I prefer lipo only because it's cheaper

[cell_man]

If you get a lifepo4 48V15AH (720Wh) with ping:
http://www.pingbattery.com/servlet/Cart ... d=24782801
- Weight: 7.5kg
- 485$ battery + 119$ shipping (to uk)= 604$ total cost.

If you get 3s*2p (zippy 6S1P at 5AH) you have a pack of 44.4V15AH (666WH)
http://www.hobbyking.com/hobbyking/stor ... _20C_.html
- Weight: 6*0.844g= 5.06kg
- 296.88$ batteries + 85.15 shipping (to uk) = 382.03$ total cost the first 2 years.
- 382.03 * 2 = 764.06$ total cost the next 2 years. (And this total assume that the lipo price remains the same 2 years later)

Ok, at the end you would have lost around 150$. And you also have to pay for additional charger. But you have a weight advantage, you can swap your lipo when needed and after 2 years you have brand new batteries. Also, we should consider that the technology evolve and after 2 years we will probably have better performing batteries.

What do you think of this calculation? Do you expect to use your lifepo4 for more than 4 years? Don't forget that batteries loose its capacity over years naturally (shelf life), so most likely the battery is not going to have much capacity after several hundred of cycles + 4 years in the belt.

The LiFePO4 pack is 8% higher capacity than the LiPo that you are comparing, even though the ping was based on 48V nominal, and 3.2V * 16 or 51.2V is the apples to apples comparison, based on that, the ping has 768, and the LiPo would then have a 15% shortfall. On top of that, you would need to use the LiPo more conservatively WRT charge voltage and DOD so you'd want to use less than the available capacity, at least 10% and more likely 20%. The LiFePO4 already has an integrated BMS, that weighs a bit. Figure in 15% reduction in capacity to keep the lipo happy, a further 8% shorfall in the LiPo capacity, multiply that by the starting weight of 5.06kg and you now have a pack of 6.5kg compared to a 7.5kg ping which includes a BMS and can be charged from a simple charger, if calculated with 15% less capacity and 15% safety margin the LiPo equivalent is 6.8kg. Did I mention LiFePO4 is far less likely to burn your house down.

Now compare 1 of my offerings, apologies for the self promotion, just letting you and others know what is out there. A 12S 20Ah A123 pouch pack. Weight is 6.7kg all in, including BMS and some mechanical protection for the cells. Nominal voltage is stated as 39.6V, but lets call it 38V, it stays above that most of thime even with pretty high power, so lets say 760Whrs. Apply the same 15% reduction in capacity to the LiPO, to keep the cells happy and correct for the smaller capacity of the LiPo in your example and what do you have, the LiPo equivalent is 6.8kg, and that is without any BMS in the LiPo. Even if you use the full capacity of the LiPo, you have an equivalent weight of 5.8kg. A stack of 12 20Ah A123 cells is 5.95kg, if all I did was fit a power cables, a couple of balance plugs and shrink wrap, you'd have a pack of about 6.2kg as a guess.

12S_20Ah.JPG (59.1 KiB) Viewed 548 times

12S_20Ah_weight.JPG (83.44 KiB) Viewed 548 times

The above pack will supply more current than most will ever need and a BMS upgrade for higher current is an option. Drop me a line if you are interested in prices, but they aren't bad at all. I really don't see how LiPo is head and shoulders above those figures, or any other cells for that matter when you figure in everything.

[cwah]

Ok I think you're right. Lipo is not always cheaper due to the added security measure we have to take (complementary AH margin) and in my example I didn't compare same capacity batteries.

I've seen that BMSBattery allows you to choose the discharge current from a lifepo4:
http://www.bmsbattery.com/packs/161-48v ... -pack.html

You can choose from 20A to 100A. Isn't 100A already quite good for performance bike?


And I've just discovered the NiCoMn batteries:

http://www.bmsbattery.com/48v/403-48v-1 ... -pack.html

388$ for a 48V15AH battery. It last 800 cycles and only weight 5 kg. Lifepo4 at 7.5 kg is 50% heavier and is more expensive at 485$.
Isn't this one the best value battery?

