72v 20ah SLA pack vs Samsung SDI 72v 24ah pack range!

[General_Lee]

Hi all, I will change my batteries configuration and I'm curious to know your opinion about this. To make short,

- Originaly I have six 12v 20ah batteries SLA (72v nominal)
- I desire to change it with Lithium Samsung SDI cell 20S8P. (to give at around 72v 24ah nominal)

If I run my bike with the same habit, can I have aproximatly the same range (km) more or less ?

Thanks

 

[saki]

Hi Lee. SLA deliver about 14Ah, and lithium about 24Ah and weighs less. Not double rang, close.

 

[General_Lee]

Saki, you mean, I will have around the same range?

With the SLA I can run between 50 to 70 Km, I hope I can have the same with Lithium!

 

[riba2233]

You will have two or three times better range with lithium. What model of Samsung cells would you use?

 

[General_Lee]

Riba2233, You think?

the cells is Samsung SDI, the model exact I'm not sure, the seller will build for me.

fully charged: 84V
fully dicharged: 50V
nominal voltage: 72V-74V

Do you think Samsung cell is a good stuff?

If the range is better, I'm impressed, because the batteries pack is so small and the weight is less.

 

[riba2233]

I don't think, I know

Samsung SDI is a maker, but I want to know the exact type of cell, that's very important.

Battery technology has gone a long way, so now we have really small and light battery packs. It's funny to even mention lead batteries these days.

 

[General_Lee]

I asked to the seller, it gave me : INR18650-29E

http://www.samsungsdi.com/lithium-ion-battery/e-bike


I hope is a good cells! :?

 

[riba2233]

Ok, those are fine, I have them in my moped, one in the avatar. But 24 ah? That could be either 8 or 9 in parallel, but you should really count on 2.7Ah max for one cell in parallel, so ask him how many cells are there in parallel.

 

[General_Lee]

It gave me 20S8P in the specs. It Mean 8 in parallel ? I think is not really 24ah, but if my compt is exact, the real ah is 22,8 ah (2.85 ah each cell) I'm right?

with 2.7, give 21,6ah maybe it will be good too? what do you think?

This pack is for my scooter. I hope to have more power and the same or more range

With the SLA I already make 70KM, with a good road condition, speed around 25 to 30 km/h. but after that, the batteries is completely discharged

 

[riba2233]

That's what I've thought. I would count on 2.7Ah. You can get around 2.85Ah but that happens only when cells are warm. So it's best to count on 21.6, which is still good, and it will give you more range and power.

 

[wb9k]

Lead SUCKS for motive applications. You will have a lot more range from a Li pack given the same stated capacity as lead. My experience with A123 LFP shows range roughly doubles over an "equivalent" LA pack. Top speed and acceleration are better as well, if the controller allows for it.

 

[999zip999]

Samsung 29e have good ah, but aren't the strongest samsung cell as far as pure power. Each cell has a trade off. Power versus range. What matters is matching your controller to battery, so if we could know more about your scooter. Or the amp draw of your controller. As it makes demands of your battery.

 

[riba2233]

Samsung 29e have good ah, but aren't the strongest samsung cell as far as pure power. Each cell has a trade off. Power versus range. What matters is matching your controller to battery, so if we could know more about your scooter. Or the amp draw of your controller. As it makes demands of your battery.

If he used weak sla batteries which are rated at 0.2C, 29E will be more than enough, they are 2C/3C.

 

[okashira]

I'm guessing 110km range. Please post back with your experience.

 

[General_Lee]

Ok guys, my setup is:

Hub motor: 1500W
Controller: 72v 33amp, but I will make a Shunt Mod probably.
Originaly it use six SLA 12 20amp batteries.
My range is between 50 to 70km.

I know, the SLA batteries is bad, but a lot of electric scooter come with this.

New batteries pack spec:
discharge - UP to continues current : 48A , Power (watts): 3500w
UP to peak current: 72A, , Power (watts): 5200w
BMS can do 50A continues and 100A peak

Do you think it is ok?


Other thing, regardless of the number amp (a lot exemple), the controller will take what he can? I'm right?

 

[General_Lee]

I'm guessing 110km range. Please post back with your experience.

For now this is the winter season, but when I can, I will post my results.

 

[wesnewell]

http://lygte-info.dk/review/batteries2012/Samsung%20INR18650-29E%202900mAh%20%28Blue%29%20UK.html

 

[999zip999]

Wesnewell what can this pack safely be run at ( amps ) for 600 cycles ?

 

[wesnewell]

An 8p pack would be rated for 5*8=40A, But I seriously doubt you'll get 600 cycles if you discharge them below 2.8V. These are basically 2C cells. At 40A they will probably sag by .3V per cell immediately, so a 20s pack will sag 6V right off the top. I certainly wouldn't put a controller on them higher than 40A. But you really need to ask people that use these cells. I only use 10C and higher rc lipo.

 

[999zip999]

He was talking 50amp. controller and I'm thought it would be maxing it out or over the top for 29e.

 

[riba2233]

29E is 2C const., 3C peak, so no worries, especially if he used lead before.

 

[General_Lee]

29E is 2C const., 3C peak, so no worries, especially if he used lead before.

Thanks guys for your comments, I can't wait to try it! My scare is the range, of course it depends how I will run my bike. I come back later (this spring) for the results...

The total lead pack is big and heavy but the new Lithium pack is small, half bigger approximately. It has a big difference. Is weird to imagine to have more power and range with the smaller pack with little cells. Anyway, I trust you and I will see.

 

[wb9k]

You will be amazed and won't ever look back!

 

[General_Lee]

Well guys, I make a 10 amp load to test my two pack, SLA vs Lithium and I'm disappointed about Lithium. I measured with a timer how many time the pack can run with this load.
The result below is similar. The Lithium pack at the end comme very hot versus SLA. My load is a Heat gun with halogen lamp who working in AC normally. I make a video if you want to see.

Check the result:

SLA Fully charged

Time voltage amp
-------------------------------
Start 82.9v 10.50 ah
0:10 75.7v 10.10 ah
0:30 74.7v 9.96 ah
1h00 72.3v 9.64 ah.
2h00 67.1v 9.00 ah
2h09 65v 8.74 ah
The temp is normal, not hot.


Lithium Fully charged

Time voltage amp
-------------------------------
Start 84v 10.50 ah
0:10 77.6v 10.25 ah
0:30 75.7v 10.04 ah
1h00 73.4v 9.77 ah (Begin to come hot)
2h00 69.5v 9.30 ah
2h07 65.2v 8.79 ah
2h09 61v (cut off bms) (pack is very hot)


What is your comments?

 

[riba2233]

Well first, the capacity difference can be seen at higher current. With such small current lead battery has full capacity. Try with 2C load...

Secondly, I think you got served with fake cells or shitty bms. I have original samsung 29E, and they don't heat up at all at 1.4C load. At 2C they are barely warm.

Can you take a picture of bare cells?