Present State of Batteries, Best Lifetime Value?

[bobotic]

Hi,

I've been reading quite a bit on this subject, here and elsewhere for a couple days. As someone relatively new to EV (e-bike to be specific), the information and choices are daunting... SLA, LifePO4, NMC, flat foil packs, round cells, building from hobby LiPos, etc. What's tough is some information is great but it can be dated by a year or two and this seems like such a rapidly evolving space in terms of tech and prices that what applied a few months ago likely doesn't apply as much at present.

My vehicle is a e-bike, so feel free to move this post to that forum, but I figure this was more of a battery specific question that was somewhat vehicle agnostic so I would post it here.

After buying a pair of those cheap 48v 1000w direct drive hub kits off ebay I was initially planning on buying SLA batteries... they were cheap (at least upfront) and the weight savings, while important, was not important enough to me personally to pony up 3x as much for a lithium based battery. After doing more research I started reading that some chemistries can have 5x the cycles. Other articles indicated that a 12AH SLA would provide less range than a 12AH Lithium counterpart. I figured AH was AH regardless of the source, but I'm no expert in this and still learning. These two factors change things a lot, because if one can truly expect 5x (or more) cycles and/or if the same capacitance in Li based batteries does provide more range then it makes sense. Coupled with the weight and form factor advantages it becomes all but a no brainer.

The initial outlay for these batteries is quite steep though and I'd be concerned if I'm investing so much into batteries that is the right battery. I use LiPo all the time for RC, but never in sizes like this. But I have enough experience to know that it is not uncommon with the value oriented (and sometimes with the more expensive ones) to get failures, puffy packs, etc - at least in LiPo and especially in the foil flat packs. At $5 - $20 its cheap enough to retire without being too annoyed. At $200, $300 or $500 that would be painful. And since I have two bikes to power I would hate to think about replacing buying another pair any time soon.

A lot of what I've read suggests LifePO4 is still currently the best battery in terms of value and performance, at least for an application like mine, would that be correct? Or would you suggest looking for another type of chemistry or technology? There seems to be a lot of really good cells out there also, and I'm not opposed to building my own packs as I've done a lot on smaller scales, but I see a lot talk about fake or subpar cells and I can't seem to find retailers selling certain cells at prices some are claiming. As much as I would like to have the time to buy recycled laptop batteries and build a pack I just don't think I have the time or fortitude to test all the cells and have the confidence in them being stored in my motorhome while I am sleeping.

At this point in time the best priced battery has been one on ebay (albeit from China) for a 48v 12AH for $230, and is only described as a ebike Li-Ion, so I would hope it was LifePO4 as opposed to LiPo, but who knows.

I guess the ultimate question is, for someone making their first battery purchase at this point in time, which solution has the best watt/dollar ratio over the course of the lifetime, and can anyone recommend any suppliers that have good prices and quality? If there was a quality pack available that had the 1000 cycle life I see claimed at under $2 per watt hour that would be a pleasant surprise, but everything I've seen so far makes me believe it is wishful thinking. :?

Thanks!
Bobo

 

[kdog]

Hi bobotic
I guess it's true that you can get good cyclability out of LA, if you are using it for say running a small light, but heavy deep draw on an e bike is not their domain. You will find a dramatic drop in capacity and cycle life running them hard. You are on the right track though with lifepo. It is a stable chemistry with ~2x cyclability of Li-ion ( although that is changing) With your requirements I would suspect a low rate battery say from ping would do , but Check them out I've not used them. Lifepo will give you years of service if used within its capabilities.
Cheap ebay batteries like the one you suggested are not the way to go IMO. It's likely to be made of cheap 18650 Li-ion ( not lifepo as you suggested) cells that won't cut the mustard in terms of cycle life, or could fail within days/weeks etc. but post a link for a better review.
Buying cheap lithium is a gamble with the odds in the house's favour.
Overall if lifetime and cost are most important, then lifepo would be the winner of all chemistries, far outweighing LA in the long run.
Kdog

 

[dogman dan]

The cheap lithium is definitely a gamble. One I just took, btw, and I'm a long way yet from knowing if that was a dumbass thing to do or not. But I have 48v 15 ah of lipo, and 48v 13 ah of NMC in the house, so I'm not totally hosed if my cheapie battery dies off early. Actually, if it lasts only two summers, I'll be happy enough because I got it so cheap.

