Thoughts on using a PC PSU to power chargers?

[vultage]

I'm looking to get a bigger charger, and it looks like for the wattage I need, I will be needing a power supply as well.

I just reallized that I have a couple of unused PC PSUs,.. 350W and 500W I believe. I've seen them used as 12v Power supplies in the past,.. and I was just wondering if anyone has any thoughts about this? I know that there are a couple of mods needed for them to work as a normal power supply, but there are lots of articles about it.

Has anyone else tried this, or have thoughts on it?

http://makezine.com/projects/compute...upply-adapter/

[vultage]

Looked through my old PC parts and found this, 700Watt ATX PSU,...

https://www.newegg.com/Product/Produ...82E16817341018

[akschu]

Some thoughts....

I think computer power supplies are fine as long as you only run one. If you run two of them in series, then you need to remove the grounding for one and operate it in a way it was never designed to do.

The problem is that running one has limitations. On the power lab 8 charger I have, the input current limit is 40 amps. If the PC power supply is putting out 12 volts, then the total input current is only 480 watts.

If you assume 90% efficiency of the charger, that's only 432 watts, and at 22.2v output, only 19.45 amps.

So if you really want to charge 6s packs at 40 amps, you really need 24v input, and the best way to do that is to buy a 24v power supply.

If you really need cheap, and multiple channels, you could get two server power supplies, and two iCharger 206b's. That would probably be less than $300 total, and give you the ability to charge (2) 6s5000 packs at 4c at the same time. Pretty good bang for the buck....

schu

[vultage]

Thanks for the feedback!!! 40 amps!!! :O,.. haha,.. I'm looking to get 6a charge rate,.. (2c),.. as of right now,. I get 1/2c charge w my 50w imax B6AC

Maybe I should of listed what I am trying to charge,..

I have 3000mah 12s,.... 2600mah 6s,.. and 3s packs to charge,.. and I've never charged anything over 2C,.. lol.

How would I work out my amp and watt limitations if I were to use the 700 watt PSU I have now?

[ronm3313]

ProgressiveRC has a couple of calculators you can use: http://www.progressiverc.com/calcs

I've been using 2 server power supplies I purchased off eBay for a couple of years. They're a lot cheaper. Here's an example: http://www.ebay.com/itm/rc-power-sup...QAAOSw9GhYfCz9

[vultage]

Cool, thanks for the links!

If that server supply is only 12v,.. what would make it any different from the PSU I have on a shelf in the other room? I would just assume use stuff I have, that is doing nothing but taking up shelf space! Only thing I can't seem to find is the Amp spec for the PSU I have.

[vultage]

Just placed my order,.. ended up going with the ISDT SC-620 charger http://www.progressiverc.com/isdt-sc-620.html

and, Chargery S600 Plus Power Supply. 26v 25a http://www.progressiverc.com/chargery-s600-plus.html

This would allow me up to 20 amps for 6s,.. IF needed,.. but since my biggest pack is 3000mah,.. and I don't plan on charging over 3c (9a) it should work out perfect, plus have plenty of headroom, if needed for another job in the future.

Now,. I need to do some studying up on Parallel charging,. I have no idea how to figure for that. Would I double the amps, for the same charge rate, charging 2 packs parallel, or keep it the same?

[flint723]

Originally Posted by vultage

Just placed my order,.. ended up going with the ISDT SC-620 charger http://www.progressiverc.com/isdt-sc-620.html

and, Chargery S600 Plus Power Supply. 26v 25a http://www.progressiverc.com/chargery-s600-plus.html

This would allow me up to 20 amps for 6s,.. IF needed,.. but since my biggest pack is 3000mah,.. and I don't plan on charging over 3c (9a) it should work out perfect, plus have plenty of headroom, if needed for another job in the future.

Now,. I need to do some studying up on Parallel charging,. I have no idea how to figure for that. Would I double the amps, for the same charge rate, charging 2 packs parallel, or keep it the same?

Yes you add up the amps for each pack.

1x 3000mah 6s : 6a (2c), 3a (1c)
2x 3000mah 6s (one stick pack) : 12a (2c), 6a (1c)
3x 3000mah 6s : 18a (2c), 9a (1c)

Also you need to make sure the pack voltages are pretty close before plugging into the parallel board or harness. And always plug in all the main leads before the balance leads.

IMO you can charge different capacity packs together AS LONG AS THEY ARE THE SAME CELL COUNT. Never plug in say a 4s and 6s together, the packs will be ruined at the very least.

But say you have 1x 2600mah 6s and 2x 3000mah 6s (one stick pack), you can charge them all together. So at 17.2a(2c), 8.6a (1c) for those three together.

Hope that helps.

[vultage]

Yes it does,.. thank you very much for the info!,.. I would only plan on P-charging for my 12s packs or maybe 2 of my 6s 2600s,.. other than that,.. I can wait,. .I'm not in a rush to get charges done,. other than taking 3 hours for a pack,.(12s),.. yea,.. lol.

you mention plugging in main pack b4 balance lead,.. I've always wondered if there was a sequence for that,. .does it matter when plugging in single packs as well? or only cause the multiple packs could try to feed through the balance lead?

[flint723]

Originally Posted by vultage

Yes it does,.. thank you very much for the info!,.. I would only plan on P-charging for my 12s packs or maybe 2 of my 6s 2600s,.. other than that,.. I can wait,. .I'm not in a rush to get charges done,. other than taking 3 hours for a pack,.(12s),.. yea,.. lol.

you mention plugging in main pack b4 balance lead,.. I've always wondered if there was a sequence for that,. .does it matter when plugging in single packs as well? or only cause the multiple packs could try to feed through the balance lead?

It's just on multiple packs, you don't want lots of current flowing through the balance leads when the packs first equalize when plugged in. It takes quite a large imbalance to fry balance leads though (plugged in a fully charged and a depleted one). So its just good practice to do mains first because you will probably notice something is wrong, and be able to disconnect it without major damage.

Only done it once myself and it was with some smaller packs (3s 2200).

[akschu]

Parallel charging is really simple. You wire positive to positive and negative to negative for packs with the same cell count. You effectively make up a pack that has the sum of the capacity, not the sum of the voltage.

You can charge all of your 6s packs at the same time, or all of you 3s packs... but a few things to keep in mind:

1. Be very very careful to not mix packs with different sell counts. You will have a spark/fire.

2. Be very very careful to not plug in two 6s packs for parellel charging if they are still in series (like if you have them on a tray or something).

3. Be very careful to not plug a fully charged pack in with an empty pack. The charged pack will charge the dead pack at a rate much higher than 5c.

I recommend using a balance board with fuses like this:

http://www.progressiverc.com/multi-p...t-xh-xt60.html

Once you have a good balance board and know to be careful, you can charge a lot, quickly....

Cheers!

[vultage]

All makes perfect sense to me,.. well seems like common sense, but as we all know,. that is not so "common" these days,. haha,..


Thanks much guys!