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Big Si

AAA replacment ??

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Big Si

Ok I have a little Blade 1.5DS and I can just get a 5s AAA pack in the nose they are 3 flat with the other 2 flat glued under the 3 in the groves the 3 have

but today up Stretton in the cold a fully charged pack after a15min flight had 1% left in it so how it flew on that I don't know but it did

they are Eneloop PRO 930 mah and new but been used a handful of times and they charge fine and hold what they say they should more in fact so its just the cold killing them as 10 mins in my pocket next to my hand warmer they are 82% which is what I would expect

I cant get anything longer in the front than a AAA so any ideas what I could use instead ?

ideally a lipo would be best but I would also need a voltage reg as well so as that needs to go in the same space as the lipo its not a lot of room so any thoughts ??

Thanks Si  

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f3fman

Have you thought of a Life which is lower voltage than Lipo,  6.6v nominal 7.2 v fresh off the charger

 

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Stormeflyer

Hi Mike

It’s the battery type (Nimh) being susceptible to very fast discharge due to their chemical make up in cold weather, fresh off the charge with only 15minutes flying we both got battery warnings. Mine are brand new quad pack 2500 mah AA’s and faired no better. It’s been an eye opener; especially when you put the load tester on the receiver pack and see the results 😳🤔🤢

I think the way to go for AA’s are 14500 Li-ion and AAA is 10440 Li-ion either with a bec dependant on servo choice if you want like for like due to access.

 

 

image.jpeg

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pete beadle

Hi Stormeflyer

I suppose we're all just plain lucky that it's never cold in the UK!:no:

Why hasn't this potential failure in niMh battery performance been exposed sooner? Most of us, previously using ni-cads for years were perfectly happy with them, but I'm fairly sure several people posted here and on other forms, that niMh's were better all round.....anyone remember why this was?

Or, could this be unintentional fake news?.......I also remember the furore that accompanied the exposure of the fact that all battery checkers had to place a load on the receiver battery to ensure a correct reading and, at the time, some of HK's battery check offerings didn't..... anyone remember that "exposure" either?

Regards

Pete

BARCS1702

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isoaritfirst

I well remember the old GP AA cells falling off a cliff in cold weather, and people losing models as soon as full crow was activated.

I thought eneloops faired better than the old GP's which claimed large capacities at the time but had very poor C rating, that became even worse in cold weather.

 

 

AAA packs have never been a good choice in my experience.

a couple of 18500 or 18650 cells may suit the model, although you would need Voltage regulators if your servos are 4.8 rated

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Stormeflyer

 

Yes I’ve blissfully flown in cold weather without telemetry in the past and didn’t give it a second thought, I used a load tester but only after quite  a few long flights!

The warnings now are when applying crow at the end of a flight.

I wonder how much extra consumption 2.4ghz with telemetry uses compared to my previous still used 35mhz? 

Out of curiosity I’m going to closely monitor my 35mhz models just to see, as I’m not even recharging them during the day.

 

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isoaritfirst

Load warnings during brakes out are fairly common on very cold days and also if you put the brakes out aggressively when heavy and at speed. 
 

 

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Stormeflyer

Hi Mike

Yes I expected that pulling more milliamperes with crow, but when checking with my trusty Hitec load tester I was shocked to see how low a capacity I had, so I recently bought a digital tester advertised for all types of batteries which would give me percentages! 🤔

Only when I received the piece of junk, do I find the instructions to read and weep!
 

“Note the capacity shown for Nicd and Nimh cells is NOT accurate and should NOT be relied upon” 😢

To think I only bought this plastic junk to adorn the Christmas tree next year 😤

So when is a battery checker not a battery checker?..............Answers on a postcard

F990A975-050C-45FB-9A11-C821FA70FD89.jpeg

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Big Si
On ‎13‎/‎02‎/‎2020 at 09:53, isoaritfirst said:

God Mike I would kill for the room you had in yours up front, mine is the DS version so the nose is 35mm shorter so I could not get an AA in even with no nose weight in the nose , I cant get anything longer than a AAA in

Where yous had maybe 85g of lead mine has took over 200g just because mine has a 2 piece tail and its a fair bit more weight than the 1 piece ( god knows why ) they have done that as with the shorter nose as well its really not helping one bit

