Author Topic: Capacitive battery charging  (Read 1406 times)

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Offline noneyabussiness

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Capacitive battery charging
« on: September 11, 2017, 05:44:04 am »
http://www.johnsavesenergy.com/CapacitiveBatteryCharger.html#.WbZUnHSubqB

Just asking the pros on here there opinion? ?

I like the desulfation bit...

Offline solarnewbee

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Re: Capacitive battery charging
« Reply #1 on: September 11, 2017, 12:43:32 pm »
What I came away with is attentiveness is a key caution here. I like the desulph too. Those caps are about $4 at my HVAC supplier I might give it a try. I'm sure if you charge a battery bank connected to an inverter that it will shut down from over voltage. Could just shut off the inverter til charging is done, off grid just sit in the dark til done ha. I know my car charger won't even start if the battery is below a certain point which is irritating so Out comes the float charger.

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Offline MadScientist267

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Re: Capacitive battery charging
« Reply #2 on: September 23, 2017, 07:21:15 pm »
I'm gonna go with "Great ACADEMIC demonstration of capacitance and AC"...

Then add "very dangerous on more than one level"... Non isolated, completely unregulated, just for starters.

Then there's the horrific power factor aspect of it (particularly amusing since the "up next" link at the end of the article is "Power Factor").  ::)

This is not even mentioning both ridiculous claims on the page and "one dimensional" measurement type stuff going on.

Please people, be careful with what you find out there.

Normally I just overlook stuff like this but that whole page has the potential to be extremely dangerous, especially to newcomers that may not understand the level of respect line sourced non-isolated circuitry demands.

In a nutshell, "don't do it".

Steve
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Offline bj

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Re: Capacitive battery charging
« Reply #3 on: September 24, 2017, 08:12:46 am »
  Well put Steve
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Offline eidolon

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Re: Capacitive battery charging
« Reply #4 on: September 30, 2017, 12:40:07 pm »
Hey, I once started a car with a toaster and it made breakfast. Even if you are skirting all safety concerns, put a bleed resistor on the caps.

Offline WooferHound

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Re: Capacitive battery charging
« Reply #5 on: October 04, 2017, 10:32:46 am »
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Offline kurt

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Re: Capacitive battery charging
« Reply #6 on: October 04, 2017, 05:40:10 pm »
zubbly was playing with that when he died but he was smart enough to use an isolation transformer on the input for safety
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Offline rossw

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Re: Capacitive battery charging
« Reply #7 on: October 04, 2017, 06:05:12 pm »
You could have left the last part off that, Kurt, and let it serve as a warning!
Statement of fact.... and an suitable warning!

"Zubbly was playing with that when he died"

Rest in peace our friend. Gone, but not forgotten!

Offline oztules

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Re: Capacitive battery charging
« Reply #8 on: October 04, 2017, 06:28:00 pm »
It is quite a simple and effective circuit Woof...

It would be nicer if it were isolated by a transformer

The use of caps to control AC currents is very widely used now days, but mostly for small power supplies in range hoods and other domestic appliances where they are too slack to use a tranny or a pwm isolated solution... it goes without saying it needs to be double insulated to get away with this on a commercial level.

So I agree with Steve, that lack of isolation is a problem, but I won't pretend it is the end of the earth or a game stopper.

There will be many instances that this can be used quite safely, but house banks and other systems where the battery cannot be isolated from ground or people is not one of them.

A gentleman on the old fieldlines used this technique to charge his EV every night.

You would think this would be a death trap, but in fact if you know what your doing, is perfectly safe. Remembering the neutral is grounded anyway, we know one side of the battery is grounded already.

Providing we choose the active to go through the cap and to the non-ground end of the bank, and it is half wave with neutral grounded.... it is perfectly safe..... as the battery is already at high DC voltage, touching it would frizzle your hair without the AC component to worry about. The half wave will cut the available energy to half before we regulate with the cap.

