EBIKE - A123 - 2.3AH AT 70AMPS

[AARONHAI1]

THANKS FOR THE REFERENCE KIN,
-JUST A TECHNICAL QUESTION - HERE IN ISRAEL, SOME GUY'S ARE SELLING...
AN A123 12 CELL PACK 39.4V AT 2.3AH AND 70AMP CONTINUOUS CURRENT TOTAL,
FOR USE WITH A 250W 36V MOTOR HUB - THEY CLAIM THAT IT CAN GO 15KM ON ONE CHARGE...

SO MY QUESTION IS: GIVE OR TAKE - HOW LONG CAN THAT LAST ON A 500W OR 750W [36V] REAR HUB MOTOR ---- OR BETTER YET,
HOW LONG ON FULL THROTTLE???

 

[Jeremy Harris]

Welcome to ES.

15km from a pack that has only around 91 watt hours of capacity seems a bit high to me, but it may be possible on flat ground, at low speed with pedal assistance.

There are some useful power calculators on the web that will give you an estimate of power needed for any speed. Here's one that works in metric units: http://bikecalculator.com/wattsMetric.html for example.

If we assume that the ebike is going to be around 25kg, the rider weighs 80kg, that the bike has MTB type tyres and the rider is sitting upright, then the bike is going to need around 180 watts to do 25km/h or around 250 watts to do 30km/h (with no wind and on flat ground)

A 91 watt hour battery pack (12 cells x 3.3V per cell x 2.3Ah = 91 watt hours) will deliver 180 watts for less than half an hour, so would have a range of about 12km maximum at 25km/h. At 30km/h the endurance would be around 20 minutes, so a range of about 10km.

If you increased the power to 500 watts continuously, the the 91 Wh pack would last for just 11 minutes, at 750 watts continuous it would drop further to just over 7 minutes.

Generally, the minimum capacity of battery pack worth having on an ebike is around 10Ah, so this pack seems just too small to be very useful.

Jeremy

 

[AARONHAI1]

Thanks a bunch - Jeremy !! I'm currently trying to decide weather to get a custom made 36V 15ah
battery pack from: http://www.osnpower.com/productID/plistone-2256470-1.html -------- [best prices i've yet found]
It's based on: - 26650 LifePov4 [36?] cells [cylinder] My sales rep. is claiming that it can run 45 minutes with 750W rear hub motor.

So Jeremy, I'll keep you posted on the exact SPECS as soon as i get them...
Quick Q. if the amp rate is the same [20 amp] controller, then do you think it could be used on a 1000w 36v MOTOR for 45 minutes?

 

[Jeremy Harris]

Thanks a bunch - Jeremy !! I'm currently trying to decide weather to get a custom made 36V 15ah
battery pack from: http://www.osnpower.com/productID/plistone-2256470-1.html -------- [best prices i've yet found]
It's based on: - 26650 LifePov4 [36?] cells [cylinder] My sales rep. is claiming that it can run 45 minutes with 750W rear hub motor.

So Jeremy, I'll keep you posted on the exact SPECS as soon as i get them...
Quick Q. if the amp rate is the same [20 amp] controller, then do you think it could be used on a 1000w 36v MOTOR for 45 minutes?

Glad to help. It would be a very good idea to look around the battery section here for info on a pack before spending a lot of money. There are some excellent packs available on the web, with most coming from China (and they virtually all come from China one way or another) but there are also some truly dreadful products about. Many here have been caught out by buying direct, so a look at the battery reports from members here will give you a better idea of what to avoid.

A 36V, 15Ah pack is a good starting point, provided it's well made and has a good battery management system. The endurance will depend almost entirely on how fast you ride, how heavy the bike is and how many hills you have to deal with, rather than the rated power of the motor. A 20 amp controller on 36V is going to give you a maximum power of around 720 watts, but in practice you will most probably average around half of that. More important is to choose the right combination of motor, battery and controller for the speed and range you want, taking account of how hilly, or windy, the area you normally ride in is.

You should get more than 45 minutes endurance, absolute maximum, if you mainly ride on the flat and at speeds up to around 30km/h or so. A 36V 15Ah battery is about 540 watt hours, so in theory it will deliver a continuous 500 watts for about an hour or so. As you've seen from that quick calculation in the last post, 30km/h is going to use around 250 watts continuous, so (again in theory) you should get two hours out of that pack at that speed.

In reality you can expect to get a fair bit less endurance for two reasons. Firstly, it's never a good idea to try and use all the capacity in the battery, as it shortens its life. Aim to use no more than about 80% of its capacity and it will last a lot longer. Secondly, hills, wind, stopping and starting will all draw higher current from the battery, so you need to take these factors into account when estimating how far you can go. All told, I believe that you should get well over an hour of useful riding from a 36V, 15Ah battery pack with a 20 amp controller, provided you don't go too fast or up too many steep hills.

Jeremy

 

[AARONHAI1]

Good point:

"Aim to use no more than about 80% of its capacity and it will last a lot longer."

8)

That's precisely why i am looking for cheap and lightweight - so i could switch packs after using half or so...
So Jeremy - do you have any recommendations?? Cheap, small, long-life and good for use on a [36v] 750-1000w rear hub motor?

