LifePo4 Voltage Question

Batteries, Chargers, and Battery Management Systems.
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dsimone   1 mW

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LifePo4 Voltage Question

Post by dsimone » Apr 22 2016 9:11pm

Hi,

Emmo makes a bike advertised with an 80V LifePo4 battery. I'm not a battery expert at all, however I'd only encountered LifePo4 batteries in increments of 12V before (ie 84V). Can someone with knowledge explain how an 80V LifePo4 battery is a thing?

Thanks!
D :)

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flangefrog   1 kW

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Re: LifePo4 Voltage Question

Post by flangefrog » Apr 22 2016 10:31pm

LiFePO4 cells are usually around 3.2V nominal so you should usually see them in multiples of 3.2V. The battery by Emmo is probably 25S (25 cells in series) or 26S for 80V. Some cells are 3.0V nominal like the 84V battery you mentioned.

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eva-michael   100 W

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Re: LifePo4 Voltage Question

Post by eva-michael » Apr 23 2016 2:22am

increase 12V means increase 4S LiFePO4
24S LiFePO4 = nominal 72V and real voltage after charge is around 79.6V. Require constant charge voltage: 86.4V-87.6V
28S LiFePO4 = nominal 84V and real voltage after charge is around 92.9V. Require constant charge voltage: 100.8V-102.2V

BTW, many supplier have 4S-24S BMS but does not have 25-28S BMS.
www.evassemble.com all for EVs.
new major website since 2014 www.evcomponents.com

dsimone   1 mW

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Re: LifePo4 Voltage Question

Post by dsimone » Apr 23 2016 10:57am

Ok. I've got a Kelly controller KEB72301X in my bike that's rated up to 90v and Emmo says their 80v LifePo4 (as a replacement for my current 72v 6x SLAs should work fine). I'd just never seen 80v as Lifepo4. Hope so.

So 25S or 26S then. Interesting. Thanks!

999zip999   100 GW

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Re: LifePo4 Voltage Question

Post by 999zip999 » Apr 23 2016 12:20pm

Do you have a link ?

dsimone   1 mW

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Re: LifePo4 Voltage Question

Post by dsimone » Apr 23 2016 12:28pm

To the battery? No, they don't list it with a page as such.

dumbass   100 kW

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Re: LifePo4 Voltage Question

Post by dumbass » May 01 2016 5:40pm

Keep in mind almost no supplier gives the true pack rating. Just as a 12v lead battery is actually dead when it get to 12v. Supplies use different voltage for cells when rating the total pack voltages. Some use the true usable voltage of Lifepo4 cell which is generally 3.2v * ? or the max recommended charge of 3.65v. If they are using 3.65v *22 cells that would be 80.3v or for convince they refer to it as an 80v pack. Maybe??

Bob

dsimone   1 mW

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Re: LifePo4 Voltage Question

Post by dsimone » May 02 2016 9:35am

It's 80v nominal, according to Emmo. So I'm guessing 3.2?
I asked for the specs but they don't have them, they told me they'd try and get them for me but that was 2 weeks ago so I'm doubting I'll get anything. I seem to have found a better lithium battery for my bike anyway, it's 72V nominal but I prefer that (sold by Armada EVS in Vancouver).

(something I've now found super common is that a lot of places will sell lithium batteries but have no idea what the specs are, what the C rating is, etc - and they're even surprised why anyone would ask, which I find nuts, even as a novice looking now. How can you deal with electric vehicles, scooters, etc., and not insist on having the spec sheets for the lithium batteries you sell? One person even got 'upset' with me for asking saying: "why do you need to know? do people need to know what the composition of the lead acid in in a battery?" ...uh, ok. Needless to say I didn't order from that person. It wasn't Emmo, they've been grand, they just didn't know the specs either but said they were trying to get them for me, which was nice).

999zip999   100 GW

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Re: LifePo4 Voltage Question

Post by 999zip999 » May 02 2016 10:36am

Why don't you give us a link to the battery you are thinking of buying before you buy. This way we could help before you buy. ? We can still help after, but after what ?
What's it for ? Motor, controller must match battery or else.

dsimone   1 mW

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Re: LifePo4 Voltage Question

Post by dsimone » May 13 2016 9:12am

Thanks everyone. I opted for a 72V NMC battery from MrScooterboost/Armada Scooters instead. First week with it installed and it's working great so far.

To answer the question above, it's for a 72V scooter with a 1000-1500W motor and a programmable 24-90v Kelly Controller (max 60A cont/120A burst).

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