my experience running LiPo on a commuter bike

Batteries, Chargers, and Battery Management Systems.
Post Reply
User avatar
headwind   10 W

10 W
Posts: 76
Joined: Mar 27 2013 6:19pm
Location: Australia

my experience running LiPo on a commuter bike

Post by headwind » Jan 14 2014 5:10am

After about 6 months running LiPo on my commuter setup, I’ve just replaced a pack which copped the brunt of my noob mistakes. So I thought I’d share my experience, in case it is useful for others trying to decide which chemistry to use.

Running 12S Zippy packs, my commute uses 2Ah out of the (alleged) 4Ah capacity. This is based on charging to 4.15v, at the end of the trip the voltage was about 3.8v. My 30A controller means the packs are seeing peaks of 7C, compared with the (again, alleged) 20C rating of the Zippy's.

Towards the end of the commute, I noticed acceleration wasn’t as good. Not enough to be a problem, but I’m glad I oversized my batteries and I really wonder if pushing 20C Zippys to even 75% capacity regularly would be a good idea. Next time my LiPos need replacing (hopefully not for a long time, now that I know how to treat them better), I’ll probably try 30C or Turnigy cells to see if they perform better.

The death of a pack in about 6 months may be partly due to me leaving the cells constantly charged to 4.15 volts (ie putting them on the charger straight after a ride, so they’re ready to ride at a moment’s notice). But I think the main factor was that they were accidentally deep discharged a couple of times, which resulted in very unbalanced cells. The most recent time, it sent a cell puffy and way below the 2.7 volts “golden rule”, so that pack has now been replaced.

As for the “new” packs, one of them has actually been in storage for over 6 months as a spare (never used). A cell in this pack initially wouldn’t charge past 4.05v, causing the iCharger to work overtime trying to bleed off voltage from the other cells. Luckily, after a few shallow cycles, this cell has come good and is now fully charging.

I must admit, using LiPo is a lot of work for a commuter bike! Buying a prebuilt LiFePo4 pack and charger would be more practical: no DIY series/parrallel connections, a charger which you just plug in and turn on without needing to know what it’s doing, not needing to devote your life to monitoring cell voltages, the battery is happy to be charged the night before and, of course, less risk of burning your house down if something goes wrong. It’s much more “plug and play”. Having said that, I love how discreet and lightweight my LiPo setup is, so I’m happy to live with these downsides.

In about 6 months, I’ll report back on how the new Zippy packs are lasting, now that I’m treating them better.

I look forward to any questions/comments you may have.

Simon
Last edited by headwind on Jan 16 2014 3:07pm, edited 1 time in total.
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 14 2014 7:31am

Obviously you get slower when your voltage is 3.8v, vs when it was 4v. So that's a lot of why you get slow at the end of the ride. I would not attribute it to 20c zippies so much as to just the way lico discharge curve graphs. But, if you see lots of sag the whole ride, that's the cheap zippies. Adding a second set for a 10 ah pack will help reduce sag under load a lot.

I also run a 5 ah size pack of 20c zippies, but using a 20 amps controller my biggest spike is only 6c, and 4c is max continuous. It's fine now, after about 100 cycles, maybe 150. I also mostly discharge about 2-3 ah per ride, but have discharged 100% a dozen times perhaps. I don't see that much sag with only a 20 amps controller. If I put the same 5 ah pack on a 40 amps bike, it sags like hell of course. Since you run 30 amps, I would say you need a larger pack, or higher c rate.

Your results, one pack puffed a cell, comes from too small a sample to infer very much about it. Of course, it didn't help to discharge it that deep that one time. But, if you want to continue using 5 ah size, it would help a lot if your next pack was either bigger, or much higher in c rate. The easy thing would be to buy two more 5 ah packs in cheap 20c, and then just carry 10 ah, or perhaps 8 ah. Overkill yes, for a 2 ah ride. But still a pretty light battery, and more range for those rides to other places.

As for killing your packs by leaving them charged all the time, it's not ideal, but it takes much longer than 6 months for that to kill a pack. They will lose capacity from that in 2 years, but not that much damage in 6 months.