 

[Jeremy Harris]

Good point:

"Aim to use no more than about 80% of its capacity and it will last a lot longer."

8)

That's precisely why i am looking for cheap and lightweight - so i could switch packs after using half or so...
So Jeremy - do you have any recommendations?? Cheap, small, long-life and good for use on a [36v] 750-1000w rear hub motor?

If you're going to carry both packs with you, then don't switch them, run them both together all the time, or better still, just get a pack that's double the capacity. Running double the capacity for a given power halves the stress on the battery pack and reduces the internal losses, so you will actually get slightly more range this way. Also, halving the current drawn from each pack, by doubling them up, will make them past longer, too. The rule with batteries is to always have all of them working on the bike, otherwise they are just dead weight that the other battery has to lug around.

Recommendations are hard, as it depends very much on how much work your prepared to do and your personal preferences. The lightest, most powerful batteries at a reasonable cost are LiPo RC packs from somewhere like Hobby King (http://www.hobbycity.com/hobbyking/store/uh_index.asp) these will give you a small, light and extremely powerful battery pack, but you will need to wire it up yourself and deal with making up wiring looms for charging etc. It's not hard, but it is a fair bit of work. There are reviews in the battery section on the Turnigy and Zippy packs, plus some on the newer nano packs, but a good starting point would be this thread: http://endless-sphere.com/forums/viewtopic.php?f=14&t=19956

If you want a plug-and-play solution, then the LiFePO4 packs from Li Ping are excellent. They are heavier than LiPo and won't deliver as much peak current, but they are reliable, easy to use and you will get very good customer support from Ping. His website is: http://www.pingbattery.com/servlet/StoreFront You will find nothing but praise here for Ping packs, they work well if you don't demand too much of them. I have been running a 36V 10Ah Ping pack for around two years now with no problems at all, it just works, all the time. If you want to get high performance from your bike at some time in the future, though, so want to draw more than around 30 to 40 amps from the battery, then I'd suggest you don't go for the Ping pack, as they are best run below about 30 amps.

Jeremy

 

[TylerDurden]

^^Good advice.^^

 

[dogman dan]

12 cells of lifepo4 = 36v nominal. My rule of thumb for 36v using typical ebike kit hubmotors has been 1 ah= 1 mile. Yes you can go further than that, much much further at 1/2 throttle riding slower and pedaling more. The rule of thumb is good for sizing a battery when you expect to ride full throttle at all times, and want to include a reserve of at least 20%, which increases the lifespan of battery packs. The reserve also allows for making it at all on those windy days.

36v 20 ah and 48v 15 ah are the sizes I like to recomend when buying from pingbattery.com. At 15 pounds and the size of a shoebox, they don't weigh too much or take up too much space, yet give you about 20-25 miles of max throttle riding. Use with 25 amp controllers or less.

If you go with that A123 pack, do run both together as one 36v pack, and expect closer to 10 k out of both.

My other rule of thumb is cut all claims by sellers for range in half. Or in this case, by 2/3 Range is not how far you can stand to pedal after the battery dies. :wink:

 

[AARONHAI1]

HAVE YOU BOYZ HEARD OF: 36V10AH Lithium Battery FROG style case
Well they offered me one 14ah and another 17ah pack w/ a 53% discount - NICE DESIGN too - is that kool or watt?? 8)

here's the info from: http://www.goldenmotorusa-d.com/index.php?pg=batt
Frog style seat post mount with Switch/Key BMS and 110V-240Vac 2A Universal Charger Weight: below 5.5Kgs
Capacities: 36V/10AH Max Discharge Current: 60A/10AH) Max Continuous Discharge Current: 30A(10AH) Charging Cycles: >800 times

Q. Any clue how long this FROGGY can last on a: GT freestyle BMX - rear hub motor 36v...500w, 750w and 1000w - 20amp controller ???

 

[dogman dan]

1 ah = 1 mile. If the cells inside are typical 1 or 2c type, then 4 ah would be a one time use deal. For the cheaper cells with lower discharge rate capability, I consider 15 ah the smallest practical size.

Belive me, if there was a great lifepo4 bike battery that good and cheap too, we'd be beating a path to it's door.

We are beating a path to lipo batteries that are cheap, and very powerfull. Very high discharge rates like 30-90c. Get them at Hobby king. But as for how far they take you, there's no magic battery that goes farther per AH. Only pedaling or slowing way down extends the range.

 

[Jeremy Harris]

Q. Any clue how long this FROGGY can last on a: GT freestyle BMX - rear hub motor 36v...500w, 750w and 1000w - 20amp controller ???

Maybe you missed it, but I pointed out a way to determine endurance in a post above, and Dogman has given you another good rule of thumb that works well enough.

Anyway, here goes again. 30km/h is going to use around 250 watts, plus the extra power needed for acceleration, dealing with wind, hills etc, so around 350 watts is a reasonable estimate. You should aim to use only around 80% of the pack capacity in normal use, to give the pack a fairly long life. That pack you've linked to is 36V, 10Ah, so 360 watt hours (36 x 10 = 360). If you draw 350 watts from it will in theory last for about 1 hour, but remembering that you only want to discharge it by about 80%, then that comes down to about 50 minutes.

