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Oct 16, 2019, 12:48 PM
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Meatball's Avatar
Great stuff David … keep us informed.

Randy
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Oct 17, 2019, 05:17 PM
DavidsPlanes
doxilia's Avatar
Thread OP
On the heels of my comment regarding open lead-acid batteries, here’s an interesting Reuter’s article on a related subject to the thread:

https://uk.reuters.com/article/us-me...-idUKKBN1WW20U

Personally I think it’s an uphill battle to even consider this as an “option” with the sights firmly set on the transformative SIB technology to come. And that’s not even to touch on the atomic mass of lead!

However, safety will always be key on a mass scale and so long as old tech has it and new one doesn’t, the former will not fall out of favour.

The funny thing is that in winter when my 20 pound lead-acid car battery has no Amps to give me, I boost it with a 1 pound palm sized Li-Ion battery...

Never fails to start!

David

PS Here she is. Used her all day as we (52 thousand to be precise) were out of power for 8 hours today. She’s so versatile (jump start, USB charger, USB charged, flash light) she practically makes coffee!
Last edited by doxilia; Oct 17, 2019 at 05:24 PM.
Oct 18, 2019, 08:29 AM
AndyKunz's Avatar
Most likely your telephone system continued to operate just fine. Pb-based cells are the primary power backup for phone systems, both cellular and land lines. Even pole-mounted systems exposed to the elements use Pb. The battery sits on a heating tray (a sheet of PCB material with a long, waving line etched into the copper) to keep it running.

This is the industry I was in before coming to Horizon.

Andy
Oct 18, 2019, 08:57 AM
DavidsPlanes
doxilia's Avatar
Thread OP
Yup,

Lead batteries are ubiquitous for storage. Cheap, reliable and relatively safe... except for the lead.

Good news is they can be recycled. In fact, if one doesn’t, they charge you! $20 at my local auto store remain for me to pick up when I return my spent car battery recently changed.

We actually have factory installed “engine block” heaters in some cars here in Eastern Canada as I’m sure you do in some states as well. Unfortunately my Japanese manufactured vehicle doesn’t have one. Cranking cars (most of them) in sub -20C temperatures in January and February is often a problem. Rumour has it SIB’s won’t have this limitation.

We’ll see...

David
Oct 19, 2019, 04:21 AM
Bo Edstrom, Sweden
Quote:
Originally Posted by RC Man
Today's LiPo batteries have much better longevity than the old ones and the price has come way down. Once the trade war is over the prices will go down more. Any new technology is going to have to be reasonably price or most will just keep flying LiPo batteries.
Maybe, maybe not.
I bought 5 cell LiPo packs (2 x 5 cells in series for 10 cell packs) last Year for over 10000 SEK (about $1000) worth and they only lasted last season, this season they did not perform as last year. They could not keep up the voltage on full throttle on powerhungry manouvres (in FAI F3A). I had to buy new this year (about same cost again). That has never happend to me before since I started to fly electric on 2007. At least 3 seasons use for F3A flying has worked before until I have really noticed any degrade in performance from the LiPo packs.
It may be that I got a bad batch but the batteries I use are specifically made for F3A usage, and I do not overload the batteries when flying, and do not take them down to lower then 15-20% capacity at flight. I always storage charge when not in use and during winter stored cold in garage, storaged charged.
Maybe on a more general lever LiPo batteries have been better and can be used longer (more cycles) if taken care of.
But I'm not sure quality is as before.

/Bo
Last edited by bossee; Oct 22, 2019 at 08:13 AM.
Oct 19, 2019, 10:09 AM
DavidsPlanes
doxilia's Avatar
Thread OP
Well, certainly liquid (LiFe) and gel (LiPo) electrolyte research has advanced in the years since we’ve been using Li-Ion batteries. They’ve increased the conductivity of the cells and allowed higher potential (and thus charge) to be achieved. This has led to the production of the so called HV cells we now have.

However, these same modern electrolyte solution additives apparently are the cause for higher cathode (positive electrode) corrosion rates and resulting formation of dendrites. The corrosion in particular is responsible for the potential loss (and charge capacity) of the cells as it results in failure to return sufficient ions back to the anode upon charge. The drop in capacity and voltage results in a battery with diminished power in fewer cycles than LiPo’s with older more conservative electrolytes.

The rationale presumably is that customers want “modern tech” HV cells at comparable cost to their predecessors. It is possible to also purchase “low cost” batteries today compared to 10 years ago. As customers we naturally gravitate to the “more punch, lower cost” concept without necessarily wondering what the TCO of such purchases may be.

Solid state electrolyte cells (Li, Na or otherwise) promise to avoid these levels of corrosion and prevent shorts so that’s the good news. As mentioned before, on a micro scale, SIB’s have exhibited stable charge voltage in experiments where the cell is cycled in excess of 23K times!!

For all intensive purposes, that’s a lifetime. Not a batteries but a humans.