One thing about the cheap battery, it's highly unlikely to have such great cells inside that you get the full rated AH from it. So you need to make 15 or even 20 ah the minimum size when you throw the dice on a cheap pack. Your 1000w kits have medium powerful controllers, so you can't buy a small cheap pack, and expect those cheap cells to handle it. Go big.

A much better plan, at least for one of your batteries, is to get a quality pack. Grin Cycles, EM3ev, for example. Trusted vendors that have a long track record for insisting on quality in what they sell. From them, you could go as small as 10 ah, but 12 or more would be much better.

The best lifetime value is going to be good cells, whatever the chemistry, and big enough to where your bike motor is not stressing the shit out of the cells. Since 20 ah of NMC is as light as 15 ah of lifepo4, the 20 ah NMC might work better.

Lastly, if you live in a really hot place, forget getting huge lifespan out of anything. A hot garage can kill any battery in 2-3 years.

 

[Triketech]

I recently did some contract work at a firm that makes airplane components, Lithium starting batteries included - although that wasn't the product I was involved with.

I had a chance to learn some pretty interesting tech info from their development curve. LiFePO4 batteries were quite superior in cycle-life over other chemistry when subjected to heavy current discharge loads even when the OEM rated discharge rates were higher for the non-LiFePO4 batteries. LiFePO4 batteries also tend to respond better at temperature extremes as well.

Then there is the added weight of LiFePO4. I run a 48V 10ah 13.2 Lb LiFePO4 rack mount; the same rack mount filled with Li-Ion 18650's 48V 10ah weighs in at 8.4 lbs. The Li-Ions have a little more volt sag but the 5 lbs advantage is nice to have even though the cycle life is less the half the LiFePO4.

 

[wesnewell]

At 15 mph, you won't use more than 15wh per mile. Multiply nominal voltage times ah to get the packs wh's. As an example a 10ah 44.4V (12s lipo) pack is 444wh. So with such a pack you should get a range of ~30 miles on flat ground, no wind, and no pedaling. If you pedal along with it, you could double or triple that depending on how much and hard you pedal.
Cycle life is subjective. Most lifepo4 packs are based on <1C discharge and charge rate (usually .2-.5C). So don't expect to get the stated cycle life if you are pulling a greater C rate from the pack. A typical 48V 1000W kit comes with a 26-30A max controller, so with a 10ah pack, you may pull up to a 3C discharge (amps divided by ah). Really boring crap, but essential to understanding life expectancy.
Anyway, when considering a battery pack, if you make sure the pack is rated to output the max amp rate of your controller (motor size doesn't matter at all) then you'll be safe. Personally I don't even consider all that weak crap like lifepo4 and 18650 li-ion cells (best used for flashlights imo). Most are rated for 3C at best and <1C at worst. I want a powerful small, light battery at an affordable price. That's why I went with rc lipo years ago and have never regretted it to this day, some 4+ years later. I'm on my 4th year and 12K+ miles on my current 20C 10ah 88.8V pack using a 40A controller.

 

[999zip999]

Lead is dead. A battery is the heart of the system, the main thing.
It would help if we knew where you live.
Do Not use lipo hobby batteries, lot of work. Look up lipo fires.

 

[Hillhater]

Battery choice depends on many things.
As with most of life choices , it usually requires some compromises between your priorities.
EG.....
Up Front cost ( cost to buy)
longevity ( and hence life cycle cost)
reliability
weight
capacity and output ratings
size/shape
Safety
availability
support
ready to run or DIY assembly
etc, etc

There is no one combination or solution that is right for everyone...

 

[rsilvers]

I tried to start a database in another thread of what battery you have and how many Wh it really is as measured by a CA, but no one posted in it.

Until we have dozens of data points, no one really knows - or at least is not saying.

