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> The Reason Why Battery Voltage Drop Under Load, battery voltage ,electronics
Sherldonnnn
Posted: February 22, 2017 09:25 am
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Many people find that battery voltage often drop under load.There are some my opinions.

First,there's no such thing as a perfect voltage source, everything (that doesn't superconduct) has resistance and resistance means you lose a bit of your no-load voltage when current starts to flow.

Second, the lower cut-off voltage is not an exact figure, there's a bit of a trade off between the lower cut-off voltage and the battery lifespan, but below 2.5V there are some irreversible chemical reactions that occur that wreck the battery permanently. Lead-acid car batteries have similar issues (but for different reasons). I don't fully understand what reactions take place when you fully flatten a Li-Ion battery although I think there are a few kinds of lithium intermatallic compounds formed that once formed, don't then easily unform. Much like how with Lead-Acid batteries you get sulphation on the plates (not all chemical reactions are easily reversible, it's very hard to un-rust a lump of iron).

What's more,as for the maximum charging voltage, you run the risk of forming metallic Lithium "whiskers" among other unpleasant things) which can puncture the electrode separator and lead to a short circuit. Seeing as Li-Ion short circuits tend to involve copious amounts of current, lots of heat is usually generated too, and heat + Li-Ion electrolyte = boiling and fire, and once air gets in, the Lithium catches fire too. 4.2V just happens to be the voltage required to fully charge a Li-Ion battery and any more voltage will start to cause unwanted side reactions. There are a variety of electro-chemical reactions that don't really get started unless there's a certain voltage gradient present. There's a similar limit in Lead acid batteries, apply too much voltage and you start to electrolyse the water into Hydrogen and Oxygen gas which (seeing as it'll be in the perfect 2:1 ratio) is highly explosive and will eventually result in all the battery's electrolyte drying out and more of those unwanted one-way chemical reactions.

Finally,I would like to express my appreciate to you for reading it and if you have any viewpoint,please don't hesitate to chat with me.Well,I would like to suggest you a company--edit well I won't let you - we call that SPAMMING - read the rules
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Jimthecopierwrench
Posted: February 23, 2017 12:33 am
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QUOTE
Many people find that battery voltage often drop under load
Well there's a eureka moment.


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MacFromOK
Posted: February 23, 2017 01:52 am
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Lol, yep. No matter how many ponies are in the corral, only so many can get thru the gate per <time measure>. biggrin.gif

But if we ever get superconducting batteries... cell phones will be able to self-destruct much quicker. beer.gif


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kellys_eye
Posted: February 23, 2017 07:40 am
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QUOTE (MacFromOK @ February 23, 2017 01:52 am)
But if we ever get superconducting batteries... cell phones will be able to self-destruct much quicker. beer.gif

Not a very good idea (superconducting batteries) as such an event would release energy in a supremely cataclysmic manner!

Albeit spectacular!

I certainly wouldn't want to be anywhere near it - say a few miles...... laugh.gif


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