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DIY laptop powerbank project

  • desolder Top 10 Forum Poster Wednesday, March 1, 2017 10:05 AM Reply

    Hey Ignatus, sorry I'm jumping in late on this thread.


    Have you seen sku.369547? MPPT controler for under USD $12. WOW that's cheap.

    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • sheepish Top 10 Forum Poster Wednesday, March 1, 2017 6:01 PM Reply

    sku.369547 might be cheap, but...


    Output anti-anti-irrigation protection: None;


    I've been wondering if it could be used in conjunction with one of the ordinary solar controllers, like sku.450706.


    Or for about the same total price, what are the chances that something like sku.454921 really has any MPPT functionality at all? The product description uses all the right words but MPPT for that price?

    Remembering 30 years.
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  • Ignatus Wednesday, March 1, 2017 9:46 PM Reply

    Hello ozOzo,


    Quote:” Were you aware btw, that clicking on the number and clicking on the little red arrow after it bring up two different pages? “

    Answer:  Yes I was aware of it.  Usually, I first only click on the SKU code link to see the minimized pop-up window of the product, if I’m just curious to see the item a person was referring to, without opening a whole product page.


    Quote: ” Perhaps also you hadn't noticed that besides the @usernaim function, there is a forum rules compliant means of sending a PPM (private pm) that only the two parties are … "


    Answer: As a matter of fact, I still have no idea how people send each other PMs, apart from the recently discovered  "at username” function. Maybe you’d like to explain to me how?

    I usually just wait till I get a PM and then reply to that


    Also, if the acronym “PM”  usually stands for private message what does “PPM" as you call it stand for?


    Lastly, I'm wondering if you know of a more userfriendly method to quote a text snippet from someone else's post in a reply?




    Hello Desolder nice to see again!

    Also a BIG HELLO to Sheepish.


    As mentioned a few posts ago, solar charging is really not my top-priority at the moment. I just started reading more about it since Sheepish asked for my opinion about DX’s solar chargers.

    I’ll experiment with these two solar charging options sometime in future:



    a.) Solar panel to (either buck, boost or buck-boost CC/CV ) DC converter to Lipo charger.

    b.) Solar panel to PWM.  PWM 12/24V load terminal (not the Lead-Acid battery charging terminal to (either buck, boost or buck-boost CC/CV) DC converter to Lipo charger

    I still have SKU: 258020 , SKU: 214310 and SKU: 239099 here, which are all catching dust and could be used in a solar test set-up. - Just a decent solar panel is missing.


    However, I’ll first have to complete building this pack and my wife already demanded that I build one for her as well.

    Yesterday, I wired everything up for a first test-run and came across my next roadblock.


    -I’m a little stuck and would appreciate your thoughts on this:




    The problem:

    I soldered the balance leads on the battery side and balance charging works fine!


    The issue is that, as soon as the balance-wire is plugged into the Lipo charger SKU: 433805 the thing starts to measure capacity of the 4s packs immidiately and continuously, even when no power is supplied to the Lipo charger itself via the external DC barrel plug.

    The goal:

    Stop electricity flowing back from the battery cells via the 4 positive balancing leads into the permanently connected Lipo charger while the charger is off and still connected, without manually removing the flimsy 4s balance wires/connector.



    The potential solution:



    I looked for a 4PST and couldn't find one. Then I found: Omron Relay 24DC 5PST-NO SPST-NC  6 CONTACTS for $70  , but the cost is too damn high.

    I also found a TINY 12V SPST automotive relay, which is easily available locally. Basically 60%  less volume than a regular sized 12V one.

    I could use 4 of them and one simple on/off switch to control them/ their coils.

    The 12V relay currently in use that switches the main load is also not being directly operated by the whole 16.8V battery.


    I’ve put this tiny step-down converter SKU: 280240 in between just to operate the relay's coil  within safe limits and have 5 more laying around.

    Therefore, I could operate the 4 relays to control the 4 balance-wires, with the power for the coils being supplied by the whole battery pack.