User avatar
headwind   10 W

10 W
Posts: 76
Joined: Mar 27 2013 6:19pm
Location: Australia

Re: my experience running LiPo on a commuter bike

Post by headwind » Jan 15 2014 1:54am

dogman wrote:Obviously you get slower when your voltage is 3.8v, vs when it was 4v. So that's a lot of why you get slow at the end of the ride. I would not attribute it to 20c zippies so much as to just the way lico discharge curve graphs. But, if you see lots of sag the whole ride, that's the cheap zippies.
Yeah, it's just at the end of the ride. Cool, I didn't realise the decreasing voltage would have a noticeable affect on performance. I assume you've achieved such a level of battery Zen that you can "feel" the exact voltage of your packs based on the throttle response? :wink:

Just wondering if you could please share your thoughts on whether the higher C-rate packs or the Turnigy 20C perform much better on a bike than the cheapo Zippy 20C's?
At the moment the two brands cost about the same for 4Ah 20C at Hobby King: (I thought Turnigy was usually more expensive)
Zippy 20C $41
Turnigy 20C $43
... and just out of interest...
Zippy 25C $51
Turnigy Nano 25C $54
Zippy 40C $56
Turnigy 30C $59
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

User avatar
wesnewell   100 GW

100 GW
Posts: 7168
Joined: Jan 31 2011 6:25pm
Location: Wylie, TX, USA

Re: my experience running LiPo on a commuter bike

Post by wesnewell » Jan 15 2014 2:42am

Might I suggest 3 of these for your 12s pack.
http://www.hobbyking.com/hobbyking/stor ... duct=19499
Need Advice? https://endless-sphere.com/forums/viewt ... =3&t=66302
Mongoose 26" Ledge 2.1 mtb bike $99, yescomusa.com 48V 1000W rear hub kit $200, Hua Tong 72V 40A controller $35, 10ah 24s lipo $217=~43mph, range=45 miles @ 20mph. 25K miles and still going strong.
Huffy Fortress 3.0 with MXUS 3000 4T motor, 24s lipo, 96V 60A controller. Total cost with extras <$700. Top speed ~50mph
My videos https://www.youtube.com/channel/UC0KW4U ... _G2wQhptMg

User avatar
friendly1uk   10 MW

10 MW
Posts: 2282
Joined: Mar 14 2013 1:18pm
Location: The not so UK

Re: my experience running LiPo on a commuter bike

Post by friendly1uk » Jan 15 2014 5:47am

headwind wrote:I must admit, using LiPo is a lot of work for a commuter bike! Buying a prebuilt LiFePo4 pack and charger is a lot more practical: no DIY series/parrallel connections, a charger which you just plug in and turn on without needing to know what it’s doing, not needing to devote your life to monitoring cell voltages, the battery is happy to be charged the night before and, of course, less risk of burning your house down if something goes wrong. It’s much more “plug and play”. Having said that, I love how discreet and lightweight my LiPo setup is, so I’m happy to live with these downsides.

Simon
Your weighing up lipo against lifepo4. Or rather, you think you are. In fact you are weighing up using a bms against using rc chargers. The cell chemistry has nothing to do with the workload you took on by buying the wrong associated electronics.

I thought zippy was rated at 100 cycles, so 6 months is about right. Turnigy is 160 cycles. $75 for 12s 5Ah as linked to above. BMS $20-$70 and charger about the same. Then you have the plug and play functionality you want. Should need cells every year or so, but you reuse the bms and charger
bmsbattery sent me broken and incorrect stuff, and won't even talk to me about it.

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 15 2014 6:13am

I have a lot more than 100 cycles on some zippy 3s hardpacks I bought last year. They are fine, still delivering most of the capacity they came with, which was slightly less than 5 ah because I don't charge to 4.2v. My impression of zippies has always been that they have about 5-10wh less capacity per pack, and more sag.

I just took delivery yesterday on a new 5 ah pack based on the 4s turnigy hard packs above. They perform exactly like the zippies from last spring. In other words, they sag like grannies tits just like zippy 20c lico. Both brands require you to have a pretty big pack to not sag several volts in 14s configuration. In a 5ah size, they sag several volts with just a 1000w draw. It's the nature of 20c lico to sag a lot, when used at 4-5c. The sag is comparable to ping used at 1.5c.

They work fine for how I ride now. 1200w dirt bike I tend to ride less than 10 mph while running some dogs. It runs on a 5 ah pack. Or the cargo bike, which now will run a 20ah pack. With 20 ah, much less sag. The cargo bike is 2000w.

