NiMh vs SLA vs Li ion on climbing hills with cargo

[chicbicyclist]

Whoa, new ebike forum...

My SLAs have been in service for almost a year now and will probably need to be replaced soon.

I was ready to order additional ones but was surprised to see them significantly go up in price so I was tihnking of just going with NiMh or Li ion instead. Was just wondering which kind of batteries is more efficient at climbing a 200 ft hills with an extra 100lbs cargo(if you're in Ocean Beach/Point Loma San Diego, you probably see me riding around with my two dogs in a Burley trailer, say hi!).

I'd stick with SLAs if they are deemed more cost effective even with the price increase.

[Lowell_]

How many charge cycles do you expect per year? LiFe packs might make sense if you can take advantage of their longer cycle life.

How many watt hours do you currently use per trip?

[chicbicyclist]

How many charge cycles do you expect per year? LiFe packs might make sense if you can take advantage of their longer cycle life.

How many watt hours do you currently use per trip?

I'm not sure how many watt hours I use per trip but it usually takes about 4 hours to fully charge it back up(out of an average of 6 hours from empty to fully charge).

I expect say, 100-150 cycles per year.

Got any info on these LiFe pack things, a link, perhaps?

I'm a bit wary on Li ions, I'm not too keen on building it myself or tinkering on a very complicated device that could explode while pulling a 100 lbs cargo uphill. I also want is as plug and play as much as possible.

[Lowell_]

http://www.falconev.com/

http://www.cheer-ocean.com/battery2.html

How many SLA's are on your bike, and what is the amp hour capacity? Keep in mind that if you switch to NiMH or lithium, your power and range will be significantly better even with equivalent capacity ratings compared to lead batteries.

[BroadwayJoe]

Industrial liquidators on Convoy st. usually have some 7AH surplus SLA's (backup lighting) for only about $7 ea. They're used and some are better than others so buy a couple extra. Probably not good for high power eBikes but I've used 'em for one of my 400W rides and I'm very happy for the price.

That said - for serious range, output, life and cash go with lithium.

[chicbicyclist]

Thanks for the tips guys.

I already use a 12 ah battery 36volts pack (3 SLA, 12 volts each), used on a 400 watt brushless motor from Wilderness energy. I use everything in the kit aside from the rack with no substitution if that helps any. I'm not looking for an up in voltage or an up in top speed, just something that has the same torque(just not worse) and same(or better) range. The weight reduction and more life cycles are just bonuses :)

I'm eyeing this: http://66.216.117.91/product_p/37v-lithium-8.2ah.htm

I'm still scared about the hazard of exploding lithium batteries though :( Someone tell me that lithiums are safe to use!

[geebee]

I don't know that the ah rate would allow enough current for your system on the uphills there is no data about the pack as in the BMS cutoff current the continuous current rating etc.
You will probally find that a decent SLA will give you the most torque in hi load situations unless you go to a large ah newer chemistry to stop the voltage sag.
LiFe are the safe lithium option with a life cycle in the 2,000 + area according to the manufacturers.

[chicbicyclist]

Do you have the link to those LiFe lithium batteries? Google is failing me.

And yes, my requirements are to haul me up a 200 ft hill over about a quarter of a mile. I'm just not sure if the Li ions and NiMh batts can compare to my stock 12 ah SLAs which can haul me up just fine(with me pedaling on my lower gears, of course).

[geebee]

http://endless-sphere.com/forums/index.php
More info and places to buy than you want to know.
Start with the battery thread. There is an ebay supplier that some of the guys have dealt with happily.
http://www.cyclone-tw.com/ These guys sell them but are out of stock at the moment.

[chicbicyclist]

http://www.falconev.com/

http://www.cheer-ocean.com/battery2.html

How many SLA's are on your bike, and what is the amp hour capacity? Keep in mind that if you switch to NiMH or lithium, your power and range will be significantly better even with equivalent capacity ratings compared to lead batteries.

I didn't see this earlier, thanks for the link!

[Abneycat]

Thanks for the tips guys.

I'm eyeing this: http://66.216.117.91/product_p/37v-lithium-8.2ah.htm

I'm still scared about the hazard of exploding lithium batteries though :( Someone tell me that lithiums are safe to use!

