Li-ion power mod

Tugo
Posts: 9
Joined: Fri Mar 03, 2017 1:46 pm

Re: Li-ion power mod

Post by Tugo »

Hello all!

I believe you don't need to mod the switch.
jye1 already made a board that do all of the things you guys want.
It is here.

And if you don't want to buy that you can even make yourself a switch from that schematic.
All you need is that transistor Q1, D2 and R3 from figure 1.
Top line is from USB, BATT line is from battery and VOUT is going to your switch on the main board of oscilloscope (SW5).
What it does is putting voltage from USB to Vout or voltage from BATT to Vout (if there is no USB voltage present).

If you have USB voltage present it is actually charging the battery and also providing power to oscilloscope.

I use it for quite some time now and it is working as expected.

Best regards,
Tomaz

EDIT: I changed link to schematic because it was wrong.
Last edited by Tugo on Mon Feb 12, 2018 12:38 pm, edited 1 time in total.
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

Yes indeed. The P-channel mosfet will normally be fully ON with the gate tied to ground, and with very little voltage drop. But when the power supply is plugged in, the gate goes high, which turns off the mosfet. You still have a diode in the other power path, but I don't think that's a problem.
Tugo
Posts: 9
Joined: Fri Mar 03, 2017 1:46 pm

Re: Li-ion power mod

Post by Tugo »

Well, yes.
But there is also an internal diode in the mosfet (between S and D) which is why it works on battery (while you don't have external voltage).

I wanted to put my pictures here so that maybe somebody else would benefit from it, but I was (and still am) a little bit too busy at the moment to do it.

My oscilloscope modifications:
- 1500mAh battery 504050 and it is like this - it fits without any modification
- charger for battery is here
- step up converter is here
- after I power oscilloscope I have this display to tell me the voltage of battery
- I also made some modification of the case so that I can upgrade firmware without opening the case

If someone is interested in any particular part of my explained mod let me know and I will upload some pictures.
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

I'd like to see a pic showing where everything is placed.

Also, do you have any noise problems with that boost converter needing further filtering? Anybody else have that problem?
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

The battery finally arrived, and I was able to complete the lipo mod.

As mentioned before, I have the old style boards, and the analog board extends about 6mm further into the lower part of the case than the newer board. So the BH6X battery just wouldn't fit. I ended up using this battery:

https://www.ebay.com/itm/390980174321

It is 50mm long by 34mm wide by 6.6mm thick, and 1300 mah. There was almost enough room to lay the booster module next to it, and in the end I just let the module lie at an angle against the battery, which worked fine. I removed the pot from that module and replaced it with two 56K fixed resistors in parallel, or 28K net, and that gives me about 8.2V output, which is about right since it doesn't go through the diode.

I hot-glued the charger module to the main board and cut a hole in the front panel for the micro-USB connector. I replaced R3 on the module with 3.3K and 33K resistors in parallel, or about 3K net, which gives me about 400ma charging current.

As I mentioned in an earlier post, I decided the leave the 9V barrel connector in place and functioning. I removed the SW5 DPDT switch and cut the traces connecting the two halves, so that it now functions as DPDT, then reinstalled the switch. Then I wired everything through the switch so that when switched to one side the scope is powered by the battery and boost converter, and when switched to the other side it's powered the 9V barrel connector, or powered down if nothing is plugged in there. In that state, the battery can still be charged, but the boost converter's input and output are disconnected.

I have decided that I won't try to charge the battery and power the scope at the same time all through the charger module. So if I need to charge and run at the same time, I'll dig out the old 9V power supply, and run the scope on that while USB is charging the battery. I don't anticipate that will be needed often, if ever.

Earlier I had removed the encoder and daughter board, bent the encoder pins backward, and soldered them directly to the main board. That left the four daughterboard pin holes empty, and I used those holes as gateways for the wires going to the switch pins on the other side of the board.

As noted in one of the early posts to this thread, the charger LEDs - red for charging and blue for completed - are dimly visible in the screw hole nearest where the module is mounted.

I have not yet done anything about a low battery indicator. Not sure if I will.
Attachments
Lipo Mod.jpg
Boost position.jpg
LIPO Mod Switch.jpg
SW5.jpg
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

I ended up placing the battery so its terminals are pressed against the side of the case. So I drilled a hole there opposite the positive terminal, and can now measure battery voltage at any time. I can measure with my voltmeter, or I can use the scope probe. With that setup, I don't think I need to do a low-battery indicator.

This mod is pretty slick. It's nice not to have to mess with the 9V power cord. I wonder if JYETech will consider making all their new stuff battery powered like they did with the Coral.
RobNL
Posts: 122
Joined: Mon Dec 25, 2017 3:11 pm
Location: The Netherlands
Contact:

Re: Li-ion power mod

Post by RobNL »

Why not like this ?
In off position you can charger the batterie without power concumption from the batterie.
In on postion you can use the 5Volt USB and the 9Volt barrel to feed the shell.
Release the USB in off position and there is no power at all to the shell.
Attachments
LIPO Mod Switch A.jpg
CU, Rob
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

RobNL wrote:Why not like this ?
In off position you can charger the batterie without power concumption from the batterie.
In on postion you can use the 5Volt USB and the 9Volt barrel to feed the shell.
Release the USB in off position and there is no power at all to the shell.
I'm not clear on this. In the ON position, it looks like it would be the LIPO/stepup and the barrel that would power the Shell. If the charger is not connected, how would USB supply 5V to the stepup?

Also, the charger I used includes the protection circuits. If the LIPO is disconnected from the charger module, I would lose those protections when the LIPO is supplying power. Of course the LIPO should have its own protection built in, but you would need to test it to be sure.

And I would just prefer not to waste LIPO power on the diode voltage drop. But it would be possible to replace the diode with a P-channel MOSFET which would have very little voltage drop. Look at the schematic in the Manual for the JYE118 charger module.

I understand that the way I did it is confusing because the switch is ON in both directions, but if nothing is plugged into the barrel, it's really OFF when switched to that source, and the stepup converter is isolated at both ends. But I also understand that I shouldn't be able to use charger power to charge the LIPO and operate the Shell at the same time, and my version doesn't prevent that. But I think the solution for that would be the JYE118 circuit using the MOSFET.
RobNL
Posts: 122
Joined: Mon Dec 25, 2017 3:11 pm
Location: The Netherlands
Contact:

Re: Li-ion power mod

Post by RobNL »

In on position the shell will powerd from the stepup untill the batterie is empty.
Now yoy can connect a 9 Volt barrelplug or USB to continue without any damage to the shell or stepup.
With USB you load the batterie and the shell, but you need a stepup who can deliver more than ~100mA to the shell and xxx mA to load the batterie.
With the batterie you use you need ~250 mA from the USB to stepup (~100 mA shell and ~150 mA to load the batterie)
In the off postion you can load the batterie with the USB and without power consumption from the shell.
So off is off and on is on, no off is on or on is off, but both is on / off and powerd the shell.

With the batterie you have (1100mA) you can work about 7 a 8 hours with the shell, I think thats enough befor you have to load.

Diode D2 is allready in the JYE schematic, so you lose all ready 0,6 Volt, a second diode into the stepup powerline is the same JYE will do from the 9 Volt barrel.
CU, Rob
alphaseek
Posts: 85
Joined: Thu Jan 19, 2017 5:24 pm

Re: Li-ion power mod

Post by alphaseek »

Attached is a drawing of what I've done. Just to be sure I understand, could you post a drawing of what you are suggesting?
Attachments
Switch.jpg
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