RunRyder RC
WATCH
 2 pages [ <<    <     1     ( 2 )    >    >> ] 748 views POST REPLY
07-29-2018 12:16 PM  13 months ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Internal resistence 1.8 mohm... Very nice... New

15 mohm... Mature

More than 25, getting older and dying...

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-29-2018 01:45 PM  13 months ago
Jamovich

rrVeteran

Maryland, USA

MyPosts All Forum Topic
The funny thing about the Revolectrix batteries is that the resistance is still very low...if not lower than the gensace batteries but they have just lost charge capacity...
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-29-2018 08:35 PM  13 months ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Wait a minute... mV is one thing... Mohm is Another thing...

You can have a very Good balanced LIPO but still bad.
You can charge a lipo successfully but still bad.

Internal resistance is the key...

After 50 cycles, your LIPO are not the Same... IR increase in such a way, that discharge capacity put your pack on seriuos bad shape.

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-29-2018 08:38 PM  13 months ago
JuanRodriguez

rrProfessor

The Villages, Florida

MyPosts All Forum Topic
Jamovich...
The funny thing about the Revolectrix batteries is that the resistance is still very low...if not lower than the gensace batteries but they have just lost charge capacity..
Revolectrix batteries have a great reputation from what I read.....

Is there a chance you can charge them on someone else's charger just to eliminate an issue with your charger ???
Been there, done that and old enough to know better.....
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-30-2018 01:48 PM  13 months ago
Richardmid1

rrProfessor

Leeds, England

MyPosts All Forum Topic
I presume he meant Mohm's.

Something's not quite right. A 4400mah pack with IR lower than 2 mohm's per cell should give very good performance and flight time!

Are you sure ALL the cells have roughly the same IR?

Are the packs puffed up when you land?

A 6 minute flight leaving 30% in the packs isn't a very strenuous flight and the packs should be lasting a long time.
60% of the time, it works every time!
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-30-2018 01:59 PM  13 months ago
Jamovich

rrVeteran

Maryland, USA

MyPosts All Forum Topic
Yes the performance isn’t the question it’s the capacity...I have done a capacity check multiple times and at least 1 pack only can take in 3000 mah, and the best 3800 (out of 4400) that is 86%...with 80% being replacement time

Battery set 1

A: 3504
B: 3886 (26/5)

Battery set 2

A: 3874
B: 3423 (26/5)

Battery set 3

A: 3806
B: 3000
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-31-2018 11:18 AM  12 months ago
Richardmid1

rrProfessor

Leeds, England

MyPosts All Forum Topic
How are you doing a capacity check? You must discharge the pack to 3v/cell slowly (no more than 0.5C) and recharge.

Do you always parallel charge the packs? It is advisable to charge the packs individually every few cycles.
60% of the time, it works every time!
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-31-2018 11:44 AM  12 months ago
Jamovich

rrVeteran

Maryland, USA

MyPosts All Forum Topic
I did the capacity check using the “analyse cycle” feature on my Revo touch charger. I also charge each battery individually never exceeding 1 - 1.5C
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-31-2018 01:11 PM  12 months ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

OK... Now, I understand your point.

If you want that your lipo packs last for more than 50 cycles, never discharge above 70%.

IMO, a lipo pack can give safely half the capacity for each flight.

So, for 4400 mah, you just can discharge 2200 mah, hopefully at 3.8 volts.

The other half is not available, just because is below 3.8 volts, not safe.

Doing such a procedure to insist to get more than 80%, you will need more expenses...

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
11-08-2018 03:20 AM  9 months ago
Rubine

rrNewbie

Dublin

MyPosts All Forum Topic
gens ace have 5000 12s 60c battery, and also 5000 6s 60c for two is fit
and if you want to get longer battery life, could obey to the lipo battery guide, never overdischarge, never over charge......
SHARE  PM  EMAIL  Attn:RR  Quote
11-08-2018 11:08 AM  9 months ago
Richardmid1

rrProfessor

Leeds, England

MyPosts All Forum Topic
Rojoalfa...
OK... Now, I understand your point.

If you want that your lipo packs last for more than 50 cycles, never discharge above 70%.

IMO, a lipo pack can give safely half the capacity for each flight.

So, for 4400 mah, you just can discharge 2200 mah, hopefully at 3.8 volts.

The other half is not available, just because is below 3.8 volts, not safe.

Doing such a procedure to insist to get more than 80%, you will need more expenses...
Obviously the less you draw out of a pack the better for longevity but only taking 50% capacity is a bit extreme. Many believe in the 80% rule and people seem to have good success with this figure and get hundreds of cycles.

3.8v is perfectly safe, that is even above nominal voltage (3.7v). 3.7v is fine as a resting voltage and anything above 3.0v under load is safe.

The only time you would take LESS than 80% out is if you were discharging extremely fast, like less than 3 minute flight times!

The longer your flight time or the easier you fly the more capacity you can draw out without the voltage dipping too low. If you had a flight time of say 7 minutes+ you could safely take the pack down to around 10% remaining.

