Battery Confusion

[JJB]

EDIT: My original post was a little long winded. Here's the abridged version:

Distance requirement: Ideally 30 miles; min 20 miles.

Terrain: Mix, but probably evens out to about average.

Speed: 20-25 MPH on the flat.

Tech: Leaning toward lithium of one variant or other.

I have a much better idea of what I'm going to need since originally posting, but I have one remaining question, that I guess I need to setup as a hypothetical. Lets say we have two batteries of equal capacity, but one is 36v and one is 48v. For the sake of argument, lets say the 36v tops out at 20 mph, and the 48v tops out at 25 mph. If both batteries were run at 20mph (i.e. 36v at 100% max speed and 48v at 80% max speed), would the efficiencies be the same, or would the 48 use less power at 20mph when compared to the 36v?

 

[katou]

Start with a budget, and a distance.

Buy from a known (to us) supplier. I send everyone to ebikes.ca, no affiliation, everyone raves about them.

Buy lithium if you can, Nimh or Nicd if you can't.

If you have more accurate questions, we can answer better. I guarantee at least 15 people read your post, but because they couldn't see a clear question, they just skimmed and moved on.

Katou

 

[JJB]

EDIT: See the edited original post.

 

[swbluto]

More information: speed, distance and terrain.

Assuming 20 mph on almost all flat land which you'd get about 20 wh/mi., that suggests you'd need a minimum of a 30*20 = 600 wH. That is, 36v*20Ah = 720 would be sufficient. 48V*20Ah would also work, given that you moderated your speed likewise. The more you pedal and the slower you go, the less energy/battery you need. Even if you pedal at 18 mph, you can cut your battery requirements by half or more.

To calculate watthour, it's easy as the average voltage multiplied by the AH.

 

[jondoh]

you need 20 amp hours in either 36v or 48v.

This guy used thundersky.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=19809&p=290533&hilit=thundersky#p290533

 

[JJB]

I have a much better idea of what I'm going to need since originally posting, and thank you guys for the help.

I do have one remaining question, which I guess I need to setup as a hypothetical... Lets say we have two batteries of equal capacity, but one is 36v and one is 48v. For the sake of argument, lets say the 36v tops out at 20 mph, and the 48v tops out at 25 mph. If both batteries were run at 20mph (i.e. 36v at 100% max speed and 48v at 80% max speed), would the efficiencies be the same, or would the 48 use less power at 20mph when compared to the 36v?

 

[dogman dan]

Those may be your cheapest way. You will have to be vigilant about overdischarging them though, so for a long ride that will often use 100% of the capacity a battery with a bms will be better. Pingbattery.com is a very trusted seller. Sure, some will have a defect, like any china product, but ping has a good track record. It will cost you about $600 including shipping for a 36v 20 ah or 48v 15 ah battery. Get the 5 amp charger and stash it at work if you can, and you will be able to recharge in about 3 hours with a 48v battery, and 4.5 hrs with a 36.

If you can't charge along the way at all, then you will have to ride about 18 mph to make the 30 miles. A larger battery will be awkward to carry. I own two pings, and the original one, 2.5 years old, has about 6000 miles on it now, and works fine but it will get unbalanced easier than it used to.

Again, for that length ride you need a bms, and a 48v battery and 5 amp charger will allow you to put a lot of charge into the bike on even a 30 min stop. With an hour of charge time, you will easily make the 30 miles at the full 27 mph speed of the ebikekit on 48v lifepo4.

If you can get a full recharge mid trip, then the thunderskies would work fine, since you would only be going 15 miles. You just need a device to monitor the voltage. Stuff like that can be found at Hobby King pretty cheap and adapted to the TS. Look for low voltage warnings in the charger section.

 

[dogman dan]

The difference between two different batteries might be measurable by science, but it isn't significant. When I tour I carry one 36v ping and one 48v ping, and each one will take me 30 miles or more if I ride between 15 and 18 mph. That even includes serious hill terrain too.

I'd advise the 48v 15 ah battery, though if you go TS, you will have 48v 20 ah. The key to long range is set the throttle to a certain speed, and pedal to add 1 mph to that. This will dramaticly lower your watts used, extending range far beyond faux pedaling. It will be moderate effort, similar to riding about 10 mph.