[BikeFanatic]

If you get a lifepo4 48V15AH (720Wh) with ping:
http://www.pingbattery.com/servlet/Cart ... d=24782801
- Weight: 7.5kg
- 485$ battery + 119$ shipping (to uk)= 604$ total cost.

If you get 3s*2p (zippy 6S1P at 5AH) you have a pack of 44.4V15AH (666WH)
http://www.hobbyking.com/hobbyking/stor ... _20C_.html
- Weight: 6*0.844g= 5.06kg
- 296.88$ batteries + 85.15 shipping (to uk) = 382.03$ total cost the first 2 years.
- 382.03 * 2 = 764.06$ total cost the next 2 years. (And this total assume that the lipo price remains the same 2 years later)

The Ping includes a charger, and the lipo does not. So cost is now equal. If I were a noob I would go for cell man or ping.

[John in CR]

The Lipo numbers are incorrect in real world use in other ways too. First, multiply cost by 1.1 , since about 10% of the cheapies are bad upon arrival or exhibit a bad cell shortly afterward. Then multiply it's weight, size, and price by 1.2 or 1.3, since you don't dare run Lipo low and need to carry extra. Then as a new Lipo user expect a significant risk of you killing one or more packs from improper handling. What's the average? I don't know maybe another 10-20% as a low estimate.

Now the biggie in terms of value, which is your time. The Lipo lovers have an extra hobby in addition to DIY Ebiking, and it consumes ridiculous amounts of time when added up. That hobby is fiddling with their precious Lipo battery packs, plugging/unplugging, monitoring, inspecting, carefully charging, and endless balancing. Let's call that number an average of 5 extra minutes per cycle, which is probably low especially considering configuring the packs and making changes. Even if you assign a crazy low value to your own time of only $5/hr, that more than doubles the seemingly low initial price.

RC Lipo packs have the smallest form factor of what is broadly available at this time, and that's their only real benefit, other than power density though I haven't seen anyone needing more than A123's power density, and much of that extra volumetric energy density is eaten up by having to carry extra to avoid discharging too deeply. They cost as much or more up front. They carry far far greater risk, and require inordinate amounts of time caring for them in a manner to make them reasonably safe.

These are the realities that make direct comparisons of $/wh or ml/wh or g/wh invalid.

John

[dogman]

All too true. All reasons why price should be part of the decision, but not the first consideration. Put it down around 10th or so on the list. First on the list is stuff like you just said.

Personally I don't spend that much time fussing with the lipo, other than returning it to a safe-ish storage. And I do pay the price, by losing a pack from time to time. I'd rather just buy another pack than fuss with it endlessly. Or spend a fortune on monitoring stuff.

[miuan]

So the 12S4P A123 pack holds about as much energy as 10S2P HK lipo.
While the A123 pack costs $350, the cheapest HK lipo equivalent can be had for $110.
I'm talking the hardcases that are said to occasionally burst on their own. I received 40 of them so far, all but one run great and stay in balance for 10's of cycles. I can easily strap them together with velcro and throw the hardcase bundle in a padded pannier bag.
Unlike the mythical depth of discharge, the time factor IS a biggie, no question here. If it wasn't my hobby, I'd certainly go with a plug n play battery, of which the A123 is a prime example.

[John in CR]

"Mythical DOD"???? I'd like to hear about a cheapie Lipo pack discharged regularly to 90% or greater DOD and lasted even close to 500 cycles. Don't forget the 3-4X that balancing time goes up. BTW, fiddling with batteries has to rank up there with watching grass grow or paint peel as far as hobbies go.

[French]

I have one of Cell_Man's A123 52v 11.5ah triangle packs for both myself and my wife's bike. I have two chargers, so after the ride I simply hit the switch of the charger, plug it in, come back 1-2 hours later, unplug, and turn off. It costs me about 1 minute to charge both bikes. These batteries should last us 5 years+, as we casually ride with our little kids 2-3 times a week for about 10-15 miles per session. I know that I paid a good premium for the battery packs, but the simplicity is priceless and the weight savings/performance value vs. Lipo in my opinion are marginal at best in my situation.

