LiPos, 300 cycles?

[OCMike]

300 cycles is a lot? Really? My battery pack comes at a cost of nearly $450. I'm spending $1.50 every time I charge + electricity$? Ypedal brags about the longevity of his LiPos (brag might not be the right word - it's not an I'm better than you brag). Granted, I think Ypedal is light years ahead of me in ability to care for batteries. But 300 cycles sucks!

Sometimes I leave my battery pack fully charged for 2 days without putting it to use. Other times I leave it discharged (~3.6v / cell) for up to 4 days without charging it. How bad is that?

Yesterday I charged right after a ride. At the end of charge cell 12 read 4.040v. All other cells were in the 4.098v - 4.103v range. I started freaking out because I don't know what the hell to do OR how serious an issue this is. So, while I'm sitting there thinking I keep scrolling through the cell voltages on my Thunder1220 charger. The charger is blinking chg/end meaning it's done with the balance charge. While I keep scrolling the cell voltages are changing and cell 12 starts dropping. So, I'm getting more worried thinking "f*ck, $450 down the tubes. What do I do, buy a replacement battery for my battery with one bad cell? I suck at soldering. Am I going to be able to take apart 6 cell LiPo battery and fix this shite?" I continue scrolling through the cell voltages. Now cell 12 is down to 3.834v. I'm probably not even thinking clearly at this point. I giggle the balance leads - Boom, all cells are in the range of 4.098v - 4.103v. But I'm thinking WTF? I take my pack off the charger and check the cells independently with hand held cell checkers and a multi-meter. It seems everything is OK. A worrisome episode though ... any guidance on the issue would be appreciated.

Thanks!

-Michael

 

[migueralliart]

I totally understand your frustration. One of the main reasons I stay away from lipo is the hassle of worrying about a big fireball. Granted this can happen with all chemistries. Lipo just seems to be the one with more issues that's all. I have a good RC charger but I would only consider LIPO if I need a lightweight powerful pack (<8AH). Plus the spaghetti of wires really sucks. It doesn't matter how well you hide it. It is still a big mess when you have 3 or more packs in parallel.

 

[mvly]

300 cycles is typical for Lipo before you have significant sag. Leaving fully charged pack at 4.2V per cell over long period of time is not good for cells. If it's 4.1V, that is fine.

I think what you stated is fine. But if you are really concerned, leave the pack fully charged for a few days. Maybe a week. You usually can easily tell which cells are weak by then. Make sure you balance charge before doing this test.

Because one of the cell in my pack is weak, all cells are showing around 4.1V but one is showing 1.28V now. The one 1.28V cell use to be 4.1V when I first fully balance charged it. This is after 3 months of sitting on the table.

 

[dogman dan]

Depends on how you treat em, and what they are. How about 50 cycles and done? I have about $400 in lipo that I did that with. I should have stored em cooler, but I didn't have a good place for doing that in summer. I should have stored em more discharged. I did store them discharged the last year and a half. 3 years on the shelf killed em. They still work, but sag like hell and have about half capacity.

Shoulda just rode more. I did till I got so sick. Use em or lose em. Another 72v 10 ah set of packs did get run a lot. I didn't count every cycle, but I think I got 250 cycles out of them, in three years. 250 track sessions, or fun as hell dirt rides..... Yeah, way worth a two bucks a ride.

 

[Ypedal]

300 cycles is not a Black and White figure......

you can get 1000's of cycles from a pack if you do not discharge it all the way empty.

Imagine your car battery, lead acid, lasts 10 years of multiple shallow cycles, ( every time you start your car ) .. but if you drain a lead acid pack to nothing, cycle after cycle, expect less than 100 before they die.

it's all relative...

I bulk charge my packs, my Chaos has a bastard pack made of 8 packs, 4 are from the same batch, 2 from 2 years prior, 2 are different brand ( zippy . and turnigy , mixed C rates, Mixed capacity ) ..

2 rows of 24 cells , paralleled at the main + and - only, i set the charger to 24 x 4.15v = 99.6v

After weeks of use, the cells range from 4.18v to 4.08v , i regularly use up to 6~7ah of the 9ah potentially available and balance charge once a month.

I DO CHECK EACH PACK WITH A CELLOG BEFORE AND AFTER EVERY CHARGE CYCLE, NO EXCEPTIONS.

This only takes 20 seconds to do, but it's far better than risking a mistake of hookup if i was going to separate the packs to individually charge on each cycle... i'd be bound to mess it up eventually..

