Wiltshire Flyer Posted July 16, 2011 Share Posted July 16, 2011 The rx batt i bought for my wing is a 4.8v NI-MH says 2200MAH, charge at 220MAH for 14-16 hours. I went to a local ms and asked for a charger for it and was offered a futaba one, chap told me that this one would have the batt charged in around 4 hours so i accepted his advice and left, it has been playing on my mind as to whether it will be safe as the batt says to charge for 14-16 hours and the chap didnt actually see the batt i had as i had bought it from another shop. So i thought i would ask someone here for advice just to put my mind at ease. Charger says- Rx 4.8 - 8.4v 600mATx 9.6v 120mA Could someone kindly offer their informed opinion as to whether this will be ok to use with the batt i have? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 16, 2011 Share Posted July 16, 2011 Are you sure it says 600 mA - not 60mA? A 600mA charger will charge the battery in around 4 hours but won't give it the correct forming charge as stated above. At around 1/4 C the battery will get quite hot once it is fully charged which won't do it much good. Unless you discharge it fully each time you won't know how long to leave it on for so a delta peak detecting charger would be a good investment. An alternative for the initial charge would be to use a standard Futaba wall charger - divide the battery capacity by the charger output and multiply by 1.5 e.g. if it's 120mA then 2200/120 = 18.33 x 1.5 = 27.5 hours. Quote Link to comment Share on other sites More sharing options...
Kozmyk Posted July 16, 2011 Share Posted July 16, 2011 I've found the info that this site gives has been reliable. hangtimes.com/rcbattery_faq See Q. #3 - They reckon 3 x c/10 14/16 hour forming charges for a new NiMh. Once formed it's up to you whether you stick with long trickle charges or go for C/2 or even C rate peak detect charges.I stick to C/2 max, preferring to err on the side of caution. Edited By Kozmyk on 16/07/2011 02:27:06 Quote Link to comment Share on other sites More sharing options...
Wiltshire Flyer Posted July 16, 2011 Author Share Posted July 16, 2011 Thanks for the replies fellas, THIS is the charger i have, says it has delta peak detection? does that mean it will be o.k? Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 16, 2011 Share Posted July 16, 2011 Fine for recharging but it's best to do the forming charge first - ideally 220mA for 14 - 16 hours but failing that do it slower and longer BUT you can't use a delta peak charger for this. It is likely to detect the first cell peaking and terminate the charge before all cells are fully charged which is the essence of the forming charge. Quote Link to comment Share on other sites More sharing options...
Wiltshire Flyer Posted July 16, 2011 Author Share Posted July 16, 2011 Thank you for the reply Martin, so the charger that was recommended to me is useless for the first charge........ for god's sake... why are the people selling the stuff not more informed? and why did they not tell me this?...........grrrr..... having a bad day....... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 16, 2011 Share Posted July 16, 2011 TBH the majority of people won't have the correct equipment to do the ideal forming charge and the equipment isn't generally available through the model trade. The wall charger which came with radio outfits was fine for the NiCd cells supplied but with the move to higher capacity NiMHs these have been left behind. Some years ago (before I came back to modelling) I built a multi-rate charger based on a kit from Maplins which gives me a timed 14 hour charge at a range of currents from 50mA to 750mA which I use for forming new packs. You've just given me the idea to add an ammeter and a variable resistor to the control circuitry to make it even more flexible!Edited By Martin Harris on 16/07/2011 15:17:27 Quote Link to comment Share on other sites More sharing options...
Wiltshire Flyer Posted July 18, 2011 Author Share Posted July 18, 2011 Can anyone advise on a cheap rx batt discharger for it please? Quote Link to comment Share on other sites More sharing options...
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