It would be tempting to think that the capacitor in this case probably mylar aluminium will stop the conduction across the dielectric gap, and so give isolation to say the active side, and the neutral is already earthed anyway......... and so safe ... yeah???........NO.

The electrons going into the cap are not the same ones coming out to do the work it is true,  they are new electrons, the result of displacement current through the cap, but do not provide any isolating properties. The current limiting is a result of the capacitive reactance of the cap, so current is controlled by the amount of uf used and the frequency of the system or XC= 1/2piFC.

So we have effectively controlled the current without the losses associated with a resistive impedance with a capacitive impedance.

So really the only downfall is the isolation problem, and thats only a problem where folks can get their mits on the system .
In isolated cases this can be a perfectly valid way of doing things.

I cannot join the chorus of folks that worry the sky is falling if we don't get protected from every little thing, but would rather get involved with saying how it could be done  with the least risk... which is a different perspective.

The number of folks getting fried from this sort of thing, pales into insignificance compared to auto accidents and shootings in the US. There are far more urgent things to get excited about than this. Consider that only 325 or so people die from electrocution in a population of 300 million annually...  interestingly over 50% of those are smart people who work in the electrical industry daily.... who should know better, the other half are people who know nothing, but play with electrical stuff every day...and plenty of them in dubious circumstance from what I see on the telly from time to time.

And I am totally baffled by the veracity of the  power factor comments...

Evolution will sort it out eventually anyway.... there are always the Darwin awards to look forward to..... although the modern RCD's will probably stop evolution from weeding them out as it should.



................oztules
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Offline rossw

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Re: Capacitive battery charging
« Reply #9 on: October 04, 2017, 07:35:39 pm »
Providing we choose the active to go through the cap and to the non-ground end of the bank, and it is half wave with neutral grounded.... it is perfectly safe..... as the battery is already at high DC voltage, touching it would frizzle your hair without the AC component to worry about. The half wave will cut the available energy to half before we regulate with the cap.

Agree with everything you said, Oz... except this bit.

Series capacitor and half-wave rectification?
Without other components, the cap will quickly charge up and not pass any further current.

Offline oztules

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Re: Capacitive battery charging
« Reply #10 on: October 04, 2017, 11:06:15 pm »
I wouldn't agree with me either...

It needs one more diode from cap to "ground", which is in keeping with the simplicity, but you can't help get the feeling your putting lipstick on a pig.



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Offline MadScientist267

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Re: Capacitive battery charging
« Reply #11 on: October 12, 2017, 06:30:52 pm »
My main issue is in its super simplicity to construct, and that caps are unforgiving at high voltages.

GFI/RCD/Etc, whatever you might want to call them, won't do anything against direct contact with a charged cap.

It isn't that there are not plenty more things lurking around on the forum/web that are just as dangerous, and many more so even, but their complexity puts them a little further out of reach for those that haven't "climbed their way up" to them and learned of the dangers of such things along the way. I agree otherwise on the Darwin awards... heh

As for the "power factor veracity", the PF is crap for the same reason line sourced switching supplies have gotten away from "simple doubler" designs. And the higher the nominal battery voltage being charged, the worse it is.

PF however was just some of the icing on the cake on this one. The dangers of such a scheme are orders of magnitude more prominent than pathetic PF.

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Offline WooferHound

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Re: Capacitive battery charging
« Reply #12 on: October 16, 2017, 10:37:22 am »
I have been considering building some LED lighting powered directly from the power outlet using this setup to control the current by adding a bridge rectifier and a filter cap on the output.
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Offline Sasaka-4628

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Re: Capacitive battery charging
« Reply #13 on: November 10, 2018, 03:09:12 am »
I'm gonna go with "Great ACADEMIC demonstration of capacitance and

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Offline BenandAmber

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Re: Capacitive battery charging
« Reply #14 on: April 06, 2019, 04:08:33 pm »
I have been using this type of charger for a couple years now and I am very impressed with what it can do but I am terrified that a dog kid neighbor or any other living thing get close to it so it limits how much I can use it it would be nice if somebody would make it safe or safer