My Chinese battery was $407 delivered and ended up testing at 820 Wh. That is a solid 2 Wh per dollar.

There is no way that any of the premium batteries from trusted suppliers can touch that because they follow laws on shipping and I found out that mine did not. Also, I don't know is how many lifetime Wh per dollar mine is vs a trusted one.

 

[ecycler]

It sounds like you are trying to calculate the area under the curve for cost per watt-hour when delivered over the lifetime # of charge and discharge cycles until the battery is for practical purposes 'used up' for given chemistries. A large, high quality LiFePo4 battery w/ BMS ran at 1C-1.5C max discharge rate is going to be the clear winner. If you run it at higher currents, though then all bets are off.

 

[Hillhater]

It sounds like you are trying to calculate the area under the curve for cost per watt-hour when delivered over the lifetime # of charge and discharge cycles until the battery is for practical purposes 'used up' for given chemistries. A large, high quality LiFePo4 battery w/ BMS ran at 1C-1.5C max discharge rate is going to be the clear winner. If you run it at higher currents, though then all bets are off.

Yes, there are huge variations in life expectancy (and capacity degradation) for any cell chemistry depending on the charge/discharge rates, depth of discharge, ambient temperature, etc.
For example,..your typical LEad car battery may last years ( many thousands of "cycles") in normal use just starting the motor a few times a day and being recharged immediately.....but use that same battery as on a golf kart with long, deep discharges, and see how long it lasts !
The same applies to any Li cell and is why users like Tesla have controls to limit the charge level and depth of discharge to keep the cells in a safe " long life" zone of operation , and as a result can offer a 8 year warranty on the pack.
So, it makes financial seance to oversize the capacity of your pack to ensure you don't prematurely kill it or distort a significant portion of its capacity.

 

[dogman dan]

Over size for the win, if you want the maximum lifespan. all chemistries. The lower you can get your continuous c rate the better, even if you have crazy high c rate lipo.

My personal best cost per mile was a pingbattery lifepo4. Mostly because I got it cheap, when the cells were not as good. V1 ping. I oversized it some, 20 ah, and it lasted 3.5 years, going about 700 cycles in 8000 miles.

My second ping only lasted 2.5 years, and because of my health, I did not use it near as much. It was 15 ah, but V2 cells. That battery got abused some, so I was very happy it lasted even that long. But cost per mile was way more.

RC lipo, bought for bikes that would abuse it some every ride, I get about 2 years from those. Those off road rides are tough on the batts, and not very long. So cost per mile is horrible. I cycled several thousand dollars worth of this stuff through race bikes, and dirt bikes.

My current Allcell battery is doing fine after a year. It never really put out 13 ah, but still puts out about what it always did, 12ah. LG cells in there, NMC or something like that. I never bothered to track cycles or miles. But it's done a lot of trips to town. Expensive battery, so cost per mile will never be close to that original Ping. But it looks fine after a year of lots of use. I should have bought the 20 ah, I'd like less sag under load.

Just bought a 48v 20 ah cheapie, too new to tell if it's going to last. Puts out 18 ah. Also NMC or something like that. 2 years from this one will make me very happy.

 

[999zip999]

Don't match battery to controller and motor kit. But over the top match your battery pack. Why run your battery at it's limits and above ?

 

[wesnewell]

I have no idea what that means. The battery pack at a minimum should be able to provide the max amperage of the controller. The motor size does not matter as only the controller draws power from the battery. If you have a 30A controller, your battery pack should be rated at a minimum of 30A peak loads, but the higher the better. I'd want a pack capable of 30A constant with peaks to 40A for a 30A controller as a minimum.

 

[bobotic]

Thanks everyone, great info. I'm definitely trying to find that right buffer between upfront cost and lifetime value. Lead is out of the question. The lithium packs from China have a price I can live with, but it is a crap shoot, but even more importantly I don't see myself waiting up to two months to start using this bike while I wait for a battery. The US suppliers seem like the best bet, but I'm running up against the price and I need two batteries (one for me, one for wife). I get annoyed when I get taxed $7 for a 9V when I'm in a pinch and have to run to the corner store, so you can imagine spending over $1,000 on batteries for me is hard to swallow even if I found the money it in the couch cushions (I wish, lol).

