George R. Vale Posted September 28, 2016 Share Posted September 28, 2016 I posted the following e-mail to Ripmax on Wednesday 21st. September. There has been no response to date: <<Dear Sirs, Battery Charger Whilst recharging a Rx battery using a Ripmax-Futaba charger model no. P-FBC32D/4 the battery exploded. The model it was in was damaged and slightly charred. Fortunately it did not catch fire, or, given the amount of inflammable material in my workshop, the house could have burnt down. The battery was damaged beyond certain recognition but was very likely a pack of four 2/3A size 1100mAh Ni-MH cells supplied by Batteries Plus on 16/4/2014. The charger was bought from HobbyStores on 16/12/2014. It is claimed to be "Suitable for Ni-Cd and Ni-MH batteries." (Photo attached.) Please advise whether this charger is normally suitable for the type of Ni-MH cells I was using. If so perhaps you would like to comment as to whether the charger may have been defective in some way so as to cause this explosion. I have noticed that the 5-cell Tx battery in my Futaba T6J Tx gets hot when using this charger, so I wonder if the "peak detect charge termination" circuitry might have failed? If the P-FBC32D/4 is unsuitable for the application perhaps you could advise me which charger I should use? Yours etc.>> I attached a few pictures of the damage and of the charger. Readers please contact me if you would like to see the pix. Unless someone knows better, I would like to warn all users of Ni-MH batteries NOT to charge them overnight. George R.Vale [email protected] Quote Link to comment Share on other sites More sharing options...
Former Member Posted September 28, 2016 Share Posted September 28, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted September 28, 2016 Share Posted September 28, 2016 Hi George, All manufacturers recommend that charging cells are Never left unattended, and are removed from the model. Most of us charge Nihms inside the model, but never overnight and never unattended, and they do get warm. Put this one down to a " lucky escape" Edited By Denis Watkins on 28/09/2016 17:11:45 Quote Link to comment Share on other sites More sharing options...
Former Member Posted September 28, 2016 Share Posted September 28, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Geoff S Posted September 28, 2016 Share Posted September 28, 2016 Those chargers seem to have been the subject of a safety recall. Geoff Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 28, 2016 Share Posted September 28, 2016 I've always been a bit dubious over dual purpose NiMH and NiCd chargers that are supposed to autosense which battery they are charging. Many years ago, I made the mistake of putting a battery on charge "just in case" as I couldn't remember if I'd used it a few days before. The next morning, the battery was in a very deranged state - luckily without having set fire to the model - and I've always presumed that it had decided I was charging a 5 cell pack and carried on pumping in 1A all night until the cells ruptured. Quote Link to comment Share on other sites More sharing options...
Former Member Posted September 28, 2016 Share Posted September 28, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted September 28, 2016 Share Posted September 28, 2016 hello George/welcome from me.....sorry to hear your tale......you'll be fortunate to get a reply from ripmax...i'm still waiting for a reply from a general enquiry some 18 moths ago....I've heard/read others are in the same boat..still waiting... ken Anderson...ne...1 ....same boat dept... Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 28, 2016 Share Posted September 28, 2016 It's a big boat... Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted September 28, 2016 Share Posted September 28, 2016 I too have had problems with peak detect chargers not stopping when they should and recently posted a thread on the subject. 600mA would sound reasonable to me for a fastish charge and the charger should have no problem in detecting the peak provided that it is set for the correct type of cells. A charge rate set too low could cause a problem as I found out to my cost. Tried a consumer cell type charger for rechargeable batteries (eneloop 1900) for a Tx which can use dry cells and this refused to stop. They got quite hot but were OK. Best advice is to get a reputable charger. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted September 29, 2016 Share Posted September 29, 2016 Lucky escape! Nimh and peak detect and a cheap fast charger = not a good mix. Nimh fast charge ideally needs a temperature probe which responds to a negative temperature changes as well as a maximum temperature, peak voltage detection (and far more sensitive than nicd), negative voltage change detection, and a timeout for the fast charge (which means the charger needs to know the size of the pack). Or, trickle charge them at 5% of C for 24 hours. There was a lot to be said for the robustness of nicd. "600mA would sound reasonable to me for a fastish charge and the charger should have no problem in detecting the peak provided that it is set for the correct type of cells" 600mA charge rate into a 1100mAh pack is almost the worst rate to use on nimh. The voltage peak is very weak at this charge rate. A full 1100mAh charge rate would be better. Edited By SuperNash on 29/09/2016 13:26:10 Quote Link to comment Share on other sites More sharing options...