 

[Evoforce]

And I like V-Power LiFePo4 48 volt 20amp hour for your application. You can bid for them on Ebay and should be able to pick one up for under $300. plus $200 for shipping, insurance, and delivery in less than 2 weeks. All of the batteries mentioned are good choices but this is the most economical choice and you will find good service also. Batteries also come with BMS and 5 amp charger.

 

[dogman dan]

Just to confuse you just a bit more, there is also the option of lipo batteries from hobby king. These are now much safer than the flaming laptop batteries of a few years back, though they are still a bit tricky to assemble the little blocks into a larger ebike battery for the electronicly uneducated.

However they do have a few advantages. Primarily they are smaller and lighter than anything for the same amount of power, so carrying 48v 20 ah would be no sweat with those. They do cost a bit, but not a ton more. You just end up spending a lot on the chargers sometimes. But once you make the commitment, lipo can allow you to keep adding capacity very cheaply later on, by buying just a few bricks at a time. You could buy 6s bricks, and series connect them into 12s. This is a voltage just about halfway between 48v and 36v, that should work great with the Ebikekit and go about 25 mph.

The lipo does not have the longevity of lifepo4 though, so the cheapest battery per trip may still be TS or ping. But they should last you a couple years. Swapping out a single pack that goes bad is easy with the lipo. If a ping gets a bad cell, it's very hard to swap out a cell.

 

[Evoforce]

And to throw in another curve... Headway batteries are also great! I still believe you should have 48 volts 20 amp hours at the least. It is all about range, range, range, without the worry of comming up short of your trip!

 

[KTP]

Actually the zippy 20C batteries in certain configurations are $0.32/WH which makes them even cheaper than PING.

$320 for a 1KWH battery (plus chargers and wiring of course).

 

[dogman dan]

But a ping may go 1000- 2000 cycles if treated nice, and a lipo may go 500-1000? Did you include the cost of a charger? bet not. But either one could go bad much much sooner of course, even when treated nice. The real bargain may be the Thunder skys or similar, but the problem is long range riding always discharges them too much.

All I know for sure, is that my own pings have been treated right, and are lasting years and years.

 

[KTP]

But a ping may go 1000- 2000 cycles if treated nice, and a lipo may go 500-1000? Did you include the cost of a charger? bet not. But either one could go bad much much sooner of course, even when treated nice. The real bargain may be the Thunder skys or similar, but the problem is long range riding always discharges them too much.

All I know for sure, is that my own pings have been treated right, and are lasting years and years.

Well technically pings also don't include the charger if you go by the advice everyone gives of upgrading to the 5 amp charger rather than the cheapy 2 amp they send. But the Ping might be the better solution for a long range, reliable pack if you don't want to experiment with different configurations and are willing to throw away a $600 battery if things go really wrong.

You are the one who talked me into Lipo anyway Dogman...what are you doing promoting the Pings again?

Btw, I just received my 2nd batch of Turnigy Lipo, all cells at 3.861 volts +/- 2mV..yes, 2mV! I had to recheck with my Fluke because i didn't believe it. The order also had the icharger 208B...it is SO TINY (but seems well made)

 

[mwkeefer]

KTP,

The 208 is nice, I recently got one for doing 8S packs faster... There is a new version of logview too.

Glad all your packs came in proper

-Mike

 

[JJB]

I'm leaning strongly toward the Ping batteries. Do they have a "BMS" built into it, or do I need to get one separately? It seems like according to the literature that the Pings include a BMS, but I could be wrong.

Regarding capacity, this is where I'm kind of beating my head against the wall. I really can't afford to lay down any more than about $500-$600 for the battery, BMS, and charger. What I'm looking at currently is the 48V 15AH Ping. The 20AH would be nice, but the dimensions really aren't ideal for my setup, and the cost is prohibitive. Either way, according to my calculations 30 miles shouldn't be an issue for the 48v 15AH, especially if I'll be pedaling (which I will be).

I'm now putting strong thought into the High Tek Bikes Aotema kit, primarily because it's a stealthier install (i.e. it doesn't raise red flags for thieves). Any experience/comments with this kit?

