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Post Info TOPIC: 48V Lithium battery packs (13S vs. 14S)
Functional Artist


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48V Lithium battery packs (13S vs. 14S)
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"Can we talk?"

...about batteries? 

 

I've got 48V systems on a couple of racers

...& have been looking into some of the Lithium battery packs that are currently available

...& then, comparing them to the EA the rule book

28 ADVANCED BATTERY CLASS

The Advanced Battery Class is intended to foster experimentation on with newer battery technologies that offer higher energy density than the more traditional lead-acid, and reflect the rapidly expanding availability and usage in the transportation industry. The weight limits are meant to keep the available power under one kw/hr, or about the same as the current Standard Class. This list will be reviewed and updated periodically

All other Standard Class rules apply with the following exceptions:

1. Any type of the following sealed production batteries may be used as long as their weight does not exceed:

 Nickel-Metal-Hydride 41 lb.

Silver-Zinc 23 lb.

Nickle-Zinc 44 lb.

Nickel-Iron 58 lb.

Lithium-Ion 15 lb.

Lithium-Iron-Phosphate 29 lb.

2. Maximum output of any battery combination used may not exceed a one-hour rating of one kilowatt/hour according to the manufacturer's data.

 

They have many, many options now available

...& the cost seems to be coming down too (~$300.00 w/1,000+ cycles) biggrin

 

So, to expand on the conversation, here is a link 

...& also, some specs (for a couple of examples) 

52V 48V 36V 24V 15ah 20ah Lithium Ebike Battery for 1000W 1800W Scooter Motor | eBay

52V 48V 20ah Lithium Ebike Battery for 1000W 1800W Scooter Motor

Fuction:
  • Waterproof and heat shrinkable casing.
  • No memory effect, rechargeable.
  • Lithium battery which is the best choice for electric bicycle.
  • Life expectancy is twice that of lead-acid batteriesCycle life 1000+.
  • Small size and light weight. Only one quarter of the weight of the lead-acid battery
  • Safer and more environmentally friendly, free of heavy metals and harmful substances.
  • Built-in BMS chip can prevent battery pack from overcharge, overdischarge, overcurrent, overheat, short circuit and extend battery life.

Here are the specs for a (13S) pack

48V 20Ah with 30A BMS Lithium Ebike Battery for 200W~1000W Electric Bicycle Motor
  • Voltage48V
  • Battery Capacity: 20Ah
  • Energy: 840Wh
  • Configuration13Series 8Paralles=104pcs cells
  • Item Length: 245mm
  • Item Width: 70mm
  • Item Height: 160mm
  • Item Weight:5.2KGS
  • Standard charge Current: 2.5A
  • Maximum continuous charge current: 5A
  • Max Continuous Discharge Current: 30A
  • Peak Discharge Current90A
  • Charger InputAC 100-240V
  • Charge Cut-off Voltage54.6V
  • Discharge Cut-off Voltage: 36.4V
  • Charger: 54.6V 2.5A

&

Here are the specs for a (14S) pack

 
52V 20Ah with 30A/40A BMS Lithium Ebike Battery for 200W~1500W Electric Bicycle Motor
  • Voltage52V
  • Battery Capacity: 20Ah
  • Energy: 1040Wh
  • Configuration14Series 8Paralles=112pcs cells
  • Item Length: 260mm
  • Item Width: 70mm
  • Item Height: 160mm
  • Item Weight:5.6KGS
  • Standard charge Current: 2.5A
  • Maximum continuous charge current: 5A
  • Max Continuous Discharge Current: 30A/40A
  • Peak Discharge Current90A/120A
  • Charger InputAC 100-240V
  • Charge Cut-off Voltage58.8V
  • Discharge Cut-off Voltage: 39.2V
  • Charger: 58.8V 2.5A

*Also, states that a specification & qualified certificate comes with each pack

 

So, FWIU most of the components, in most the 48V systems that I use, are capable of handling up to/less than ~60VDC