The only way to know how much you can remove from a pack is to look at the ESC logs to make sure the pack isn't dipping below 3.0v/cell under load.

Hope this helps.
60% of the time, it works every time!
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
11-08-2018 11:12 AM  9 months ago
Jamovich

rrVeteran

Maryland, USA

MyPosts All Forum Topic
Yes it would be ridiculous to only discharge batteries to 50% to guarantee advertised cycles (the usual expectation is 150)...that would make of ridiculously short flight times!
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
07-22-2019 01:01 AM  34 days ago
Exercom

rrNovice

Ladysmith BC Canada

MyPosts All Forum Topic
my understanding of li-Po technology was it would free us from the evil lead acid never go below 50% DOD. if we are now considering not charging to 100% and not going below 30% we are back to a 50% bucket.

The storage charge i think was to reduce stress on the ion selective membrane when not in use for long periods of time .Sounded good and did not reduce my fly time.
But if you can never go to 4.2v it would suggest to me that a (low grade) or thinner membrane has bin selected offering better IR numbers on day1 at the cost of life cycle and capacity
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
08-07-2019 01:56 PM  17 days ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Base on my observation doing charging lipo, I develop a simple ecuation:

CapC = CAP / 2

If you discharge your lipo pack at to 3.7 volts per cell, the maximum amount of charge your lipo pack take is half the label capacity.

For example, if you have a 5000 mAH lipo pack, the maximum amount of energy you pull out is 2500 mAH.

The rest, 2500 mAH, is not available and is related to discharge your lipo from 3.7 volts to zero.

Now, other parameter is C.
Capacity of discharge.

For example...

Pack 5000 mAH 20C, mean your lipo has 100 A peak discharge.
Pack 5000 mAH 40C, mean your lipo has 200 A peak discharge.

Your application consumption is 80 A... So... Which pack do I choose?

Safety factor.

You most consider a safety factor.
Low safety factor, bad choice but cheaper.
High safety factor, good but expensive.

So, 80 of 100? Low safety factor. 100/80 = 1.25

Or 80 of 200? High safety factor. 200/80 = 2.5

Low safety factor means less circling, less life span.

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-07-2019 02:06 PM  17 days ago
Richardmid1

rrProfessor

Leeds, England

MyPosts All Forum Topic
Rojoalfa...
If you discharge your lipo pack at to 3.7 volts per cell, the maximum amount of charge your lipo pack take is half the label capacity.

For example, if you have a 5000 mAH lipo pack, the maximum amount of energy you pull out is 2500 mAH.

The rest, 2500 mAH, is not available and is related to discharge your lipo from 3.7 volts to zero.
Not quite. This is why the '80% rule' came about, if you discharge to 3.7v/cell it will take roughly 80% capacity so for a 5000mAh pack that would be 4000mAh.
60% of the time, it works every time!
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-07-2019 02:40 PM  17 days ago
wjvail

rrKey Veteran

Meridian, Mississippi

MyPosts All Forum Topic
Often there is some usable capacity below 3.7 V/C. However, more often there is one or more cells that have dropped off the cliff and continuing to fly the pack will damage these cells. That only makes them perform worse on the next cycle further damaging them. By ending a flight at some safe voltage we preserve the useful life of all the cells.

Study the screen shot below. It is typical for many LiPo packs. Focus on the group of 3 thin lines. They are the individual cells. Notice the black cell, cell 2, has begun to lose voltage before the other two. My charger has discontinued the dis-charge to protect this cell but your ESC won't. The safe solution is to stop flying with capacity for ALL cells still remaining.

"Well, nothing bad can happen now."
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
08-07-2019 11:13 PM  17 days ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Very interesting point.

I recalled I was thinking to fly my trex600E with a balancer connected and check the castle creation data logger... Then, I realized esc discharge is higher and insane that my little voltz balancer... So... I forgot to do this crazy test.

My lipo packs flies up to 3.8 volts per cell... About 30% energy remained...
When I charge my lipo pack, it is constant my result...
Lipo pack takes 70% of CAP/2, always...

The 80% limit is base on flying up to 20% of CAP/2... It means less life span.

At this time, from 2012, each pack has 64 cycles... My packs are still running up to 3 min per flight doing sport normal flight ... No more...

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-14-2019 01:48 PM  10 days ago
Richardmid1

rrProfessor

Leeds, England

MyPosts All Forum Topic
Age will decrease the usable capacity unless they are kept in very specific conditions. 7 years is a long time!60% of the time, it works every time!
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-14-2019 03:01 PM  10 days ago
Rojoalfa

rrVeteran

Punta de Mata, Monagas-Venezuela

MyPosts All Forum Topic
/
/

Oh...yes!

That is why a new lipo pack purchase recently could be an old lipo manufactured...

/
Saludos cordiales,
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <     1     ( 2 )    >    >> ] 748 views POST REPLY
 Print TOPIC  Make Suggestion 

 11  Topic Subscribe

Sunday, August 25 - 5:58 am - Copyright © 2000-2019 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online