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Feb 18, 2020, 07:14 PM
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Quote:
Originally Posted by John61CT
Can as in possibility, not will as in certainty.

Lots of variables involved.

Have recently been several recent discussions along these lines

https://endless-sphere.com/forums/vi...27180#p1527180

https://endless-sphere.com/forums/vi...t=250#p1528131
First link had 11 posts and no real data.
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Feb 18, 2020, 10:11 PM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
And it pertained to the interests and requirements of eBike enthusiasts so we're mixing apples and oranges again. Testa's power system, cell selection and architecture is designed around a 1C average discharge rate and 1200lb pack weight. So it's another example where a particular devices properties would not mirror ours

Joe
Feb 19, 2020, 02:37 AM
Registered User
OK yes, in a very high-discharge context, it is important to select cells that are well designed and built to withstand that.

Quote:
Originally Posted by rampman
I just retired a low IR/high C pack after 1306 cycles. A new record for me and at 40C discharges
That **is** amazing, which pack / cells?

Do you think any special care parameters get credit too, or just their high quality?
Feb 19, 2020, 08:21 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by MCSGUY
... I extended the leads to about 11” (10awg) and plug them together in series using 5.5mm bullets. I added capacitance at the ESC using one of Castles capacitor modules. ...
Purpose and installation of the extra capacitors explained in
Too long wires batteryside will kill ESC over time: precautions, solutions & workarounds - RCG


Vriendelijke groeten Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
e-flight calculatorswatt-metershigh power motor tips&tricksCumulus MFC
Feb 19, 2020, 10:27 AM
Frankenstein recycled packs
rampman's Avatar
Quote:
Originally Posted by John61CT
OK yes, in a very high-discharge context, it is important to select cells that are well designed and built to withstand that.

That **is** amazing, which pack / cells?

Do you think any special care parameters get credit too, or just their high quality?
When I test cells I am often asked to not reveal certain things. Sellers respect this in me and I won't budge from their requests so please quit prying; it won't happen. These may never make the market, I have no information on that at this time.

I have found that the lower the IR the higher the quality of the cells for high amperage output and longer cycle life. They don't get as hot as higher IR cells under the same discharge C constant so they last longer.
Many "standard" cells only last around 300 cycles and they quickly lose capacity after that. These are cells that test around 20-25C when new based on the online IR tool jj604 has provided us.

Rick
Feb 19, 2020, 10:42 AM
Registered User
Quote:
Originally Posted by rampman
so please quit prying
Wow no idea testing was involved, thought just a normal pack, no intent to "pry"
Feb 20, 2020, 04:33 AM
Hamburger
hamburger's Avatar
Quote:
Originally Posted by John61CT
Can as in possibility, not will as in certainty.

Lots of variables involved.

Have recently been several recent discussions along these lines

https://endless-sphere.com/forums/vi...27180#p1527180

https://endless-sphere.com/forums/vi...t=250#p1528131
Could you please take issues of batteries for low current applications to its own separate thread?
Feb 20, 2020, 09:01 PM
big ignore list/drama is dumb
brushless55's Avatar
Uhhmmmm.........?
"Major Breakthrough: Graphene Batteries FINALLY Hit the Market"

Major Breakthrough: Graphene Batteries FINALLY Hit the Market (9 min 6 sec)
Feb 21, 2020, 02:21 AM
Registered User
Cough "investor video presentation" cough.... lol

It will be great for our types of applications when it happens.
Feb 21, 2020, 06:00 PM
Registered User
A friend just bought ten HK Panther 5000 6s lipos and was asking me about the weight. The website says 920g but his are all around 860g. My older 65c graphenes are 890g so HK must have changed something. I also have two Panthers, mine also weigh about 860g.