My life is busy enough, I don't want to worry about setting my house on fire, or myself should I crash!

In the end, to each his/her own!

[mvly]

I just prefer Lipo because of the configurability. I am sure if you contact cell-man and give him a dimension and he might be willing to customize your battery exactly to the dimension you give him. However for me, I would like to add/delete cells and check them out once in a while. I know that a BMS can do that for me, but after reading a lot of stories about failing BMS and having a defective BMS myself, I would prefer to complicate the charging a bit for better maintenance of the battery. John is right about all the increase in price of Lipo if you factor in all the disadvantage of Lipo. But as for now, I think I will save my money and wait for LiMn to get cheap enough. It's proven to be better and lighter than LiFePo4.

[neptronix]

"Mythical DOD"???? I'd like to hear about a cheapie Lipo pack discharged regularly to 90% or greater DOD and lasted even close to 500 cycles. Don't forget the 3-4X that balancing time goes up. BTW, fiddling with batteries has to rank up there with watching grass grow or paint peel as far as hobbies go.

95 cycles and counting to 90% DOD, only needed to balance them twice so far... actually the second balance was not needed at all. Still delivering the full 5AH.

RC Lipo is great. Sort out the duds from the studs, treat them nice, and you can bulk charge to 90% DOD ( 5% off the top, 5% off the bottom ) for hundreds of cycles.

Nothing beats them for the weight/size/energy. If i was a daily commuter, my second choice would be the A123 cylindricals though, as i'd be up to about >300 cycles by now.

[sk8norcal]

I have one of Cell_Man's A123 52v 11.5ah triangle packs for both myself and my wife's bike. I have two chargers, so after the ride I simply hit the switch of the charger, plug it in, come back 1-2 hours later, unplug, and turn off.

is it necessary to unplug the charger ?
I think I will forget to do that half of the time....

[veloman]

If you want to get your bike running, not have tons of headaches and buying extras all the time, go Lifepo4, hands down the best choice. Ping even includes a charger. Plug and play. If you want a challenging hobby, sure lipo and makita lith-ion cells are a good choice.


Factoring in your labor time, lifepo4 is by far cheaper if you are just starting out. FAR FAR cheaper.

[French]

I have one of Cell_Man's A123 52v 11.5ah triangle packs for both myself and my wife's bike. I have two chargers, so after the ride I simply hit the switch of the charger, plug it in, come back 1-2 hours later, unplug, and turn off.

is it necessary to unplug the charger ?
I think I will forget to do that half of the time....

I leave the chargers plugged into the wall.

When I said unplug / plug, I meant from the charger to the battery and not from the charger to the wall.

[999zip999]

Just put it on a timer and walk away. Yes I would keep my charger unplug or on a timer to cut the power to it if not in use.

[veloman]

Just put it on a timer and walk away. Yes I would keep my charger unplug or on a timer to cut the power to it if not in use.

I use a surge protector that has an on/off button. As soon as it finished charging, I unplug from bike and flip the switch on the surge protector. If i leave my charger on it stays a little warm. Best to be off when not in use IMO.

[cwah]

Just an update on the batteries specs:


- Lipo are still the best in term of performance, especially with the new zippy compact. Even at 85% usable capacity it still top at 150wh/kg. It's however the most expensive now.
- NMC are the cheapest one. Too bad about the low C rate
- A123 are much more expensive, but has the most value on long term because of its cycle life.

[Pure]

It really depends on your needs. If you want safety, then go LiFePo4, if you want high rate of discharge and up front savings, go LiPo. If you want both safety and a high rate of discharge, go A123. Price isn't as important as having a battery that fulfills your requirements.

My only complaint about paying through the nose for A123 (and other safe chems) is that with the way battery tech is evolving, and prices are going down. You pay for a battery that can last 5 years, but is out dated and worth half (new) of what you paid for it in 2-3 years.

[cwah]

For me Lifepo4 is "expired" now. Why get the heavy lifepo4 when you can just get the A123 that have higher volumetric density (wh/kg) and higher C rate? They are both as safe.

And lifepo4 is barely cheaper than A123. So I don't see why I would ever get them.

