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Welded Battery Pack for DX6i


Simon Roberts
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Well obviously it is not correct for me to dispute a particular clubs policy - but this does seem a bit OTT. BMFA guidelines suggest that using dry cell /spring loaded contact battery boxes in airborne radio equipment is not a good idea, but in a Tx - I see no issues really.
As for a dry cell leaking and catching fire - I would love to see the evidence of that one.
I wonder just how particular they are with everyones models and their power supplies.... such as checking for black wire disease and gummed up switches, poor wiring, ancient NiCDs etc etc.
To my mind there are FAR greater risks in certain models in every club, than this one.
You would need to get a flat pack style battery and solder on the correct connectors, and somehow remove the spring contacts off the original battery bay etc.
I should have thought that this will certinly void any waranty etc.
I'm sorry, but I just think this is a bummer
 

Edited By Timbo - Moderator on 28/04/2009 17:50:04

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I actually agree with the model club about this.
 
My experience of loose cells is that non welded cells are a disaster as the contact between the batteries & the holder deteriorates & eventually you loose power. My TV remote does exactly the same & I bet yours does too.
 
I can understand that where dry cells are used in this fairly high load application the batteries are changed frequently & that this reduces the problem but with nicads that are left in place to be recharged disaster is not far away.
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I agree with Timbo, this does seem to be knowledge of part of a BMFA recommendation being applied in the wrong place.

I use a DX6i with rechargeable individual cells, I've left it on by accident overnight and they were still working many hours later, so it is not a high load.

If there ever was any problem with contact resistance, then this would eventually start to show with a low battery alarm, and you wouldn't fly with that going off anyway.

The welded pack recommendadtion is for packs in a vibrating airframe surely?
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The current drain on the DX6i is remarkably low. 

I measured just 87 m/a consumption - even after fitting the power indicator display, as described in my piece about modding the unit - compare this to the DX7 which is 280 m/a ( with the standard linear regulator ) and I reckon you are good for many many hours of flying with the DX6i.

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Sorry I did not mean high load but rather batteries that are changed relatively frequently - say monthly. It was meant to highlight the difference with the TV remote example I used where the batteries can last 12 months or more but with which I ALWAYS find that bad contacts set in before the battery is flattened.
 
Over 30 years many of the radio problems that I have seen have been traced to the power packs of transmitters & receivers. Those with loose cells have a lot more contacts to fail than those with welded packs & this, in my experience, does make them more prone to failure.
 
Personally I would not fly with loose cells but that is my choice.  
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Here's a blast from the past. Many years ago, when I was a lad, and cars were nowhere near as reliable as they are today, the motor maintenance magazines used to advise cleaning the battery contacts before winter, and coating them with vaseline (petroleum jelly for international readers).
This seems to be very effective at keeping corrosion at bay, and I still use it on all battery terminals and charger terminals.
Just a word of warning - use a smear, not a blob.
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But this was only really necessary due to rather harsh environment and chemicals involve - it was not unknown for battery acid to be splashing around the place, and the terminals also suffered from wet and dry conditions, vibrations, and so on. Thsi is hardly the case with out Tx batteries!
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Well i made a battery pack myself from a Futaba Rx battery pack, removed the wire and the shrink wrap and made some contacts on the pack to connect to the + and - terminals in the back of the Dx6i, All works perfectly and can be charged at the field if needs be.
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  • 2 years later...
i use 4 AA rechargeable batterys and when fully chaged they give 6volts on a big charge and 5.6volts normally in 2 years never had a problem so why 5 AAA smaller more joints dont make sence
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Whilst I accept that my TV remote's batteries often need a twirl, I must say I wonder, despite Hamish's experience, about the likelihood of an in-use failure in a transmitter.
 
I would think it more likely that a failure would occur on switch on before any current is flowing and not once the fairly steady discharge has been established.
 
I did acquire a DX6i recently but it's my intent only to use it for indoor flying and the batteries will probably remain untouched for fairly long periods so perhaps I'll find out the (not particularly) hard way whether my supposition is right!
 
Dry cells for airborne packs subject to vibrations are a definite no-no though.
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Just to elaborate a bit on my experience, if I can recall, the display started flashing and then went blank. Had I the presence of mind I could have "twirlled" the batteries and regained control. As it was I retrieved the model about 1 mile away and it had come down on a barn roof and slid to the ground only breaking part of the wing which was easily repaired.

In addition I had a keycam fitted and it was very interesting to follow its very stable flight, although I do not wish to repeat the event.
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Posted by Hamish on 08/11/2011 23:41:51:
Just to elaborate a bit on my experience, if I can recall, the display started flashing and then went blank. Had I the presence of mind I could have "twirlled" the batteries and regained control. As it was I retrieved the model about 1 mile away and it had come down on a barn roof and slid to the ground only breaking part of the wing which was easily repaired.

In addition I had a keycam fitted and it was very interesting to follow its very stable flight, although I do not wish to repeat the event.
 
My DX6i batteries have yet to run down but a flashing display suggests to me that a low voltage might have been experienced. Did you try some extended testing with the same batteries after the incident or just take them out and try them again for a short time?
 
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The Blackburn clubs diktat does seem a bit harsh but if you saw where they fly you would probably understand their caution (paranoia..!!??) It really is right in the middle of a country park frequented by the public.....pretty much surrounded by football pitches etc.
 
I am amazed they are allowed (or indeed want) to fly there at all really.......I have seen a model have to abort a landing because a dog ran across the strip.....rapidly followed by his owner trying to get the pooch back on his lead.....
 
Amazingly they fly the odd model jet too........
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