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Old 12-31-2011, 11:41 PM   #1
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Default Upgrade power, charger help please

Hi guys, i am upgrading my charger and now need a power supply as I have several lipos and now several cars in my garage. I want to be able to charge several batteries at once and also fast charge them at a higher rate ( within safe range ) to get better performance. Lipos are 5000mah and bigger 2s and 3s. Am hoping on some advice on my current list as I am not that clued up on this electric stuff. These are the chargers I am looking at currently Imax B6 Duo
http://www.skyrc.com/index.php?route...t&product_id=2
SkyRc B6 Ultimate 800W
http://www.skyrc.com/index.php?route...product_id=121
SkyRc B6 Ultimate 200W x 2
http://www.skyrc.com/index.php?route...product_id=123

And power supplies
Imax Rc B60
http://www.imaxrc.com/Products.aspx?Para=77
Protek RC Super Pro 40
http://www.amainhobbies.com/product_...-138V-40A-520W
Imax Efuel 30a
http://www.skyrc.com/index.php?route...&product_id=48

Any advice and help would be greatly appreciated.
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Old 01-01-2012, 04:56 PM   #2
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..... I want to be able to charge several batteries at once and also fast charge them at a higher rate ( within safe range ) to get better performance...

Lipo doesn't show performance gains from charging at higher charging rates like NiMh does. The only thing you do by charging lipo at higher charge rates is reduce charging time. Some say cycle life is reduced, but testing and experieince indicates otherwise. Your lipos have to be rated by the manufacturer for charging at higher than 1C charge rates to safely charge at higher than 1C charge rates.

As far as chargers and power supplies go, you need to be more specific - how many of what size (mah and cell count) lipos you want to charge at once and at what charging C rate. That sets the output power the charger needs and also determines the size of the power supply.

The parallel charging boards available today are set up to charge 6 lipos (same cell count - this is requirement of parallel charging, and lipos should be same discharge rating and age) that are 2S and 5000mah at 1C requires 252watts from charger. This would also require a charger that has a max charge rate of 30amps which is going to be the limiting factor in charging multiple high capacity lipos. A 2C charge on 6 5000mah 2S lipos in parallel would require a charger with a 60amp max charge rate and that's beyond anything available that's I'm aware of.

Depending on your lipos manufacturer's ratings for charging, safe charge rates could be 5C or higher. I parallel charge two 4S 5000mah lipos at 3C (30amps) since that's the max charge rate of my charger. Lipos are rated to 5C charging, but beyond my charger's max charge rate.
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Old 01-02-2012, 12:16 AM   #3
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Thanks now slightly more confused!! Haha. I want to be able to charge at least 2 batteries of 2s and also 3s. They will be at least 5000mah and 30 to 40C. I want to get into racing so want them charged fairly quickly. Have I got any power and chargers that are adequate? What would be best?
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Old 01-02-2012, 05:44 PM   #4
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What you're wanting to do is something that's unusual, charge two 2S and two 3S lipos at the same time on one charger, its going to be confusing, especially if you don't have much experience with charging ordinary situations much less something that's unusual, involved and a little more complex than typical lipo charging.

Since you can only parallel charge same cell counts - you can't charge a 2S and a 3S together in parallel, you'll need some kind of dual or multi-port charger. You could charge two 2S lipos in parallel in one port and two 3S lipos in parallel in the other port at the same time. Two 5000mah 2S lipos in parallel is the same as charging a 10,000mah 2S lipo, two 3S 6000mah lipos is same as charging a 12,000mah 3S lipo. A 1C charge rate for a 10,000mah paralleled combo is 10amps, for a 12,000mah paralleled combo 1C charge rate requires 12amps. Either of those Duo type chargers linked has enough output power, the paralleled 6000mah 3S requires ~151watts so 200watts per port is sufficient. The prob is the charge rate which is the usual limiting factor.

If you want to charge at higher than 1C charge rate, you'll want charger with max higher charge rate and more output power . The only one you linked with more than 10amp per port is the B6 Ultimate 800watt. Charging the two 3S lipos presents the largest power demand due to their higher voltage, even with the 800watt (400watts per port) charger you'd only be able to get a 1.7C charge due to the 20amp max charge rate (252watts required).

This would be simpler if you would charge one lipo in one port at a time.....
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Old 01-02-2012, 08:04 PM   #5
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So if I was to be charging one lipo per port, are the chargers and power supplies adequate? I am really aiming to reduce charge times, ad I will have several batteries to charge. Are there any recommendations from what I have linked?
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Old 01-06-2012, 12:09 PM   #6
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The limit will be the 3S due to its higher voltage. With 200watts, you could charge a 5000mah 3S at a little over 3C, if the charger's max charge rate would allow. These are 10am max charge rate chargers, so all they can do is 2C charge on a 5000mah 3S (or 2S) lipo.

