keith ellis 2 Posted January 4, 2013 Author Share Posted January 4, 2013 checked the spelling ,, think it maybe down to chineese to english translation error.. the charger is around 7 years old so most likely not for lipo's but yes will get a dedicated charger for the lipo's as i have read a few scare stories, fires and the like..I have a field battery , the usuall 12v 7ahm battery,, would this be powerfull enough to run a fast charger for these or is something more along the lines of a small car battery better. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 5, 2013 Share Posted January 5, 2013 Hi Keith - well that field battery will just about about do for 3s batteries - but allowing for charger losses etc you will only get two battery charges of it - at best! You see your lipo's are 11.1v - pretty much the same as the field battery - and they need 2.2Ah to fully charge. So two charges is 4.4Ah, assuming your charger is about 80% efficient that 4.4 Ah will take about 5.5 - 6Ah out of your field battery! Doesn't leave enough for a third charge. You really need a leisure-style 12v lead-acid job to recharge at the field. I use a 70Ah battery - but I have a lot of 6s batteries, you could probably manage well with something a bit smaller - say 30-40Ah or so. BEB Quote Link to comment Share on other sites More sharing options...
kc Posted January 5, 2013 Share Posted January 5, 2013 Well in practice the 12 v 7 amp hr field box battery that I have has recharged my four 3S 2200 Lipos at the field which gives me 8 flights a day from just 4 Lipos. Best thing is it keeps the field box battery in use and it does not deteriorate through lack of use. Worth saying that the fully charged 12v 7 amp battery also started my car when the car battery went flat through leaving an interior light on for a couple of days. Very handy! Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 5, 2013 Share Posted January 5, 2013 The only way that's possible KC is if you leave quite a bit in the Lipos. BEB Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted January 5, 2013 Share Posted January 5, 2013 BEB is correct....you can't argue with the laws of physics.... Quote Link to comment Share on other sites More sharing options...
Andy48 Posted January 6, 2013 Share Posted January 6, 2013 Posted by Biggles' Elder Brother - Moderator on 05/01/2013 00:23:53: Hi Keith - well that field battery will just about about do for 3s batteries - but allowing for charger losses etc you will only get two battery charges of it - at best! You see your lipo's are 11.1v - pretty much the same as the field battery - and they need 2.2Ah to fully charge. So two charges is 4.4Ah, assuming your charger is about 80% efficient that 4.4 Ah will take about 5.5 - 6Ah out of your field battery! Doesn't leave enough for a third charge. You really need a leisure-style 12v lead-acid job to recharge at the field. I use a 70Ah battery - but I have a lot of 6s batteries, you could probably manage well with something a bit smaller - say 30-40Ah or so. BEB Can I suggest a compromise? A 24ah gel battery comes in at £30 delivered. **LINK** This is half the price of a leisure battery, and half the weight, yet should be good for many more flights. Can I also add a plea about safety? Any of these batteries are quite heavy lumps, and god forbid, in an accident, could be much more dangerous than the accident itself. Imagine being hit on the back of your head by a battery travelling at even 30mph after your car stops suddenly in an accident. The safest place is in the passenger footwell, or the rear passenger footwell. Edited By Martin Phillips on 06/01/2013 16:38:35 Quote Link to comment Share on other sites More sharing options...
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