frank killan Posted May 12, 2017 Share Posted May 12, 2017 I am thinking of converting my futaba radio to lifepo4 batteries please could anyone advise if this is OK. Thanks tiffy Quote Link to comment Share on other sites More sharing options...
Andrew767 Posted May 12, 2017 Share Posted May 12, 2017 I used them in a T7CAP and had no issues. I used the ones from HobbyKing. Andrew Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 12, 2017 Share Posted May 12, 2017 Which radio is it Frank? I converted my 10C years ago with a 3S LiFe battery & it's been brilliant....lasts for ages between charges. The longest I have gone is a cumulative time of 5 hours (as shown on the Tx timer) over several weeks & I only charged it then because of paranoia.......the voltage was still steady at 9.8V. I recall it took slightly over half capacity to charge it back up again so still plenty of life (groan!) in it even after 5 hours. Another plus point is that you can charge it when you get back from the field & it will hold it's charge for weeks if not months.....unlike NiMH cells which go flat whilst you watch them..... Buy with confidence I would say..... PS I'm sure you know but you do need a dedicated LiFe setting on your charger. a LiPo setting will not do. Oh & keep the charge current down to under 1A too....the internal wiring is quite thin as it's designed for slow charging NiMH batteries not fast charging LiFe batteries Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 12, 2017 Share Posted May 12, 2017 I have a 14 SG operating with life batteries. The only downside is that you can no longer charge the battery through the charging port on the Tx. Most Tx life batteries now come with an additional lead on with a micro connector so that you can charge them without pulling the dedicated power lead from the tx. My ones came with an adaptor for the micro connector matted to a female futaba socket. I have a 2.1 Ah battery and after 2 hours use it needed 0.454 Ah from the charger to get the smoke up to the required level. I'm not quite sure what Steve is saying in his PS but I always balance charge my ones and futaba recommend the life battery to be removed from the transmitter to carry out the charging cycle. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 12, 2017 Share Posted May 12, 2017 With the set up in the 10C I can charge the LiFe battery via the normal charge port in the Tx. No need to remove it for charging. I was just pointing out that the internal wiring in the Tx is quite small gauge so keeping the charge current low to avoid overloading the Tx wiring. Given the low discharge current I see no need to balance charge every time. Quote Link to comment Share on other sites More sharing options...
frank killan Posted May 13, 2017 Author Share Posted May 13, 2017 Thanks for the above chaps. What concerns me is using lifepo4 as the RX pack, the voltage that can be attained, can this be tolerated by the RX/servos. I have built a kamco kadet to teach my grandson, using a futaba dual rejection RX on 35meg and 6ea tx. Thanks again chaps. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 13, 2017 Share Posted May 13, 2017 Most receivers are designed to run on a fairly wide range of voltages and 2S LiFe packs shouldn't present a problem to any modern system I'm aware of. Servos may be OK but there are some which don't tolerate higher voltages than a 4S NiXX pack. A simple and reliable (depending on your soldering skills!) precaution for any 5S capable servos is to add a silicon diode in series with the output (from 3 Amps rated upwards depending on the expected load) which takes @ 0.6V off the supply voltage and a margin of safety against the freshly charged voltage. Quote Link to comment Share on other sites More sharing options...
frank killan Posted May 13, 2017 Author Share Posted May 13, 2017 Thanks Martin. I have read somewhere that fully charged a Rx pack can attain 7.2v would such a diode be adequate or would a higher value be required. Also I know nothing about charging life cells and would be grateful for advice. Thanks for your help. FK Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 13, 2017 Share Posted May 13, 2017 I don't know what other folk use buy, after spending quite a few quid on multiple chemistry chargers I settled on the following, bearing in mind I only use my chargers for charging the lipos on my starter and the life batteries in my tx and models. Indoors I use an IMAX B6 AC which will operate both from mains and from a 12V car battery, but I only use it indoors on the mains. It cost about £22 a few years back.The B6 does nicad, nimh, lipo and life and also lead acid At the field I use an IMAX C403 which operates from 12V only. This is the easiest charger I have to use, but it only does lithium chemistry batteries and, if I could only have one charger, it would be it. you can change between lipo li-ion and life sequentially with a button, turn the amps up with a rotary switch and thats about it. It beeps at you when the battery is full. It cost about £15 two or three years ago. The B6 is advertised on e-bay at £21 currently, which annoys me I have to say!!! It's coincidental that both are IMAX btw. They both work well and the only problem that I had with them was the chrom buttons fell off if you inverted them. A drop of cyno fixed that. Edited By Braddock, VC on 13/05/2017 20:20:11 Quote Link to comment Share on other sites More sharing options...
Andrew767 Posted May 13, 2017 Share Posted May 13, 2017 Frank...Just be careful about which servos you use as some say 6v and really mean it. Andrew Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 14, 2017 Share Posted May 14, 2017 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
frank killan Posted May 17, 2017 Author Share Posted May 17, 2017 Thanks for all your advice chaps. FK Quote Link to comment Share on other sites More sharing options...
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