Phil 9 Posted March 31, 2018 Share Posted March 31, 2018 if you use a lipo rx battery what type of voltage regulator do you use? Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted March 31, 2018 Share Posted March 31, 2018 When I use a 2S LiPo I use a Power Box Digiswitch. It's a bit expensive but is software driven and has an inbuilt LED to provide a warning of low voltage. However, if you are using on-board telemetry, then all you see is a voltage of 5.9 v. So, by the time the LiPo actually reaches 5.9 v it's done for. I am now also using a 2S LiFe which does not need a voltage regulator as it's 6.6 v off charge. I'm using this setup in a 35 cc petrol model with another 2S LiFe pack to supply the ignition system. I use JR servos and they are fine with that voltage. An ordinary good quality switch is fine with a 2S LiFe pack. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted March 31, 2018 Share Posted March 31, 2018 The other alternative is to use a SBEC, several around but the rating would depend on the size of the model and number of servos. You could of course just use high voltage servos which are designed to run on a 2s Lipo and not use any voltage regulator. Like Peter though I use 2s LiFe which has the same voltage as a 5 cell Nimh battery, rather than Lipo and regulator. Quote Link to comment Share on other sites More sharing options...
Dickw Posted March 31, 2018 Share Posted March 31, 2018 Depends to some extent on what load you are supplying. I have been using the Jeti SBEC for a few years reliably in one model. Several of my other models with Lipo Rx battery now use HV servos so don't need a regulator. Dick Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted March 31, 2018 Author Share Posted March 31, 2018 I have a LiFe battery and it is this I wanted to replace. The reason being there is no reliable way of checking the remaining capacity. your supposed to work out how much power is used per flight and calculate how many flights each battery will give you allowing a reasonable safety margin. but I'm not great at keeping count of flights and would much prefer a reliable method to measure the battery before each flight hence the reason to change to lipo. you have just reminded me I do have a powerbox sensor switch **LINK** but I always thought it was a bit bulky for my acro wot Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted March 31, 2018 Author Share Posted March 31, 2018 it will be supplying 5 Hitec HS225MG servos in an acro wot Edited By Phil 9 on 31/03/2018 17:46:37 Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 31, 2018 Share Posted March 31, 2018 Where possible I am changing over to 2s LiFe packs. My scale models have just two x 700 ones feeding a Failover switch. I previously used two x 1900 Eneloops. The LiFe packs seem to take very little re charging in comparison for reasons beyond me. I would say that if you do a lot of flying in one session then either re charge during the day or fit spare packs to be safe. There is no way of checking them. Other models of mine seem quite happy on a single 700, 1100 or 1800 pack. I also use them in my Tx`s and they seem to last forever compared with higher capacity NiMh`s. If you are worried you could use a suitable UBEC or even adapt a speed controller. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted March 31, 2018 Share Posted March 31, 2018 Presumably you'll have a mechanical on/off switch in the feed from LiPo to the voltage-regulator, not in the feed from regulator to Rx and/or servos. Otherwise your LiPo will drain, albeit very slowly, if left connected. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted March 31, 2018 Share Posted March 31, 2018 You should never leave a LiPo connected and in the aircraft when you are not using it. The current drain with the Powerbox switch is minimal during the time of operation. I always fit the LiPo before flight and remove at the end of the session. You need to have a LiPo outside the aircraft to charge it. The same does not apply to LiFe cells. Quote Link to comment Share on other sites More sharing options...
Rich too Posted April 6, 2018 Share Posted April 6, 2018 I am also a fan of LiFe batteries, they suit my infrequent and short flying days. Is there no way to get around your issue? They are so convenient to use compared to LIPO that it seems a shame you have to change. Quote Link to comment Share on other sites More sharing options...
Rich too Posted April 6, 2018 Share Posted April 6, 2018 You could experiment (on the ground!) with a low voltage alarm set at 3.3v. With decent batteries you may get a lot of time to land before the voltage drops to 3v and then falls off the cliff. I may try this myself..... Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted April 6, 2018 Author Share Posted April 6, 2018 Posted by Rich too on 06/04/2018 07:15:47: You could experiment (on the ground!) with a low voltage alarm set at 3.3v. With decent batteries you may get a lot of time to land before the voltage drops to 3v and then falls off the cliff. I may try this myself..... I don't have any telemetry. I think I will try a lipo. It will get rid of the doubt I experience after I have been at the field all day and start to clock up a good number of flights Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted April 6, 2018 Share Posted April 6, 2018 I found that my Hitec servos were not happy being driven directly from a 2S LiFe. After taking some measurements, it appeared that 6.2V was the maximum that they'd tolerate before they'd start to operate in a rather jittery manner. Worth checking. Futabas are all happy up to 7V I find. Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted April 6, 2018 Author Share Posted April 6, 2018 I have not had any problems so far with the servos running direct from the LiFe battery. I was just worried about them running low Quote Link to comment Share on other sites More sharing options...
