24S 10P A123 Pack. Worth the effort?

[njs]

These guys are so full of shit:

You are now chatting with : Ricky
Ricky: Hello there! Please provide me your Order ID number (If any) and request/concern briefly.
You: AJG-035
You:I was wondering if you offered any kind of discount for colleges building electric cars. I plan to buy about 20-30 battery packs.
Ricky: I'm sorry, but we only give discounts for Gold and Platinum members.
You: What do I need to become a Gold or Platinum member?
Ricky: If its your first time to place an order with us, you're considered as a Standard Customer. When you successfully place your 1st order, you will be automatically upgraded to Gold Membership. and receive discounts. After you have placed at least 10 orders, your membership will be upgraded to Platinum Level and receive even bigger discounts.
You: So if I were to buy 10 of the batteries separately, one at a time, I would then become a Platinum member and be eligible for the discount for the last 20 batteries?
Ricky: That's correct. But you wouldn't be saving on shipping.
You: So if I were to buy 10 trivial priced items, that cost almost nothing to ship, and then buy all 30 batteries I would also get the discount?
Ricky: Correct
You: Do you have a manager?
Ricky: Yes, but unfortunately he's not here right now.
Ricky: You can send an e-mail at cs@hobbyking.com
Ricky: You can request for your message to be forwarded to our manager.
You: I've sent one. I feel like he would be interested in giving a discount for such large orders (20-30 batteries).

 

[tostino]

I know it may be annoying to deal with, however, I think it is worth pursuing.

On another note, I know it's not scientific, but when I went out to the dirt bike park to ride trails, I would only have to refuel once in an entire day of riding, and that was close to the end of the day. Stock capacity tank for the CRF250r is 1.5gal. And keep in mind, this is off road with heavy acceleration and hard braking. You would see much better results on the road.

 

[liveforphysics]

The ninja engine will never provide as low of BSFC's as the CRF250.


In other words, you will get more chemical potential energy turned into mechanical energy from the CRF than the Ninja.

HC support is what it is. They have to talked to a thousand 10 year old kids everyday asking them which airplane can fly there pet dog to school. I'm above platinum there if you want someone to order for you.

 

[njs]

Can you quote me the prices for platinum members? If it only 5 bucks it's not a big deal.

Here's the one I think would work best:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8585

 

[liveforphysics]

Can you quote me the prices for platinum members? If it only 5 bucks it's not a big deal.

Here's the one I think would work best:

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8585

OOPS! I meant to PM not reply

*deleted*

 

[njs]

New plan:

Pack will be 74V 30 Ah of the Turnigy 25C (5S pack)

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6499

There is a pretty significant price break from the 30C to 25C. I'm not sure if the 15 or 20C is powerful enough, and the price difference is not as large unless going for the Zippy Flightmax, which seem to have quality problems according to the reviews.

After watching the video on evtv.me I am mostly disinterested in doing any kind of top balancing. Balancing is better at the bottom, and stringing the weak batteries in parallel with stronger ones will give a relatively even discharges and allow us to only use 3-4 LCD displays in determining LVC.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9282

http://www.hobbycity.com/hobbycity/store/uh_viewitem.asp?idproduct=7704

74V 30Ah, will require 6 packs in parallel, and 4 in series. The car has 2 sides, so the batteries should be split evenly between them for weight distribution.

My first thought was making both sides 74V and splitting the Ah evenly between the two. But if I want the batteries in parallel at the cell level it would be good if they were in closer proximity. I'm now thinking 37V for each side, with the cell balancing wires of each pack directly connected to the other 5 parallel packs. I will need to build a simple unit that will allow the direct connection of 6 balance plugs. 4 should be all we will need. If I am able to get 7 connections in parallel, I could even have a port to attach an off the shelf hobby city charger + balancer.

So does anyone know an easy way to build a unit that will accept 7 5S balancer plugs and create a common line for each of the parallel sets?

 

[grindz145]

Wow, I am actually surprised how cheap these lipo cells are even compared to my recaptured Konion cells.

Liveforphysics, do you have trouble with the LiPo cells expanding, I know that is one of the mechanical engineering challenges when making actual batteries out of them. It's hard to have a rugged case that can allow for expansion.

Why don't more people use these packs instead of the duct-tape Ebay junkers? Whats the trade-off?

-Troy

 

[vanilla ice]

Whats the trade-off?

If you screw up, they can burst in to flames.. Also the LIFE has a proven record of long calendar and cycle life. Lipo may also be capable of this with reduced peak voltage and DOD, but that has yet to be seen.

 

[grindz145]

Whats the trade-off?

If you screw up, they can burst in to flames.. Also the LIFE has a proven record of long calendar and cycle life. Lipo may also be capable of this with reduced peak voltage and DOD, but that has yet to be seen.

The LiFe can burst into flames if you screw up too. Its not pretty, I've seen it. It seems like it's alot easier to puncture the cells. However, from what I've seen they don't don't vent as violently as the metallic cans do. Calendar life definitely seems like an issue. Seems to be more on the bleeding edge.