Ping Battery Confusion...

[bringageek]

I do know that if I was using say, the 36-72V 25A Infineon Controller from the folks over at ebikes.ca, I would need a battery that can provide at minimum 25 Amps... and if using the 24-48V 35A one, the battery needs to be able to provide at least 35 Amps... the same with the 36-72v 40A controller, battery needs to be able to deliver 40 amps. Therefore, if I were to hook up one of ebikes.ca's 36V 9Ah (which says 27A MAX) battery units to the 35A or 40A controller, bad things would probably happen... assuming anything happens at all that is.

Now when it comes to ping's batteries, the specs on their website have me a little confused.... For example, their 48v 15AH LiFePO4 pack details a Rated Discharging Amperage of 15 Amps and a Max Continuous Discharging Amperage of 30 Amps and a Maximum Discharging Current of 60 Amps. Or their 48v 20AH pack lists 20, 40 and 60 respectively. Which one of these three is the one I should be paying attention to?

Phil

 

[gensem]

Ping recommends that you do NOT exceed the 2C figure, which is 30amps for the 15ah battery and 40amps for the 20ah one.

 

[dogman dan]

My advice is to limit 15 ah pings to 25 amp controllers. Others report good lifespan using 35 amp controllers, and in truth, you'd have to be climbing real steep hills to pull 35 amps continous. Most typical motors will only go fast enough to pull amps in the low 20's at full speed on flat ground.

My advice is fairly consevative, 25 amp controllers, because you just might have hills like that.

 

[gensem]

As Dogman just said, you are better off with a smaller controller, because they usually overshoot the current.

 

[Kin]

Ping recommends that you do exceed the 2C figure, which is 30amps for the 15ah battery and 40amps for the 20ah one.

For the record, I believe gensem meant to say "Ping recommends that you do not exceed the 2C figure"

So for a 10ah battery 2C = 20amps. For a 20ah battery 2C = 40ah.

Dogman recommends a slightly more conservative ~1.65C rating.

 

[gensem]

I did not noticed the NOT was missing.
Its fixed now.

Thanks Kin

 

[Kin]

By the way, I want to clarify the essence of your original question.
For a 20ah pack, why does pin say 20A, 40A, 60A?

Basically, because 1C is the "totally within specs" state. 2C is the "max continuous C". And 3C is the "burst rating" so for very short times 3C can be delivered without too much damage. A word on the burst rating is that it really shouldn't be used.

1C is just more gentle on the battery than 2C. Word of an experienced member, Dogman, says that a controller matched to ~1.65C is a good medium to take care of the battery (I reached the 1.65 number by dividing the 15ah battery suggested for the 25a controller) .

 

[bringageek]

First off, thank you peoples!

I was leaning towards choosing the 25A controller already... Now armed with your info and advice, the 25A controller it is! While I have your attention -- and since we are talking about Ping batteries already -- maybe you fellas could help me decide on which battery as well.

In what my Dad likes to call the "Readers Digest Version" or RDV, my understanding is that batteries with more volts means more Umphf!*, and the more amp hours means greater runtime/distance. My initial thoughts are that the 48V 15Ah pack should probably be a solid choice for me, however, what I'm wondering is whether or not it's worth the extra $125 to go with the 48V 20Ah unit instead? I mean... that's pretty much the cost of the controller... And although when I finally do pull the trigger and start the buying/building phase of this projects I do plan on making sure I don't do it half-assed, but I'm not made of money over here... 125 bones is a 125 bones... Is the extra 5Ah worth it?


Alternatively, since I am considering moving into that general snack bracket for the battery, what about the 60V 15Ah pack? it is only another $40 more than the 48V 20Ah... what kind of change in overall performance could I expect if I did go with that instead? would you? worth it?



*And by Umphf! I mean it will have more kahunas... power... faster....

 

[bringageek]

Also gensem, what do you mean by "they overshoot the current"?

 

[el_walto]

Your bike will move almost identical speed with a 15ah or a 20ah pack. Your bike will be using up to 25a x 48v = 1200Watts either way. The 20Ah pack will just give you more distance before it runs out of power and make your bike more heavy. The 20ah is also harder to mount on a bike because it's larger.

If you put the 48v 20ah ping with the 35amp controller you would get 35a x 48v = 1680Watts to your motor. This setup be better for acceleration and better at climbing hills than 25amp option. You would also get this many watts from a 15Ah ping pack with 35amp controller, but the 15ah ping pack would be over stressed and damaged shortly, also technically not get you as far.

The 60v pack will make your motor spin more rpm (essentially higher top speed) also giving you a bit more power output 25a x 60v = 1500Watts of power. You only want really want to do this if you plan on riding on lots of flat ground at high speeds, or while using a small wheel. Not an efficiant setup for climbing hills.

You have a few things to figure out. It's confusing i know. ebikes.ca simulator may help you out.

 

[dogman dan]

In general, the 48v 15 ah ping is the biggest size you can easily carry on a bike. Once you go to the 48v 20, you need to have it in panniers. The larger 20 ah will be way too heavy carried high on a rear rack, and it will not fit in bikes frame triangle space.

Idealy, you get the 15 ah and fit it into the triangle. You'll need a frame with the space. The 36v 20 ah, is actually the same number of cells, so that one fits and carries nice too. Easiest of all to carry, is the 36v 15 ah. The 36v 10 ah, I only recomend for 15 am controllers.

In the end, you want to buy the range you need. 36v 20ah, or 48v15 ah will take you about 30 miles at 18- 20 mph. About 22 miles at 25 mph.

48v will go faster, sometimes as fast as 30 mph depending on the motor winding. 48v will have more umph to get up steeper hills as well.

 

[999zip999]

A controller at 40amp. and hills is what kill a cell and bms on my 48v20ah Ping. An easy fix with Ping suport. So I would keep it at 25a.-27a. max. I put mine in the triangle of a 22in. frame.

 

[gensem]

Also gensem, what do you mean by "they overshoot the current"?

Its not hard to see a 25a controller drawing over 30a during hills.

 

[gurshark]

In general, the 48v 15 ah ping is the biggest size you can easily carry on a bike. Once you go to the 48v 20, you need to have it in panniers. The larger 20 ah will be way too heavy carried high on a rear rack, and it will not fit in bikes frame triangle space.

Idealy, you get the 15 ah and fit it into the triangle. You'll need a frame with the space. The 36v 20 ah, is actually the same number of cells, so that one fits and carries nice too. Easiest of all to carry, is the 36v 15 ah. The 36v 10 ah, I only recomend for 15 am controllers.

In the end, you want to buy the range you need. 36v 20ah, or 48v15 ah will take you about 30 miles at 18- 20 mph. About 22 miles at 25 mph.

48v will go faster, sometimes as fast as 30 mph depending on the motor winding. 48v will have more umph to get up steeper hills as well.

dogman, how do you get the distances each battery will take you at differing mph? is there a formula, or is it empirical knowledge?

 

[dogman dan]

10,000 miles of riding. Gives you a real good feel for what your CA says under all kinds of conditions. And what the range is at different speeds.

Some pedal harder and get more, some have less flappy coat and don't carry panniers. I figure you have to get at least what I do.

 

[Kin]

If you find your wh consumption at a few different speeds while peddling at a constant effort, you could calculate your drag coefficient, if for some reason you really needed to know a precise range of estimates.