To be honest I've seen a lot of people on this forum are having success with the RC Lipo packs and the price to performance seems like the best. The original reason I was not considering it is was because a lot of the "choose the right battery" type of articles elsewhere on the web it seemed to infer that Lipo had a similar cycle life to SLA... like it was just SLA without the weight. But it seems like people are putting a lot of miles on those, more than you'd get from SLA from what I understand. I'm aware of the dangers of Lipo, I run a lot of different packs in planes and quadcopters, and I have on occasion abused packs of all sizes and the worst I've ever had is a swollen pack that needs vented. Being a cheap skate I still abuse them when they have some usable life left, because capacitance drops significantly, but I've never had any fires or anything, but I always charge sketchy packs in the garage on the concrete floor. I know the bike pack will have a lot more potential and make it more dangerous, so I'll be treating them a lot more respectably and maintaining it.

Being DIY enthusiast I will admit that building a pack from reclaimed 18650's looks interesting and economic (cost of time removed), but even after reading the mega thread I still have some questions.

The other option I was considering, which is pricey in relation to my budget and needing two of them, is the Li-Ion NCM battery from BMS. $400 for a 48v 20ah seems like the best value I can find from a US retailer at this point for plug and play.

So many decisions...

I'm leaning towards a Hobby Lipo since it won't be a lot more than I would have spent on SLA from what I see... that go with the Li NCM battery. I suppose always do one of each too since I need two batteries. I'll still explore building a pack at some point, but I'm hoping to get my kit on the road asap and I can work on a backup pack more leisurely.

 

[rsilvers]

I don't see myself waiting up to two months to start using this bike while I wait for a battery.

Delivery took me 10 days, and that was only because it was not in stock. Normally 7 days.

48v 20Ah for $400 from a US supplier? Which battery do you mean?

 

[bobotic]

Sorry, I was mistaken... I thought BMS was selling a NMC battery but it actually appears to be LiPo (Li-Ion NiCoMn). The chemistry listed is what made me think it was NMC at first glance. Edit: I was also mistaken that BMS was a US retailer. I have never seen a Chinese supplier have a website that didn't look like was built 10 years ago and was fully written in English.

I hoping some with more experience can confirm this... but it appears under typical ebike applications (3 - 5C) that LiPo can achieve a similar cycle life as packs made with 18650 and perhaps even NMC. BMS states that the NMC are good for ~800 cycles. I've read that LiPo is rated for ~300 cycles under hobby (high C) use, but the theory is that under low C and low discharge it may be as high as 500 - 800? Does this sound feasible, anyone have any real world evidence to back this up?

The reason being is if LiPo under ebike application can get close to 500 cycles it starts to make it real win for me in terms of price, weight, performance, etc. LifePO sounds like the best lifetime value for sure. But the only price reasonable enough for me to afford right now would be a 48v15ah from China for $338. I just don't want to wait for it cross the Pacific and especially if it doesn't perform well. I'm also not sure if the 15ah lifePo will be underer powered for a 1000w hub. I'm sure it will be fine in my use (I like to pedal) but I know the LiPo can handle it for sure.

I think that leaves my options for right now as LiPo and 18650 based packs and I'm thinking that LiPo is probably the way to go.

BMS sells as 48v15ah pack with BMS unit and charger for $289 (https://bmsbattery.com/ebike-battery/248-48v15ah-li-ion-shrink-tube-ebike-battery-pack-ecitypower-battery.html).
The strange thing is it lists the current as 30amp (2c), and with most liPo being 10 or 20c I would expect it to be more like 150 or more. They sell the "High-C" version for $309 but it has no charger or no mention of a BMS unit. I'm not sure if the High-C version is a gimmick and the regular version is the same but neutered on the output, or if they are different cells being used. Thoughts?

