What batteries are you using?

... and the compress/not compress (fixture) topic is controversial!

But if I decide to do it, then thinking about using an airbag like solution (with an air bag door wedge e.g.?)

Gute Air Shim, Air Wedge Bag Pump, 3 Pack Commercial Inflatable Air Wedge Pump Bag Tool, Professional Leveling Kit & Alignment Tool, Air Bag Removal Tool for Variety of Jobs, 330 LB Rating, 3 Sizes https://www.amazon.com/dp/B09NLY62RT/ref=cm_sw_r_awdo_navT_g_GM5TKQX6SX0HEXZZWZ3T

with a shrader valve and a Fox Air Shock hand pump like this e.g.:
www.ebay.com

FOX SUSPENSION AIR PUMP WITH GAUGE 300 PSI ALL FLOAT 3 EVOL RC2 XMR EVOL R | eBay

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(only the gauge resolution does not really help for 10-14 psi 🤗)
 
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I've seen a few youtube videos where guys "compress" the pouch cells with threaded rods on either sides of the batteries.

I've been thinking a lot about this lately, and if I was to do it again, I'd probably go with the batteries SQCTS found. The benefits outweigh the cons. Even making an explosion proof steel housing would still weigh a lot less, be cheaper and probably cost less.

With varyious testing techniques, I'm kind of getting results all over the map with my LTO cells. But it's looking like for a 63 volt charged pack, my "best case" scenario is only 50 volts at 550 amps. Frankly, I'd like to see a solid 55 volts...

Which begs the obvious question - SQCTS - what brand of batteries are you using again?
 
AlexLTDLX said:
I've seen a few youtube videos where guys "compress" the pouch cells with threaded rods on either sides of the batteries.

I've been thinking a lot about this lately, and if I was to do it again, I'd probably go with the batteries SQCTS found. The benefits outweigh the cons. Even making an explosion proof steel housing would still weigh a lot less, be cheaper and probably cost less.

With varyious testing techniques, I'm kind of getting results all over the map with my LTO cells. But it's looking like for a 63 volt charged pack, my "best case" scenario is only 50 volts at 550 amps. Frankly, I'd like to see a solid 55 volts...

Which begs the obvious question - SQCTS - what brand of batteries are you using again?
Click to expand...
Alex the company is SMC Racing.

Highly Regarded as Top 3 lipos on the market for both RC cars and RC Airplanes. Smaller company but very strict about the quality of his products.
 
I've actually been working on the load tester. Since resistance testers seem to vary a lot (based on the one in my charger showing significant variations under slightly different conditions), a direct load/voltage drop test is probably a more reliable indicator. But I might buy a resistance tester too. I am actually considering going over there at some point in the near future and test their stuff (if they'll let me...)
 
SQCTS said:
Alex the company is SMC Racing.

Highly Regarded as Top 3 lipos on the market for both RC cars and RC Airplanes. Smaller company but very strict about the quality of his products.
Click to expand...
Nice!

But even their baddest packs come with 10 AWG cables (only).

So for us builders we at least need to think about 2-3p just for the cabling (the C rating / IR already seems awesome) pulling those multiple hundreds of amps (not just peaks!).
Has a direct impact on cost as well 😁
 
I just want you to buy one of those AC resistor testers so at least one of your tests is directly comparable to the rest of us with the same test method.
 
MkngStffAwesome said:
I just want you to buy one of those AC resistor testers so at least one of your tests is directly comparable to the rest of us with the same test method.
Click to expand...
I did ... and the values I posted were measured with this one:

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it actually IS a "four line YR1035+" ...
 
MSA (that's what I'm calling you from now on - MkngStffAwesome is too hard to type out) - would you be willing to try something for me? Or anyone that has a resistance tester. Put a Lipo in the fridge - get it down to near freezing. Take a measurement. Then, every so often, as it warms up, take another reading. If you can figure out a safe way to get it up to 120* F (60* C), I'd love to see how it changes.

Also, I'd love to see how batteries change based on state of charge, too.
 