Hopefully the new lighter Panthers maintain the performance and cycle life the HK Graphenes are known for.
Feb 21, 2020, 07:15 PM
aka JetMan Joe
MCSGUY's Avatar
Thread OP
Quote:
Originally Posted by malcolmm
A friend just bought ten HK Panther 5000 6s lipos and was asking me about the weight. The website says 920g but his are all around 860g. My older 65c graphenes are 890g so HK must have changed something. I also have two Panthers, mine also weigh about 860g. Hopefully the new lighter Panthers maintain the performance and cycle life the HK Graphenes are known for.
I'm going to venture some (hopefully) logical guesses here. The same issue has arisen with the CNHL G+ Graphenes which have the same source.

On one hand, outside of rigorous distributor QC oversight they get what the suppliers are making "this week". The more 'stuff' in the pack the higher the unit cost so the delta spread over 1000 units is over 13lbs less 'stuff' to pay for. If that's the reason behind it, it seems kinda petty to my way of looking at it. On the other hand it's no stretch thinking a 920g pack is just too heavy, that's certainly been my operating premise the past year. So it's possible to envision a case were someone realized the excessive weight was costing sales (at least mine anyway), so the question becomes how heavy is too heavy? Considering equal formulations the lighter the pack the lower the C capability, the more stress for a given load so the lower the number of life cycles.

I'm willing to bet real money a 860g Panther is not the honest 55C pack the 920g was. But in the real world who needs a 5000mah pack that swings a 275 amp bat? IF the 860g unit maintains voltage well at 150 amps (which indicates a ~2 minute flight) I'd be good with that. Assuming the 860g Panther is good for 200 cycles under this max use profile (a safe assumption) I'd get 4 years worth of use out of it.

I can't say what the threshold of value is for anybody else, nor can I venture a definitive answer to when "lighter" crosses over into bait and switch. But I would say a lighter 50C Panther will be more useful then a heavier 55C unit.

Joe
Feb 21, 2020, 07:53 PM
Registered User
Just a thought:
Capacity of the battery is defined by the volume of electrolyte. Discharge current - by electrode area and thickness (for high currents).
Let's say factory got access to a thinner, lighter and more porous separator (that sponge saturated with electrolyte between electrodes).
Then they can make a slightly thinner and lighter lipo without sacrificing characteristics (a smaller distance between electrodes will also reduce IR). Amount of materials used would remain the same (except separator).
The only drawback would probably be an increased risk of internal shortcut...
Feb 22, 2020, 08:18 AM
Registered User
I think if it were the vendor as customer or improved materials driving the lighter weight trend, they would change and market the new specifications as a user-valued improvement.

The shipped units just getting lighter than spec'd will not drive increased sales on their own.

Quote:
Originally Posted by MCSGUY
On one hand, outside of rigorous distributor QC oversight they get what the suppliers are making "this week"
Seems more likely it is just the normal lack of diligent oversight allowing the supplier manufacturer to cut costs that is the root cause.

The actual power capacity may not suffer that much, and maybe the (easier to detect) Ah actually stored as well, but

I'd be willing to bet lifetime cycles at a given usage pattern will suffer proportionately with reduced active materials.
Feb 23, 2020, 09:19 PM
Registered User
I have had 4 CHL batteries graphene go bad after around 35 charges. Each one had a bad cell. I leave them charged all the time and use them once a week. Am I destroying batteries because I leave them charged for a week without using them?
Feb 24, 2020, 01:09 AM
Registered User
scott page's Avatar
Quote:
Originally Posted by lesbaron
I have had 4 CHL batteries graphene go bad after around 35 charges. Each one had a bad cell. I leave them charged all the time and use them once a week. Am I destroying batteries because I leave them charged for a week without using them?
The damage is cumulative. Leaving them charged - over discharging - over amp discharge - etc. all have an effect. I have a substantial investment in batteries so I TRY to be very fastidious about their maintenance. I always usually discharge them to 3.75 after returning home from flying. I charge them the night before flying (overnight at < 1C) .

But - yes. In my experience, leaving them charged is degrading their performance and shortening their life.


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