Tektronix 222 (yet another) battery pack option

[Spawn]

First a little background information; I always wanted one of these (222 or 224) just to have in my collection with old equipment, but these are difficult to find here in the Netherlands, finally I found one but not for a reasonable price if you ask me, still bought it...

When it arrived, I noticed it had a metal viewing hood, never saw one before on a 222 or 224, it also adds some protection to the knobs.

It didn't have a power adapter, I am using a 20VDC 4.5A Lenovo laptop power adapter.

But let's talk about the reason why I started this topic, I wanted a battery pack for this little scope, there was plenty information on the internet, but I was couple years too late in battery pack game, I really wanted kitsune-denshi's solution, but his site does not work fully anymore, then in his topic there was someone selling assembled kit through eBay or his own webpage, but the website was gone and there was nothing on eBay anymore, PM'ed both guys but didn't receive any response, which is understandable since it was long time ago.

I have seen people using Power Sonic PS-832 battery, but had to modify the scope housing to fit the battery, that is a BIG no-go for me, the other option was using AA NiMH batteries and solder them together like Mr Carlson's Lab did, but I didn't want the battery's glued together, I didn't even have to solder the batteries since I have a Sunkko spot welder, but his solution give me some ideas.

I went with a different approach, using two 8x AA battery holders, gluing the holders back to back so I can reach both sides, first I wished there was 7x AA battery holders but when I finished the 8x one fitted perfectly and had room on the 8th battery compartment to put some of the wires, 8th compartment is soldered together since I need 7 batteries to work.
The battery holders were 0.2mm too high, for those who don't use proper measurement units, it is almost nothing
Used a disc sander on the battery holders to fit in the battery compartment of Tek 222, and then glued them together.

With this solution, I can replace the batteries easily when needed, I can even run the scope with 7 batteries instead of 14 in emergency.

Then the batteries:
I got some EBL AA 2800mAh NiHM batteries for less than €1 each from Amazon on prime deals day. After watching some reviews, it is hit-and-miss with these batteries, but of course I watch the reviews after I bought them... In worse case these batteries have 2000mAh and best case almost full capacity, this means in the worst case the package should keep Tek 222 7 hours powered, (current draw of the Tek 222 is 550mA)
Battery configuration is 2x parallel from 7x series batteries.

EBL battery specs:


Finished battery pack:

Protected with inline fuse holder, used a fast 1.4A fuse

Battery holders are from Aliexpress:

The 222 came without the original battery, so I didn't have the battery connector, I used this 3P molex connector from Aliexpress, pin pitch is 3.96mm

Measuring the current after just charging the batteries through the scope, batteries stop charging at 9.7V (1.39V each cell) as mentioned before Tek 222 draws 550mA through the batteries:

When it started with charging it was almost putting 1A to the batteries through the scope, and started dropping really fast till the batteries were full, this is within the fast charging specs of the EBL batteries.

Here is the battery still connected while Tek 222 is off, current draw is almost nothing:


Battery pack is in the scope:

I may or may not go a little crazy with disc sander at the top right part of the battery holder 

Running on battery:


Running on battery again with battery lid on:


I am pretty happy with the result, I hope it gives someone an idea in the future.