trebor Posted February 12, 2018 Share Posted February 12, 2018 What setting would you use to set up a low voltage alarm ? I've just been looking at information on my recivers working at 4 - 10 volts. Would 4.5v be ok for a warning alarm or could I go lower. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted February 12, 2018 Share Posted February 12, 2018 4.5v is the default setting on the Multiplex receivers for a 4 cell battery, that seems a reasonable compromise, too high and it will go off every time the servos are loaded up, too low and if the battery sees a sudden high load there might be a significant voltage drop which could lead to a Rx brown out. If you are running a 5 cell battery, then say 5.5v should be OK. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 12, 2018 Author Share Posted February 12, 2018 I should have mentioned it's Frsky setup, I have 4 cell and 5 cell batteries in various models so should the low setting be different depending on battery size ? Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 12, 2018 Share Posted February 12, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted February 12, 2018 Share Posted February 12, 2018 Doesn't matter what radio system it is, what you are setting the alarm for is a failing (i.e. discharged) battery before the voltage drops right off. Around 1.1v per cell would give you adequate warning, slightly higher on a 4 cell battery as it is closer to the min voltage of the Rx. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 12, 2018 Author Share Posted February 12, 2018 Could I run the 5 cell packs down to 4.5v or is that risky. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted February 12, 2018 Share Posted February 12, 2018 Posted by trebor on 12/02/2018 18:34:48: Could I run the 5 cell packs down to 4.5v or is that risky. 0.9v per cell is basically completely discharged and the voltage drops off really quickly after that. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 12, 2018 Author Share Posted February 12, 2018 Thanks I've always looked at electrics as a ( Dark Art ) Quote Link to comment Share on other sites More sharing options...
John Stainforth Posted February 12, 2018 Share Posted February 12, 2018 I always fully charge my RX batteries before I go flying and I find that I can do a lot of flying before the loaded voltage comes down to the nominal voltage. So I would probably set an alarm to 4.8V for a 4.8V battery- but I've not tried this in practice. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 12, 2018 Author Share Posted February 12, 2018 I must admit I always fully charge mine but now I've got this Frsky telemetry I might as well learn how to use it. It's good to have another indication of something going wrong. I have a few volt spy's and volt readers mounted in the planes but you can't see them in the air. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted February 12, 2018 Share Posted February 12, 2018 Posted by trebor on 12/02/2018 19:03:06: I must admit I always fully charge mine but now I've got this Frsky telemetry I might as well learn how to use it. It's good to have another indication of something going wrong. I have a few volt spy's and volt readers mounted in the planes but you can't see them in the air. Exactly, my telemetry has picked up both a battery which was under performing and also a faulty switch. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 12, 2018 Share Posted February 12, 2018 When I used Nixx cells I used to set two alarms, the first at 1.1v per cell, ie 4.4v for 4 cell 5.5v for 5 cell. This would give the 'batlow' warning on a 20 seconds repeat. The second alarm was at 1.0v per cell with 'batcrt' every 10 seconds. Quote Link to comment Share on other sites More sharing options...
PatMc Posted February 12, 2018 Share Posted February 12, 2018 FrSky D series Rx's work down to 3.5v & X series down to 4V. IMO alarm as Bob says should be set at 1.1v/cell with repeats every 20 secs or so but land ASAP. It's important that the voltage limit is set per cell not as a flat lowest voltage. At 4.4v a 5 cell battery is in a worse state than a 4 cell. BTW I use a single lipo on a small HLG used as a light wind slope soarer without any problems, Rx is a FrSky V8R4. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 13, 2018 Author Share Posted February 13, 2018 Thanks for this, I must write it down before I forget. Sign of getting old ! I'm amazed this taranis hasn't got a notebook program as it does everything else. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 13, 2018 Share Posted February 13, 2018 IIRC you can attach a text file to each model that will be displayed after switching on or swapping model. I think it was in earlier OpenTX versions, I'm not sure if it's still available. OpenTX University Edited By Bob Cotsford on 13/02/2018 09:52:13 Quote Link to comment Share on other sites More sharing options...
gangster Posted February 13, 2018 Share Posted February 13, 2018 Trebor. You would be better off not setting an alarm at all than set a 5 cell to 4.5 volts. There is a lot of difference between 4.5 volts from a 4 cell pack which means they are getting low and 4.5 volts from a 5 cell pack which means all the cells are way way down. In the same way I have seen models safely landed with one cell short circuit on a four cell pack hence only about 3.6volts. No way would a radio system work on a four cell that had all cells flat and dropped to 3.6 volts. Edited By gangster on 13/02/2018 10:38:29 Quote Link to comment Share on other sites More sharing options...
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