My A123 cells are dying... help?

[sikeston34m]

Originally Posted by lincpimp

Ok, looking back at your problem... Not sure why the cells are dying, where did you get them?

Also that esc is poor, but a MMM and run 5s lipo with your current motor, or go up to 6s lipo and drop down to a 520kv motor. Either way you get to buy some stuff... Some 30c flightpower cells would be nice, like the 3200mah packs for 6s. Not sure what the weight difference would be though.

I'm with Linc on this one. Alot of your problem is your ESC.

The startup routines very from ESC to ESC and they are not created equal.

Quark does pretty good, but I think Castle has them beat even with starting an outrunner under a load like a direct drive setup does.

[wulfgang]

I can't do 6S2P! This is a buggy, not MT. Remember that I said it is already too heavy with 6S1P? I'm looking to go down to 4S, and there are plenty of people running 4S A123 with inrunners.

The cells came from brand new Hypersonic 2S2P packs. However, I bought the packs from a hobby shop on ebay.

Thanks for the comments, everyone. I'll probably just get the MMM and see where it goes from there.

[lincpimp]

Originally Posted by wulfgang

I can't do 6S2P! This is a buggy, not MT. Remember that I said it is already too heavy with 6S1P? I'm looking to go down to 4S, and there are plenty of people running 4S A123 with inrunners.

The cells came from brand new Hypersonic 2S2P packs. However, I bought the packs from a hobby shop on ebay.

Thanks for the comments, everyone. I'll probably just get the MMM and see where it goes from there.

If you do try to run 4s a123, you will definately need 2p config. and that will be heavier than the 6s setup you currently run. A123 cells are heavy for their capacity, no way to get around that. The MMM should help the startup, and you are geared (kv-ed?) for around 40mph with your current setup. I would stick with the motor and battery combo you have and try the MMM. The addl programming it offers will help you get the startup right, and if you limit the punch control it will help the current spikes to the a123 cells.

From what I have heard the packs that some ebay seller had were very old, may be why your cells are dying... Plus the load on them is high...

[JThiessen]

Originally Posted by wulfgang

I can't do 6S2P! This is a buggy, not MT. Remember that I said it is already too heavy with 6S1P? I'm looking to go down to 4S, and there are plenty of people running 4S A123 with inrunners.

The cells came from brand new Hypersonic 2S2P packs. However, I bought the packs from a hobby shop on ebay.

Thanks for the comments, everyone. I'll probably just get the MMM and see where it goes from there.

I was waiting for you to tell us where you bought the packs. I'm now 100% certain that you have the same packs that I purchased from Hopmeup.
I bought 6 4S2P packs, and out of those, I had 5 bad cells. There are many others that have had that same thing occur from this vendor.
I was able to get two of the cells "recovered" by pulling the packs apart and charging the individual cells back up using a low ampreage Nimh setting on my Hyperion. However, I have had to be diligent with the pack they are in because it is overly suceptible to over discharge. I had a thread a while back venting about this vendor and the way they treated me, but when you do the math, the price per cell was pretty low. And I learned a LOT about creating packs. I also ended up with a GREAT soldering iron (Hakko), which if I were you, I'd get something similar. You wont regret the investment. The pencil irons just dont cut it. I have applied more than 5 seconds of high heat to a cell in certain instances and have not had an issue. My choice was to either keep heating it to get it to flow, or throw the cell out - so it was a no loose situation. And yes, that was with the Hakko. Sometimes, some vairiables make even a good iron a moot point.

[TexasSP]

Originally Posted by sikeston34m

I'm with Linc on this one. Alot of your problem is your ESC.

The startup routines very from ESC to ESC and they are not created equal.

Quark does pretty good, but I think Castle has them beat even with starting an outrunner under a load like a direct drive setup does.

Agree. Never used the Quark but the MMM handled my outrunner very nicely. Couldn't see a need for a smoother startup.

Also like said by JThiessen get a better iron. The hakkos in my opinion are flawless and the best out there for the money. I have had mine for 8 months would moderate use and still have the original tip in perfect shape. Having a good soldering station changes the game drastically and makes soldering a breeze.