User avatar
headwind   10 W

10 W
Posts: 76
Joined: Mar 27 2013 6:19pm
Location: Australia

Re: my experience running LiPo on a commuter bike

Post by headwind » Jan 15 2014 8:27am

dogman wrote:I just took delivery yesterday on a new 5 ah pack based on the 4s turnigy hard packs above. They perform exactly like the zippies from last spring. In other words, they sag like grannies tits just like zippy 20c lico. Both brands require you to have a pretty big pack to not sag several volts in 14s configuration. In a 5ah size, they sag several volts with just a 1000w draw. It's the nature of 20c lico to sag a lot, when used at 4-5c.
Thanks for the info. I read somewhere that Zippys were the "reject Turnigys" at the factory, so it's interesting to here otherwise. As an upgrade, would you recommend the Zippy 25C or the Turnigy Nano 25C (even though they're about the same price at the moment)?
friendly1uk wrote:Your weighing up lipo against lifepo4. Or rather, you think you are. In fact you are weighing up using a bms against using rc chargers. The cell chemistry has nothing to do with the workload you took on by buying the wrong associated electronics.
With all due respect, how is an iCharger 108B, Cellog and CycleAnalyst "the wrong associated electronics"??
Ok, most days I don't take the CA on my work commute. But it's a known distance and well within the battery's range.
friendly1uk wrote:I thought zippy was rated at 100 cycles, so 6 months is about right. Turnigy is 160 cycles. $75 for 12s 5Ah as linked to above. BMS $20-$70 and charger about the same. Then you have the plug and play functionality you want. Should need cells every year or so, but you reuse the bms and charger
In my case, the 6 month lifespan is more related to the couple of accidental deep discharges than the number of cycles, I believe. This is based on the other 6 month old pack still performing fine (I only downgraded it to the spare so that my regular battery would be 2 fresh packs, not a mix of old and new)

To explain the "plug and play" statement in a bit more depth:
- no DIY series/parrallel connections: 12S packs ain't cheap, so many of us are running packs in series. Many casual commuters would be scared off by the mass of spaghetti and/or soldering needed to make up the series connections
- a charger which you just plug in and turn on without needing to know what it’s doing: I'll admit I didn't take into account LiPo BMSes, which I don't know much about. But a LiPo BMS also involves some electronics knowledge to set up, as opposed to a LiFePo4 kit where the battery, BMS and charger is all integrated and ready to go
- not needing to devote your life to monitoring cell voltages: my attitude is to use the electronics to *assist* in keeping the cell voltages in a safe range, but not to rely on the electronics. Horses for courses, but LiPo has a greater fire risk than other chemistries and I'd rather not burn my house down
- the battery is happy to be charged the night before: from what I've seen, other chemistries don't mind as much being left at full charge while waiting for the next ride
- and, of course, less risk of burning your house down if something goes wrong: as others have said, with LiPo you've got to be expecting a fire, especially while charging. Hopefully it never happens, but with the higher stakes of LiPo, I prefer to play it safe.
wesnewell wrote:Might I suggest 3 of these for your 12s pack.
http://www.hobbyking.com/hobbyking/stor ... duct=19499
Wes, thanks for the link. Wow, that's a significantly cheaper way to get 12S than 2x 6S. I've never used a hardcase, is there a way to see if a cell is starting to puff in a hardcase?
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

User avatar
izeman   10 GW

10 GW
Posts: 4916
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: my experience running LiPo on a commuter bike

Post by izeman » Jan 15 2014 9:11am

headwind wrote:Wes, thanks for the link. Wow, that's a significantly cheaper way to get 12S than 2x 6S. I've never used a hardcase, is there a way to see if a cell is starting to puff in a hardcase?
no. you will notice once the hard case is broken in two halfs.
there are advantages and disadvantages of hardcases:
pro: better physical protection
con: you know something's wrong if it may already be too late ;)

User avatar
Ykick   100 GW

100 GW
Posts: 5558
Joined: Nov 26 2009 6:10pm
Location: San Diego, California

Re: my experience running LiPo on a commuter bike

Post by Ykick » Jan 15 2014 9:23am

You can't use RC Lipo without a BMS for long if you don't really watch things for a useful picture of individual cell degradation. In fact, old RC Lipo is particularly difficult to "catch" dying cells.

You can run for months or even years in some cases and one day the pouch ruptures, impurity eats through, etc. If you're not paying attention things can and probably will go bad fast.