    Question:

    I’m wondering if placing a relay in between each balance-charge lead / wire will be an issue with the relatively small amount of current and voltage that needs to flow through each relay and be reliably measured by the Lipo charger? -Will it have an impact on the charging results?






    EDIT : DELETED SOLUTION 2



    Solution 2.)



    Yeah, slow thinker here...


    Obviously, any type of diodes won't work and therefore  P-channel MOSFETs in reverse won't work either.





    Kind regards,

    Ignatus



    Edit 1: typos

    MAJOR EDIT 2 : DELETED OPTION 2, because I understand I came up with that option while having a brain freeze




    EDIT: THIS PROBLEM HAS BEEN SOLVED

    Project update:


    My above question about feasability to have each balance-wire to go
    through one 12V automative relay has been answered by myself a few posts
    down from here.


    !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I did a test and IT WORKS !!!!!!!!!!!!!!!!!!!!!


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    post edited by Ignatus on 3/2/2017 at 7:16 AM
  • gasbag11 Top 10 Forum Poster Thursday, March 2, 2017 1:08 AM Reply

    Hi Ignatus. 


    I just sent you a (true) PM. Click on "My Account" then "Personal Messages" to see it. Or you'll see the message when you check "Latest Posts". 

    Use the "Reply" button (lower right corner of the PM) to reply privately or the link to reply in the forum.


    The first time you PM someone has to be with the @ like normal if they haven't sent you a PM. 


    I think PPM just means personal private message, meaning truly private as opposed to the @ which just a way to call someone's attention to a thread they haven't posted in. 


    As far as quoting, we just italicize the quoted text.


    Btw, Using bold text or upper case letters is considered shouting on most forums. 

    NO! I don't know why DX screwed up the site so badly.
    Ask them.
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  • Ignatus Thursday, March 2, 2017 3:55 AM Reply

    Hi Gasbag :)


    I know how to reply to a PM, but thanks for the detailed effort and I've received your PPM / true PM ;) Thanks!


    The factor that I wasn't aware of was : "The first time you PM someone has to be with the @ like normal if they haven't sent you a PM. "


    Truth is that till yesterday I wasn't even aware that @username in forum posts creates a PM.


    Anyhow, it is slightly misleading that under "my PMs" in the "from" field it is written  "Ignatus" instead of your username.


    -Not very practical if this would be an active forum.


    Now, I unfortunately still don't know how you've send me the true PM. I understand that you were able to send it only because I wrote your @username in the beginning of this thread.


    Also, after reading ozOzo's last post, I wrongly assumed that there are more ways to send a true PM to somebody without first being mentioned by the person whom I'm trying to contact, with my @username in the public forum.


    P.S.:


    Caps lock?- Sure that is considered to be shouting, but first time in 20 years I hear that bolded text is considered to be shouting on the net.


    I use bold font mainly because it helps me to format my unusual long posts and this text editor has already very limited feature set.


    It is also supposed to help the reader split my eternal monologues into readable sections and help them distinguish between two or more persons, when I'm quoting others.


    -As far as I can remember most proper/commercially developed forum software (phpBB, vBulletin etc.) those  that have the Quote feature inbuilt uses cursiv, bolded font when quoting.

    I wouldn't be surprised if the previous version of this forum did the same. (Maybe I'm wrong and I just don't know where I picked up this habbit.)



    /sarcasm on


    Anyhow, this is all sooooo super off-topic again, I'm sure people who stop by to learn how to built a DIY laptop powerbank will love to read these type of conversations.


    /sarcasm off




    Kind regards,

    Ignatus

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    post edited by Ignatus on 3/2/2017 at 3:57 AM
  • sheepish Top 10 Forum Poster Thursday, March 2, 2017 4:48 AM Reply

    Truth is that till yesterday I wasn't even aware that *username in forum posts creates a PM.


    username is an actual user whom you just PMed, but usernaim (whom you and ozOzo PMed earlier) is not.


