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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 05-14-2011, 12:13 AM   #1
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Default EP Buddy ParaBoard (Parallel Charging Board)

Just wondering if anyone else has used these before. I picked this up at Joe Nall yesterday. Basic premis is to charge multiple batteries on a one-off type charger. You add up the C-rated amps of all the batteries and charge at that rate. I tested it today doing a balance charge on two 2200 mAh batteries and they were balanced to the third decimal point and both batteries were done in 35 minutes (both had been used in the Stryker and down to about 11.5 volts). But just wondering if anyone has used them and found any problems.

It is a lot cheaper (only $20) than a multi-tap balance charger and if it works ok then why not.

My idea is to use them is only with like batteries, in other words only 2200 3s batteries not mixing c rating or number of cells.


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Old 05-14-2011, 01:05 AM   #2
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Originally Posted by RCFlyer44 View Post
Just wondering if anyone else has used these before. I picked this up at Joe Nall yesterday. Basic premis is to charge multiple batteries on a one-off type charger. You add up the C-rated amps of all the batteries and charge at that rate. I tested it today doing a balance charge on two 2200 mAh batteries and they were balanced to the third decimal point and both batteries were done in 35 minutes (both had been used in the Stryker and down to about 11.5 volts). But just wondering if anyone has used them and found any problems.

It is a lot cheaper (only $20) than a multi-tap balance charger and if it works ok then why not.

My idea is to use them is only with like batteries, in other words only 2200 3s batteries not mixing c rating or number of cells.

It's a fantastic device for parallel charging, and Dale is a real asset to us. I suspect there are quite a few of them in use.
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Old 05-14-2011, 02:26 AM   #3
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Originally Posted by spad View Post
It's a fantastic device for parallel charging, and Dale is a real asset to us. I suspect there are quite a few of them in use.
Cool, not sure who Dale is but sounds like maybe the designer from your post. So I guess I all I need to really do is make sure I don't exceed the 10 amp rating of my charger and probably should invest in a power supply instead of using a battery.
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Old 05-14-2011, 12:12 PM   #4
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Any good suggestions on an AC to DC power source, 13.8 volts and maybe 20 amps at least for a good price?
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Old 05-14-2011, 01:20 PM   #5
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I have to admit I don't really understand how those things are supposed to work. How can you balance the cells of multiple batteries in parallel? Let's say I have two batteries, one that is perfectly balanced and one with the voltages all over the place. Obviously the balancer would need to work a lot harder on the ill-balanced one. Are they just relying on charge leaking across the parallel-coupled cells so they eventually equalize? Does anybody know? Where's Dennis when you need him?

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Old 05-14-2011, 03:30 PM   #6
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Originally Posted by RCFlyer44 View Post
Any good suggestions on an AC to DC power source, 13.8 volts and maybe 20 amps at least for a good price?
Dale owns EPbuddy.com-great guy.

Go to either progressiverc.com or epbuddy.com (both are outstanding sellers) and buy an Icharger PS350 power supply: small, quiet and efficient-I've used one for two years.

As far as "how" parallel charging works, as far as I'm concerned, it's pure magic!
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Old 05-14-2011, 08:19 PM   #7
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Originally Posted by spad View Post
Dale owns EPbuddy.com-great guy.

Go to either progressiverc.com or epbuddy.com (both are outstanding sellers) and buy an Icharger PS350 power supply: small, quiet and efficient-I've used one for two years.

As far as "how" parallel charging works, as far as I'm concerned, it's pure magic!
Thanks Spad, I think I am going to get it from EPBuddy. I picked up the parallel board from a vendor at Joe Nall who was from Ohio but it wasn't EPBuddy itself. I wrote to EPBuddy to ask a couple questions about the charger and then I think I will order it. Might put the 20amp Icharger on my wish list too!!
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Old 05-14-2011, 08:30 PM   #8
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Originally Posted by NJSwede View Post
I have to admit I don't really understand how those things are supposed to work. How can you balance the cells of multiple batteries in parallel? Let's say I have two batteries, one that is perfectly balanced and one with the voltages all over the place. Obviously the balancer would need to work a lot harder on the ill-balanced one. Are they just relying on charge leaking across the parallel-coupled cells so they eventually equalize? Does anybody know? Where's Dennis when you need him?
Hmmm... Now that I think of it, I think I can answer my own question: The higher the voltage, the more resistance when you're trying to charge them, so the cell with the lowest voltage will suck most of the current and will quickly catch up with the higher voltage cell.

HOWEVER... If you're charging three batteries at 3C and two of them are fully charged and one is completely discharged, all the current would flow through the discharged one and you'd end up charging at 3C instead of 1C. Isn't that a pretty substantial risk or is my reasoning completely wrong? Does the board have some kind of current limiting circuitry to prevent this from happening?

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Old 05-14-2011, 08:46 PM   #9
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Originally Posted by NJSwede View Post
Hmmm... Now that I think of it, I think I can answer my own question: The higher the voltage, the more resistance when you're trying to charge them, so the cell with the lowest voltage will suck most of the current and will quickly catch up with the higher voltage cell.

HOWEVER... If you're charging three batteries at 3C and two of them are fully charged and one is completely discharged, all the current would flow through the discharged one and you'd end up charging at 3C instead of 1C. Isn't that a pretty substantial risk or is my reasoning completely wrong? Does the board have some kind of current limiting circuitry to prevent this from happening?
I can tell you when I checked the balance of the two batteries that were charging at the same time through my charger it showed all the cells at the same voltage about a minute after starting and every time I checked afterwards they were at the same voltage. It was two 2200mAh batteries one at about 11.47 volts to start with and the second at about 11.54 to start with. I was quite impressed that both were fully charged and balanced to the third decimal in 33 minutes using balance charge mode.

Probably do three the next time and four the time after that to see how this goes. Will probably have to stop there since 4 batteries will be charging at 8.8 amps and my charger is rated for 10amps and I am not going to take it to the limit. But 4 batteries in the same time it used to take me to do 1 is well worth the $20, especially when I was thinking of buying a multi-tap charger.
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Old 05-14-2011, 09:02 PM   #10
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Originally Posted by NJSwede View Post
HOWEVER... If you're charging three batteries at 3C and two of them are fully charged and one is completely discharged, all the current would flow through the discharged one and you'd end up charging at 3C instead of 1C. Isn't that a pretty substantial risk or is my reasoning completely wrong? Does the board have some kind of current limiting circuitry to prevent this from happening?
I went looking for an answer after you asked this myself and found this on a thread in another board:

What happens if I connect packs with different states of charge?
A current will flow between the packs. However, this current is not very high, even if one pack is full and the other depleted. Yet, it should be avoided to connect packs with a state of charge differing over 50%

Here is a site that explains everything in a nutshell with great diagrams:

http://sites.google.com/site/tjinguy...allel-charging

It was a pretty interesting thread with lots of questions and answers about parallel charging.

Here it is (hope I don't get in trouble for recommending checking out another board ): http://www.rcgroups.com/forums/showthread.php?t=932319
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