles, they will eventually develop high internal resistance and fail.


The trouble with lithium rechargeables is that you have to use them periodically, and that isn't practical when I have so many devices that use them.  I have cameras, tablets, computers, radios, test equipment, gun optics, power tools, flashlights, video game consoles, headphones and earbuds, toys, and more, all of them powered by internal, non-user-serviceable lithium cells.


I want the backup device, (this power bank) to be user servicable.


I absolutely despise the trend towards disposable electronics with proprietary internal batteries.


Yes, recharging is cheaper than buying alkalines.  But not for devices you only use a few times a year.  And I have a ton of devices that only get used a few times a year.

One option I can think of is the cordless battery inverters like this:
https://egopowerplus.com/nexus-escape/

You can get them for most any battery system (red, yellow, blue, etc).  If you then buy aftermarket battery packs, they are easier to crack open to fix/modify.  Its not a perfect solution, but its the direction I went to charge stuff.

I went down a rabbit hole on this stuff and you can get little spot welders and pure nickel straps to fabricate your own packs.

It doesn't look like what I want exists, and it's sad because the vast majority of these power banks use 18650 cells, but none of them are designed to be opened up to replace the batteries.

I did find a couple of smaller power banks that are designed to take 18650 cells and can be opened up to charge and replace them, but they only have USB output ports, no 12V.

I don't know if this can be taken apart or not.

https://www.anker.com/powerhouse_757?ranMID=43469&ranEAID=TnL5HPStwNw&utm_source=rakuten&utm_medium=affiliate&utm_content=1_2116208_Skimlinks.com&ranSiteID=TnL5HPStwNw-3LEYMjTWwWHIkZTOd7.U2Q

Lots of power, no idea if it meets your requirements though

I don't believe something like what you described exists - although I think it would be a home run if anybody developed such a thing. Especially if it used 18650's or 21700 cells.

https://powerwerx.com/solar-portable-power

I was looking at these.
I make my own LiPo4 batteries from stock cells.

I just finished this up tonight. It uses Ryobi 18v batteries. USB and cigarette lighter on the front and a power pole on the back.

Attached File

Can you tell us more about it?  Did you make the 18 volt ryobi battery contact interface?  3d printed?   Tell us about the regulator and how much current you can sink out of 1 or 2 of those batteries.  Is it a simple analog regulator with a pass transistor or some kind of DC to DC switcher?  OEM off the shelf product or something you whipped up yourself?  I sure have a lot of questions don't I?

That's a neat idea, using commonly available power tool batteries.

Tons of Power bank components and kits on Ebay.
Search "Power Bank kit" "Power bank case 18650"

Heres an example

Power output is limited. hopefully, the 12v limit fits your requirements.
"PD" output protocol is available with some kits offering higher output.

Uses unprotected cells. Great for scavenged cells.

https://www.ebay.com/itm/284466949809?hash=item423b8d2eb1:g:4ewAAOSwujFgBagB

You will need to make the barrel jack to powerpole.

Charging input: 5V 2A (Micro-USB)
DC output: DC5.5*2.1-2.5MM 3.6V/2.5A;5V/2.1A;6V/1.8A;9V/1.1A;12V/0.6A
(Output with current limiting and temperature protection)
USB port output: 5V/=2.1A(max)
it need unprotected 18650 battery 2000-6000MAH


Honestly IMHO i would use the tool battery adapters that are available.
Some are designed for DC to DC variable output at much higher current.
If your are handy add a usb module.


Etsy, amazon and ebay all have them.
https://www.etsy.com/shop/DesignMakeShare?ref=simple-shop-header-name&listing_id=1066465791

@dawg69

Did you find plans somewhere, or just figure it out yourself?

If the former, do you know if plan exist for the Rigid batteries? I have a ton of those with lifetime warranties...

I 3D printed the case based on this: https://www.thingiverse.com/thing:4778323/files  I had to make the case taller to accommodate the larger converter.

The tabs for the batteries are linked in the plans above. I used this converter which is supposed to convert 24v to 12v and handle 30A. I get 12.2v from it so I'm not sure how well it will run things like a radio that is rated for 13.6v. I have not had a chance to try it out on that yet.

The switch, USB outlet, 12v outlet, and voltmeter came from this.


Inside view

Attached File

Sucks that you can't tweak the voltage on that converter.

I agree. There were some adjustable ones available, but not at that amperage. It's a work in progress.

I *really* need to get a 3D printer. Damn, that's cool.

It's really the handiest tool I've purchased. You cannot go wrong considering how cheap they have become. Youtube and Google will teach you what you need to know to operate it. It isn't difficult.

You can make guns too!

Here are some protective rails I printed for my FT 891. Much cheaper than the commercially available ones.

Attached File

Thanks. That is very interesting to me.

You can easily rig in a couple of USB-C PD devices from coolgear.com and/or make any sorts of mods you wish. Or just build your own entirely from scratch.

Note: they have usb chargers that will accessor anywhere from 9 to 24 volts DC, you could buy the above box and rig in ability to accept power tool batteries pretty easily.


Also, are your sure about needing to use lithium?  I’m reasonably certain that lithium batteries store in a medium charged state are good for many years. But perhaps I’m thinking of another chemistry.

From what I know I think you'd be better off with a Lithium Iron Phosphate battery instead of a whole bunch of Lithium-ion cells made into a pack.

I finally got around to testing the Ryobi battery power supply with my Yaesu FT891. It seemed to do just fine with my minimal tests. I'm going to take it along to scout camp next week to run the Yaesu, so the big test will tell how well it really holds up. Fingers crossed.

Good luck.  It will be interesting to hear how it works out.

Something like this? Or copy the idea and roll your own.

https://powerwerx.com/pwrbox-portable-power-bioenno-batteries

I do like these and it has everything except the charger and the battery.  I'm probably going to have to be in the roll your own camp.  It would be great if I could get a charger that worked with solar, 12VDD, and 110V AC and automatically detected battery chemistry.  It would be nice to be able to swap in or out gel cell batteries, LiFePO4 batteries, lirhium ion, lithium polymer, NiMh, etc. and have the charger detect and charge them safely.

I have a charger that will do all those chemistries but you have to configure it for each.

I think replacement options area good idea except don't you need to match the electrical characteristics of the batteries to get the most performance?  I know that Tesla does this on each battery in their packs.

I bought one of these a couple years ago with a Bioenno 40ah lithium battery. The battery is small enough that I am able to keep the charger and some power cables inside the box. Total weight is about 12 - 13 lbs., so it's very portable. It can also accept 12V SLA batteries. IMO, the design and workmanship were very well done. I could not be more happy with it.

I also bought the solar panel with built in charger that Powerwerx sells. I haven't tested it too much aside from basic functionality, though.

The battery box gets the most use at a friend's off grid cabin that he has wired for 12VDC. He keeps a small SLA battery on a solar trickle charger so that if we get there after dark there are lights for unloading our vehicles. We'll disconnect that after unloading and then plug in either his or my battery box, either of which provide plenty of power to run lights and/or small fans over a long weekend.