I have enough interest in EV battery packs to carefully watch individual cells and keep a close track of anomalies. No problems commuting but it's a lot of work to keep such a close eye on things.

Many users see/read about some of us using these for commuting and think it's all "Sunshine & Unicorns" when in reality we've simply got a fetish for battery cells used in an EV battery pack.
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

- Frank Sinatra

User avatar
friendly1uk   10 MW

10 MW
Posts: 2282
Joined: Mar 14 2013 1:18pm
Location: The not so UK

Re: my experience running LiPo on a commuter bike

Post by friendly1uk » Jan 15 2014 12:14pm

headwind wrote: With all due respect, how is an iCharger 108B, Cellog and CycleAnalyst "the wrong associated electronics"??
It is not the plug and play experience you seem to be seeking.

Picture this if you will. You yourself have a power supply, a charger and a battery. Between the power supply and charger you have one flex. Between the charger and battery you have spaghetti. Rather than undoing all the spaghetti and leaving your charger and power supply at home, why not fix the charger to the bike (it is only tiny) and just leave the power supply at home. It's only one flex to disconnect.

This turn of events is all that separates the bms users from the rc one's. Same wiring.. It is just about where you unplug it every time.

Pity your charger is 6S but you could fit two. They couldn't simply share the same supply, as it would be a short. I think it is just a couple of diodes to make it work though. I would have to draw it to be sure. I will if your eager though.


My pack is also three 4S 5Ah Turnigy Hardcases. They connect to my bms using little balance wire extension leads. One of which I trimmed two wires from with a sharp knife. That was the little wires done. The big wires had banana plugs on, but my bms didn't. So take a banana lead like you might find at school or college, and chop it in half. This gives you short bits of wire with a plug on one end. The other needs to go to the board. Either soldered or bolted if you crimp on an eyelet. The actual BMS is $25 and will give 40amps. The 240w wall charger $30

http://www.ebay.co.uk/itm/like/17120725 ... =95&ff19=0
http://www.bmsbattery.com/smart/330-lif ... eries.html
http://www.bmsbattery.com/alloy-shell/2 ... arger.html


I'm going to draw it as some point. I may edit it in later
bmsbattery sent me broken and incorrect stuff, and won't even talk to me about it.

User avatar
wesnewell   100 GW

100 GW
Posts: 7168
Joined: Jan 31 2011 6:25pm
Location: Wylie, TX, USA

Re: my experience running LiPo on a commuter bike

Post by wesnewell » Jan 15 2014 2:00pm

I've got 1.5 years and ~6K miles on my current pack of 10ah 24s2p. Haven't kept track of the cycles, but it's probably <200. If you don't run them down below 3.5V they should last a long time and a lot more than 200 cycles. They are totally drained with 0% soc at ~3.3V. Running them lower than that will kill them a lot faster.
Need Advice? https://endless-sphere.com/forums/viewt ... =3&t=66302
Mongoose 26" Ledge 2.1 mtb bike $99, yescomusa.com 48V 1000W rear hub kit $200, Hua Tong 72V 40A controller $35, 10ah 24s lipo $217=~43mph, range=45 miles @ 20mph. 25K miles and still going strong.
Huffy Fortress 3.0 with MXUS 3000 4T motor, 24s lipo, 96V 60A controller. Total cost with extras <$700. Top speed ~50mph
My videos https://www.youtube.com/channel/UC0KW4U ... _G2wQhptMg

User avatar
headwind   10 W

10 W
Posts: 76
Joined: Mar 27 2013 6:19pm
Location: Australia

Re: my experience running LiPo on a commuter bike

Post by headwind » Jan 16 2014 6:15am

Ykick wrote:Many users see/read about some of us using these for commuting and think it's all "Sunshine & Unicorns" when in reality we've simply got a fetish for battery cells used in an EV battery pack.
:lol: Very true.
friendly1uk wrote:Picture this if you will...
Thanks for the suggestion. I'm happy with my setup, but your idea sounds like it would make the charging process much simpler.
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 16 2014 7:04am

I will buy turnigy when it's in stock, rather than zippy. This is based on the cells being physically slightly larger, and in the case of ones I bought three years ago, the turnigy had more capacity.

On the other hand, if you were trying to cram 24s or whatever into a particularly small space, the smaller size zippy compacts might be the choice, at the price of an ah or so less capacity.

