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Forum Index : Electronics : Increase voltage out.

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bob.steel
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Joined: 27/02/2020
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Posted: 12:14pm 04 May 2020
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I want to read a battery voltage with a multimeter but I want it to read an extra 150mV  . I need a voltage doubler type circuit that just increases the voltage a little by 150mV.

Its just a generic question Can this be done ? How?
 
Warpspeed
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Posted: 09:21pm 04 May 2020
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What is your nominal battery voltage ?
Cheers, Tony.
 
bob.steel
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Posted: 08:09am 05 May 2020
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I want to do it on 3.7v Lithium cells and I want to cut charge at 4v say rather than 4.2v.
Most of the chargers turn off at 4.2v I want to have that same charger chip turn off at 4v.
Edited 2020-05-05 18:11 by bob.steel
 
Warpspeed
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Posted: 11:16pm 05 May 2020
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I am sure it would be much easier to modify the battery charger to do this, or perhaps build yourself a charger.
Cheers, Tony.
 
bob.steel
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Posted: 11:32pm 05 May 2020
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So how would I modify a charger to do this then?
 
bob.steel
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Posted: 11:39pm 05 May 2020
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I hoped there might be an easy solution .
If I wanted to read 600mv less I could use a diode . Or with a shottky even less.
Is there no approach I can take to increase the reading by a set amount?
I'm sure there must be .
The answer to nominal battery voltage is just manufactured because I could not see what difference that would make except bring the set of readings I want down in the low voltage range rather than high voltages.

Anyway I'm still looking for an answer if possible to suit as many voltages as poaaible. There must be a way.

I'd also like to know how you would modify a charger to do that or even build one .
Edited 2020-05-06 09:41 by bob.steel
 
bob.steel
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Posted: 11:45pm 05 May 2020
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Perhaps it will help to explain that when I charge my mobile phone if the battery charges to 4.2v it does damage inside the battery thus reducing its life.

By building something onto the charger to increase the volts out reading I could effectively stop the charging at 80 to 90% of capacity at which point it is known that no damage to the SEI layer occurs .

There are billions of chargers out there all taking the final charge too high.Thats only recently been discovered . It will take a long time then for charger manufacturers to change the cut off voltage considering the battery must charge initially to 4.2v to create the SEI layer but you want to cut it off early on all subsequent charges . I dont know how long it will take them to solve that.
Edited 2020-05-06 09:51 by bob.steel
 
Warpspeed
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Posted: 12:03am 06 May 2020
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You could modify the circuit that monitors the charger output voltage.
Usually there is a voltage divider consisting of two resistors.  
Changing one or both resistors would alter the charger output voltage setting.

I cannot tell you EXACTLY how to do it without having either the correct circuit diagram, or having the charger in my own hands to inspect and figure out.
Its really the only solution that is going to work.
Cheers, Tony.
 
nickskethisniks
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Joined: 17/10/2017
Location: Belgium
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Posted: 01:15pm 07 May 2020
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  bob.steel said  Perhaps it will help to explain that when I charge my mobile phone if the battery charges to 4.2v it does damage inside the battery thus reducing its life.

By building something onto the charger to increase the volts out reading I could effectively stop the charging at 80 to 90% of capacity at which point it is known that no damage to the SEI layer occurs .

There are billions of chargers out there all taking the final charge too high.Thats only recently been discovered . It will take a long time then for charger manufacturers to change the cut off voltage considering the battery must charge initially to 4.2v to create the SEI layer but you want to cut it off early on all subsequent charges . I dont know how long it will take them to solve that.


No, they already know it a long time... I only know it about 10 years...
 
bob.steel
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Posted: 10:26pm 07 May 2020
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Thats not the case if you research it . They have known about the SEI formation and importance for a long while  . Only 12 months ago they were able to establish that pure Lithium is laid down to create it and that process continues and lays down more each time you get the voltage to 4.2 v and they could actually see it happening.This extra lithium clogs the passage of Lithium ions through the elecctrolyte thus reducung the capacity each time you go there. There is a youtube video on it somewhere.
 
renewableMark

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Posted: 11:00pm 07 May 2020
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If it's the battery in a mobile you are worried about, have a think about how long the phone will last, or need updating anyway.

The phone will likely break, or you'll toss it before the battery is stuffed anyway.
Cheers Caveman Mark
Off grid eastern Melb
 
bob.steel
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Posted: 09:15pm 08 May 2020
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I must look after my things way better than you or you have some secret I am not privy to . I have a huawei phone and I'm on my 3rd battery now. Screen is cracked but I did that in the first week getting used to it. Its probably 4 years old by now . However it is batteries in everything ,laptops,radios,power banks,clocks . Anything rechargeable these days.

The younger generations are more "toss it in the bin and get a new one" he he.
Anyway I guess no one else has any suggestions to raise the read voltage?
Edited 2020-05-09 07:18 by bob.steel
 
renewableMark

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Posted: 10:47pm 08 May 2020
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I have never replaced a battery in a phone, had a few for a couple of years each.

Pulled out a 5 yo old one for my son to use as a hot spot recently, works just as well as it did new, (just screen cracked).

