Author Topic: Charging battery (Read 1832 times)

Larry Wong · « **on:** August 24, 2019, 05:20:10 PM »

How long can you keep a charged battery before using?

Shorts,David · « **Reply #1 on:** August 24, 2019, 08:52:57 PM »

Good question Larry. My dad and I were just asking the same question. Nicads shouldn't be charged more than a couple hours if you want full voltage because there is high decay from peak voltage. Lipos however hold much longer and aren't supposed to develop memory, but I've heard they eventually do??? I've left mine for about a week and still had full voltage, but am I building memory? Let's see what others have to say.
David

Crist Rigotti · « **Reply #2 on:** August 24, 2019, 10:43:18 PM »

Quote from: Motorman on August 24, 2019, 09:31:49 PM

I get them back to storage charge the same day but from what I've heard I might be comfortable leaving them charged for use the next day if I had to.

Motorman

Ditto

Ken Culbertson · « **Reply #3 on:** August 25, 2019, 11:38:56 AM »

I don't go more than a day, two at the most. My problem is that I only have one charger and if I am going to fly Saturday I need to start charging Thursday Night and if it gets cancelled I have 6-8 batteries to get back to storage. IMHO this is the part of electric that needs the most innovation.

Let me add a sub question. I have balanced my motor/battery/prop/rpm/time stuff to give me approximately 37% left after a pattern. Is it safe to leave the battery at 37% for a week and just charge it again without going to storage?

Ken

Fred Underwood · « **Reply #4 on:** August 25, 2019, 02:56:22 PM »

Battery University is a great resource for most all battery types. For Lithium batteries,

https://batteryuniversity.com/learn/article/lithium_based_batteries

Leaving at high charge, charging rapidly, discharging too low and leaving at low discharge and other conditions tend to lower the number of cycles, not suddenly kill batteries outright. Meaning, you don't necessarily notice any difference in use. Even smart phone Li batteries tell you that the battery is low at 20%. Many recommend charging to less than 100% to extend the number of cycles. You can get more cycles if you don't charge above 4.1 and stay away from 20% discharge, not practical for most of because of capacity and weight.

The problem is usually how to discharge as most charges have very wimpy and slow discharge capacity. There are discharges available separate from charger with better loads and discharge rates.

Ken, 37% is safe but I'm not sure if best (affecting total number of cycles). In one table of Battery University, they recommend 40% for storage, other places say 50-60% so those should all be acceptable and 37% OK. Assuming that all of the batteries have approximately the same use, remaining capacity and voltage, then parallel storage charge. I bumped my storage charge to about 59 - 60% during regular flying season. Then the time to run charge is less and I make up the time that I used after flying.

How to prolong Li batteries,

https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

Summary of Do's and Don'ts

https://batteryuniversity.com/index.php/learn/article/do_and_dont_battery_table

IMHO, Battery University is a good read for electric flyers.

William DeMauro · « **Reply #5 on:** August 25, 2019, 03:29:59 PM »

Quote from: Ken Culbertson on August 25, 2019, 11:38:56 AM

I don't go more than a day, two at the most. My problem is that I only have one charger and if I am going to fly Saturday I need to start charging Thursday Night and if it gets cancelled I have 6-8 batteries to get back to storage. IMHO this is the part of electric that needs the most innovation.

Let me add a sub question. I have balanced my motor/battery/prop/rpm/time stuff to give me approximately 37% left after a pattern. Is it safe to leave the battery at 37% for a week and just charge it again without going to storage?

Ken

Not knowing what charger that you are using makes answering a bit more difficult,but if I were working with just one charger I would bring all my batteries up to storage mode when I was done flying,which would make things better for the battery and easier to charge next time i went out flying. That would also allow you to parallel charge if you wanted to next time you went out flying should you have that ability or choose to do it. There are a few stand alone dischargers out there. Some involve light bulbs , some don't. I have the skyrc one, it works ok but could be better.. I also use powerlab 8 chargers which give me both a fast charge and an acceptable and accurate discharge to storage. I do parallel charge and discharge all the time. Remember never to leave your batteries unattended while charging or discharging.
Fred got in ahead of me while I was typing this so there is some repeat info here. We can probably argue all day as to what the best storage numbers are but we know it falls in the 40%-60% range, anything above or below that seems to be harmful to the battery.