    -As far as I can remember most proper/commercially developed forum
    software (phpBB, vBulletin etc.) those  that have the Quote feature
    inbuilt uses cursiv, bolded font when quoting.


    They just use italics for quoting. They don't use bold unless they've been set up in a weird, non-standard way.


    Maybe the Master Class thread would be a good place to continue with forum tips.

    Remembering 30 years.
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  • gasbag11 Top 10 Forum Poster Thursday, March 2, 2017 4:49 AM Reply

    Anyhow, it is slightly misleading that under "my PMs" in the "from" field it is written  "Ignatus" instead of your username.


    That's because it was a reply to a PM you sent me with the @. 

    @Ignatus should say it's from me. 


    Okay, I'll let you get back to work now. :)

    NO! I don't know why DX screwed up the site so badly.
    Ask them.
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  • Ignatus Thursday, March 2, 2017 5:45 AM Reply

    Alright, guys.


    Slowly, very slowly I'm grasping functionality of this forum.


    Seems there is a differnce between "Reply to this thread (in Electronics) " and the reply button that's on a users personal post.


    OMG cough , cough... I guess it's never too late to learn weird forum software.


    Also, I meant italics of course and the font bolding... not sure where I've seen it, but I copied that style. from somewhere. typical me .. weird, non-standard city dwelling, Metro-Sapien hermit.


    As for this thread going off-topic so many times. - Well, its good fun talking to you and I'm truly happy to have you all here!


    I can always make a new thread with short instructions, schematic, BOM and some pics when the project is complete.


    - Then others who want to build one don't have to read the next 20  pages of this thread that may or may not contain anecdotes of woodstock, the good old times / when everything was better, what we had for lunch today and useful forum tips.


    Lolz @usernaim - I guess I'll have to register that one now ;)


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    post edited by Ignatus on 3/2/2017 at 5:47 AM
  • sheepish Top 10 Forum Poster Thursday, March 2, 2017 5:57 AM Reply

    I guess it's never too late to learn weird forum software.


    Sadly we're almost forced to learn how to use the Stupid New Forum Interface. I say "almost" because we still have the choice to not use it.


    Well, its good fun talking to you and I'm truly happy to have you all here!


    Honestly, this is the most interesting thread here at the moment. I'm learning lots about how to use and charge Li-ion batteries.


    - Then others who want to build one don't have to read the next 20 
    pages of this thread that may or may not contain anecdotes of woodstock, ...


    LOL. My first thought was bourbon, but it could also apply to rifles. Oh yeah, and a music festival.

    Remembering 30 years.
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  • Ignatus Thursday, March 2, 2017 7:10 AM Reply

    My first thought was scotch, second moonshine, third ... but I didn't want to sound like a dipsomaniac.



    Project update:


    My previous question about feasability to have each balance lead to go through one 12V automative relay has been answered by myself.


    - The result is promising.


    I can obviously not be sure that this is the case for all 12V automotive relays / all brands.


    I actually own a few differnt relays 1xSPDT from DX, 2xSPDT from other source and 1X SPST from a local source.


    The local 12V SPST relay which I just tested looks very similar to SKU: 289783.


    I must admit that my $10 multimeter is not state-of-the-art technological equipment, but I couldn't see any voltage drop whatsoever.


    I also connected the Lipo balance charger to a 2s Lipo cell setup and routed the positive balance lead of the first cell through the automotive relay.


    The relay's coil was operated by a seperate 12V source.

    With and without the relay, the cell No1 in the 2s test-battery setup was being read as 3.96V!


    Therefore, I assume tthat he resistance of the relay is negligible and it is indeed possible to route a balance charging wire through a 12V automotive relay.



    Now, this whole experiment ignites an additional new idea:


    The Lipo charger has a buzzer that makes some sound when all cells have reached 4.20V, but it doesn't automatically disconnect.


    -It is a $12 or so Lipo charger. You get what you pay for...


    However, I'm trying to think of a way to utelize the buzzer's electricity to trigger a relay that switches off all the 4 balance-wire relays....



    ...to be continued.










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