 

[dogman dan]

The Aotema is a very good kit, but just a bit faster than a 9 continent. With a smaller diameter, it has just a tad less leverage on hills, but still climbs up to 7% grade easily on 36v. And will climb steeper on 48v. But on a really long ride with lots of steep hills it will run hotter than the 9c on the hills. But it doens't run that hot, and easily took a year of my ride, which in summer is 15 uphill all the way miles home in 105F weather.

Still a great motor though, and very fun at 48v, with 30 mph top speed. See the reviews sections for more details on my year of commuting on an aotema. I really liked the sensorless controller for the clean looking wiring on the bike. Just a lot less wires hanging out of the controller.

Do you really need 30 miles without any charging? to get that out of the Aotema you really will need to ride 18-20 mph. You can't pedal signifcantly at 30, and in any case, wind resistance does in your efficiency at 30 mph. But if you can just charge for about 3 hours with the free 2 amp charger you have it made to make it all the way. If you can afford it, get the 5 amp charger for sure, since 1 hour on that will get you the same effect.

The ping will come with a bms and 2 amp charger. You can also use an sla charger safely on it, if you want a cheap spare charger to stash at work, or whatever. I keep an inexpensive 4 amp sla charger at work myself.

Re ktp's comment. Ping remains the best lifepo4 option I know of, for a battery to operate at 25 amps on a long daily commute. Smaller and lighter than a headway, safe to charge anywhere, more cycles than lipo. Don't get me wrong, I'm loving my lipo too. Much better when real performance is desired, like my kart track racer, or my dirtbike. But I still love my pings for a long ride. With two of em, and a 15 mph speed, I can ride 70 miles nonstop. And not be carrying a bunch of stuff for the recharge oustide some buisness to ride further.

 

[JJB]

Thanks very much for the help. Regarding distance, etc, I pretty much need to plan for having enough capacity to do the trip myself. The eventual destinations will be internships, and I don't know if it will be possible or appropriate to charge up while there (but I'll certainly carry my charger and an extension cord if the opportunity presents itself).

Thing is, I think most of these calculations rely on 100% power from the motor...but I don't need to run the entire trip under electrical energy. I've been using a bike as my primary mode of transportation for a year, and can easily do 15 miles (round trip) under my own power without issue. I can do more than that -- I can do the whole 30 if I had to -- but it'll get to be too much over time, especially considering I go to the gym five days a week and have other responsibilities on top of that.

So I want electric to [literally] take the load off. The added speed will help too; I can do the 15 miles in about 45 minutes at an average 20 mph.

Thanks again for the guidance. I've gone from completely ignorant to reasonably knowledgeable in a short time.

 

[KTP]

Oh, you have no worries if you are in shape and pedal some. Most of the people on here are spastic about batteries running out because they may have to actually pedal a mile or two to get back home

I have done 50+ miles on a 14s2p pack (about 50V, 10AH, 500 WH) by assisting with the pedals, average speed of 18+mph, on a recumbent, which is heavier than an upright.

 

[jdcburg]

Although I am currently experiencing some weirdness with them (see http://endless-sphere.com/forums/viewtopic.php?f=14&t=20202) you could think about the barebones 12V 20ah Thunderskies. I got 2 packs within a week of ordering from Elite Power Systems for $20 s&h. You'd want 4 packs for 48V. I bought mine without a BMS. I use a Turnigy Accucel 8150 balancing charger ($42 + s&h) plus a Celllog 8M ($15 + s&h) for my "BMS." The charger balances while charging and the Celllog tells me individual cell voltages during use so I know if one is low. It has programmable alarms for high and low voltage. I also use a Turnigy WattMeter to tell me my ah use. The charger requires a power supply. You can connect the Celllog to the same balancing plug you use for the charger. It's a little complicated but the price is right - jd

 

[Evoforce]

It's true, most of us have more than one bike. And alot of us started out only converting one of those bikes for fun and transportation. We could ride the non-converted bike if we wanted to. I (speaking for myself), converted the rest of the bikes because it is way too much fun to ride e-bikes, and why have the non-converted bike setting there unused? Once you add all the new stuff to your converted bike, it will not be nearly as light to pedal around! Some of us are at that age where are knees, ankles, backs, etc, are shot. Enjoy youth and sweating while riding to work while you can. :lol:

 

[swbluto]

Yes, you could do the "gradual approach" if you want. Get 10Ah now if you want, and then if you find you need more, you can always buy more later. Although, this approach doesn't work *quite* that well with the pings since there's an extra $30-50 in shipping cost with split shipments, but that's just reflects the risk of trying out 10 Ah of first to see if that's all you need. Headway cells would work well with this method along with Lipo, but it seems you wanted an integrated 'neat' solution (i.e., n00b friendly).