I have been using the MY-1020 48V 1,000W brushed motors

They are rated to draw ~20A (1,000W/48V = 20.83A)
(they draw a bit more on hard accelerations ~30A & a little less when cruising ~15A)
...& the 48V 1,000W YK-31 speed controllers, have a pre-set low voltage cut-off of ~41V

So, it looks like the battery parameters to power these systems should be
...top voltage charge level under 60V (to NOT over voltage the components)
...a low voltage level under ~40V (to NOT over dis-charge or drain the battery pack too low)
...& capable of delivering up to ~40A (to NOT draw more amps than the pack (&/or BMS) are capable of)

 

So, it looks like both battery packs would be usable on 48V systems

...but, IMO it looks like the 52V battery pack would be a better "match" for this system because:

The voltage range of the (13S) 48V pack is
Low: 36.4V thru High: 54.6

Whereas the voltage range of the (14S) 52V battery pack is
Low: 39.2V thru High: 58.8V

So, the 14S battery pack has a higher top voltage (which should help the moor produce a higher initial top speed)
...& also, has a more usable voltage range (so, more of the packs capacity, is usable)

 

* Notice: The 48V is configured as 13S8P (104 cells) is listed at 840Wh

...& the 52V configured as 14S8P (112 cells) is listed at 1,040Wh

 

So, would the 1,040 Wh spec be an automatic disqualifier? confuse

...or would that give us maximum energy (being able to use a whole/full 1kWh) while racing

...while still leaving a bit of a "safety" margin?



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Functional Artist


Senior Member

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Posts: 156
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No comments?

More info (personal commentary) biggrin

These 48V ~1kWh Lithium battery packs are only
...~3" tall x ~6 1/2" wide & ~10" long
...& weigh ~12 lbs.

SAM_2964 (1).JPG

As opposed to using (4) 12V Lead Acid batteries that would probably be
...~10" tall x ~20" wide & ~24" long
...& weigh ~150 lbs.

& 

So, to point out the obvious, these Lithium packs

...take up considerably less space

...weigh considerably less

...& can be "cycled" (dis-charged & re-charged) ~1,000 times

&

You/me/we are NOT ever going to get 1,000 cycles out of a lead pack

 

* Notice, these battery packs also come with a charger, manual & specification/qualified certificate smile

SAM_2965 (1).JPG



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nickg


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I agree with you that Electrathon should progress forward from lead acid. I am not totally sold on LiPo technology, but I do like LiFePO4 technology since those cells are a lot less fire-happy than LiPo.

Cost-wise, I don't see that lead acid has any advantage any more. They keep getting more and more expensive and they degrade so quickly that the real cost is quite high for them.

However, none of this is even relevant if we don't have a functioning governing body and any races to compete in.

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Nick Gilbert

College of Engineering, George Fox University

Newberg, Oregon
ProEV


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Functional Artist wrote:

 

So, would the 1,040 Wh spec be an automatic disqualifier? confuse

...or would that give us maximum energy (being able to use a whole/full 1kWh) while racing

...while still leaving a bit of a "safety" margin?

 

This is the dreaded slippery slope. How do the organizers make sure that the driver only uses the 1,000 Whr allowed? What "safety margin" is too much? 

 

One project that I got distracted from was building a black box that every car could run that would track power usage. That way any pack was legal but everyone would be limited to the same capacity. My prototype used a $18 arduino with a shield that included GPS and reading current and voltage. It is Wifi connected which means both the organizers can track lap times and power usage and the teams can use an old phone and browser as a driver aid. I have too many projects at the moment and this has fallen off the list.

Some people have tried packs that look like the ones you are looking at. The quality has been quite varied and there have been a couple of packs that died after a couple of races. The packs also tend to shut down during the race especially if the current is close to the BMS limit. If you do order, insist on the higher amp limit and then test it when you get it. A contactor opens under fault conditions. I think you have to wait for it to reset.

Here is my review of the ones I tested. Be sure to read the second post. They looked just like the picture:  https://electrathonamerica.activeboard.com/t66140971/proev-tests-an-18650-lithium-pack/

 



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Cliff

www.ProEV.com
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