Question about energy density.

[Electric Personality]

I noticed these Winston cells: 270 ah weigh 8.9 kg/ cell. https://shop.gwl.eu/Winston-40Ah-200Ah/WB-LYP260AHA-LiFeYPO4-3-2V-260Ah.html
The battery cells from dongguan 280 ah, weigh about 5.3 kg. https://wholesaler.alibaba.com/prod...tml?spm=a2700.icbuShop.25813.2.4adc70eftkzVSa
Presumably, they have the same chemistry.
Why the significant difference?

 

[John Frum]

The packaging as in the yellow stuff
The blue cells are just thin aluminium covered with shrink wrap

 

[BarkingSpider]

One component is the battery construction and casing. Just look at those older BYD LifePO4 boxes that are popular, they are incredibly heavy at over 160lbs, 1/3 of the weight is just the cooling fins, then they are using solid copper and lots of it for interconnections. Then they are wrapped heavily in a type of vinyl. Very high quality and very safe. All of that extra material really adds up. Compare that with a bare 18650 Lion cell that weighs ounces, but can burst into flames easily (as I found out). My bet is the RJ cells are using better and more expensive construction techniques than others.

 

[gnubie]

I've posted this before, but it never hurts to post it again. How badly things can go with unknown quality (ie, are the damaged etc) unprotected lion (not lifepo4) 18650 cells.

 

[BarkingSpider]

You better believe it. Here was my garage in 2017, 1 week after buying some *genuine* 18650 Li-on batteries from Ebay. I nearly lost the whole house. I will only use LifePO4 from now. It took over a year and a ton of money to fix the damage. Luckily no-one was hurt.

 

[Electric Personality]

40% difference in mass is a lot just for the cases....
It is the same chemistry between the batteries, liFePO4.

I need to get rid of a bunch of old rc lipos lying in my garage though...

 

[Raj174]

The chemistry is the same. As smoothJoey said, the difference is in the ABS plastic shell as compared with aluminum. The ABS shell on my 195ah cells weighs 2.5 lbs. I think the 270ah Winston cells would be about 3.3 lbs. of ABS plastic.

 

[Ampster]

I've posted this before, but it never hurts to post it again. How badly things can go with unknown quality

This was more about overcharging that battery than about unknown quality. I have watched a lot of his videos and they admitted they charged it with no High Voltage Disconnect. The charger they used, looked like a fork lift charger. They left it unattended at high amperage. That is a classic way to ignite NMC.