 

[JJB]

I have another little conundrum, if you guys will indulge me...

I'm debating between the Ping 48v 10AH or the 36v 15AH. The advantages of the 48, as I see it, are faster top end speed (by a few MPH), better hill climbing, and somewhat less expensive. The advantage to the 36V would pretty much boil down to added capacity...I'd be able to get roughly three extra miles off the 36v.

Hmm. I dunno. The 48v is appealing for the speed and hill climbing, but I don't know how much difference this will actually make off paper and in real life. On the other side of the coin, I question whether or not I'd actually need the added capacity (and cost) of the 36v, given that I not only plan to pedal, but want to.

Also, as an aside, all the kits I've looked at have been front wheel, for the most part. I'm wondering, are there any disadvantages to front wheel? Just for the sake of simplicity, I'd much rather go with a front wheel kit.

 

[dogman dan]

Because the 22 amp controller in the motor kit can pull 2c out of the ping battery, only a fool would buy a ping, or vpower, or TS battery in 10 amp hours. You will hammer the thing to death fairly fast. On an uphill start, you can pull a momentary spike of 40 amps. Way too much for a 10 ah battery. In cruise mode, pulling about 12 -15 amps, you will still be pulling 1.5c. Too much.

15 ah is the minimum recomended size for batteries made from 2c lifepo4 cells. Better lifepo4, or other chemistry lithium can be much smaller. With a 3c cell, then 10 ah works because 3c= 30 amps for a 10 ah battery. You need a battery rated for 30 amps continuous, or more.

Furthermore, the small battery will get 100% discharged every ride, and will get more or less perpetually out of balance. This will make it act like an even smaller battery. Spend the 600 for a 48v 15 or 36v 20 ah battery. Ride at less than 20 mph and you will have just enough range, but expect to leave the battery on the charger 100% of the time you are not riding, to get it back into balance.

My estimates of range are NOT based on overweight rider no pedaling riding of short distances. I pedal moderately hard all the way, adding 1-2 mph to the motors speed in the most efficient way. Only by riding this way, or going very slow do you get more than 30 miles out of an unaerodynamic, pannier loaded bike with a 48v 15 or 36v 20 battery. My normal range is about 35 miles,( at 18-20 mph) giving me less reserve than I like for keeping the battery happy and lasting a few extra years. That is why I say, if you can, charge for an hour somewhere with the 5 amp charger. If need be, do the charging on the way home, when you can spare a half hour at a place you have found a free plug.

To see what it will feel like to pedal with a direct drive motor with the battery off, set your brake to drag pretty good, and then add 30 pounds to the bike.

If you are going to pedal without the motor, back off, change plans, and get a gearmotor that has a freewheel and weighs less. Then get 4 6s 5000 mha lipo batteries. That will give you 10 ah at a voltage halfway between 36v and 48v. The batteries will be 20 to 30 c discharge rate, and very very light. Now, without the motor on, you will be pedaling a bike with 15 pounds added, and no brake dragging. Lots better for the occasional assist type riding.

Even lighter, would be a friction drive and only two lipo bricks.

 

[dogman dan]

Re the front vs rear. My conclusions are that personally I prefer front hub on the street, but demand rear hub in dirt.

Base your choice on the kind of bike you are going to convert. There are lots of problems with front hub on some bikes. Suspension forks in particular, or even steel forks that have deep cups for QR hubs and are very very light and thin. Special c washers from ebikes-ca solve the QR problem, or you can make your own, by grinding down a regular washer. Also there are issues of disk brakes, or simply the question of does the motor fit between the forks at all?

With rear hub, there are often problems with the gears. Often the motors will allow 6-7 speed clusters while your bike has 9 and uses thinner chain. that type of thing.