IR will decrease with an increase in temp thats for sure. It would be really interesting by how much though ... But i couldn't bring my self to heat up a lipo ..lol i figure it would need to be heated up for some time to ensure it was heated through.. for me i could see the value in testing from 0c to 60c But LTO since that is what im indenting on using. IM not sure how i could heat it up to 60c... my wife wouldn't be happy with me putting it in the oven
 
Alex i'm going to test the IR of a Lipo, LTO and Lifepo4 at different temps... 27ish 4ish and 65ish.. it will be interesting..
 
I actually looked up temps where you live - it never really gets hot (or cold, for that matter). In fact, I want your weather. My point is you could've just put the cells out in the sun during the summer, but that won't work for you. For me, it would. And if/when I move down to Texas, we could fry them. But yeah, I wouldn't do the oven either.

Actually, I just had a thought - how about a small duct tape/foam insulation box with a 100 watt lightbulb inside? That would be pretty controlled... and those readings would make a great youtube video...
 
so first set of results in

27c
Life 3.77
LTO 0.31
Lipo (4 cells) 14.63

11c
life 3.93
LTO .40
Lipo 23.3

LIfe 4% worse
LTO 29% worse
Lipo 59% worse

Interesting... especially when you consider 11c is not that much cooler than 27!
Will try hotter tomorrow
 
That's great info. Thanks! I went ahead and ordered myself one of those YR1035 meters too. I'll check the A123 cells and the Lishen cells too.
 
I find this extremely interesting.. while i had predicted the change based on temps i had not predicted the difference between the chemistries to be so pronounced..

I currently have them on my 3d printers bed with a cover over them at 65c . We will see.. Early results suggest similar disparity between the chemistries, but now with resistances dropping.

I am also testing with a second batch of batteries to see if the drops are consistent between the chemistries . Lastly i have added a Samsung lion 18650 into the mix out of interest.
 
Right group two of batteries
LTO's and Life are all new cells in both groups

25.5c
Life 2.65
LTO 0.34
Lipo 11.93 (new 5s)
18650 70.2

10c
Life 2.88
LTO .40
Lipo 15.05
18650 76.1

Life 8.6% worse ( This Life was always much better than the other cell )
LTO 17.6% Worse
Lipo 26.1 % worse ( new lipo )
18650 8.4 % worse


Group 1 heating

65ish c
Life 3.70
LTO 0.24
Lipo 10.68

From 27c
Life 1.8 % Better
LTO 22.5% better
Lipo 27 % better

NOTE
Group 1 Lipo was slightly puffed to start with.. After heating it is now puffed thicker than a new 5s .. It is only good for the bin.
This lipo got to this resistance (ish) at a relatively low temp and didn't get much better with continued heating.. i think it just got wreaked instead


Conclusion. RC lipos will get you killed if used in your engine bay.

No heating testing of group 2 batteries because i dont want to weak my new lipo.
 
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Is that a typo in the first LTO reading? I'm guessing it's supposed to be .34, not 34. Those LTOs of yours seem quite good. And the idea of using the 3d printer bed to warm them up is genius. Tell me you're shooting youtube vids of this testing, right? It'd definitely be good fodder for gaining views. I also thought that LTO cells were supposed to be more temperature stable. Maybe because the readings are so low that even a slight difference shows up as a significant percentage?
 
i recon these LTO's are amazing considering there "Small Size" 32145
Im intending on making a video.
LTO's have a wider operating temp, but for resistance i dont see there there is much comparative information in relation to Temp / IR..
Because these have such a low IR to start with it makes a big difference with the rounding.. and as they change it's a bigger percent... HOWEVER the actual resistance value is better than anything else for the LTO's so i guess it depends on how you express your findings..

Group 2


25.5c
Life 2.65
LTO 0.34
Lipo 11.93 (new 5s)
18650 70.2

10c
Life 2.88
LTO .40
Lipo 15.05
18650 76.1

Life = 0.23
LTO = 0.06
Lipo = 3.12
18650 = 5.9

Testing done at nominal voltage.
 
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