DC Supplies

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Thought I’d post this pic of a 12V dc supply in the build. It’s to power a car radio that serves as my input source. IMG_0843.JPG
It’s made from recycled laptop Lion cells.
 
classAchap is very brave by the look of the heat required to solder the battery tab welds!
Li cells must be charged the correct way, unlike lead acid or NiCad. They also must not be completely discharged or will be permanently damaged.
Overcharge them and you will have a fire, discharge too quickly and an explosion.


True, true, true. I have a cast metal box for the battery and another separate box for the charger which consists of 3 (gutted) commercial Li-Ion chargers. The chargers are permanently connected, via Schottky diodes, and are on a timer for daytime (solar) charging and are in their own cast box.
I’d be interested to hear of other efforts like this.
 
I thought Li-Ion should not be trickle charged, and that to do so quickly destroyed them.


Yes, I believe that’s true. I don’t think this constitutes trickle charging though. The charger should not exceed 4V1 and the diode drops this to 3V6 or so. At this voltage a charged cell will just stop drawing current - I think I checked this early on. Accidental over-discharge is a greater concern but we will see - it’s obviously experimental.
BTW how do you post LtSpice? I’m thinking of posting the .asc using paper clip, will that display the circuit and be downloadable to LtSpice?
 
.asc is on the list of permitted attachments.
Each Member can simply click on your attachment link and it should request an "open LTspice"


Ok Andrew, I see what’s happened, I’m using iPad/TapaTalk which has a different interface. I know LtSpice schematics show using the DiyAudio interface but I can’t see how to show it in TapaTalk.
So, let’s see if loading the .asc works:

No. That doesn’t work. ‘Paper clip’ goes to my photos same as ‘scene’

I’ll see if I can get TapaTalk working on the PC maybe that will have a better GUI.
 
those lithium packages need to be balanced, i.e. during the charge process you have to monitor each cell and limit its voltage.


That would be true if they were charged in series - but they aren’t. Think of it as just 3 cells in series were each cell has its own floating 4V1 charger giving ~12V. Now, replace each individual cell with block of 12 cells in parallel. They can’t go out of balance - yes?
 

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...I’ll see if I can get TapaTalk working on the PC maybe that will have a better GUI.

If you have a PCMac, you can use the Web Browser there. Then you get the DIYA interface which has been honed over many years to the needs of this community.

TapATalk is more for casual chatrooms. It expects you may upload a picture of, say, your car; in modern systems these will all be in a "Pictures" folder. (Bad plan but you can't argue with Mac/MS/Android.)

...iPad/TapaTalk ... ‘Paper clip’ goes to my photos same as ‘scene’

In my PC browser, I have defaulted the Web Upload desination to my "upload folder", which I cleverly named "111" so if I get lost, it will be easier to find.

From there I "can" navigate to other folders. Some O/Ses make this hard.

What-ever the device's upload favorite folder is, it may be best to use the file-browser to find where your ASC work files are stored, COPY the one you want, navigate back to the upload folder, and Paste. This indirection avoids confusing LTSpice or Brower/TapATalk with extraneous folders it shouldn't normally work in.
 
Lithium chemistry batteries are not voodoo poison! Certainly they have some guidelines that must be followed for best safety and performance, but they are not nearly as volatile as they were years ago when they made their way into the first fire happy laptops.

Charging Li batteries should be done within there stated specs, "trickle" charge vs. "rapid" charge varies from battery types. Some batteries are made to provide high charge/discharge at the cost of total capacity - think drill batteries. Some are made to have a high capacity, but low current capability - think phones. This creates charge criteria that is related to the capacity of the pack - the "C" rating of the pack. Usually this rating is given something like 5C/1C. For discharge/charge capability of the battery in terms of it's capacity. So a 2650miliAmpHour pack of 5C/1C could be discharged at 5*2.65A = 13.25A and charged at a rate of 1*2.65A = 2.65A.

Overvoltaging a pack is the most dangerous scenario you can put yourself in. And these newer 18650 type cylinder cells have multiple safety mechanisms in place to prevent a catastrophic "thermal event". Vents and fused connects go first to try and maintain a manageable environment for the battery.

Balancing of this type of battery is a low priority. For a high discharge pack with many cells in series it becomes a high priority. For a low series count, low discharge rate system you may check them with a DMM every so often to ensure a cell(s) hasn't died.

Low voltage is harmful to the cell. Especially storing the cell at a low voltage for an extended period of time. Charging a low voltage cell with a low charge current until "recovered" voltages are produced is a common practice. A low voltage cell starts to grow dendrites across the anode/cathode boundary creating micro short circuits and reducing capacity.

For best performance (read: longest life) of a cell it's best to keep the cell within 80-20% of maximum capacity, keep the cell in a moderate temperature climate, reduce the discharge current of the cell, and avoid high multi-C charge currents.

Li chemistry batteries are a fantastic battery system and when used with some simple guidelines with newer constructed batteries is a very robust solution.
 
Ok Andrew, I see what’s happened, I’m using iPad/TapaTalk which has a different interface. I know LtSpice schematics show using the DiyAudio interface but I can’t see how to show it in TapaTalk.
So, let’s see if loading the .asc works:

No. That doesn’t work. ‘Paper clip’ goes to my photos same as ‘scene’

I’ll see if I can get TapaTalk working on the PC maybe that will have a better GUI.
Please don't use the "paper clip" quick attach.
It creates an attachment that takes us OFF page. The Member then needs to return to page after reading the attachment.

If one were in the middle of typing a reply and needed to view a pic, then clicking on the pic link using that paper clip attachment takes one off page and the part written reply is LOST forever.
 
Please don't use the "paper clip" quick attach.



OK Andrew, that’s noted. I think we’re still slightly at cross purposes. As I write this I’m in Tapatalk on an iPad, it offers me just 4 option icons: camera, scene, paper clip and ‘/‘. They all seem to do the same thing - they take me to photos. As I said, if and when I want to post .asc I’ll go to the PC. But yes, I’ll be aware of your warning. Thank you.
 
Scroll down and select Go Advanced (it's next to Post Quick Reply).
That takes you to a reply page with additional options and one in there is the Manage Attachments.

This is all described in that link I gave you and others.



No. Still at cross purposes. The options you mention are not available to iPad users on Tapatalk. I have no problem using the DIYA interface that’s all fine. Not a problem. I was hoping to use Tapatalk because, in other respects, it’s very convenient. Seems I can’t but that’s fine - I just wanted to know.
 
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