Phil 9 Posted June 20, 2013 Share Posted June 20, 2013 How do I work out rx battery size. I am planning for a .60 size model with six servos and it will have two rx batteries through a power box sensor. I don’t want to add too much weight so just sticking in two large capacity batteries is a bit of a waste Quote Link to comment Share on other sites More sharing options...
stuey Posted June 20, 2013 Share Posted June 20, 2013 Two li-fe packs would probably be the lightweight ticket if the servos can handle the voltage these days. Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted June 20, 2013 Author Share Posted June 20, 2013 would two 700mah life batteries last long? Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted June 20, 2013 Share Posted June 20, 2013 What servos are you using Phil? Digitals will consume more mAh..... Tell us about the Powerbox unit too? Does it drain both batteries equally (thus you would have effectively a 1400mAh battery on board.... Personally I might be tempted to use the 1100 size (HK right??) they are not much bigger or heavier... Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted June 20, 2013 Author Share Posted June 20, 2013 Savox SC0252 digital servos. I think the power box draws from one battery and uses the other as a back up and only switches over if the first battery voltage drops too low Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted June 20, 2013 Share Posted June 20, 2013 MG996Rs and 3152s in my King Altair take around 90mAHr per flight for general gentle pattern flying, balanced between the two batteries, so in theory two 700s should be fine for a dozen flights. In theory. I use 1100 LiFes through the HK clone powerswitch just to be safe, though the Tornado and Blue Angel use single 1100 packs and I rarely fly them more than 4 times between charges. I'd imagine 3D flying would be a very different matter with much higher drain. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted June 21, 2013 Share Posted June 21, 2013 Rather than look at capacity you need to look at the voltage sag underload, a 4 cell 800 mah AAA pack might drop a lot of volts if put under load on a fast plane with large control surfaces. As the powerbox sensor also regulates the voltage I'd go with 2 Lipo or Life batteries Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted June 21, 2013 Share Posted June 21, 2013 Forgot to mention above I have a couple of 2400 mah AA packs that are rubbish, just waggling the sticks on the bench with 4 regular servos in a plane was enough to cause the telemetry Rx low voltage alarm to go off. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted June 21, 2013 Share Posted June 21, 2013 Frank certainly makes a good point....it seems as capacity of NiMH AA cells has gone up their ability to maintain voltage under load has reduced...often the reason why Sub C cells are preferred....the larger cells hold up their voltage better. Personally I've switched to LiFE cells completely now...a 2S unit plugged straight into the Rx.....I find them to be excellent with no self discharge & good voltage stability.... Quote Link to comment Share on other sites More sharing options...
Greybeard Posted June 21, 2013 Share Posted June 21, 2013 I use these 1000mAh LIFE cells, they are quick to recharge and lightweight. Considering that at one time we could only get 500 mAh Nicads packs and we flew all day with those I'm quite relaxed with double the capacity and increased voltage we now have available. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted June 21, 2013 Share Posted June 21, 2013 I use these......1100mAh & half the price..... Quote Link to comment Share on other sites More sharing options...
Greybeard Posted June 21, 2013 Share Posted June 21, 2013 Posted by Steve Hargreaves - Moderator on 21/06/2013 14:28:24: I use these......1100mAh & half the price..... and out of stock. Quote Link to comment Share on other sites More sharing options...
crispin church Posted June 21, 2013 Share Posted June 21, 2013 hh lifes are good or get singles and make up your own packs how long you thinking of flying for ? and do you really need a power box on a 60 size ? 1 life will do all day Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted June 21, 2013 Author Share Posted June 21, 2013 Posted by Steve Hargreaves - Moderator on 21/06/2013 14:28:24: I use these......1100mAh & half the price..... I just ordered some of the above. in stock from hong kong Quote Link to comment Share on other sites More sharing options...
Greybeard Posted June 22, 2013 Share Posted June 22, 2013 They’ll be flat by the time they arrive. Quote Link to comment Share on other sites More sharing options...
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