In this and the following post (too many images for one) I would like to share my DSO150 battery mod using two lithium cells (without a voltage regulator), one module for battery protection, one for charging and one charge level indicator module. I haven't used the device heavily since I made the mod, but so far it appears to be working nicely.
In the first reply to my posts upsss writes that the scope will behave unpredictably on low voltage with two lithium cells without a boost regulator. I'm assuming he is right about that, so be warned!)
- 2 lithium cells repurposed from a dead Canon LP-E5 battery which I was able to restore to sufficient capacity. The cells from this battery fit the empty space in the DSO150 amazingly well (a little too large) and give hours of battery time.
https://shop.usa.canon.com/shop/en/cata ... pack-lp-e5
- battery protection module for two lithium cells "HX-2S-02 3A"
https://www.banggood.com/HX-2S-02-3A-Pr ... 16563.html
(the canon battery has a protection module built in, but I had accidentally damaged that one (lifted a pad) while I was testing it the cells)
- charging module for two lithium cells based on TP5100
https://www.banggood.com/TP5100-Single- ... 06863.html
This module accepts input voltages in the range of 5-12V (or even up to 18V, though not recommended), so any 9V power supply used before the mod will still be adequate. (Update:
I discovered that actually at least 9V (presumably at least 8.4V) of input voltage are required for this module to load two cells in series to their full capacity. Lower voltages (I tried 7.5V) are not boosted up and the charging never finishes. I assume that the 5V from the specification refer to loading a single cell, which this module can also do (configured with a solder jumper on the PCB).)
- charge level indicator panel for two lithium cells
https://www.banggood.com/2S-3S-4S-5S-Li ... 95698.html
I had never actually tried to run the battery low until after this post. Now I'm noticing that 1) the module I received looks different than the image at Banggood (mine has the button on the sime site as the IC and has SMD LEDs) and 2) that my module is actually meant for 1 cell, not 2; so with 2 cells, it always shows the battery as "full" until the protection module kicks in. Bummer.
Rewired the indicator to measure only one of the two cells, now it works like a charm!)
- superglue, insulation tape, double-sided tape and some random bits from my bench
I didn't take photos during the build (no camera available at the time), so here are a few disassembly shots instead:
The charge level indicator in action. It lights up only a few seconds after pressing the button, using no power at all when idle.
Here it is inactive.
As you can see, I have drilled a hole for the first green LED (which indicates full charge) to be clearly visible. I glued a small piece of thin, transparent plastic behind so that no dust can get inside. For the two green LEDs between that green one and the red one I only removed some of the material from the inside of the casing so that they are somewhat visible through the wall. The red one (which is the last one still to light when the battery charge is low) didn't need that, as apparently this plastic is more transparent to red than to green.
The button itself is made up of a shortened brass screw and a nut, carefully filed and fixed together with superglue, hanging loosely in a drilled hole in the casing. Pushing the nut makes the screwhead push the actual button on the module.
Not strictly part of the battery mod, but made in the same frenzy: A glued-on non-turn washer from a bike makes for a crude, but functional hook, so that I can put the DSO150 up on my wall.
First step of disassembly. The charge level indicator is visible on the inside of the frame, held in place by double-sided tape.
After removing the digital PCB most parts of the mod become visible: the two pouch cells hidden under black insulation tape taking up almost the entire space on the back, the charge module in front of them and the protection module squeezed in the very bottom on the very bottom.
You can see pretty much all of the circuit here, too. Note the spot where the yellow wire connects to the digital PCB of the scope: There I removed the diode D2 as a convenient way to break up the circuit. (Also with the drop of the diode the voltage of the two cells probably wouldn't be high enough to power the scope.) The black insulation tape is there to prevent contact to the charging module.
Note that I had to rewire the charge level indicator after writing this, since I discovered that it is calibrated for one cell, not two. I desoldered one lead of the light-grey/blue double wire from the middle of the PCB and resoldered it on the left where the dark grey wire connects.)
Detail from the side: A narrow piece of hard paper with a bit of foram, glued to the inside of the case at its ends, gives a bit of necessary mechanical support to the indicator board (without it and attempt to push the indicator button would just push the entire board inwards.
Note the (almost…) matching holes in the hard paper and the indicator PCB: This is done so that the LED from the TP5100 charging module can also (barely) be seen through the casing, thus giving a visual sign for if the battery is currently being charged.
As you may imagine, the charge level indicator was the most time-consuming part of the mod by far.
Here it is in action.