David

PS I often read and reply to forum posts using my cell phone as I am now. Curiously, after over 5 years of use and 1-3 daily charges using fast charge rates (10W charger), my cell phone’s battery (purchased September 2014) is still delivering an 86% charge capacity which according to the phone manufacturer implies “peak performance”. Evidently some batteries last longer than others.
Last edited by doxilia; Oct 19, 2019 at 10:33 AM.
Oct 19, 2019, 12:20 PM
DavidsPlanes
doxilia's Avatar
Thread OP
Today’s news on the topic:

Alternative chemistry solid state electrolyte “mass scale” (storage, EV’s) low cost, safe, high capacity technology announced using Lithium-Sulphur (Li-S) and Lithium-Selenium (Li-Se) liquid electrodes. This is true “reverse” engineering!

Named SELL-S and SELL-Se batteries, here’s the article I first came across in Spanish:

https://www.hibridosyelectricos.com/...505030899.html

Here’s an equivalent press release in English:

https://www.greencarcongress.com/201...1016-sell.html

David
Last edited by doxilia; Oct 19, 2019 at 01:42 PM.
Oct 21, 2019, 04:12 PM
I just want to go fly!
walter3rd's Avatar
Just to clarify.... can I store my lipos in the garage over a long cold winter? All my batteries are always stored at storage charge. Thanks. I have been keeping them in the house. Is lower temps better for storage? Thanks
Oct 21, 2019, 11:55 PM
DavidsPlanes
doxilia's Avatar
Thread OP
Walt,

In principle lower temperatures make the batteries less reactive so also safer. The problem with storing them at say 0C is that they can condense when brought back to room temperature (22C). Condensation inside a LiPo battery is very dangerous and can lead to a fire. Because of this it is often recommended that LiPo’s be stored in a fire proof bag or box at room temperature or a few degrees below (5-15C).

David
Last edited by doxilia; Oct 22, 2019 at 12:53 PM.
Oct 22, 2019, 06:19 AM
Registered User
Have to disagree there, a few degrees above zero is optimum for battery life.
Oct 22, 2019, 08:01 AM
A man with too many toys
I have always been told that storing at 1/2 charge makes them much safer. You only need a fire save container when charging. I have heard that storing inside a refrigerator for the winter extends the life. I use to do that but not the last couple of years and I have not noticed any difference.

I think there is a lot of incorrect information circulating when it comes to LiPo batteries.

.
Oct 22, 2019, 08:18 AM
Oxford Panic
AndyOne's Avatar
Original data from Sony who were pioneers in Li-Ion chemistry* is, the lower state of charge and the lower the temperature they are stored at increases the charge retention of the cell.
State of charge must obviously be above the minimum voltage of 2.5 to 3 volts per cell depending on the exact make up of the electrodes.
*Same chemistry as in Li-Po

A.
Oct 22, 2019, 08:18 AM
Bo Edstrom, Sweden
Brand new LiPo batteries are nowadays charged tp only 30% capacity when shipped. At least the LiPo I have received lately has that capacity level when they arrive to me.
I think it should be OK to storage charge LiPo to 30% capacity without any harm to the cells. It is less eneregy in the battery pack then also and that is good for storage safety (fire hazard).

/Bo
Last edited by bossee; Oct 24, 2019 at 04:08 PM.
Oct 22, 2019, 09:29 AM
Oxford Panic
AndyOne's Avatar
Quote:
Originally Posted by SuperNash
...
Either way it sounds a few years from mass production cells - 5 or 10 years?

This IS the trouble with new battery developments they are always just out of reach of a production solution.


There have been so many announcements over the last couple of decades and where are they now?


A.
Oct 22, 2019, 10:18 AM
DavidsPlanes
doxilia's Avatar
Thread OP
Just getting back to Walt’s question: “can I store them at lower temps”, I think the short answer is yes, one can.

My reply above was meant to convey that putting batteries in the fridge or leaving them in a cold garage hovering around the freezing point (MD?), could lead to a potentially risky situation. So the comment is directed at safety not battery longevity.

Since we all live in different parts of the world with greatly differing climates, I think it’s important to asses those conditions and how they may affect our batteries. As an example, if we left batteries during winter in an unheated garage where I live, the batteries would solidify at -25 to -30C with unknown consequences when “thawed out” effectively bringing them from -25 to +22C in a half hour or so. That’s almost a 50C change in temperature which can lead to condensation or other chemical mishaps. The ambient humidity is also an important factor - our winters are much more humid than those on the west coast or at higher elevations.

In short, for purposes of safety but also longevity, we should all assess how our local climate could impact a wrong decision. We should decide whether safety over longevity is a priority or whether both can be achieved at the same time.

Finally, it’s worth noting that even at storage charge, LiPo’s can at any time short and catch fire. It generally doesn’t happen but it’s always a possibility. As such, storing batteries in a fire proof container, particularly if kept together (a cascade chain reaction can be very serious), away from materials that can catch fire, is a wise decision. A cement or ceramic surrounding area for storage of the container is also a good idea.

David
Last edited by doxilia; Oct 22, 2019 at 10:24 AM.


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