Hi Guys! Hobbyking has just released this new batteries meant to be used in multicopters. While they have an increased capacity/weight radio, they have sacrificed power output (they are rated at 10C).
While I think this is a good idea, I´m wondering how is it going to affect the battery market in general these new concept.
I´m going to buy the 6S version to test them when they are released but in the meantime I think we can start discussing if this is the way to go and of course, the uses for them (mainly Aerial Photography or FPV)
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Quadzimodo, it isn't so , you are missing the point.
As you know, the more C the more weight of the battery.
This is because the metallic part of the battery, needed to allow high currents to circulate internally, increase with high C of discharge, since metal is the heavy part of the battery.
Battery cycles are affected by several factors, temperature and the rate of discharge are the main.
If you drain each time you use a battery the total Amperes it can deliver , i.e. 90A for a 3000mah 30C, you will see after only a dozen of cycles, swelling and a reduction in capacity.
For a Lipo or a LiOn battery, the "ideal" rate of discharge is 1/10 of his capacity.
It would guarantee the deliver of nominal capacity and hundreds of charging cycles.
So, as a rule of thumb, if you want to be shure to keep you battery in good health, drain just the 25% of the total amperes while hovering.
Luc - It is not clear what part of my comment you are suggesting isn't so, or how I may have missed the point. I was indeed responding to your comment questioning the cyclic performance of these newer lower C offerings, so feel free to school me.
When you said :
"In fact it actually becomes increasingly difficult to make a cell which is resistant to heavy cyclic use as C rating increases, so it might well go the other way."
I had understand that you was saying that low cyclic problem affect mainly high C batteries and these low C were less subjected to that problem.
With lithium battery construction, as with most (if not all) chemical batteries, there is an ideal balance to be struck between plate surface area and plate thickness.
A higher ratio of surface area to plate volume means thinner plates. Thinner plates provide low internal resistance as well as high current potential. These gains in power density do however come at the expense of resistance to cyclic use (so plates degrade quicker). This is especially true at high DOD (Depth of Discharge), such as is native to our application.
A lower ratio of surface area to plate volume means thicker plates. Thicker plates provide superior resistance to heavy cyclic use (delivering more durability in high DOD applications), but higher internal resistance and lower current potential.
As a result of the above, and as I said original, 'it becomes increasingly difficult to make a cell which is resistant to heavy cyclic use as C rating increases'. This is because we are effectively seeking a battery with attributes from both ends of the spectrum (both thin and thick plates).
So, it stands to reason that a battery which is designed to be 50-75% less power dense than another (assuming all else remains the same) may gain energy density or gain cycle life, or a combination of both.
Also, judging by your comment, it appears you are confusing rate of discharge (power in A) with depth of discharge (capacity in Ah).
If the weight is as promised by HK it can be an interesting battery but as it was already said, the discharge factor must be quite low on normal use, about 2 or 3 C if a good number of charge cycles without shorten capacity are wanted.
It is a good choice for very efficient multirotors.
I'll say forget them if you have a DJ S800 :)
In my case I am building a quadcopter (probably an octacopter in the future) that it will be in the air for 30 minutes, so a 2c rating will be enough for me and I always charge them at no more than 1C so I am expecting them to last if the quality is good.
The fact that they don´t have them in stock right now means that probably many people bought them and we´ll start to see some test really soon.
Has anyone that reads this post bought one?
I bought these batteries yesterday .
I watched the Hobby King Daily video on these and apparently they are eventually going to have them up to 4S 10,000mah.
As it is now they are out of stock on 3 of the 4 sizes they have listed.
And personally it will be important to have these in the US warehouse too.
There are some other cells which are built to weigh less (similar to these) but are not a low C rating but they have greatly compromised numbers of recycles and experience serious loss of capacity after just 20 or 30 uses.
That's why I was concerned about recycle life.
These seem to offer similar capacity and capability to MaxAmps at a fraction of the cost if you can use the reduced C rating.
The next stop after these is really the 18650 Lithium batteries at a 2 to 3 C rating for the newest ones.
But if you can use them you can nearly double energy capacity.
I've often wished I didn't need to "waste" weight on a C rating I don't need. With a single battery, I hover at 16 amps and "cruise flight" is usually 20-30 amps depending on how hard I push it. With two batteries, the added weight adds approximately 5 amps to all of that, but cuts current draw per battery in half.
So these would indeed be the most efficient way to power my lumbering non-acrobatic multirotor. If I didn't already have four batteries, I'd order more today. They're probably what I will buy from now on as needed.
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