Turnigy LiFEPO4 packs - Page 8 - RC-Monster Forums

suicideneil · 11.24.2009, 03:10 PM

I've seen the hvmaxx esc handle 5s2p, but that is slightly different to an evx2..

Parallel setup has nothing to do with voltage (normal cell count)- its just an easy method to double the runtime & reduce the voltage droop under load ( a stock brushed setup isnt gonna pull alot of current regardless).

Your esc is setup to use a pair of packs in series (2x 2s for example), so you will have to either rewire your esc to take a pair of 5s packs in parallel, or just do like Linc said and use a normal 2s Life pack on each input.

You seem to be over-thinking things- its nowhere near as complicated as you imagine- read my tutotials page, should help abit:

http://robotwars.00server.com/tutorials.html

Finnster · 11.24.2009, 03:21 PM

In all fairness, MA may be correct in saying they are "reject" cells. However, one should not assume that rejected material is bad material. Rejected material maybe 99% quality of accepted material, and no differences may be noticed in anything but specific bench tests.

Any manu process will have a failure/rejection rate. What is done with this scrap material is interesting. There is no reason why a manu can't classify grades of reject material and sell them as such wholesale. Its a common practice in many industries.

Outlet stores began as sellers as "reject" or surplus material. Lots of people still find good deals and qualty goods at outlet stores.
EG: I really like Le Creuset cookware, but its very expensive MSRP. I buy all my cookware as seconds at their outlet stores. For much of the products, you can not tell the diff from the firsts and seconds, and the few you can are usually due to minor cosmetic errors. However, they did fail QC as a first run material, and are not sold as such. I am very happy with all my seconds, and more happy with the 70% less I paid for it. I can promise you it makes no fraking difference in how the food comes out.

Finnster · 11.24.2009, 03:24 PM

Can the EVX2 handle 14cells NIMH? Even 5S Life is 18.25V, which is less than 13cells NIMH fully charged. Hard to believe they would make the specs that tight that it wouldn't work, then again, if you blow it up, don't blame me.

jpoprock · 11.24.2009, 03:37 PM

Quote:

Originally Posted by lincpimp

Not sure if the evx2 can handle 5s LiFe cells in series, that would be 18v fully charged...

Sorry. I was speaking of a 2s on one side, and a 3s on the other. Both 4500mah's to equal 5s.

So now what say you about that?

suicideneil · 11.24.2009, 03:44 PM

That should work fine- 2s on the BEC side, 3s on the other.

lincpimp · 11.24.2009, 03:59 PM

Quote:

Originally Posted by jpoprock

Sorry. I was speaking of a 2s on one side, and a 3s on the other. Both 4500mah's to equal 5s.

So now what say you about that?

I understand that you planned to run a 2s on the bec side, and a 3s on the non bec side. I was just not sure if the evx2 can handle that...

If it can handle it you should be good to go.

sikeston34m · 11:35 PM

Just a little update here.

After running 5 or so cycles through the MM Pro in the e maxx running a HV4400 with sinter rotor/5mm shaft, it was time to move them to my E Revo.

My E Revo is setup with:

MMM ESC
Medusa 36-60-1500 geared 22/40 using Mod 1 gears.

This is more of an amp hog than the E maxx setup.

The packs handle the E Revo just fine. They have alot of punch.

I've ran them in the E Revo 4 times now. Two of those times were both in the same hour today.

20 amp charge rate.

They come out of the E Revo about 100 degrees. Still not bad, but this does show they are being pushed harder.

magman · 11.28.2009, 11:38 PM

Thanks for the update sike...I am thinking of getting some of these for my daughter's truck

himalaya · 11.29.2009, 05:49 AM

Quote:

Originally Posted by jpoprock

Sorry. I was speaking of a 2s on one side, and a 3s on the other. Both 4500mah's to equal 5s.

So now what say you about that?

A123s have huge voltage drop under load, 2.5V/cell is pretty typical. The BEC has no way to provide 6V output with only 5V input.

Maciolus · 12.01.2009, 04:08 PM

Do you know exact size of single cell (4500mAh pack is 2P)? I am wondering if it is possible to make saddle pack for 1:10 buggy.

lutach · 12.01.2009, 05:38 PM

Quote:

Originally Posted by Maciolus

Do you know exact size of single cell (4500mAh pack is 2P)? I am wondering if it is possible to make saddle pack for 1:10 buggy.

I have attached a picture of what the cell looks like, but you can have it with the leads like the other picture of the 5000mAh. The size of the 2250 cell is: 9mm X 34mm X 104. I have other pictures of the other cells available if you or anyone else would like to see.

lutach · 12.01.2009, 05:44 PM

This would be best to make a saddle pack, but you have to stack a few of them to get the capacity up enough. The factory can do other sizes, but need a large enough order though. The size of that one is: 10mm X 45mm x 43mm.

Finnster · 12.01.2009, 05:52 PM

Quote:

Originally Posted by lutach

I have attached a picture of what the cell looks like, but you can have it with the leads like the other picture of the 5000mAh. The size of the 2250 cell is: 9mm X 34mm X 104. I have other pictures of the other cells available if you or anyone else would like to see.

These are cells you have access to? How much are they? 2x 5s1p or 6s1p 2250 would be perfect for my HV Savvy. What is the burst? I see A spikes usually in the 65A range, and upto 90A. That's only 40C max.

LMK

lutach · 12.01.2009, 06:01 PM

Quote:

Originally Posted by Finnster

These are cells you have access to? How much are they? 2x 5s1p or 6s1p 2250 would be perfect for my HV Savvy. What is the burst? I see A spikes usually in the 65A range, and upto 90A. That's only 40C max.

LMK

I have access to basically all the manufacturers of cells in Asia. I haven't asked for price for any of them since I really don't have any interest of having liabilities nightmares incase something goes wrong

. I'm in the process of having 2 LiFePo4 cylindrical cells made and it should take around 30 days. One is a 2/3A size for minis and it should have a capacity of 300-500mAh and a Sub-C size one with a capacity of 1200-1400mAh. I can get pricing and MOQ if you want. Also, they'll be fresh cells so it should take around 30 days to get them made.

lutach · 06:08 PM

Quote:

Originally Posted by Finnster

These are cells you have access to? How much are they? 2x 5s1p or 6s1p 2250 would be perfect for my HV Savvy. What is the burst? I see A spikes usually in the 65A range, and upto 90A. That's only 40C max.

LMK

I think you would love the following then. See pics

. Should I get them all here and mess with MA a little? I really don't care about making a profit on them and I would just have people sign

some paperwork that would clear my name from any wrong doing if they get hurt in any way, shape or form. What do you think?

Edit: The size for the 2700mAh is: 7.5mm X 43mm X 125mm.