[veloman]

It really depends on your needs. If you want safety, then go LiFePo4, if you want high rate of discharge and up front savings, go LiPo. If you want both safety and a high rate of discharge, go A123. Price isn't as important as having a battery that fulfills your requirements.

My only complaint about paying through the nose for A123 (and other safe chems) is that with the way battery tech is evolving, and prices are going down. You pay for a battery that can last 5 years, but is out dated and worth half (new) of what you paid for it in 2-3 years.

Are prices falling that fast? I am skeptical.

Isn't a123 just a brand of lifepo4?

I do think a123 is the best all around ev battery. I got a cellman pack, haven't used it much yet though. My "2c" lifepo4 with about 200 cycles on it is doing great.

[Pure]

Perhaps not that fast but it does seem to constantly be evolving/getting better. I know the LiPo of 2 years ago was twice the price and dangerous as hell, with crap discharge rates.

[Philistine]

Everytime I see this thread topic I laugh. It is like having a thread titled "I only like having Sasha Grey as my girlfriend because she makes a really great cup of coffee". The cheapness (or otherwise) of lipo is probably the very last consideration I factor in when choosing it as my preferred chemistry.

Don't get me wrong, I like cheap (and I like good coffee), but there is a few things I am really enjoying before I get to that.

[nechaus]

I do like nanotech for the weekends, have friends that come over and drain my batteries, i can charge them super quick and go again.

[Pedrohlt]

I think you're all forgetting about headways. you can get them at 1.3usd per Ah from the factory. So for a 12S1P of 38120's you get 39,6 10Ah nominal and able to 10C discharges and 5c charges rates witch is good for most people.

Just to compare:

12S1P of 38120's : 39,6v 10Ah - 396Wh - 3.96Kg - 156USD (just the cells) - about 2.53Wh/$ - 1000~1500 cycles

10S2P of Turnigy LiPo: 37v 10Ah - 370Wh - 2.66Kg - 142USD (just the packs) - about 2.60Wh/$ - 400~500 cycles

so lipo is about 37% lighter and a bit cheaper, but you still have the plug'n'play of the LiFe(with a good bms of course), the safety and twice or more lifecycle at almost the same price.

[dogman]

I like both, lifepo4 for one type of use and lipo for another.

Right tool for the job is the logical choice. Decisions based entirely on cost are stupid. Cost per cycle is a factor, but not the most important thing to be considered.

When I want to rip a 16" 2x6 into 1x2's, do I choose a sawsall? No, I use the right tool, a table saw. Same logic should be how you choose your battery, your controller, your bike, your motor, etc.

[electr0n]

Last year when I was looking to replace my tired 8 amp hour nicad.I was considering between a ping and the lipo's from hobby king. I already had a 48 volt pack and I wanted to go up in voltage to 72 to increase my performance and reduce the weight I was carrying. I ended up going with the lipo because it was a less expensive up front cost among other things. I got an Icharger, some silicone wire, a bunch of connectors and 3 zippy 8 amp hour 6s batteries plus shipping to Canada for a little under $500. At the time I was only running a little 20 amp controller but event that would have required that I got at least a 15 amp hour ping. So comparing the 60v 15 amp hour ping that's almost $700 before shipping. It's quite a bit more expensive up front. The pings would also be quite a bit heavier too and the low c rate sucks. Now that I'm using a 40 amp controller the pings are completely out of the question and I plan on moving up to 60 to 65 amps soon.

I've been running my lipo's just about every single day for almost a year now. Half the year I've been discharging down to about 22.8 and charging twice per day. My batteries are still performing well enough. I'm pretty happy with my lipos and plan on getting more soon. I would like to give the a123's a go but they are pricey up front. One thing I don't like about the lipo's is the charging. I charge one pack at a time and I balance charge every single cycle because I don't want to have a fire. One big benefit to the lipo is the modularity. I really like how easy it is to add or remove packs to increase voltage or amp hours.

Anyone running a123's and have gotten close to 1000 cycles or more? I figure I'm probably somewhere around 300 to 350 cycles on my lipos and still going good.