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

[General_Lee]

General lee,

There is few questios here to discuss.

When comparing SLA and li-ion the first major diff is the weight. But we all know already.

The second thing is about the performances: the SLA suffer from Peukert effect ( please search on the E-S there is a lot of discussions already about that.

The peukert effect is a negative effect that the lead acid battery havd with make them to have their rated Ah to vary according to the discharge rate.. and it's not just a question of Ri. the usual lead acid battery are rated at a rate of C/20.. so if a battery is rated 20Ah it will give you 20Ah but at a discharge rate of 1A. If you discharge them at 10A they will give you around 15Ah. But it's not a question of Ri and heat loss at high rate.. it's more chemical and it's a particular effect that Lead acid have.

The real question you need an answer is how many Wh my pack is capable to produce at the average rate i'mm be using it!

In fact if you bought cheat cells from a seller that sell mostly cells for flashlight there is a chance that these cells will not be qualified for med-high discharge rate.

The best action is to buy cells from guys on E-S !.. there is a lot of group buy or guys offering to build pack and that also want to keep their great reputation to continue selling them as well.

If a 8p group became very hot at the discharge rate you tested it mean one thing:
these cells have abnormally high RI (internal resistance). Sometime if these cells are like that and are new it mean that they are counterfeit or original but very old witch make them to have increase of internal resistance, or just rejected cells.

When you want energy for ebike power ( Wh at med-high rate), you need both Ah and low Ri. These two requirement can be obtained with trusted sellers. :wink:

From my experience with the battery you pay for what you get on ebay about battery.

If you ordered battery that does not meet the spec that are displayed on the auction, then you can contact Paypal and ask for help, Paypal are hungry for fee and we all know as well but when you need help to solve an issue they do the job well and you get satisfied in most cases.

Doc

Big thanks Doc I read a lot in the forum to understanding many things

I bought my pack here: http://e-greenmotion.com/ (Ebay name: naama1485) I not bought by Ebay.

You know this place? the guy seemed give a excellent services! but I was wrong.

 

[wb9k]

I'm confused about the data provided by the seller, which shows the 30A to be the higher discharge rate cell. Maybe the specs he has are erroneous, or he has "modified" the documentation? Samsung's own website should certainly be considered the authority here. What a world...

 

[wesnewell]

For this pack I pay arround 1000$ US. My probleme is, I supposed to have 29E but I received 30A. What is the difference about total power and range with the same configuration? If the difference is so small, I will keep it.

http://lygte-info.dk/review/batteries2012/Samsung%20INR18650-29E%202900mAh%20%28Blue%29%20UK.html
http://lygte-info.dk/review/batteries2012/Samsung%20ICR18650-28A%202800mAh%20%28Purple%29%20UK.html
They are 2 different battery types. And assuming the BMS used is set for 4.2V charge, then you'll not see the full potential of the 30A cells. But on the bright side, charging to only 4.2V should extend the life cycle quite a bit. So if longevity is what you are looking for, the 30A cells may be a better choice. Yes, the 29E is a 1C rated cell, and the 30A is a 2C rated cell.
I've said t before, and I'll say it again, these type cells are best used in flashlights and e cigarettes. 20C rc lipo is many times more powerful and a hell of a lot cheaper. A 74V 25ah pack will run ~$625 and be rated for 500A output. And there is a large selection of 20s bms available if you want one. Here's a few.
http://bestechpower.com/74v20spcmbmspcbforli-ionli-polymerbatterypack/

 

[riba2233]

I would ask my money back if I were you.

 

[okashira]

Not good. The 29E is a good ebike cell, 30A not good at all except really low power. Cycle life is probably meh as well.
I could make you a pack out of even better cells (Model S) for less then what you paid.

 

[General_Lee]

wesnewell
-----------
About Lipo, maybe I will use it for my second E-bike . Thanks for the link.


Riba2233
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The seller can rebuild other pack but I need to ship the wrong pack to him and I need to pay shipping for send and reship! Never, it her fault not mine and I loose a lot of money with that.

Remember him guys!


Okashira
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I keep your name for the future



Maybe with my 1500w E-scooter it will be OK.

 

[Doctorbass]

wesnewell
-----------
About Lipo, maybe I will use it for my second E-bike . Thanks for the link.


Riba2233
-----------
The seller can rebuild other pack but I need to ship the wrong pack to him and I need to pay shipping for send and reship! Never, it her fault not mine and I loose a lot of money with that.

Remember him guys!


Okashira
----------
I keep you for the future



Maybe with my 1500w E-scooter it will be OK.

Here on E-S there is a kind of black list to note all bad sellers I think.

Doc

 

[General_Lee]

thanks Doc, I didn't find this topic but is very good idea to have it :lol:

Befor to bought at this place, I ask at E-bike.ca, but the guys not build 72v pack like I need, they not have a time for this.

I asked to sun-thing28 but they can't build with my specific dimension, I needed to buy the pack already builded

And finaly, I asked to evassemble.com but the guy answered me six week after sended my email, I thought he never would contacting me.

Anyway, the life is not ended