My wife gets a laptop supplied by her school, when she was on maternity leave 7 years ago she had to hand in hers, so I bought her a laptop.
Just pulled that out for my son to use for home schooling, still works fine, when charged it lasts for 3 hours, which is probably fine for a laptop with a big screen.
The ipad he normally uses is at least 4 years old.

None have had new batteries ever.

Maybe it's the brands or the price bracket (cheap crap) that makes them more susceptible to early failure?
Cheers Caveman Mark
Off grid eastern Melb
 
bob.steel
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Posted: 10:57pm 08 May 2020
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Mm just being contrary I think and I don't believe you understand the process I have explained . Have a bite and hang on for dear life approach. 1500 posts ...I hope they are not all like these irrelevant.

They store quite well at about 40% state of charge but charging them to full damages them .

Here is some of the current research you might avail yourself of

https://www.sciencedaily.com/releases/2020/02/200205132307.htm

https://www.sciencedaily.com/releases/2020/05/200508083542.htm

This search below will give you current topics and the loss of cappacity is a common theme and reason for the research.

https://www.sciencedaily.com/search/?keyword=SEI+lithium+#gsc.tab=0&gsc.q=SEI%20lithium%20&gsc.page=1
Edited 2020-05-09 09:16 by bob.steel
 
Warpspeed
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Posted: 11:42pm 08 May 2020
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So why don't you just buy or make yourself a charger to your own specifications ?

Fully adjustable voltage and current limited bench power supplies are readily available, and the Chinese ones are not that expensive.


Cheers, Tony.
 
Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 344
Posted: 12:50am 09 May 2020
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I have had a cannon camera battery still working after 15 years
2 old Lg phones obsolete 2g,  nothing wrong with the batteries 8 year old, still ok
Bauhn phone battery still working but obsolete.
latest phone is an OPPO A5   and it now has a fat battery and I also suspect it to be over charged causing the problem, its also build in and as yet I have not found a replacement battery for it in AUS.

I had some camera battery charges, opened them up to find they where adjustable, so the next idea would be, to see if the oppo phone usb charger is adjustable.
Or go with a power supply as Tony has suggested.
Cheers Aaron
Off The Grid
 
renewableMark

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Posted: 02:29am 09 May 2020
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  [ said  QUOTE=bob.steel 1500 posts ...I hope they are not all like these irrelevant.



No need to be an ass hole mate, I simply stated mine have all been fine for many years, perhaps it's the rubbish brands cheapskate pomms buy that's the problem??
Cheers Caveman Mark
Off grid eastern Melb
 
bob.steel
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Posted: 04:02am 09 May 2020
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  renewableMark said  
   said  bob.steel 1500 posts ...I hope they are not all like these irrelevant.
No need to be an ass hole mate, I simply stated mine have all been fine for many years, perhaps it's the rubbish brands cheapskate pomms buy that's the problem??

Ha Ha  hark at the kettle calling the pot black ! I'm in Arizona anyway chum.

Warpspeed-A power supply is pretty simple stuff and of course I have and could make many.
I have an old AT supply and another later Dell that will put out whatever I want . A small device from ebay would make it adjustable in voltage and in amperage. The supply you show I have but they do not show the correct voltage when in a charging situation also.

Revlac-I have a camera battery too that is probably 10 years old and is still good. Its probably only been charged 20 times in its lifetime and is NiMh. I'm looking at batteries that are charged twice a week like laptops , phones etc. However the being adjustable point is new. I had not considered that the charger might have such an adjustment and thats worth looking for. First charge could be full and subsequent charges less!

That's not the question nor is it the answer and this thread is simply derailed by the irrelevant posts now.


The question remains how to stop such a supply at a point desired?
Say I want to stop charging at 4.1 Volts . The charger is set for 1 amp at 4.2v which is where it is supposed to be for that cell . How would I disconnect it when the plate voltage gets to  4.1 vols? Could I build another circuit to put inline that would sense the cell plate voltage and cut supply?
Edited 2020-05-09 14:16 by bob.steel
 
renewableMark

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Posted: 12:12pm 09 May 2020
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I don't think you are a nice person, but I'll help you (as best I can) anyway.

Chargers for aeromoddeling are able to have their parameters set very specifically, perhaps look at those. It's been a while since fiddling with them, but there are lots of settings to adjust. Look at hobbyking web site.

Just out of curiosity I googled adjustable lipo charger, it came up with the exact thing I was thinking of.

BTW they will do multiple chemistry types.
Cheers Caveman Mark
Off grid eastern Melb
 
bob.steel
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Posted: 09:38pm 09 May 2020
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Nahh
Any chargers I google are adjustable only in the input charge voltage at best and current

Example

NOT cut off voltage .
You can adjust the input voltage to 4.1v maybe but that just means a slower charge time to get to that voltage because there is slightly less "push".

I'd be interested in finding one with some sort of adjustment of the actual charging chip used . IE using a TP4056 designed to cut off at 4.2v exactly but can be adjusted to 4.1v cut off.

People should understand too that LiPo cells are 3.7v nominal but spend most of their charge time at about 3.9v . Its not linea as I understand it. They can be charged easily and safely with a 5v input limiting the current to a quarter of their capacity without damage but when the plates get to 4.2v they are damaged.

A circuit example

So there are many chips available for various cut off voltages but I don't see how I can set them to cut off a bit lower ?



Edited 2020-05-10 07:54 by bob.steel
 
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