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2 packs to increase cell count

Old 07-28-2012, 08:22 PM
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RobT
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Default 2 packs to increase cell count

Can anyone point me to information about using 2 packs to create a pack that seems like it has a higher cell count? For example using two 5 cell packs to make one 10 cell pack.

In order to reduce the loss at the connector I was thinking of soldering 2 connectors onto the ESC, but then worried it might "detect" the wrong cell count when the first pack was plugged in and not adjust when the second pack was plugged in.

Thank you,

Rob
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Old 07-28-2012, 09:37 PM
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Sir Crash-A-Lot
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Sounds like the 2 connectors at the ESC would put the batteries in parallel and that increases the capacity of the battery. You need to put them in series to increase the cell count. You need to use the negative wire of one battery at the ESC and the red wire of the other battery at the ESC. The connect the remaining red and black wire together.

I will try to locate a picture for you. I run 12s all the time with 2 6 cell packs.

Mike
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Old 07-28-2012, 09:42 PM
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hayofstacks
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Running two identicle batteries in parrellel increases the capacity(we use two 1800's to make a single 3600mah 3 cell on my dads advance). Running them in series increases voltage, but not capacity. I have not tried to run two non-identicle packs in series, but I have seen it with two of the same battery.

We have thought about running 4 batteries, 2 each in parellel, then connecting them together in series to give us a 3600mah 6 cell for one of our larger planes.

Deans connectors should be good for about 40 amps continous, and about 60 peak. Increasing your voltage and propping down to get the right specs, should lower your amprage slightly for the same thrust, but this has a lot of factors you need to be mindful of.
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Old 07-28-2012, 09:47 PM
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JetPlaneFlyer
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You just need to make or purchase a series harness, no requirement for two connectors on the ESC. Also the ESC wont detect anything until the second pack is connected because until that point the circuit is not completed.

A series harness:
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Old 07-28-2012, 09:49 PM
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Sir Crash-A-Lot
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I could not find a photo quick so I took one.

You can see the red of one battery connected to the black of the other pack. The two remaining wires connect to the ESC. These are my 2 6-cell packe wire for a 12-cell application.

Mike
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Old 07-28-2012, 09:56 PM
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RobT
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Sir, makes sense. What connectors are those? How do you charge?

Jet, with that setup, isn't the "output" deans the limiting factor? As hay said deans are only rated for about 40 amos, and I am looking at a 100 + amp setup?

Thanks
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Old 07-28-2012, 10:01 PM
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Sir Crash-A-Lot
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My connectors are Anderson Powerpoles. I use them on my 50cc Goldwing Extra that I run the 12s pack on. I draw 100 amps and about 4500 watts max and they are working just fine. I use the 45 amp Powerpoles but they have been tested to 200 amps without issues.

People also use bullet connectors on higher amp systems but I had them disconnect a few times in flight so I switched. Not a single issue since switching.

Mike
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Old 07-28-2012, 10:04 PM
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Sir Crash-A-Lot
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Cool video of a test.

[media]http://www.youtube.com/watch?v=QeTTw9i8WEc[/media]

Mike
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Old 07-29-2012, 12:07 AM
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Originally Posted by Sir Crash-A-Lot View Post
My connectors are Anderson Powerpoles.

Mike
And one huge joy of the Power poles is they can be used to add packs in series without any harnesses as you can plug them in that way.

Mike
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Old 07-29-2012, 08:46 AM
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JetPlaneFlyer
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Originally Posted by RobT View Post
Jet, with that setup, isn't the "output" deans the limiting factor? As hay said deans are only rated for about 40 amos, and I am looking at a 100 + amp setup?

Thanks
Yes, but you can use any type of connector to make up the harness, just use whatever the battery is fitted with. In principal the harness is the same as the picture taken by Sir Crash a Lot.. but Sir's version does reduce the number of connectors in the system so is the more elegant solution.

Remember that in a series hook op the amps is the same throughout the harness, i.e. all the connectors experience the same current.
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Old 07-29-2012, 08:58 AM
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JetPlaneFlyer
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Originally Posted by Sir Crash-A-Lot View Post
I use the 45 amp Powerpoles but they have been tested to 200 amps without issues.
As were the Deans in that video. In fact the deans connector was undamaged even at 380A.. It only failed because the wire became so hot that the solder melted!