The other option is to buy packs from HK. I can get 2 x 6S 16000mah = 12S (48v?) 16ah for about $240. I believe the BMS battery uses 13S though. My LVC I believe is around 41v, so I think with 13S I would need a different LVC solution to prevent over-discharge.

I suppose I could get a 7s and 6s pack, but then I'm back to reading for hours again making sure I know how to charge and balance different sized banks, lol.

At this point it is looking like LiPo is the best option for my present situation. I just need to make sure I am purchasing the right LiPo setup. That setup from BMS for $289 sounds pretty appealing, but the low C worries me and I'm not sure if it is actually LiPo like it says and not 18650 cells.

 

[rsilvers]

There is no point in listing BMS prices without adding in the shipping cost.

My 18650 pack is $425 with 7 day air shipping, 48v 20 claimed Ah.

If LiPo was the way to go then Tesla would use it. Though maybe they just don't like the fires.

People report two years at best with hobby LiPo. Not sure how many cycles that is.

 

[bobotic]

I was under the impression BMS and another retailer I was looking at were US based because they were on a list of US suppliers I found somewhere. I can't really afford any of the Li batteries I've seen available from US suppliers so far. If anyone knows of one selling a 48v15ah for around $300 let me know.

I guess this makes my mind up for me... I guess LiPo is really my only viable option to get a Li setups on both bikes and do it without waiting for it to cross the ocean on a boat. I can either go with a 12ah config for $180 or a 16ah for $240.

I don't have a 6S lipo charger though, so I'll need to get an Imax for $20 off ebay. That still means I would need 4 of those to charge each of the four 16ah packs. Seems like a PITA to setup and charge compared to just plugging a charge cable into the pack. No free lunch, I know. I could get a single charger but that sounds even worse having to remember to come back at a certain time and hook a different one up and rinse repeat.

On my smaller RC lipo packs I can bulk charge several packs at once and is slower but I don't mind because I do it overnight. I will balance the packs individually once in a while just to make sure they are good, and they always are for the most part. The wonky and puffy packs that got abused I will balance charge every time.

Is there any cheap charger out there for 24v or 48v that will handle LiPo? Can I use just a regular car battery charger, or? I wouldn't use it every time, but so long as the cells are staying balanced I don't think it would be any issue.

Or, anyone have any sources for a reasonably priced BMS that can run a pair of 6S1P packs? That would solve all my charging issues if there is a reasonable 48v charger on the market.

Thanks!

 

[Lurkin]

What price do you put on your time?

Pay more now, less upkeep and risk ever after.
Pay less now, more upkeep and risk ever after.

How long would it take you to save the difference between Lipo and a 18650 pack?...

 

[kdog]

maybe take a few moments to reconsider your last statement...
'can I use a car charger to charge my Lipo?'
If your goals are still cost, cycle life and your house then I would say stick with Lifepo

 

[bobotic]

If LiPo was the way to go then Tesla would use it. Though maybe they just don't like the fires.

From everything I've read LiPo is clearly the way to go in terms in power density, current output and price. But that is only half of the equation in a production vehicle, be it a bike or a car. Things have to be as maintenance free as possible also. LiPo does not fit that half of the equation unfortunately. There would be too much maintenance either for the customer or dealership.

While it is not ideal, I don't have a problem with putting the packs on a balance charger and monitoring cell health if it means I don't have to use SLA's. When I purchased my kit I saw a lot of bikes coming with SLA's and (surprisingly based off of stuff I've read here and other forums) a lot of people have been content with them so I figured I would be also. And heck, maybe I would be, because I like to pedal my bike (but just want to go farther and faster with the same amount of pedaling)... but I dread the idea of spending $100 for lead for each bike only to find out I don't and now I'm $200 further away from getting Li batteries.

I'm convinced LifePO has the best lifetime value, I just wish the initial outlay wasn't such a large investment and I wish there was a domestic source that would allow easy return or warranty claims on such a pricey investment. I haven't found any NMC sources in the US either that in the same ballpark as the overseas counterparts. In fact, I don't recall being able find any regardless of price.