Fred Underwood · « **Reply #6 on:** August 25, 2019, 03:52:28 PM »

One other idea for those not needing to discharge to 20% to have enough capacity on a flight is to split the difference. Charge to less than 4.2v and find the numbers that leave say 25%. You might find that charge to 90% and discharge to 25% works in Ken's case. That should prolong battery life/cycles. Try to set charger to say 4.15V and check % remaining after as flight, and the slowly work down. From your numbers, you may well be able to use 4.1V (about 90%) as top of charge and still have plenty left. Of course the ability to control those parameters is charger dependent. I recommend Powerlab 8, or PL 6. Discharge is still painfully slow on those if you have several batteries to do. But they can be parallel discharged so that you don't have to change over batteries several times.

Here is a discharger thread

https://stunthanger.com/smf/gettin-all-amp'ed-up!/battery-discharger/

Larry Wong · « **Reply #7 on:** August 26, 2019, 05:53:58 AM »

Quote from: Larry Wong on August 24, 2019, 05:20:10 PM

How long can you keep a charged battery before using?

OKEY I think I have the answer! charging Battery's the night before flying or the same day of flying is I deal , then discharged to storage at days end?

FLOYD CARTER · « **Reply #8 on:** August 27, 2019, 05:27:12 PM »

I've been flying large e-stunters for about 6 years, now.. I made a battery discharge gizmo using a couple of auto headlight lamps to take a fully charged LiPo down to a storage charge. However, I haven't always done that. I have left LiPo batteries at full charge for several weeks, giving them just a "top off" the day before flying.

My collection of LiPo batteries all seem to perform the same, whether or not they were put on storage charge, or left at full. I'm giving up on the idea.

Larry Wong · « **Reply #9 on:** August 27, 2019, 08:37:53 PM »

Quote from: FLOYD CARTER on August 27, 2019, 05:27:12 PM

I've been flying large e-stunters for about 6 years, now.. I made a battery discharge gizmo using a couple of auto headlight lamps to take a fully charged LiPo down to a storage charge. However, I haven't always done that. I have left LiPo batteries at full charge for several weeks, giving them just a "top off" the day before flying.

My collection of LiPo batteries all seem to perform the same, whether or not they were put on storage charge, or left at full. I'm giving up on the idea.
[/quote ]Floyd I have been doing about the same sometimes I come home after a day of flying I just leave them even some fully charged batteries thill the next week night before and charge them, and even top off the charged one. Was just wondering what is in general the best way?

Fred Underwood · « **Reply #10 on:** August 27, 2019, 09:57:01 PM »

The best way is to have the batteries at storage charge when not in use. Not necessarily most practical, but best in terms of longevity and cycles per battery. Best from a personal user standpoint my be most convenient. Batteries normally loose capacity with use, cycles, and time, and that normal aging process may be faster without best care. You can verify that at battery university.

In an ideal battery world, the batteries get charged shortly before use, and the brought back to storage charge after they have had time to cool and stabilize their chemistry and voltage. Charging the morning of flight and taking to storage charge after the flying day is probably best. Meaning bring up to storage charge, or down to storage charge if not flown. Most other ways seem to work, but most likely result is fewer cycles and faster capacity loss. If you try to fly 400 - 500 flights/year on 4 or 5 batteries you would likely notice the difference in battery care toward the end of the season. If you fly much less, you may see the batteries last a second season and be happy, but the number cycles will still likely be less. Some keep a log of cycles on each battery and then know how they last.

Author Topic: Charging battery (Read 1832 times)

Larry Wong

Charging battery

Shorts,David

Re: Charging battery

Crist Rigotti

Re: Charging battery

Ken Culbertson

Re: Charging battery

Fred Underwood

Re: Charging battery

William DeMauro

Re: Charging battery

Fred Underwood

Re: Charging battery

Larry Wong

Re: Charging battery

FLOYD CARTER

Re: Charging battery

Larry Wong

Re: Charging battery

Fred Underwood

Re: Charging battery