Ideal battery use?

[SunnyD]

I took 2 flights yesterday, took each battery from 100% to about 70% for a 10 min flight. Should I recharge to 100% on my next flight day?
I see lots of warnings about taking off with less than full battery (though I'm not planning on a solid 20 min flight), but I also had this question:
-the battery has a limited # of cycles (any guess how many?), and would a charge from 70% to 100% count as one? Or should I wait until it's at 25-30% before I recharge.
I wouldn't consider starting a flight at 40% or below, but my 2 70% batteries seem safe.
Thoughts?

 

[microlinux]

It's not the things you plan for that you have to be concerned about. Charge your batteries to 100% before flying and then have a beer for being smart. It doesn't create any extra wear on the battery.

You can probably get hundreds of cycles out of a properly maintained battery.

 

[nwcove]

recharge to 100% before flight. i always fly my batteries down to 40% ish every flight , then charge back to full shortly before a new flight. im sure some LiPo gurus will chime in, but there are many posts on the forum about battery maintenance and the issues that can occur if you begin a flight with a battery thats not fully charged. i would never fly a 70% battery the next day after a flight.

 

[With The Birds]

To answer your question- charging from 70% to 100% puts 30% of a charge cycle on the pack.

 

[tcope]

It's best to charge them up but it's not an absolute. The issue is that the percent of charge is a "guess" by the software. So you could see 70% but under load that might really be something like 50%. This is one reason why people get into trouble when launching using batteries that are less then 100%.

I'd highly recommend that you charge the settings in the Go app to also display the voltage of the battery. You can search this form for a post on what acceptable and low charges are (msinger has a good post on this). Pay attention to those numbers as they are more accurate.

 

[With The Birds]

The most often encountered issue with bad consequences is launching with a pack that has commenced the auto discharge routine. I have no hesitation launching with a pack above 50% within hours of last flight.

 

[solentlife]

It's best to charge them up but it's not an absolute. The issue is that the percent of charge is a "guess" by the software. So you could see 70% but under load that might really be something like 50%. This is one reason why people get into trouble when launching using batteries that are less then 100%.

I'd highly recommend that you charge the settings in the Go app to also display the voltage of the battery. You can search this form for a post on what acceptable and low charges are (msinger has a good post on this). Pay attention to those numbers as they are more accurate.

Correct .... despite some so-called experts that claim otherwise.

Nigel

 

[solentlife]

The most often encountered issue with bad consequences is launching with a pack that has commenced the auto discharge routine. I have no hesitation launching with a pack above 50% within hours of last flight.

Auto-discharge terminates moment you touch the ON button of the battery ... there is no residual effect other than the partially discharged battery.

Nigel

 

[solentlife]

Charge cycles so far according to my and others I know observations increments based on full charge / discharged figures - not on partial.

Nigel

 

[With The Birds]

Auto-discharge terminates moment you touch the ON button of the battery ... there is no residual effect other than the partially discharged battery.

Nigel

I would agree (logic supports this view) absent the fact that there have been issues reported in this forum and elsewhere of sudden power loss in flight for users with seemingly healthy packs where the common factor was auto discharge had commenced. For inspire users also it seems.

 

[solentlife]

I would agree (logic supports this view) absent the fact that there have been issues reported in this forum and elsewhere of sudden power loss in flight for users with seemingly healthy packs where the common factor was auto discharge had commenced. For inspire users also it seems.

Not disagreeing ... anythings possible with electronics ... but first I have read of it.

I think here would be a problem to actually confirm the auto-discharge as the culprit ? I take it that people have just assumed that because they tried flying after the start day of discharge - they assume its the reason.

How would you confirm ? I'm always skeptical of fall from sky claims as I believe most are faulty connections such as dirty or user hasn't pushed battery fully home.

Nigel

 

[With The Birds]

Not disagreeing ... anythings possible with electronics ... but first I have read of it.

I think here would be a problem to actually confirm the auto-discharge as the culprit ? I take it that people have just assumed that because they tried flying after the start day of discharge - they assume its the reason.

How would you confirm ? I'm always skeptical of fall from sky claims as I believe most are faulty connections such as dirty or user hasn't pushed battery fully home.

Nigel

You may be able to assist with the confirmation here- at least to the extent you have disassembled packs and convenient access to smart boards (I recall you saying you and an electronics savvy friend had some some battery reverse engineering).

If you measure the values of the bleed resistors used to perform balance during charging (seemingly it is these resistors that are employed during the auto discharge routine) and the values differ we have a likely explanation. Even if the values are close if each cell is independently terminated into a load during auto discharge even slight cell characteristics will provide for different discharge levels.

As you wouldn't no doubt have experienced after many years of Lipo experience an unbalanced pack will often provide for one cell hitting LVC way before the total pack voltage reads as significantly down in total capacity. If there is one thing we know about the DJI smart board and AC firmware it is that battery shutdown occurs when one cell hits LVC.

 

[Macphreak4evr]

i never have 100%, when i fire it up when "warming up" I usually take off with 98% or so

 

[solentlife]

"As you wouldn't no doubt have experienced after many years of Lipo experience an unbalanced pack will often provide for one cell hitting LVC way before the total pack voltage reads as significantly down in total capacity. If there is one thing we know about the DJI smart board and AC firmware it is that battery shutdown occurs when one cell hits LVC."

Sorry I agree with first part - but last part no.

Yes an unbalanced pack will likely end up with a cell drawing down more rapidly and increasing its inbalance to others. It can lead to LVC triggering even when other cells are above LVC individual cell limit ... as LVC works on TOTAL voltage unless you use a separate alarm such as Quanum etc. which will alarm on ONE cell hitting low figure.
DJI board is a total voltage charge controller and only as far as we determined providing cell data for telemetry info. The board does not trigger shut down or LVC when one cell is too low. It triggers shutdown on TOTAL voltage.
The other factor is the failure of the DJI board to actually allow balancing to complete fully ... once the board detects full voltage - it shuts off. Doesn't care if one cell is high and another low. I know some will lay claims that they have seen the balancing occur ... sorry I will always ask for real evidence of that - as it has not been observed in packs we tested. We tested both DJI original and non-original and obtained same results.

Personally - I would like to see DJI change to a more normal LiPo style and let users have full access to their packs cells. To be able to use proper programmable chargers which give full balancing and storage functions. Surely given the majority of RC is done that way - it indicates a safe and reasonable path ? No need for hand-holding ...

Nigel

 

[solentlife]

i never have 100%, when i fire it up when "warming up" I usually take off with 98% or so

That is because no battery actually hits true 100%. As it charges it warms up. That and internal resistance means that charger sees 100% but once battery is disconnected - within moments the % drops slightly to its true level ... often 97 - 98%.

Its funny actually because the opposite happens after a flight. You land with example 35% and 5 minutes after landing if you checked that pack again once rested would likely show 40% or more.

Nigel

 

[Bazza.]

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[solentlife]

Does anyone have details of the life expectancy of a p4 battery? Who’s got the most charge cycles?

I have 5 so far [emoji56][emoji56]

Go ask on the P4 forum ?

Nigel

 

[Bazza.]

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