Tony Read 2 Posted September 29, 2016 Share Posted September 29, 2016 So is charging at 50% capacity of nicds ok? I do this on a couple that are still going strong and have not had a problem. if so, what makes nimh's different in this respect? Really interested to know. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted September 29, 2016 Share Posted September 29, 2016 Tony Most any rate is ok with nicd. They're tough as boots and easy to deal with, in an electronic sense, for the charger. The difference is with the peak detection stuff, which fast chargers use as the first (and sometimes only) method of sensing when the battery is full. On a nicd, when you go to "only just past full", the cell voltage drops quite fast, but with a nimh, the voltage drop is much slower. The result of this, is the nimh charger has to be more sensitive to this voltage drop. This of course originally meant a bit more developed circuit with more & better components and a bit more cost. Manufacturers looking to make a budget charger would have had a sketchy peak detection (which brings the risk of overcharging). These days, cheap chargers just use a controller chip - the chip has to be set up right though, again, something you'd trust is done with a reputable charger, possibly not with a cheap one. The voltage thing is best explained with a picture (see http://www.mpoweruk.com/chargers.htm) , note the difference between the blue and green curves: Nimh will show a bigger peak drop with higher rate charges (~ 1C). But a slower (~0.5 C) rate gives a very subtle drop - bad news if your peak detection is a bit borderline. As Martin said, best advice, get a reputable charger. Quote Link to comment Share on other sites More sharing options...
Tony Read 2 Posted September 30, 2016 Share Posted September 30, 2016 Very helpful. Much appreciated. Quote Link to comment Share on other sites More sharing options...
rcaddict Posted September 30, 2016 Share Posted September 30, 2016 Ive noticed that with ripmax emails - they are very selective which ones they answer Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted September 30, 2016 Share Posted September 30, 2016 Posted by oldgit on 30/09/2016 13:54:46: Ive noticed that with ripmax emails - they are very selective which ones they answer .. they must be super selective..i was wanting to buy something... ken anderson..ne...1....... audit/purchasing dept. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted September 30, 2016 Share Posted September 30, 2016 Ken, have come to the conclusion I would not like you as an enemy. don fry..ne...1....... avoiding enemies dept. Quote Link to comment Share on other sites More sharing options...
gangster Posted September 30, 2016 Share Posted September 30, 2016 Best advice is to get a reputable charger. Yes but many would say that Futaba is a reputable manufacturer. There has been a lot of profound wisdom about charge rates deta peak etc. on this string However this is a bit of consumer equipment supplied by a reputable manufacturer and it would appear that it was used correctly for the correct purpose You should not need to be a bar room electronics expert to charge a toy aeroplane with the manufacturers supplied kit We dont get profound and complicated when we charge our phones etc Something was clearly wrong here Having saidd that Futaba are spectacularly vague about batteries, voltage settings on the 6 and 8 j Quote Link to comment Share on other sites More sharing options...
George R. Vale Posted September 30, 2016 Author Share Posted September 30, 2016 Thanks for all those swift replies. Obviously none of you work at Ripmax Dennis Watkins -- the info. has clearly passed me by, ISTM suppliers should be shouting it a bit louder. Taking batteries out of models on a regular basis would be impractical for most of us though. Geoff Sleath -- You're right, there's a whole list of Futaba chargers that have been recalled and I've got two of the damn things. I'm appalled that Ripmax couldn't be bothered simply e-mail me to return the charger. Others --`cheap charger' etc. -- so where should I get a better charger than the manufacturer's own, to charge 5-cell Tx and 4-cell Rx? I bought the only one I could find listed and this is what happens. I never wanted a fast charger anyway! Quote Link to comment Share on other sites More sharing options...
Don Fry Posted September 30, 2016 Share Posted September 30, 2016 In my view, a charger gives electrons in, out, can cycle a battery, and can do as asked. The batteries as supplied by maunfacturers, or others are unproven, and suspect. Best tested before flight, by a proper charger. And it is not as supplied by the manfacturer. In other words, spend a few quid. And in all fairness, a Nimh should not be hot. That is a clue you are doing the equivalent of hitting a dog with a wrecking bar. Wisdom is having a profound believe that you are being fed marketing lies. I tell the truth. Quote Link to comment Share on other sites More sharing options...
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