 

[bobzilla]

personally I can not complain of my li-po pack that reached nearly 400 cycles and current consumption of up to 300A
and I did everything that needed to be done just for the li-po: 34 (now 33) cells and 3p: 18 parcels of which the first 4 years, ... mixed-Turnigy Zippy, C different new and used .. last 8 packs nanotech 50c (used in 2 different locations) .... an incredible blend of everything that can exist in terms of li-po!!!
well ... still have 90% capacity and I can also do 160km with Cromotor to the low speed of 30 km / h....ma 118 even if I open the throttle furioso.l 'only care is to Do not load more than 4,11 / 12 V and not download them below 3.5 V. ........ many occasion where they were loaded half capacity, for ex. 3.85 V
the budget at the end of charge with these VCLAMP self-built setup precisely to 4.12 V with 7A and sometimes very slow to load 1A
every 7/8 port all cycles to 4.1 V and I end the post with a small Imax b6 that balances and charge up to 4.2 V. .. it takes little time because it has to check only 0.1V
I find myself at the end of all cells well-balanced, yet performance ........... BUT NOT Treat Me Like EXAMPLE! ...........'m just lucky

 

[Kingfish]

My CAs say I've had 87 "cycles". That's a bit unbelievable considering I've recently crossed the 10,000 mile threshold on ebikes. Except for about the one month that I had LiFePO4, the rest of the miles have been on Zippy FlightMax 15/2C 5S1P 5Ah RC batteries. The first year I abused the shit out of them - and they show it by being puffed. The super-puffs are in the R&R pile.

My last year has been by far the best - ever since I did the major overhaul last summer with the upgraded battery bus: No sags. Once in the whole year I hit LVC just as I reached my doorstep. These batteries were hand-picked out of my stash for Cross-Country; no defects, all late model editions with the 10-AWG power wires. They look pretty dang good after a year - except for the wear and tear.

For taxes, I've kept pretty scrupulous records of my rides; it's my primary vehicle and we (meaning the Royal-We, as in me, myself, and I) :wink: are taking the full deductions for business. Odd as it may seem, I did not record a single ebike mile in 2009, though I spent over $5k USD on ebike parts.

In 2010, I had a total of 54 business trips by ebike, plus - the 2010 Road Trip to Cali and various other practice runs that totaled 4303 miles. The investment that year was over $12k.

2011, it started to get a little more crazy: I have listed 145 trips not including the dailies from the 2011 Road Trip to Cali (21 days of riding). Total miles for the year = 4629. My ebike investment exceeds $15k.

2012 - I have a personal injury, Yes, Yes! I injured myself playing Xbox! And I could not ride my ebike for 6 months due to Quadriceps Tendonitis from... <drum roll please> sitting cross-legged on the couch! I blew out my knee playing games late into the night. Not by falling off the ebike, or crashing, or clipped by a wayward driver... no. I'm sorry - I apologize, I yam shamed to admit, I'm an Xbox junkie. That said, my ebike miles trailed hugely that year with just 169 miles recorded with 11 trips. That was the year I really knuckled down and learn how to leverage public transportation.. and Speed-Limp! Despite the slowdown, I still shoveled out $2k that was well-spent on rework and overhaul.

2013: The year is not over. I do not have a running total of investment to report (that will be sorted in January 2014) though it is less than 2012 because the ebike is operating in top form. I've made 64 business and pleasure trips this year-to-date totaling over 1100 miles.

The total battery cycles thus would be roughly equal to 54 + (145 + 21) + 11 + 64 = 295. However - as I previously stated, I rotate batteries - so no single battery has ever seen 295 cycles, let alone 100. Doing the math -> I've invest $22k to go 10k miles for less than $0.0044/mile/charge -> $44 USD in electricity to go 10k miles! And actually... I was on cross-country for 3k miles so it didn't cost me a dime On the Road.

Frankly, I think the batteries will physically wear out before they reach their chemical design limits; they will get beat to death or bloat out from abuse. Though I am really glad my stewardship has greatly improved.

I appreciate those that have brought me to this station where I feel confidant about maintaining my ride. It's a bit heavy, but I mean it. 8)
Seriously, to the ES Community - Thanks! KF

 

[iperov]

4.15V lipo 800+cycles FTW

 

[Ykick]

4.15V lipo 800+cycles FTW

I'm also in that club - 3 years in use and counting.

 

[bobzilla]

.........

 

[OCMike]

ummmmm .....

Well Played Sir!

 

[cal3thousand]

Mike,

My plan to leave the pack in a (semi-)discharged state if possible and charge before the ride. My charges generally take about an hour and it takes me that much time to get ready in the morning.

The pack sits on my stoop on concrete along with the charger when bulk charging (85% of them are at bulk). It has a Method's protection kit, so I pop it on and don't worry too much since overcharging is what causes a MAJORITY of LiPo fires.

I check the individual cells often just to be sure there isn't anything weird. I have LVC on the CA set so that I'm around 3.6v / cell at lowest. But my battery is planned out so that I am usually at nominal voltage at the end of the day. Leaving them there is fine. Even if I don't ride for a couple weeks (doesn't happen), I'm good. Leaving a pack fully charged for a couple weeks is a NO-NO. Think of it kinda like a gas can. Would you leave a full one in your house for a week? Better to have it a bit lower

Also, having an RC charger that would do storage mode is very nice. I'm starting to use this iCharger 4010 DUO (abit overkill), and it makes life much easier. If I did have a pack that was too high and I didn't have time to 'ride it out', I could put it on the iCharger and have it put them into a safe storage voltage.