BAC-ESJ: lipo 5V regulator with voltage alarm, readout, charge port and switch - RC Groups
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Apr 15, 2009, 05:40 PM
Magicsmoke maker
Inflexo's Avatar
New Product

BAC-ESJ: lipo 5V regulator with voltage alarm, readout, charge port and switch

Ideal for small slopers with two to four small (9g class) servos. The BAC-ESJs are originally for the DLG crowd but since a lot of them go sloping I thought that the sloping groups would like to know about them too.

The BAC-ESJ takes a 2S lipo input and provides a 5V regulated output with up to 1A peak current and provides in addition many features such as low-voltage alarm, voltage readout and integrated on/off/charge switchjack.

The biggest gains you get from moving to a lipo/regulator combination is that you can now have your lipo precharged a few days before the day of flying and it won't be half flat on the day. You get a lot more flying time due to the higher lipo capacity for the same mass. The voltage blink readout lets you know what your lipo voltage is. The low voltage alarm lets you know when it's time to stop flying.


* Very low weight - 6.1g
* Very small - 28 x 12.5 x 10mm
* 2S lipo input
* 5V output
* LED-blink voltage state indicator (full scale)
* Over voltage alarm (Vin > 8.5V)
* Under voltage alarm (Vin < 7.0V)
* Buzzer alarm
* 1A linear BEC for minimum RF interference
* Extensive decoupling for even quieter RF levels
* 250mA constant supply, 500mA for 1 minute, 1A for 10 seconds (thermally limited - better cooling gives longer duration)
* Thermal and short circuit protection
* High quality, low power, low (RF) noise micro controller
* Large copper backplane to improve heat-sinking of linear regulator.
* Supplied with 50mm RX lead, 100mm female servo battery lead and combo charge/switch plug.

Available at -
Cost: $49 AUD (~$34 USD)

The PLD-BAC-ESJ (BEC Alarm Combo) has been made as small as possible but still packed with needed functionality and now provides LED and audio indication of battery status and most significant of all, now an electronic switchjack and charger combo port.
Last edited by Inflexo; Apr 15, 2009 at 08:10 PM. Reason: Added the price
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Jun 11, 2009, 02:07 AM
Magicsmoke maker
Inflexo's Avatar
Hrmm... completely forgot I had this thread here

As an update, all the units now come with 22AWG wire, JST 2-pin input for the lipo and charge lead, also still the red servo plug to the receiver.

Aug 17, 2014, 06:36 PM
Build & Fly

Big Bump

Any plans to make more of these? I will pre-order several today to provide an incentive!
Aug 17, 2014, 09:08 PM
Magicsmoke maker
Inflexo's Avatar
It's been a looooooong time. I think most people ended up using the original BAC thread instead over at

Anyhow, as yet, no plans. Can't get the cost down any more to where it's acceptable ( compared to HK ) and since the production run would require a restart of everything and be quite small there'd be a lot of new overheads.

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