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Old Jul 16, 2014, 10:02 AM
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United States, IL, Champaign
Joined Aug 2012
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Question
Power Board Battery Charging

I am new to using power distribution boards and haven't figured out the easiest way to charge batteries in the plane. There are several different brands and distributors of these redundant power boards.

How can you charge the redundant Rx batteries if they are buried under a tail hatch for balance without having to keep unplugging connectors and causing them to wear? Do you run separate on/off switches and charging jacks for each battery? Maybe use 3 switch/jack sets, 2 for Rx batteries and 1 for gas electronic ignition battery?
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Old Jul 17, 2014, 12:13 AM
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Joined Dec 2013
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Hello jwellsy... I run two power busses for the servos with redundant batter packs... two receivers with their own redundant batter packs... the way I have mine setup, the servos have 2 NMh packs with their own switches... each switch has a charge port to plug into, so in the off position the packs can be charged through the charge port on the switch... both battery packs feed both servo busses simultaneously... if one pak or switch goes bad for whatever the reason, the other pack will continues to provide power.

The same with the receivers packs, there are two redundant A123 packs with their own switches and charge ports... both packs provide power to the two receivers simultaneously, if one pak or switch goes bad, the other will provide power.

I also have (will have) a separate battery pack for the ignition system with a transmitter controlled kill switch.

So there is a total of 4 switches that have to be turned on (5 if you include the ignition), 2 for the servo busses and 2 for the receivers... for piece of mind, each switch has an LED that lights when turned on and power is being drawn from the batter packs, no light means no power draw,and there is a problem somewhere in the circuit; either in the switch / plug connections or with the battery pak.

Also, its a good idea to cycle your plug connections now and then, don't just rely on the fact that the plugs are gold plated... resistance can occur in any type of plug-in connector... I cycle my connectors every time I go to the field to fly... I have a check list I go through to make sure I don't get complacent and forget something... check your battery voltages after every flight... NMh, 1.1 volts per cell and its time to quit and recharge... A123, 3 volts per cell and time to recharge... play it safe.

***EDIT***
These are the power busses I'll be using http://www.servocity.com/html/servo_power_boards.html


John M,
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Last edited by John_M_; Jul 17, 2014 at 12:32 PM.
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Old Jul 17, 2014, 08:11 AM
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United States, IL, Champaign
Joined Aug 2012
899 Posts
John, thanks for the thoughtful reply. My mind is still getting bogged down with the switches. My LiFe's and my power board both have Deans connectors with wires 4x the diameter of servo and switch wires. Even Mirical switches don't come with wire gauges of a battery. It seams odd to have to bottle neck down down wire gauges at a switch and I'm having a hard time wrapping my mind around that being a safe way to go.
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Old Jul 17, 2014, 12:27 PM
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jwellsy I understand your concerns... you could argue the same fact about the contacts inside the switch itself... ... somewhere in the path there is always a weaker link... those power boards I linked to from servo city allow you to make up your wire harness from the battery to the switch etc... you can always makeup your own switch harness with heavier gauge wire and the deans connectors all the way through to the power boards, or you can change the existing wire and connectors from the switch you're using with a heavier gauge wire and the deans... you could also use a badger or Wolverine switch http://www.fromeco.org/categories/Switches... they have a good reputation... and if you go with the Wolverine switch, you get true redundancy, 2 battery packs shared with load balancing, and automatic pack isolation if a cell shorts or goes open.

I've always tried to keep it simple and safe... the more devices, gadgets and plugs you have connected increases the points of failure.



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Last edited by John_M_; Jul 17, 2014 at 03:44 PM.
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