Lipo alternative ideas?

[kfxguy]

18650s for minis and 26650s for full size classes are in the naviga rule book, as an alternative to LiPos. They are not LiPo they are LiFePo4 so have a lower voltage than LiPo they are also heavier for the power or the weight, but they are a much more robust cell, less suseptable to overdisharging, with a high cycle life, and the chemistry doesnt like burning as much. There are now rectangular LiPo like packs LiFePo4 packs that are robuster than LiPos without the weight and form factor penalty of the metal case.

The originals are A123 cells the 26650s had a very high power density at the time and 3s2p 26650, was roughly equivalent to the 2s 5000mAh we got with 280g 6 or 7 yerars ago, a little more power, but with a chunk more weight, they were pretty popular, the 3s 1100mAh 18650, was never really competitive with 110g of LiPo for minis which was 2s 1800mAh at the time,but things have moved on a lot for LiPos and they have been outclassed, now for the same 280g we have 50% more energy, I haven't seen an 18650 or 26650 pack being used for many years. Although they hasve been cloned a lot since I last used them, most offer higher energy density but less power density, for torches and laptops etc, I havent heard of any with more power density than A123s, which are a genuine constant 30A for 18650 and 50A for 26650. The best way to buy 26650s was as a twin pack of dewalt 32v(Europe) or 36v(USA) batteries, which contain 10 A123 cells each, for the same price as 10 loose cells from A123. The typical 2000+mAh 18650 is only good for about 5A continous before the voltage drops to the same level.

I still have mine, and they will never go back in a boat. I really must get around to stripping them out of their 3s packs and making a 4s5p lightweight car battery from them.

Good info Paul. Thx

[Hydrocarbon82]

18650s for minis and 26650s for full size classes are in the naviga rule book, as an alternative to LiPos. They are not LiPo they are LiFePo4 so have a lower voltage than LiPo they are also heavier for the power or the weight, but they are a much more robust cell, less suseptable to overdisharging, with a high cycle life, and the chemistry doesnt like burning as much. There are now rectangular LiPo like packs LiFePo4 packs that are robuster than LiPos without the weight and form factor penalty of the metal case.

The problem is 98% of normal 18650's are not LiFe, they're LiNiMnCoO2 and similar (INR, IMR, etc). Their full resting voltage is 4.2v, but their min voltage is a bit lower than normal Lipo. It actually takes a considerable low voltage to damage, let alone kill them. I worked at a retailer selling/returning/repairing the common hand tools using 18650's, specifically less-safe chemistries than today, and NEVER saw one returned from leaking - let alone fire/smoke/etc. I have a pile from salvaging junk batteries where just 1 cell was unbalanced.

With Tesla opening their own battery factory soon, we'll likely see more advancements & cheaper prices soon.They're going with 26650's iirc, 30% more capacity for a given volume, so other companies may start matching that. Also all their previous suppliers will have unused assembly lines. Some of the best 18650's are in the 30A continuous range, and just 5 years ago it wasn't much over 10A. In 5 more we'll probably see much better Li-Ion cells as well as much more robust LiPo cells.

[kfxguy]

Well the 26650 in the configuration would hold up in amp draw but they might be a little too big. I don't have anything on hand that takes those so I may order a couple to see if they would fit in my application. I don't think they will. Evacuee Thea that I need them to fit in is 1.840" wide and two batteries wide would be around 2". I could always just see if the 18650 would hack it. Kinda be an expensive experiment if they didn't. I'd like to compare back to back runs between the 18650 vs lipos I have already. This still might be a viable safe option for recovery boats and low speed play stuff.

[srislash]

I've read about a few possible improved technologies but haven't seen anything yet. Guess it's going to be a little while longer. I was contemplating contacting one of the companies to see if they would be interested in letting someone test them in the real world.

I've been thinking of doing same. Was thinking of reaching out to Revo since their stock seems to be dwindling and not replenishing as of late. Are they working on something??

[kfxguy]

I've been thinking of doing same. Was thinking of reaching out to Revo since their stock seems to be dwindling and not replenishing as of late. Are they working on something??

I don't know. I'm agitated at them right now.

[CraigP]

Yes, we need more options... But I would need to see cylinder cells have IR's no higher than 5milliohm. I haven't seen anything near this so far. The lower the IR, the higher the C-Rate and manage heat better.

[Hydrocarbon82]

It could be a solution for 20-30A boats, I have tried my 20A cells, Samsung 25R 2500mAh (used in most Milwaukee brand "Fuel" batteries), on my Axial crawler that pulls ~15A w/30A peak no prob. I normally use these in a ~20A 3S brushed application with much higher peak. I soldered flat nickel strips/tabs onto them and added a balance plug, so I just charge them like my lipo's. 0.5C is ideal for life and 1.5C max. 4.2v max, 2.5v min for these cells, 20A continuous & 100A max <1sec burst.

DO NOT BUY any battery with the words ULTRA or FIRE in the name. Only buy Samsung, LG, or Sony where user reviews show pics of capacity tests. There are tons of re-wrapped fakes, even tiny 10mm cells put inside an 18mm case & the rest filled with sand. The last test I saw was for a 9000mAh 18650 and it only held ~450mAh. Gearbest seems to be one of the better places for cheap, genuine cells.

[CraigP]

Great info, thanks!

[kfxguy]

Thanks!

[kfxguy]

I'm going to start a new thread about a different lipo manufacturer that I came across that I didn't know about, to see if anyone else has run them.....

[Peter A]

[kfxguy]

Well.....after doing a search it seems as if a few people have tried the batteries I had in mind. I had known that tp power was selling batteries but last I checked they didn't have anything I was interested in. Now they have a huge selection now but after reading it seems as if Revos are ahead of them power wise. But that was two years ago. They may have improved by now. I think I'm still gonna give them a shot. Maybe they won't puff just sitting there on storage charge being brang new.

[Peter A]

I have to say that the Revo Go packs do not seem to deliver any better than my 3 year old 427's. The IR's on them are also higher on most cells. To be fair the Turnigy blue 40C packs are still pretty reliable and cost effective, just a slow boat from Aussie to get them if they are in stock. It is real hard to get any decent lipos in NZ due to shipping restrictions, and those that are retailed here...moonbeams. Example, a 6s 5000 mah 60C dinogy $235 (NZ$) The Revo Go packs $195.
It makes it real hard to make FE viable against a 26cc zenoah for $340, boaters here would rather burn dinosaurs. Funny though how they will spend $7-800 on a mod motor though (or several motors)!