It seems my only option for getting these bikes powered in the next week or so is to go with LiPo. I can power both bikes with a 16ah pack and get a 4x6S balance charger for $260 each and be able to get a lot of use out of them. If I go with 10ah that price is closer to $200 ea (saw those 6s10ah packs were on sale for like $30/ea a while back... wish I hadn't learned about it as it makes me cringe thinking I could have build a 20ah pack for $120 or had 10ah for both bikes for the same price).

 

[bobotic]

What price do you put on your time?

Pay more now, less upkeep and risk ever after.
Pay less now, more upkeep and risk ever after.

How long would it take you to save the difference between Lipo and a 18650 pack?...

Do you have a link for a US supplier using 18650 cells? I couldn't find one. If the prices between those comparable I would definitely go with Li-Ion, but everywhere I checked it was overseas delivery or bust. IIRC I think I found a listing for someone building to spec but they were mucho expensive also.

 

[nutnspecial]

Bulk charging lipo is the way to go imo. Teslanv sells MW hrp's cc/cv supplies that are working excellent for me and others. In my experience, you'll only need to balance if you draw them too hard or low, or if the packs are subpar from the factory.
3 of my 8packs have 1 weak cell, which I occasionally have to balance with the rest as they drift. To balance, I mostly use a gophert 0-30v supply and directly charge the occasional low cell. My I606 balancer takes sooo much longer because it tries to charge all the cells, then bleed off the high ones, plus if you want to charge the whole pack, it's a pita to reconfigure all to parallel, and then the balancer just doesn't have the current for price vs the meanwell hrp.

There are threads for 'gophert' and 'teslanv hrp' -should be easily findable with those keywords.

And btw, I'll second the lipo, nothing like it for weight, power, price. More of a learning curve over a bought pack though, at least for a newcomer like myself.

 

[bobotic]

maybe take a few moments to reconsider your last statement...
'can I use a car charger to charge my Lipo?'
If your goals are still cost, cycle life and your house then I would say stick with Lifepo

You took my statement out of context. I was basically asking if there are decent solutions to bulk charge healthy and balanced packs. If this was for 3S or 4S I would already know the answer, I just haven't ever charged anything 48v, I don't know what type of chargers are available and reasonable for such a task.

Like I said, I balance all of my LiPo packs reguarly, but I bulk charge them probably on the order 5 or 10x as often as I balance charge them. If they are staying balanced they aren't going to go out of whack bulk charging them. Just FYI all of my LiPos get charged on the middle of concrete pad and on the larger packs I put a steel box over them. I'm not concerned with the safety of LiPos because I am familiar with them from years of RC plane and more recently quadcopter use. Now making my own pack from used 18650 cells... yes, since I have no experience outside of what I've read I would be apprehensive about testing, sorting, wiring and monitoring them. I'm sure that would become a non-issue as well once I become familiar with it through hands on experience. It sounds like a fun project, just not today.

 

[rsilvers]

If LiPo was the way to go then Tesla would use it. Though maybe they just don't like the fires.

From everything I've read LiPo is clearly the way to go in terms in power density, current output and price.

Nope. The best 18650s have 1.75 times the watt-hours per gram as hobby LiPo:

https://www.youtube.com/watch?v=adfydRg8PYU

As for price, I paid $407 delivered for 48v 20Ah. They just raised the price to $425.

http://www.aliexpress.com/item/48V-20AH-Electric-Bicycle-Lithium-Battery-with-BMS-Charger-Rear-rack-Aluminum-battery-48V-1000W-Samsung/32309134019.html

LiPo:

http://www.hobbyking.com/hobbyking/store/__61510__Multistar_High_Capacity_6S_16000mAh_Multi_Rotor_Lipo_Pack.html

A pair of them would be 710 watt-hours for $270.67 delivered. That would be like $366 delivered if it were the same capacity, which is not much cheaper than $425 considering that the 18650 pack comes with an aluminum enclosure, a key-lock, a mount, a BMS, a charger, and basically no risk of fire. I can't think of any reason to use hobby LiPo unless you are drag racing and need a very high C rating.