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**paulsouthport** · 22-12-2011, 03:29 PM

The lower power chargers, like the B6, A606 etc. are all 12V DC only (approx - they all allow some margin), 24V would almost certainly make them go pop. The higher output chargers start to need to 24V when the charge current gets really high - the higher the voltage the less current is needed for the same watts output.

So really, it depends on what charger you are looking at? At the low end a A-6-10 will produce 200W at 12V. You could parallel charge two 6S packs at just under 1C each but you'd be pushing the charger to it's limits. Of course, they are cheap so you could buy 2.

Or, invest a bit more are get a premium charger with a 24V input. Most of them can work at 12V also but need the 24V to work to full charge rate ability

**ronny p** · 22-12-2011, 04:01 PM

You can have multiple out puts on most server psu with outputs supplying 12 and 24v. So this would suit you now and later on when you upgrade your charger. I have 2 hp psu that i will be doing soon so i can use a pl8 to its max. :-)

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**cjcj1949** · 22-12-2011, 06:25 PM

It's not always a good idea to follow plans on the internet. One server PSU gives you 12V and all you have to do is join up some wires and cover up some mains leads. Once you start adapting things it all gets a bit questionable especially when metal cases meant to be at earth are no longer at earth. If in doubt find an electrician and ask him.

**rapidgaz** · 22-12-2011, 06:55 PM

You could try using the dell poweredge 6650 psu's these are a good choice as the ground is separate from ac to dc, they are 900 watts each and use a c19 type ac connection. So a much safer bett.

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**stocksy27** · 22-12-2011, 06:58 PM

sounds complicated but is quite easy , cases cant touch and 1 earth needs removing either on the dc or ac, i chose the ac as its the easy way that way no need to open the PSU up, cover them in heat shrink then MDF box, i now have 25.4 volt 1200w of very reliable power, been charging 2 12 cell 3700m lipos off them at 3c no problems for £35

**Sharpedge** · 22-12-2011, 09:00 PM

Thanks for the link dani_r, I've just picked up one of the units from the bay. Will use a single one to power my charger until I get a few more opti packs, then will be going 24v for sure. Right now I'm using an old computer psu which has 24A on the 12V rail but the total wattage is only about 350W so it's not going to be good enough for 4 5000 packs.

**xygax** · 22-12-2011, 10:47 PM

Originally posted by stocksy27 View Post

sounds complicated but is quite easy , cases cant touch and 1 earth needs removing either on the dc or ac, i chose the ac as its the easy way that way no need to open the PSU up, cover them in heat shrink then MDF box, i now have 25.4 volt 1200w of very reliable power, been charging 2 12 cell 3700m lipos off them at 3c no problems for £35

Please tell me this isnt for real. You have removed the protective earth from one unit.... Go and read the thread on Talkheli it tells and shows you how to do it properly and stay alive... It takes as litle as 30mA to kill a human...

Steve

**asomaro** · 22-12-2011, 11:40 PM

Take Steve's (Xygax) comments seriously guys - this electrickery stuff can kill you so you really must get it right.

Cheers,

**rapidgaz** · 22-12-2011, 11:45 PM

Have a look at these type, these both stayed earthed as normal and the cases can touch so no harm to us. http://www.helifreak.com/showthread.php?t=331196

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**xygax** · 23-12-2011, 02:42 AM

Beware americans..... They only have what we call saftey voltage 110v.... the mains in the uk is 230v +10% -6% according to G5-4 the international standard for electricticy supply. Whad does that mean.

That means that the peak to peak voltage on a uk supply = 230 * Sq(2) * 2V or 230 *1.414*2=650V...! if somthing goes wrong and a fauit occurs in the primarary section of a switch it can in a worse case make the case live at this voltage if you have removed the proctevive earth...

and just so that you really focus on this properly its connected to that little lipo you are plugging in and out of its terminals.

Do it safely not the american way. I have had a propper shock off of a saftey transformer in UK with wet hands. That is 55v to earth. and belive me it hurts a lot. i have also had lots of shocks from 230v with dry hands and that hurts a lot less...

Read this post in full it shows you how to do it safely Building a 24 volt capable power supply

after page 5 you will see the safe way of building these. i have described it in full. The case cant rise above the protective earthing conductor voltage and that means it cant kill you.... When you have to sit through the ammount of saftey videos every year that i have to you will learn a little bit of respect for the invisable energy that comes from little holes in the wall.... The americans still use it for frying people.... The english try really hard to avoid that... if you need more information just go and read IET Wiring Regulations BS 7671:2008(2011) its there and has to be complied with and for that reason there are very few deaths in the EU that relate to domestic electritcity supplys....

Remove the earths and you could end up a statistic...

Be safe

Steve

**dani_r** · 23-12-2011, 10:16 AM

Thanks for the replies! Certainly lots to think about.

Does anyone know this 'Robo-Grant' chap from the talk heli forum?

He had a post on there saying he was making some huge PSUs for £150??

**dani_r** · 23-12-2011, 10:34 AM

Originally posted by rapidgaz View Post

Have a look at these type, these both stayed earthed as normal and the cases can touch so no harm to us. http://www.helifreak.com/showthread.php?t=331196

Sent from my iPhone using Internet.

Thanks for that

I've been reading up on this link http://www.helifreak.com/showthread.php?t=310694

And I think that's the way to go to be honest!

**Andy from Sandy** · 23-12-2011, 10:47 AM

And I think that's the way to go to be honest!

So on page 6 half way down it shows one psu insulated with the ground removed. You seriously think this is the way to go?

After someone with real experience tells you it is not you ignore sound advice?

**Andy from Sandy** · 23-12-2011, 10:50 AM

Mr Safety Officer if someone comes to the field with one of these I think you should not allow it unless categorically it can be proved it has been constructed as per xygaz's (Steve's) instructions.

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