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Battery Backer and Glow Driver
 Moderated by: Spe, colin, admin, AdeH
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 Posted: 29 June 2013 09:55 am
1st Post

Joined: 26 September 2011
Location: Gillingham, United Kingdom
Posts: 61
At the club meeting I was chatting with Phil about my new project (Dave Boddingtons Piper Cub)  I stuck a couple of pictures on our Boddington balsa bashers forum.  Anyway I mentioned that I just got some Digital servo’s cheap from TJD’s (JR DS599).  I now realise why you asked what voltage they were Phil.  I think I probably dropped off as they are only 4.8v :P
 I was looking at battery backers as suggested and came up with a couple of makes:
SM services [UK] Ltd have a couple of items
SM34 Backer Monitor:  Sadly for me this seems to only work with 6v servo’s.   They do however sell a Powersave (Split supply) that works with 4.8v.  For some strange reason it does not recommend for the use of 2x4.8 batteries but it does seem to work ok with 2x6v batteries?
The other one I found was EMS Ultimate Battery Backer
Which sells on ebay for 31 dollars.
I’ve also looked  for a Glow driver and come up with one from SMC models.
Does anyone have any experience with these or can recommend other makes?

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 Posted: 29 June 2013 11:05 am
2nd Post
Phil F
MMFC Committee Member

Joined: 15 April 2010
Location: Sittingbourne Pothole Capital Of World
Posts: 1197
Hello Bob . I think the safest way to use those servos is to use a GOOD capacity (C cell) 4.8 v pack . Any 5 cell pack will exceed its nominal 6 volts when fully charged and will probably go to near 7 volts and can possibly  damage those servos. Most servos now can accept the higher voltage from life batteries etc (above 6 volt) you could use two 4.8 volt packs without a diode  fitted but its not recommended as a defective battery pack can drain the other . If you fit a diode into a 4.8 volt pack it will reduce the voltage bu 0.7 volt , just above that of a discharged pack. This low voltage can affect your 2.4 rx and cause a brown out when all servos are used and the voltage drops . By using the "C" type cells they can deliver much higher current without dropping the voltage so the Rx is supplied and happy. The SM service battery backer is easy to use and works well but will as said only works with 5 cell packs due to the diode voltage drop. The battery seporator is only to protect the Receiver from the higher voltage but most modern Rx's are now classed as high voltage and will work up to 12 volt as will some servos . You could look at Voltage regulators that deliver 5 volts but do check that they will supply the required amperage .The sm services on board glow unit is simple to use and works very well .

The secret of flight is to aim at the ground and miss
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