For sure you can kill good packs in 6 months, that's different in my mind than "6 month lifespan" My first packs of 30-40c turnigy got killed fast. Those got some very high c rate discharges to below 3.5v several times. At the time, I had only 5 ah of it, and pounded those packs hard.

Re detecting packs dying, if you smell that solvent, you know you have a big problem to hunt down. It can be hard to find the one that's leaking. I have taken the whole pack apart, aired it out outside overnight, then put each pack in a ziplock bag. One or more bags will have the stinky pack when you open the bags later.

User avatar
TheBeastie   1 MW

1 MW
Posts: 1832
Joined: Jul 28 2012 12:31am
Location: Melbourne Australia

Re: my experience running LiPo on a commuter bike

Post by TheBeastie » Jan 16 2014 8:21am

dogman wrote: As for killing your packs by leaving them charged all the time, it's not ideal, but it takes much longer than 6 months for that to kill a pack. They will lose capacity from that in 2 years, but not that much damage in 6 months.
I remember there was another post on here about 8 months ago with a guy complaining that lipo is BS because he can't get them to last beyond 50 cycles.
He eventually spelled out his whole charge routine etc and he was charging them up to 4.2v and leaving them for the next day etc so he had them ready when needed.
Once he said that everyone jumped on him and basically said he was being stupid/killing his packs for leaving them fully charged and thats why he couldn't get much more then 50cycles.

I doubt I could find the thread now, but I am pretty sure you were part of that thread.
Speed Kills Range, 10mph = 46 miles range, 20mph = 20 miles, 30mph = 8 miles rangehttps://goo.gl/1JNL53
Over Charging Kills ur battery bit.ly/1hzWKl4
Consider PAS as your only throttle https://goo.gl/Kg1F8F
Fuel-Cell is the ultimate battery coupled with 4th-gen Nuclear
https://goo.gl/TcKtHs https://goo.gl/ZhFFot https://goo.gl/gfa215
10 Square Miles of solar panels = 0.12GW average power! https://goo.gl/Ub1S39

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 16 2014 10:50am

I was charging those first set of lico packs to 4.2v, and storing them ready to ride. At the time, I was working still, and wanted to be ready to go dirt riding when I got home from work in the early afternoon. By the time they would get charged, it would be time to make dinner rather than ride for fun.

Anyway, I saw very little degradation in capacity from either the turnigy or the zippy pack in 1 year. The turnigy pack got used a lot, while the zippies ended up sitting because they were less fun to use due to voltage sag of a lower c rate pack.

After 2 years, both packs had lost at least 25% capacity, and by 3 years, both sag like mad and can only be used at 1c or less. about 50-60% capacity if used at 2c. In the end, I bet I never put more than 30 cycles on that set of 8 zippy packs.

Shoulda put the zippies in the freezer, at 3.7v. At the time, I just thought I still wanted to use them right away if I did break them out.

In summary, I'm sure you can still get one year out of packs kept at 4.2v. If you don't kill them other ways. Kff's, going to below 2.7v when a parallel plug comes loose, 5c use below 3.65v, letting them chafe holes in cells, etc.

Rutiger   100 W

100 W
Posts: 116
Joined: Jan 03 2013 6:04am
Location: Brisbane, Australia

Re: my experience running LiPo on a commuter bike

Post by Rutiger » Jan 19 2014 6:11am

TheBeastie wrote:He eventually spelled out his whole charge routine etc and he was charging them up to 4.2v and leaving them for the next day etc so he had them ready when needed.
Once he said that everyone jumped on him and basically said he was being stupid/killing his packs for leaving them fully charged and thats why he couldn't get much more then 50cycles.
Hmm, interesting. That's something I've not come across in all of my Lipo reading, so I'm glad to see it now.
I was hoping to charge my pack before bed and then just get up and ride to work in the morning, but if that will severely reduce the life of the pack, I shouldn't be doing this.

So how do other commuters deal with this?
Do you get up early and charge the batteries then? Do you do a partial charge and then top the cells up in the morning?

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 19 2014 7:03am

Some have the time to charge in the morning. If so, why not do that.

You could just charge to 4v in the evening, then have a shorter charge in the AM.

Personaly, I'd just put $300 per year into my battery budget, and just charge them in the evening. I think you will get a year for sure, unless you are killing cells in other ways, like physical damage, overdischarge, etc. At some point, you are balancing your life with just some money. Your life wins.

