A Question on Softpack LiPos

[Captain Courageous]

Hello,

 

I hope this makes some kind of sense.

 

I have a new transmitter (Flysky FS-IT3B) which takes EIGHT AA batteries.

 

There are a few YouTube videos where you take out the AA battery holder and replace it with a 3S LiPo battery pack.

 

The space inside is limited not so much by the length or width but the height - only around 18mm - and most LiPo packs are thicker than this.

 

My question is this.  Is it safe (taking all due precautions that is) to open up a softpack and "unfold" the cells so that I can fit a larger capacity pack in.

 

I could then re-wrap in appropriate heat-shrink.

 

The YouTube vides show a 2500mAh 3S pack being fitted, the largest I can find from a UK supplier that meets the 18mm thickness criterion is 1000mAh.

 

Or, for transmitter use, is a 1000mAh pack good enough?

 

CC

[Tug]

That's probably enough, transmitters don't use that much power. At the risk of wasting cash, try the 1000 first and see how you get on?

 

Unfolding packs could have risks with tabs touching each other? I'm not sure, but I'm sure someone else on here will have a better idea. 

[locky]

Overlander may have one that fits https://www.overlander.co.uk/lipo-batteries/11-1v-3s.html

https://www.overlander.co.uk/lipo-batteries/11-1v-3s/2700mah-11-1v-3s-35c-supersport-pro-lipo-battery.html

 

I'm sure that you will find one of suitable size and capacity, just need to spend time searching. I wouldnt risk stripping a lipo pack. The cell tabs arent that robust.

[Captain Courageous]

13 minutes ago, Tug said:

That's probably enough, transmitters don't use that much power. At the risk of wasting cash, try the 1000 first and see how you get on?

 

Unfolding packs could have risks with tabs touching each other? I'm not sure, but I'm sure someone else on here will have a better idea. 

Hi Tug,

 

That's what I was thinking.

 

Used it last race meeting but didn't finish the session after I ripped a corner off the car after a 'slight tussle' with another car!

 

I then took the LiPo down to storage charge after the meeting and forgot to look at how much it had dropped during the session.

 

Here's a pic of it in situ.

 

 

CC 

[Captain Courageous]

10 minutes ago, locky said:

Overlander may have one that fits https://www.overlander.co.uk/lipo-batteries/11-1v-3s.html

https://www.overlander.co.uk/lipo-batteries/11-1v-3s/2700mah-11-1v-3s-35c-supersport-pro-lipo-battery.html

 

I'm sure that you will find one of suitable size and capacity, just need to spend time searching. I wouldnt risk stripping a lipo pack. The cell tabs arent that robust.

Hi Locky,

 

Thanks for the post.

 

That 2700 looks tasty, but it is too long.  I said that space isn't really limited by length or width but thickness.  The 2700 is 16mm thick according to to specs but 133mm is just slightly too long.

 

The available space in the battery compartment is just 110mm long (and for the record, 59mm wide).

 

I bought the Overlander 1000mAh and that fits in fine - there's acres of space however, so needs some foam padding (see my previous post for picture).

 

CC

Edited November 11, 2023 by Captain Courageous

[locky]

Plenty capacity https://www.aliexpress.com/item/1005002332883373.html

[locky]

Alkaline AA cells are about 2500mah. I've used rechargeable nimh 2000-2500mah in gt3b/gt3c tx without issues. Using one lipo cell is simpler for recharging, but I'm using rechargeable AAs elsewhere so always some charged at hand. You will need to have a low voltage alarm for lipo to prevent excessive discharging. An alternative to lipo are life batteries. I use them for nitro receiver packs.

[Nitroholic]

https://www.fingertechrobotics.com/proddetail.php?prod=T-3S-1450

 

I've always used Turnigy transmitter packs like the one above. Thats not where I got them...just the first link I found.

Edited November 11, 2023 by Nitroholic

[Captain Courageous]

On 11/11/2023 at 13:18, locky said:

Plenty capacity https://www.aliexpress.com/item/1005002332883373.html

 

Thanks once again Locky.

 

Looks like it just fits inside the Flysky FS-GT3B (which is identical to the FS-IT3B which I have - the only exception being that the GT3B uses the AFHDS protocol and the IT3B the AFHDS-2A protocol).