You can do this calculation for any pack capacity. As I mentioned previously, be wary of buying stuff online until you've read the good info in the battery threads and the manufacturers to avoid section, as there are lot's of pretty rubbish batteries about in amongst the good stuff.

Jeremy

 

[dogman dan]

Need to get new glasses, Ida swore I was seeing 4 ah for the froggy pack. I was just looking at the pic seeing a 4 ah cell size, and missed it in the text that the pack would be 14 ah or larger. Wonder how they make a 14 ah pack outa 4 ah cells?

Might be worth a try if you have a good price on it. but not if the cells are 18650 size. Quite a few stinker packs out there made of those cheapo 18650's.

 

[AARONHAI1]

AHHHH - TURNS OUT THEY ONLY HAVE 10AH PACKS - SORRY!!!!

Answer to Mister DogMan:

Might be worth a try if you have a good price on it. but not if the cells are 18650 size. Quite a few stinker packs out there made of those cheapo 18650's.

ok - so here's the info on the FROG STYLE BATTERY PACK/CASE - Lithium Manganese Oxide [CELL] MODEL: JD-LF-04 -- AND -- JD-LF-05
14ah and 17ah - they givin it to me for around $200usd a piece - watta u think?

 

[Jeremy Harris]

ok - so here's the info on the FROG STYLE BATTERY PACK/CASE - Lithium Manganese Oxide [CELL] MODEL: JD-LF-04 -- AND -- JD-LF-05
14ah and 17ah - they givin it to me for around $200usd a piece - watta u think?

They might be OK, they might be total rubbish, it's hard to tell, because I don't recall anyone here having tried these yet. They are cheap, which makes me suspicious, because we've not yet seen cheap dedicated ebike battery packs that have turned out to last or perform as advertised.

If you can get a warranty, and if the cost of shipping them back for repair/replacement under warranty is such that the warranty is worth having, then by all means give them a try, they may turn out to be OK. It looks to me as if these packs are made up from laptop type cells, so I doubt they will be good for the high discharge rates they quote (laptops only need cells that will deliver about 0.5C), but if you only need around 15 to 20A they may be OK.

Jeremy

 

[AARONHAI1]

OK - SO HERE'S THE MOST RECENT OFFER FROM: http://www.goldenmotor.com/
Battery model: JD-T-02 80*140*250 36V 17AH 5.5kg with a charger APPROX. $500usd for two...
The reason i'm interested in it is because i can fit it into an underseat toolbag or saddlebag on a 750w motor.

it's pretty much the inside of the: JD-T-01 - 3E - SERIES [silver Box type]... Does anybody recommend these silver rack-packers??

 

[dogman dan]

Including shipping to you? BTW 17 ah is not going to fit into an underseat bag. It's going to be shoebox size, I garanutee it. The frog case does look about the right size for 4 ah.

Beware of cheap ground shipping too, lotsa batteries arrive dead after a too long boat ride. We've never heard of GM being a great battery supplier, so you'll just have to be the guinea pig, and test this one for rest of us. A few years back GM had some quality problems with 10 ah 18650 lifepo4 packs. But these are different. The motors are ok, and always have been.

 

[Jeremy Harris]

OK - SO HERE'S THE MOST RECENT OFFER FROM: http://www.goldenmotor.com/
Battery model: JD-T-02 80*140*250 36V 17AH 5.5kg with a charger APPROX. $500usd for two...
The reason i'm interested in it is because i can fit it into an underseat toolbag or saddlebag on a 750w motor.

it's pretty much the inside of the: JD-T-01 - 3E - SERIES [silver Box type]... Does anybody recommend these silver rack-packers??

Have you looked in the battery section of this forum? I've just done a quick search for you, looking for "goldenmotor" in the battery specific section and found these threads:

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=9939&start=0

http://endless-sphere.com/forums/viewtopic.php?f=14&t=5128&p=76725&hilit=goldenmotor#p76725

http://endless-sphere.com/forums/viewtopic.php?f=14&t=22432&p=326510&hilit=goldenmotor#p326510

None seem to answer your specific question, so I'd guess that, as I mentioned before, it's looking unlikely that anyone here has tried one yet.

One thing you can be sure of is that if folk here have tried something and found it to work well, then the news pretty soon gets around and a quick search of the forum will pop up loads of hits. The fact that there's nothing that turns up in a very quick search makes me think there's nothing special about this pack. Then again, someone has to be the first to try it and give us all a report...................

Jeremy

 

[AARONHAI1]

DogMan said:

Including shipping to you? BTW 17 ah is not going to fit into an under-seat bag. It's going to be shoebox size, I guarantee it.

Battery model: JD-T-02 80*140*250 36V 17AH 5.5kg - i'll check into the size, whatever this means - 80*140*250 [dimensions]
From what it seems - basically you aren't recommending the FROGGY battery?
Well then what about the: JD-T-01 - 3E - SERIES [silver Box/case type]???