Having said that, I hate Deans because they are a pig to break.
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Old 07-29-2012, 10:19 AM
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ron_van_sommeren
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'Multiple choice' pack lay-out
The Script Asylum
-> RC calculations
-> electrical
-> System wiring
and
-> LiPo pack wiring

(the other items in the electrical menu are also very useful for e-folk)


Vriendelijke groeten Ron
diy motor tips Drive Calculator
diy motor group Cumulus MFC
Get a life ... get a 3$ Wattmeter

Last edited by ron_van_sommeren; 07-29-2012 at 01:59 PM.
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Old 07-29-2012, 11:50 AM
  #13  
RobT
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So if I understand, I could connect the neg to the positive of the batteries and then the other set of neg and positive to the esc.

How many amps are 4mm bullets good for?
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Old 07-29-2012, 02:05 PM
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ron_van_sommeren
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Even though it says cells here, you could also read it as packs and use this tool
www.scriptasylum.com/rc_speed/lipo.html
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Old 07-29-2012, 05:49 PM
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Larry3215
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The amp rating on most connecters is the max make/break amperage. In other words, its the maximum amperage that can be flowing through the connecter while its being plugged in (make) or unplugged (break).

We dont usually plug or unplug packs while the motor is running at full throttle, so it normally doesnt apply to us.

Its not that the connecters will instantly fail if you make/break at more than the max rating, but their useful life expectancy will be reduced by arching.
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Old 07-30-2012, 02:49 AM
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Originally Posted by Sir Crash-A-Lot View Post
Cool video of a test.

[media]http://www.youtube.com/watch?v=QeTTw9i8WEc[/media]

Mike
That was a very good demonstration of high currents and various connectors. IMHO, the Deans connectors that are soldered in place do have a weak spot at the soldered connection. Solder has a much higher resistance value than copper wire.

As for the Anderson Power Pole connectors, their are two different versions of this unit. One we used at work for years, the second sold for RC use. The RC version has a much cheaper pin than the units we used at work, even though the RC version will plug into the connectors we used at work. The Allied Electronics connector is obviously higher grade.

I had one of the "Cheaper" APP connectors on my 65 Amp alternator supply for the Cellpro Powerlab 8 charger. At 53 amperes continuous, for 20 minutes, that APP connector melted. That did not happen on the other end of the same wire with the connector from Allied electronics.

Take a look:
http://www.wattflyer.com/forums/showthread.php?t=64539
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Old 07-30-2012, 03:15 AM
  #17  
RobT
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Originally Posted by Larry3215 View Post
The amp rating on most connecters is the max make/break amperage. In other words, its the maximum amperage that can be flowing through the connecter while its being plugged in (make) or unplugged (break).

We dont usually plug or unplug packs while the motor is running at full throttle, so it normally doesnt apply to us.

Its not that the connecters will instantly fail if you make/break at more than the max rating, but their useful life expectancy will be reduced by arching.
So you Re saying Larry that we should not worry about the ratings to deans or xt60's and put then in something that is going to be pulling 100 amps?
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Old 07-30-2012, 06:09 AM
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kyleservicetech
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Originally Posted by RobT View Post
So you Re saying Larry that we should not worry about the ratings to deans or xt60's and put then in something that is going to be pulling 100 amps?
What is saving our connectors is the fact that they are not pulling these high currents for more than a few minutes (if that) during a flight.

Take the standard Deans connector, run 45 amperes through it for a half day, and it is going to get HOT. Same for the standard APP connector.

Those Anderson Power Pole connectors also come in a 2X size, where each dimension of the connector is doubled, making it a very large connector. This connector can handle up to #2 copper wire, depending on which terminal is used. (http://www.wattflyer.com/forums/showthread.php?t=46890)

I wired up a battery system for a club member on a fan motor that pulls well over 100 Amps. For this system the EC5 connectors were used. These connectors are very nicely made. Methinks for anything over 100 Amps or so, this connector should be considered. It's available from several sources, including: (It must be popular, several sources have it backordered)
http://www.rcboca.com/e-flite-ec5-de...FQa8KgodvF4AIQ
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