 

3500mAh is overkill however for a Tx.  I'd prefer something like 1500mAh or so but haven't been able to find one in my searches.

 

That Aliexpress link has however allowed me to search there (never used Aliexpress before - are they okay?)

 

On 11/11/2023 at 17:06, Nitroholic said:

https://www.fingertechrobotics.com/proddetail.php?prod=T-3S-1450

 

I've always used Turnigy transmitter packs like the one above. Thats not where I got them...just the first link I found.

 

That's the kind of thing I was looking for but 22.60 Euro (plus S&H I guess) means a tad expensive.

 

Thanks for the link however.

 

CC

[Captain Courageous]

On 11/11/2023 at 14:09, locky said:

Alkaline AA cells are about 2500mah. I've used rechargeable nimh 2000-2500mah in gt3b/gt3c tx without issues. Using one lipo cell is simpler for recharging, but I'm using rechargeable AAs elsewhere so always some charged at hand. You will need to have a low voltage alarm for lipo to prevent excessive discharging. An alternative to lipo are life batteries. I use them for nitro receiver packs.

Only problem with rechargeable NiMH AA batteries is that 8 x 1.2V = 9.6V not the 12V that the transmitter wants.

 

I tried that with some Fujimax NiMH 2800's that I had but the Tx was soon shouting that the voltage was too low.

 

That's why, I guess, people have been fitting 3S Lipos which, when fully charged, give 11.4V

 

CC

[locky]

Forgot to mention I replaced the voltage regulator which means it operates to lower voltages with nimh and added custom firmware. Just came a cross this thread...https://www.tamiyaclub.com/forum/index.php?/topic/100554-fly-sky-fsgt3b-v20/

[wolfie1]

Unless you use rechargeable aa lithium batteries they produce 1.5 volts each, i have some for my traxxax tx and so far so good

[Lone-wolf]

The very best idea is what i did to my GT3b i made a 12v 3000mah Li-Ion rechargeable pack using 3 18650 cells cost was about £15, the thing with a lipo it needs to be at storage  when not in use, then you get a chance to go out and play and lipo needs charging, the Li-Ion likes to be left with plenty of charge in it, so i charge mine about 4 times a year

[JonnyUK]

Not sure if it helps but I have an absima transmitter and I use one of these 2s lipo packs.

Designed for transmitters and have an auto low voltage cut off. I never put them into storage mode (don't have a charger to do this) and they haven't puffed up.

They are available with a couple of different plugs fitted.

Stock radio is 4x 1.5v but works fine with the higher voltage. 

I would check what the max voltage allowed is though before you go higher.

[Captain Courageous]

@Lone-wolf That looks to be a great idea!  Stupidly, I didn't think of fabricating my own (which is something I used to do with the old 1.2V NiMH packs - I'd buy a shrink-wrapped 'stick' pack, open it up and rearrange the cells because most stick packs were two rows of cells end-to end  in a 2 x 3 arrangement whereas my chassis needed 6 cells in a 1 x 6 side-by-side arrangement.

 

Off now to research individual Li-ion cells (are they more forgiving on storage than Li-Pos)

 

I'll have to reasearch but does '18650' refer to the size of battery (like 'Sub C or AA and the like) or is it specific to the 3000mAh capacity?

 

Addendum:  A 18650 Battery is a lithium-ion rechargeable battery.  The first 4 digits of the designation “18650” indicate the physical dimensions while the 5^th digit indicates it is a cylinder cell.  The standard 18650 battery is approximately 18mm diameter by 65mm in length.

 

There are also 16500 / 17500 / 17650 / 17670 cells which are 16mm and 17mm in diameter and variously 5cm / 6.5cm and 6.7cm long - but prices are horrendous!

 

For example, I have found (on Amazon) a 4-pack of the 16500 cells but the price is £28 (or £7/cell).  I'll stick with the 1000mAh 3S ovelander pack for £14!

 

@JonnyUK Sadly that pack isn't suitable as the Flysky FS-GT3B / FS-IT3B requires 12V and isn't too happy below around 9V as far as I can gather.

 

A 2S, 7.4V pack is probably just too low a voltage.

 

CC

Edited November 24, 2023 by Captain Courageous