Rich too Posted April 6, 2018 Share Posted April 6, 2018 Fingers crossed I’ve never had an issue. Fair enough Phil, but some of my models have the batteries buried deep inside and LIPO for those would be a royal PITA ! Quote Link to comment Share on other sites More sharing options...
Rich too Posted April 6, 2018 Share Posted April 6, 2018 I don’t fly all day so I get the issue. If it were me I’d be tempted just to recharge half way through the day at the field. Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted April 6, 2018 Share Posted April 6, 2018 Phil: The question I would ask is after a days flying, how much charge does the LiFe take? You can then work out quite easily how much longer you could safely fly. Personally, I'm a great believer in simplicity. A voltage regulator or battery backer is just one more thing to go wrong. I've also found that nearly ever case of mysterious radio issues that I've investigated can be traced back to a regulator or backer. LiPos also drop off very quickly when exhausted, and whilst the available battery checkers can give an indication as to how much charge is left, I do question their accuracy! I struggled to find two that give the same result connected to the same battery! My advice would be to stick with the LiFes, and just check how much it takes to recharge after a set number of flights. That should give you a good indication of how many flights you can reasonably expect - but remember to leave yourself an adequate safety margin! -- Pete Quote Link to comment Share on other sites More sharing options...
Tim Flyer Posted April 6, 2018 Share Posted April 6, 2018 Or if you are really worried about power running out why not just buy a spare or bigger LIFE, as if you are considering switching to LiPo you would need to be removing the battery for charging anyway. With my LIFE batteries I do monitor how much I put in on each charge to make sure it seems correct given the number of flights I had . I seem to use very roughly 300ma on my typical 3 or so flights on one of my models . Given the battery is 2000ma that leaves a lot of safety margin. I have telemetry but don’t visually check that whilst flying but do the usual ground checks on servos using it. If you don’t have telemetry I believe some of the other battery testers can also test voltage under load? Edited By Timothy Harris 1 on 06/04/2018 09:59:05 Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted April 6, 2018 Author Share Posted April 6, 2018 Many thanks for all the replies. Lots of food for thought there. There is an argument that even with LiFe batteries I should be using a regulator. Maybe Peter is right and I should go with the old adage"if it an't broke dint fix it" Quote Link to comment Share on other sites More sharing options...
Dickw Posted April 6, 2018 Share Posted April 6, 2018 Just a thought, but for the planes where I use a Lipo for the Rx I don't remove them for charging as they are buried in the fuselage. I just balance charge through a 3 pole socket in the fuselage. Admittedly I only use 2s Lipo and they are small ones (300mAh), but it has worked OK for me for several years. The downside is that you need to make up suitable adapters to link the main leads and the balance leads in to one 3 pin. Dick Quote Link to comment Share on other sites More sharing options...
Rich too Posted April 6, 2018 Share Posted April 6, 2018 Posted by Timothy Harris 1 on 06/04/2018 09:58:25: Or if you are really worried about power running out why not just buy a spare or bigger LIFE, as if you are considering switching to LiPo you would need to be removing the battery for charging anyway. With my LIFE batteries I do monitor how much I put in on each charge to make sure it seems correct given the number of flights I had . I seem to use very roughly 300ma on my typical 3 or so flights on one of my models . Given the battery is 2000ma that leaves a lot of safety margin. I have telemetry but don’t visually check that whilst flying but do the usual ground checks on servos using it. If you don’t have telemetry I believe some of the other battery testers can also test voltage under load? Edited By Timothy Harris 1 on 06/04/2018 09:59:05 that’s exactly what I do, and generally use around 200ma per session or six flights - that’s per battery so 400ma in total. The mininum I use is two 1100mah batteries so tons in reserve. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted April 6, 2018 Share Posted April 6, 2018 Just a note, as my own hangar consists of 12 sport and scale models within 5 to 6 foot wingspan A 60 size motor is rather big in my collection, so there are not many extra gizmos All models have external charge/voltage check socket, and all powered 4.8v packs with 4 to 6 std servos Are checked for full charge on arrival at the field, then every flight after the 1st 3 flights of the day. If just one green light goes down of the row, the field charger is attached until the beep beep beep of full charge again. It has been found that although this is not the best way to treat your receiver pack It is absolutely the best way to treat your friends safety and that of the public, and the bonus is that you usually Get your model back in one piece Quote Link to comment Share on other sites More sharing options...
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