I have found some 16340 cells 700mah and shorter than a AAA and only a couple of mm wider and they say they work from -40 to +60 so hope they should do the job and also a couple of 18350 (1200mah) same length but 14mm same temps so if they would fit would be great but think 2 of them and a bec might be hard to get in but they will be here later today so will have a play

kinda hope they are a lot more weight than the AAA pack so I can get rid of a bit more lead and make a bit more room

I also think years back we wrapped our batt,s and rx in lots of foam where we don't now and that's 1 part of the problem as my Gulp is made out of that very hard black foam and  has a 4 cell AAA pack in the centre of the fuz and I have flow that on the Orme all day with Kev in very cold weather with no problems what so ever and I think that is why that  keeps the cold out and as its covered in vinyl  no cold gets in where a glass nose cone keeps sod all cold out

could be wrong 😕 

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Big Si

As you can see very little room for much of anything 😞 

blade .15.jpg

blade 1.5.jpg

blade 15.jpg

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satinet
On 13/02/2020 at 16:35, Stormeflyer said:

 

Yes I’ve blissfully flown in cold weather without telemetry in the past and didn’t give it a second thought, I used a load tester but only after quite  a few long flights!

The warnings now are when applying crow at the end of a flight.

I wonder how much extra consumption 2.4ghz with telemetry uses compared to my previous still used 35mhz? 

Out of curiosity I’m going to closely monitor my 35mhz models just to see, as I’m not even recharging them during the day.

 

A telemtry rx uses about 100mah i believe.

Battery testers only test voltage (some under load). The charge state is extrapolated from that info, nothing more. 

Even telemtry rxs show information that is very weather dependent. Cells don't get discharged by cold per se. What you are seeing is an inability of the cell chemistry to deliver the required current due to the effect cold has on the chemical reaction. I.e crow brakes which draw a lot of current. 

The way the cells change when the temperature changes is obviously a problem for us when it gets cold but it works the other way round too. Some chargers won't charge in low temps as a safety feature (e.g power tools). 

Hobby king round lipos might be another option. 

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Big Si

Well I have managed to get 2  x16340 700mah cells in just with 14g of lead the 18350 1200 mah cells just would not fit even with some Dremel work dam them lol

I had to pull the rx out and shove the CC bec there in a piece of foam to keep it centre of the fuz and away from the push rods

then make the leads to size and fit, then shove the rx back in

it just went behind the rx and in front of the front wing bolt . talk about lack of space, man its been a tough build but hope its sorted now and will fly in the cold for more than 15 mins and have more than 1% left so now I just need a good flying day to find out 🙂 

They say the will work from -40 to +60 but I am not going to test that and just take there word for it 😉 

also need to find a home for 2x 18350 cells now

have a Gorgeous New 2 piece wing Toro 1m DLG (Thanks very much Neil ) that I might see if 1 will fit in the nose as think it might just and if so on a 1200 mah cell would get a weekends flying in with out needing a charge LOL

 

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FrankS

I'm running my Mini Blade with a 700 mah 2s LiFe pack, fits easily. Best thing is that they don't lose charge in storage. I have a telemetry Rx (Multiplex) and can fly for hours with no worries.

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SilentPilot

Can you store LiFe fully charged? 

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Big Si
1 hour ago, SilentPilot said:

Can you store LiFe fully charged? 

I store all my cells fully charged and always have even my lipo,s

I have some 5s 3900 mah packs from Hobby King before they were that name and they are still going strong and used very often in a 2M F3A plane

flat or almost flat is in my view the worst way to leave any make of batt

my mate always stores his lipo,s at what they say to store them and he keeps getting a cell go down every now and then so wont be doing that with any of mine  :-/

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wookman

You are getting away with it because you use the packs frequently. I lost a few sets of batteries for my infrequently used F5j keeping them fully charged. The seem to last better now I keep them at storage charge and just charge them fully before I go flying. I put them all back to storage voltage afterwards as it may be months before I use them again.

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SilentPilot

I think, and I’ll only say this quietly because many probably disagree, but I think that LiPo batteries can be kept fully charged so long as you don’t let them get cold.

Optimal storage is ~3.85v and fridge temperature but I won’t put mine in a fridge!

 

(hiding from flak now!) 

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isoaritfirst

LiFe cells like to be kept fully charged 

much easier to manage. 

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FrankS

Only LiFe cell I've managed to damage, was one I accidentally left switched on for 2+ weeks, even then I managed to get some charge into it and now use it for model set ups etc.

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