LiPo - LiIon Battery Swap

[Hunka Hunka Burning Love]

I've seen a couple of people swapping out their 18650 cell packs for LiPo ones.  How safe would doing this be?  It appears that they give a bit longer range?  I snuck a peek in the Finnish Local Meet thread using Google Chrome Translate, and I found this photo of a Gotway MCM4 HS.  I think EUC Extreme uses LiPo packs as well.

I believe that's a 4S 14.4V 10000 mAh Turnigy power pack used in remote helicopters most commonly.  In series you get 28.8 V so how does one bump up the voltage to the 60-67 volts needed for these EUCs?  Maybe there's two more packs on the other side making it 57.6V, but is that enough?  It sounds like you get a lot more range with these packs, but are there any dangers due to the different chemistry and properties of LiPo vs LiIon?   The price is about $60 per pack so four would cost $240 total which isn't too bad in cost.

Okay you Finns - give us your secrets!!!

 

[HEC]

1 hour ago, HunkaHunkaBurningLove said:

I snuck a peek in I believe that's a 4S 14.4V 10000 mAh Turnigy power pack used in remote helicopters most commonly.  In series you get 28.8 V so how does one bump up the voltage to the 60-67 volts needed for these EUCs?  Maybe there's two more packs on the other side making it 57.6V, but is that enough?

It's rated at 14.4V for RC models purpose which is 3.6v per cell but actually fully charged they will be 4.2 - 4.25V per cell so four of those will give you required 67.2 - 68 V. They have also a good 10C rating which means at their capacity the set can provide continuous current of 100A!!

The main "disadvantage" is that to keep those in a good shape you'll need to use a good balance charger. But you can charge those at 10A or more (if your charger is capable of such currents) so you can be ready to go really soon. With to sets two swap you can double the range or decrease the "downtimes" between charges,

[US69]

The 14,4 are just 4 * 3,7 Volt in series....which each cell also going to 4,2 Volt when full loaded and a range of about  3,3 to 4,2 exactly like our 18650 cell....

So 4 packs of this nominal 14,4 Volt cell is exactly the same as one 16Seriell 1p Pack of 18650....

 

But this 18650 pack of 16s1p Pack can have a max of 3500mah means 16 * 3,7 * 3500 = 207watthour max, which has to be compared to this LiPo with 4 * 4 * 3,7 * 10000mah = 592wh!!!Watthour

So this is massive more...but the MVM4 is fully packed with this also......and with 18650 you (could) get it to a max of 828wh.....( 2 * 414wh on each side)

 

The Advantage of this LiPo Pack is the max load (draw)factor o 10C = 100Amp....but in the end i would compare it with a 680wh of 18650 pack???.....

 

And: You Need Special chargers for LiPo's !!!

And: They can be very dangerous when they got a damage.....and and and.......

 

[esaj]

AFAIK, LiPos uses similar lithium-chemistries than the "standard" 18650-cells, but due to different structure, the internal resistance can be made far lower, thus they're capable of delivering much more current. As already mentioned, the downsides are that they don't have any BMSs, so you need a separate balancing charger. Also, they can get damaged much more easily than metal-covered 18650's.

I've made a little bit of research into the RC LiPos, and what I found out (from some guy who used to sell them) is that the big manufacturers decline to touch RC LiPo manufacturing with a yard long stick (apparently they want to concentrate on laptop and mobile phone LiPo-batteries?), instead, all of them are built by a handful (about 20 or so) of smaller factories in China, with much less precise manufacturing precision than the large manufacturers, and thus the quality can change a lot between batches. So although there are lots and lots of different LiPo-packs (ie. names), basically most of them come from the same sources (for example, I have a hardcased 5500mAh / 11.1V / 3S -pack on my desk that says "X-Power", but is manufactured by Shenzhen Vigor Battery Co, which sells lots of different LiPos under different names). The guy also later found out that one of the factories they had ordered the packs from had also sold the defect ones they had returned under a different brand name, although they had been told that the packs were going to be destroyed

EDIT: I don't know for sure, but I think the "big names" in RC -world (like Turnigy) do test the batteries themselves and weed out any defect ones, so probably buying a known brand name RC Lipos is relatively safe though?

[Pingouin]

Hi,

You normally should need another charger, or the batteries will never be fully charged.

I would not recommande Turnigy packs, I have been in RC world for over 15 years (including acrobatic Rc helis), and you should go for quality lipos, Turnigy tends to loose 20% of their capacity in 50-100 cycles...

You should not need any "30+C" discharge rated batteries, they will be heavier, and they are for extreme use purposes, like acrobatic RC aircrafts which can drain more than 200A in peaks.

For good batteries, look for "Thunder Power", "Hyperion", "Kypom" etc