Charging at 2C versus charging at 1C will reduce charge time, but not by half. Lipo charges in 2 stages, constant current (CC) followed by a constant voltage (CV) stage. Doubling charge rate cuts the CC part in half, but not the CV part. So a theoretical 1C charge which takes about 1hr, at 2C would take maybe 40min. 3C charge rate is where you start to see significant charge time reduction. 3C for a 5000mah is 15amps, for a 6000mah lipo its 18amps. This requires a charger capable of 20amps max charge rate or better. The only one of the 3 chargers you linked that has that high of a charge rate is the SkyRc B6 Ultimate 800W which has 20amps in each port.

To run a charger charging two 3S 5000mah lipos at 3C you'd need a PS with ~455watts. Any of those linked appears to supply more power than that.

All this assumes you have lipos that are rated for higher C charging....
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Old 01-06-2012, 01:46 PM   #7
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Thank you for all your help. I am starting to understand. I will purchase the 40a power supply to start with then decide exactly want I want from a charger.
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Old 01-07-2012, 07:00 PM   #8
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Glad to help, been there myself and it can be kind of difficult, especially now tha there are so many on teh market.

When you have more questions, we're here to help out.
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Old 01-09-2012, 06:52 AM   #9
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Thank you for all your help. I am starting to understand. I will purchase the 40a power supply to start with then decide exactly want I want from a charger.
I agree with Duster, you'll need as muc power as you can on 12V and 24V output and if you want simultaneous charging which is childproof best you get a charger that is IR based with automatic functions. Also helps if you have active vrs passive charging too
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Old 01-31-2012, 11:26 AM   #10
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This info is helpful for me too. I also wont to charge faster than 50w and am looking at the SkyRc B6 Ultimate 800W for my needs. My friend just bought a 400w, two 200w per port charger from hobbyking and I like it, but I wont more power.I will use this for racing off road and flying with 12 cells.

Last edited by Tim3; 02-05-2012 at 12:41 PM.
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Old 01-31-2012, 01:07 PM   #11
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I say for a power supply, buy a used Compaq or HP or DELL server power supply off eBay for cheap cheap and use that.

I personally bought these two DELL power supplies for $15 off eBay. They are 550W each. I thought I would run them in series as to get me 24V at 1100W but once I got my charger and did some research, I didn't need all that, so I just keep the other as a spare.

Here is the basic HowTo I followed. His site has info for tons of other power supplies. I feel confident that the power supply is QUALITY, compared to some of the ones that are for RC use are just Chinese crap. These sell for cheap because they are used in obsolete servers. They are still great power supplies and when brand new and the servers they went in were state of the art, these were insanely expensive.
http://sites.google.com/site/tjinguy...ects/server-ps

Here's the link to my auction I won before and a stock image of a power supply.
http://www.ebay.com/itm/ws/eBayISAPI...E:L:OU:US:1123


I use a Hyperion EOS 720i Super Duo3, which is their flagship dual battery charger. It has a maximum 500W per port (totally independent of each other) and 20A per port. Charging 2S (what I run), I can charge 2 5600mAh Turnigy Nano-Tech LiPo's (8C charge rate max) at 20A each and it takes about 27minutes per battery to charge and balance. Probably 5 minutes or more faster to eliminate the balancing ,but I am in no rush.


I foresee an issue within the 12V at 550W not being sufficient if I was charging 4S or 5S etc. batteries at the same time. I only own 2S anyhow, so it's not happening now. IF I get to that point, I'll take the other one and make it 24V 1100W in series I suppose...
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Old 01-31-2012, 02:21 PM   #12
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I go to Progressive r/c. They have alot of different power supplies, as high as 1100 watts. They also have combo deals. They also have power supply calculators to figure your min needs. He has these items + the chargers due the fact his customers are heli guys who use multiple cell counts. So he has what they need.

http://www.progressiverc.com/
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Old 01-31-2012, 09:04 PM   #13
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Originally Posted by JimmyG View Post
I go to Progressive r/c. They have alot of different power supplies, as high as 1100 watts. They also have combo deals. They also have power supply calculators to figure your min needs. He has these items + the chargers due the fact his customers are heli guys who use multiple cell counts. So he has what they need.

http://www.progressiverc.com/
Just be careful guys that the PS's you get have floating outputs and be sure to connect them to the same AC phases for inputs
Also the chargers run 12V or 24V up to certain power limits. A dual channel charger rund independently...thus each channel will probably give you 50% rated power at 12V and you can get 100% per channel only at 24V.
If yuo can series those floating output PS's would be the best.....
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