I was just cruising around looking at different e-bike forums and happened to come across this post. This company that makes that pack is actually the LBS for e-bikes around here, while i've used components from them but not their batteries, I know these guys safety test their products.

Not an expert on this, but SLA batteries do well under high stress situations, so I would presume that they are well suited to hill climbing.

One suggestion! While I know you mentioned not desiring more speed, my personal solution would be:

You could switch to 48v, a battery with the same watt-hours available wouldn't weigh any more than a 36v, and as long as you rode it at the same speed it would give you the same range. That would mean much more potential for hill climbing at the same weight, regardless of chemistry.

[cerewa]

check out the info on LiFePO4 (lithium iron phosphate) batteries. All sources say this is a type of battery that is very safe. You would have to heat it to 800 degrees celsius to make it explode, apparently. At 800 degrees, (which is above the melting point of aluminum) exploding batteries are the least of your worries.

google:
http://www.google.com/search?q=lifepo4&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
wikipedia:
http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

[chicbicyclist]

Thanks for the linsk guys. I'm not new to ebikes but this LiFepo4 thing is new to me. Deffinitely thinking of going with the life batteries.







I was just cruising around looking at different e-bike forums and happened to come across this post. This company that makes that pack is actually the LBS for e-bikes around here, while i've used components from them but not their batteries, I know these guys safety test their products.

Not an expert on this, but SLA batteries do well under high stress situations, so I would presume that they are well suited to hill climbing.

One suggestion! While I know you mentioned not desiring more speed, my personal solution would be:

You could switch to 48v, a battery with the same watt-hours available wouldn't weigh any more than a 36v, and as long as you rode it at the same speed it would give you the same range. That would mean much more potential for hill climbing at the same weight, regardless of chemistry.

That makes alot of sense.

I was actually thinking of doing that but the complexities are quite daunting. Would it work with my stock WE brushless hub that is supposed to be suited for 36V? Where do I get the batteries? Do I just add another 12v to a li-ion/Lifepo4 36volt pack?

[cerewa]

Don't add a 12V battery to a 36V pack. Individual cells that are used together should have the same amp hour and voltage ratings. You'd want to buy a 48V pack instead.

I just talked to Jeanne from www.atenenergy.com ... they have 36V and 48V (and other voltages) LiFe packs for sale at low prices... don't buy from the other places linked in this thread without calling them for a price quote first, because they may save you a ton of money. (itselectric.ca USA is selling 36V 8Ah for $399 US while aten energy is selling a better (36V 10Ah) pack at i think $245 plus shipping).

I had to try a couple times to get ahold of aten energy but if you go to their website and call the number shown for Jeanne, she will probably either pick up her phone or get back to you quickly if you leave a message.

[Abneycat]

That makes alot of sense.

I was actually thinking of doing that but the complexities are quite daunting. Would it work with my stock WE brushless hub that is supposed to be suited for 36V? Where do I get the batteries? Do I just add another 12v to a li-ion/Lifepo4 36volt pack?

I would personally just make sure your setup will make the switch without difficulty. I've not got experience in Wilderness Energy, but the worst case scenario is that you'd need a higher capacity controller.

That aside, its not much of a daunting task. You just want to figure out equivalent energy. Volts times Amps = Watt-hours, which is what you'll use to compare batteries at different voltages. Use the solid numbers, then factor in the real world differences.

36v SLA @ 12 aH = 432 Watt-hours. This is your battery,
Remember that if you're used to SLA, the numbers on Lithium will decieve: They'll provide a much more constant power output as the battery runs down, and last longer amp-per-amp overall. You might see your range on an equivalent watt-hour battery increase noticeably.

One of the best things for you in this case, is that SLA will lose hill climbing power as it runs down. Lithium will lose little, if any.

[chicbicyclist]

Thanks for the helps guys. The primary reason why I stuck with SLAs was because the "higher end" battery types were still too complicated/dangerous two years or so ago. These LiFe batteries sound AWESOME and I'll most likely make some calls come Monday.

For those of you using the Life batteries and aren't really tech heads, how smooth was your experience with them(i.e. were they easy to maintain, little problems, etc?).

Cerewa, does that $245 include the life battery charger? Cause that's really cheap O.O

[cerewa]

chicbicyclist-- no, no charger. A post on this thread (http://bikeforums.net/showthread.php?t=326941) says that with a charger and "BMS" and shipping included it's $362.