The strategy I'm trying to adopt is 10 ah of new cells each year, giving me a 20 ah pack that is at least half new each spring. Charge to 4.1v if possible rather than 4.2v.

User avatar
izeman   10 GW

10 GW
Posts: 4916
Joined: Jun 21 2011 8:25am
Location: vienna, austria
Contact:

Re: my experience running LiPo on a commuter bike

Post by izeman » Jan 19 2014 7:25am

time will kill those cells more than anything else. at least for me. i just doesn't matter how much you abuse those batteries if you don't ride on a daily basis ;) i'm more the bike builder than the rider. i like to ride my bike once they are finished, but never long enough to come close to battery boundries. for testing my new batteries i charged them to 4.2v and let them sit for a week to see if some cells fall faster then the others. only one out of 120 cells lost significant voltage (0.1v). but personally i would NOT let them sit fully charged for a longer period. charge them to 3.85v and charge to full voltage before i leave. the lower the voltage the lower the damage done in case something bad happens. having a powerful charger helps a lot. if you can charge 2c your bike will have full voltage from 3.85 to 4.2 within 15min. even without a foam bath with candles in the morning :wink: you will need more than 15min from getting up to walking out of the house!

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 19 2014 7:36am

One way to think about it, for a commuter.

You get up, and ride to work, say leaving the house at 7 am. You work all day, and return home, say 6 pm, and put the battery on the charger. Viola! you just had your batteries at less than 4v for 12 hours of the day.

So if you do charge in the evening, with the charge finishing at say 8 pm. you now have your batteries stored at full charge just 11 hours of the day. You just cut the time they sit degrading by 50%. Not too bad. :mrgreen:

The mistake I made was wanting to have them ready to ride at 4.2v all the time, and as a recreational ride the result was days sitting at 4.2v waiting for me to break them out to ride. At some point, like I said, it's how convenient you want it to be vs just money. In a busy life, if there is any money, money loses.

Do some calculations of what other means of getting to work would cost, and you will find plenty of budget for 10 ah worth of new cells each year.

Rutiger   100 W

100 W
Posts: 116
Joined: Jan 03 2013 6:04am
Location: Brisbane, Australia

Re: my experience running LiPo on a commuter bike

Post by Rutiger » Jan 19 2014 8:43pm

Thanks for the replies, that all makes sense.

I will need to do some testing to see how long it takes, but I should be able to charge to 3.8-4ish and then top up in the morning.
My pack will be 30Ah at 12S, and charging 12S with a Hyperion 1420i @ 24v, so I'm guessing it won't take too long to top up.

User avatar
dogman dan   100 GW

100 GW
Posts: 34930
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: my experience running LiPo on a commuter bike

Post by dogman dan » Jan 20 2014 8:14am

Depending on your morning routine, it can be very possible to charge to about 4v, then top up in the AM.

Myself, I never could just open my eyes, jump in pants, and head out. I need one or even two hours of coffee drinking, shitting, even if I don't eat a breakfast. But even if you have the time, it might be worth the cost in lifecycle to just charge to 4.1v in the evening, and be done with it.

User avatar
Ykick   100 GW

100 GW
Posts: 5558
Joined: Nov 26 2009 6:10pm
Location: San Diego, California

Re: my experience running LiPo on a commuter bike

Post by Ykick » Jan 20 2014 8:40am

I normally terminate charging around 4-4.1V/cell and next day when I begin getting ready for work will fire-up a quick top charge to around 4.15V/cell. Doesn't require much time or extra effort - and coupled with ample Ah capacity to begin with I don't even "need" to do it for my usual commute.

Honestly, sometimes I don't get around to terminating the charge early so it finishes at roughly 4.15V/cell and sits overnight or even a day or two. My last batch of recently retired +3yr old RC Lipo had been treated that way. Little, if any, degradation over the long term.

I also performed temp testing on RC Lipo a year or two ago and noticed/recorded a distinct significant rise in cell temperature charging between 4.15-4.2V/cell. So, I merely stay away from the 4.2V/cell charge and concede about 250mAh capacity.
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

- Frank Sinatra

kiwipete   100 mW

100 mW
Posts: 45
Joined: Nov 13 2013 9:40pm

Re: my experience running LiPo on a commuter bike

Post by kiwipete » Jan 23 2014 4:55pm

Like the OP, I run a commuter bike with a 12S 5AH little Lipo pack and have an ICharger 106B. And again like him, I like the bike and lightweight aspect of the Lipo, but not so much the "care and feeding" of the Lipo.