[wulfgang]

Originally Posted by JThiessen

I was waiting for you to tell us where you bought the packs. I'm now 100% certain that you have the same packs that I purchased from Hopmeup.

!@#$!# Yes, that is who I bought them from. I think they were around $10/cell, which is the only reason I chose them over a Dewalt pack. Well, good to know, and thanks very much for chiming in.

So I guess I need new cells and a MMM.

At the moment, I am completely impressed by the Weller 80 W iron, and I can't see the reason to get a better one. With the Weller, I could easily tin/solder the A123 cells in the 1 sec suggested by people in this thread... it's just that when I learned to solder, I was taught to let it sizzle for a few seconds to ensure that no cold joint forms. In the future, I'll try to solder it as fast as possible. For more precise work, I have a nice regulated Weller station.

Again, thanks for the responses.

[lincpimp]

Originally Posted by wulfgang

!@#$!# Yes, that is who I bought them from. I think they were around $10/cell, which is the only reason I chose them over a Dewalt pack. Well, good to know, and thanks very much for chiming in.

So I guess I need new cells and a MMM.

At the moment, I am completely impressed by the Weller 80 W iron, and I can't see the reason to get a better one. With the Weller, I could easily tin/solder the A123 cells in the 1 sec suggested by people in this thread... it's just that when I learned to solder, I was taught to let it sizzle for a few seconds to ensure that no cold joint forms. In the future, I'll try to solder it as fast as possible. For more precise work, I have a nice regulated Weller station.

Again, thanks for the responses.

I have a weller station and a wahl gun (for nimhs and larger wire) and they both work great. I also have a non adjust able 40w snap on pencil style iron, and a few others... I am sure the cells were bad, and the esc is just not performing as desired. Give the MMM a try and I am sure that you will be satisfied with the performance... No need to get another motor.

I also bought 6 2s2p packs from Hopmeup on ebay. Had one cell vent and pop, after doing a few speed runs in a 6s2p config with a neu 1515/1y. Other than that they have been fine, and a lot better than the other non a123 lifepo4 cells. Have since combined them to be 3s2p packs, to run as 6s2p series pack.

[suicideneil]

The non-A123 brand cells tend to have half the discharge ratings of proper cells, so using them in a 2p or 3p setup is the only way to avoid cooking them. Shame about Hopmeup, but it sounds like he's flogging rather old packs which are near the end of the lives...

[JThiessen]

Originally Posted by anson

Have since combined them to be 3s2p packs, to run as 6s2p series pack.

I did that also - those things are huge, aren't they! I've since taken them back to 2s2P packs.

[wulfgang]

I finally got a Dewalt pack and the MMM the other day. Based on what I've read here, I dropped down to a 5S A123 pack (from 6S) because it doesn't seem like the 6S is necessary.

So the results are that the MMM is of course very nice, very smooth, and very fast. This thing hauls tail on 5S and even on the street it has limited traction until about 15 mph or so. I couldn't get the fan on the MMM to come on (I could only go full throttle for a few seconds where I was running).

But I still cannot wheelie, and that makes me sad. The buggy comes in a 7 lbs, but I think the outrunner is mounted too far forward to be able to wheelie. That's probably a good thing for balance and 4WD traction, but it doesn't help much with RWD traction (my setup is direct drive to the rear diff, no front wheel drive).

Definitely a grip and balance issue. If you want wheelies that badly you could try setting up the suspension for weight transfer to the rear. You've got more than enough power (maybe too much) to flip it so it's down to setup.

[wulfgang]

I think I'll probably just go with an inrunner at this point. I want to run in dirt, rocks, and snow, and I haven't been able to come up with a good way to seal the outrunner to make sure bad stuff can't get in but cooling air can get in.

[highflier]

I think it could be the building of your packs.

1) When you built the packs do you install balancing taps? Do you balance first several uses?
2) When you disassembled the packs, the tabs can spin.. But DON'T do that. spinning the tabs is bad and will cause the cell to die a early death.

I use 6s1P pack and have no issues in my Emaxx with a 9xl and BK controller.
going to install my MMM and Medusa for the summer soon. :)

Highflier