ADVICE? -> 72V 30Ah LifePo4 Battery/BMS Specs

[starlightkayak]

Hi guys,

I picked up the Kelly KEB72301X controller recently and I want to ensure that the new battery pack I order is right (I'm not an expert, which is why I'm hoping you can lend me your advice!)

Controller: http://kellycontroller.com/keb72301x24v-72v150a30kwe-bike-brushless-controller-regen-p-274.html

When I speak with the battery mfgrs, I believe I should be asking for the following (correct me if I am mistaken?):

+ LifePo4 Battery Pack 72V 30Ah
+ Continuous discharge current of 60A / 120A peak - burst (A123, high C rating)
+ 30A Maximum Charge Rate (I want to buy and consistently use a 10A intelligent charger to begin with)

Thanks geniuses!

 

[999zip999]

What's it for ? A big bike pack or small motorcycle pack. Plus motor-controller

 

[starlightkayak]

motorcycle/scooter

 

[wesnewell]

Looks like battery current draw is configurable up to 150A, so if you set it to 60A, you want a pack that will deliver 60A. If you set it to 150A you want a pack that will deliver 150A.

 

[starlightkayak]

Yeah, thanks. The controller is set to do 60A continuous (measures just over that on the cycle analyst, 61.8A), and it'll do 120A burst for a few seconds only. Just want to make sure that any battery I ordered would be able to handle it. So if I get a battery and BMS with 60A continuous I should be ok?

 

[amberwolf]

Just so that people can better help you, this is a link to your controller/motor troubleshooting thread:

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=62617

and I've also linked that one to this one, because you don't really have complete info in either thread.

 

[starlightkayak]

After riding for a while with the new controller in, I can see on the CA that it's using 61.7 Amax. Definitely need to order a battery rated for 60A continuous.

 

[amberwolf]

Amax just means the peak momentary current, somewhere in the trip. It is probalby only that high during acceleration from a complete stop.


What current do you see onscreen during typical cruising, and what do you see during acceleration other than at the initial startup from a stop?

Those would be the continous currents your pack wil lsee all the time, and you definitely would want to plan for htose. Bu tyou might not need a pack that can do the 61A continously, if it doens't see that except for a moment here and there. (though if it *can* do that, it probably also won't sag as much in voltage, and your startup torque and quickness off-the-line might be better, if the sag causes them to be less presently).

 

[starlightkayak]

amberwolf, you are made of awesome. Thank you!

She runs at about 40A/continuous on the cycle analyst and goes to 61 when necessary for torque.

I've posted in my LiNiCoMnO2 battery question thread to ask for recommendations. You are all so generous with your time, so grateful.

 

[starlightkayak]

So today, a vendor on aliexpress told me that a 72v 10A aluminum intelligent charger I was looking at would only charge a 72v30ah (lifepo4) pack to 90%, but that a 72v 5A charger would charge it to 100% - does that make any sense to anyone? I can't fathom it... he's the only vendor that's said that so far. I thought I'd pop in here and see what you all thought of that. What might he be referring to?

 

[dnmun]

total nonsense. you can buy the EMC-1000 from BMSbattery.

 

[starlightkayak]

That's kinda what I thought, too.
Thanks for the rec!

 

[wesnewell]

So today, a vendor on aliexpress told me that a 72v 10A aluminum intelligent charger I was looking at would only charge a 72v30ah (lifepo4) pack to 90%, but that a 72v 5A charger would charge it to 100% - does that make any sense to anyone? I can't fathom it... he's the only vendor that's said that so far. I thought I'd pop in here and see what you all thought of that. What might he be referring to?

Impossible to say without knowing what you were looking at, and knowing the actual configuration of the pack you have. All chargers should state their max output in a perfect world. If you have a 24s lifepo4 pack (actual nominal of 76.8V) w/o bms you need a max output of 86.4V for 3.6V per cell. With a bms, it could be the same or higher. You'd need to know the specs of the bms.

 

[amberwolf]

So today, a vendor on aliexpress told me that a 72v 10A aluminum intelligent charger I was looking at would only charge a 72v30ah (lifepo4) pack to 90%, but that a 72v 5A charger would charge it to 100% - does that make any sense to anyone? I can't fathom it... he's the only vendor that's said that so far. I thought I'd pop in here and see what you all thought of that. What might he be referring to?

It would only happen if that particular 10A charger they have isn't actually the right voltage for the pack, and the 5A charger is.

Otherwise, a faster charger isn't gonna charge a pack any less than a slower one...it's just faster.