There is the charging and all the palaver that goes with that and also of course you have to be vigilant against over-discharging at all times. The plug-and-play nature of a commercial LifePo4 pack with BMS and a bulk charger is compelling.

So I have looked at buying and integrating a BMS and buying a bulk charger but that has issues too: I don't like the typical HVC and LVC limits of most BMS out there and would like to go more conservative (HVC of 4.1 and LVC of 3.65). But smart/programmable BMS's are expensive or have issues and then I need to buy/make a bulk charger as well.

So what I'm going to end up doing is this:

For HVC control I'll keep my Icharger 106B and will do parallel balance charging and will be using a smaller variant of the really clever "Series/Parallel changing plug/socket combo" as described by member 'Tench' in this thread: http://endless-sphere.com/forums/viewto ... =2&t=39489. This will give me a really simple way of charging (and discharging): At night (or first thing in the morning) unplug Lipo pack, plug Icharger in with two simple plugs only (in my case I'll be using a MPX connector combo for the charge cables and a DB15 for the balance leads) and (assuming you do this in a safe place) you're set. When you're ready to leave, you plug the discharge cables in with one simple plug. This way I don't have to buy any more gear, can set HVC to whatever I want, keep my pack in balance and have pretty much plug-and-play charging.

For LVC control, I'll be using a Cycle Analyst which I have ordered last week, so I can easily keep an eye on things (pack voltage, amp hours etc) and if I want to, use it to control current draw or act as LVC that I can set to whatever I want. It does this of course at a pack level, rather than cell level, but assuming the charging is done as per above, the pack should stay in balance very well.

So it's not totally plug-and-play yet, but things will hopefully be a heck of a lot simpler, with way less 'spaghetti' wiring around the place and less chance of ending up with KFF somewhere down the track.

User avatar
wesnewell   100 GW

100 GW
Posts: 7168
Joined: Jan 31 2011 6:25pm
Location: Wylie, TX, USA

Re: my experience running LiPo on a commuter bike

Post by wesnewell » Jan 23 2014 5:47pm

If you have a typical 48V controller, LVC in it will be 42V. That comes out to 3.5V per cell under load. For a 5ah pack that will result in ~3.65V per cell resting. You will never be able to go below ~4% soc no matter how you try and squeeze that last little bit out. The simplest solution for monitoring a lipo pack is a simple voltmeter.
http://www.ebay.com/itm/Waterproof-Digi ... 0846310527
For charging, a 12s charger makes it pretty easy to balance charge the pack without disconnecting the serial connection. A Thunder 1220 300w charger would charge your 5ah pack in ~45 minutes.
Need Advice? https://endless-sphere.com/forums/viewt ... =3&t=66302
Mongoose 26" Ledge 2.1 mtb bike $99, yescomusa.com 48V 1000W rear hub kit $200, Hua Tong 72V 40A controller $35, 10ah 24s lipo $217=~43mph, range=45 miles @ 20mph. 25K miles and still going strong.
Huffy Fortress 3.0 with MXUS 3000 4T motor, 24s lipo, 96V 60A controller. Total cost with extras <$700. Top speed ~50mph
My videos https://www.youtube.com/channel/UC0KW4U ... _G2wQhptMg

User avatar
crossbreak   100 MW

100 MW
Posts: 2874
Joined: Aug 02 2011 11:20am
Location: Germany
Contact:

Re: my experience running LiPo on a commuter bike

Post by crossbreak » Jan 24 2014 6:30am

I have 4 12spacks: two 5ah, one 10ah and a 20h. All with bms, Most times I use the 20ah for the ~45km commute to have some reserve if something unplanned happens.

My charger can do 15amps, I always charge till one cell hits 4.2V and let the bms cut the power. Some minutes later, the short time switch (for safety) cuts the power anyway. The highest cell has dropped and the balancer does the rest, so they are at ~4.12-4.15V over the night. Maybe I should lower that for the 20ah pack since I dont need the full charge anyway most times.

I charge only on the balcony, since the charger fan is noisy and it feels saver that way.

The 5ah packs are mostly used for shopping by my gf and mother in law... and by me and my friends for basement-garage-racing :D Can be recharged in 15 minutes.

Post Reply