4s M1 A123 cells on Mamba Max 5700? - RC-Monster Forums

brijar · **4s M1 A123 cells on Mamba Max 5700? -** 06.11.2007, 09:28 PM

I'm planning on getting a Mamba Max 5700 system for my Rustler and some A123 cells from a Dewalt pack, and I was wondering if, since the A123's are only rated at 3.3v per cell, you can wire 4s to the Mamba Max esc, which is less voltage than the 12 NiMh cells it is rated for? If not, could you explain why I couldn't do that, or at least link to a thread that discusses 4s A123?

Also, I have a Villain EX that I run 14 cells in a lot, and I would like to know if it is safe to wire a 2s pack to the BEC side of the EVX and a 3s pack to the other side for 5s, or 16.5v? It will be really light weight, and fast too:018:.

Thanx,
Brijar!!!

zeropointbug · 06.11.2007, 09:54 PM

4s A123 no problem, even 5s would be A okay.

2s A123 is too much for BEC voltage, I have tried it, and it acts funny, receiver kept shutting down... etc. UBEC is best.

BTW, I just bought a Villian EX for myself, I plan to run 5s2p A123 pack in it. :017:

brijar · 06.12.2007, 12:05 AM

Well, the EVX in the boat has 2 input plugs. One of them runs the internal BEC, the other just adds extra voltage, so you can just put a jumper on it to run only 1 pack. The problem with that is the internal BEC can only handle probably 7 or 8 cells I think without getting really hot.

I think I should have specified that I am going to try and use the internal BEC of the MM controller. I am pretty sure that you can use more cells if you cut the red wire, which disables the BEC to the RX.
If you can't run 4s on the MM ESC with internal BEC, then I may just use my 5 volt regulator to run the BEC like I do on my stupid XL-1 (I've had 3 that the BEC's and sometimes reverse just quit for no reason:mad:1).

If I were you, I'd be careful if you're going to run 2p in a boat. I run water cooling on the motors, and the can get rather hot on 14 GP3300's, and will get even hotter with a stock non-water setup. Not to mention 10 cells will be really heavy. But hey, good luck with whatever you decide to do. It really is a great boat!

Thanx,
Brijar!!!

06.12.2007, 12:06 AM

The MM esc will comfortably handle 5S A123, or it should anyway. The problem that you will run into is over revving the motor.

Castle creations set the battery limits on the Mamba Max systems based on the number of rpms the motors will turn at a pariticular voltage. The maximum rpms recommended by Castle is 65,000. With a 4S A123 setup, you will likely exceed that rpm limit. I also have to warn you that the motor will likely run hot too. It's also going to be more sensitive to gearing.

Unofficially, I was told by the guys at Castle that they test their motors up to 80,000 rpms. At that point, the motors start to tear themselves apart. If you can, you might want to try out a 4600 motor on that battery setup. It won't run as many rpms, but will be far more tolerant to gearing.

zeropointbug · 06.12.2007, 12:36 AM

Quote:

Originally Posted by brijar

Well, the EVX in the boat has 2 input plugs. One of them runs the internal BEC, the other just adds extra voltage, so you can just put a jumper on it to run only 1 pack. The problem with that is the internal BEC can only handle probably 7 or 8 cells I think without getting really hot.

I think I should have specified that I am going to try and use the internal BEC of the MM controller. I am pretty sure that you can use more cells if you cut the red wire, which disables the BEC to the RX.
If you can't run 4s on the MM ESC with internal BEC, then I may just use my 5 volt regulator to run the BEC like I do on my stupid XL-1 (I've had 3 that the BEC's and sometimes reverse just quit for no reason:mad:1).

If I were you, I'd be careful if you're going to run 2p in a boat. I run water cooling on the motors, and the can get rather hot on 14 GP3300's, and will get even hotter with a stock non-water setup. Not to mention 10 cells will be really heavy. But hey, good luck with whatever you decide to do. It really is a great boat!

Thanx,
Brijar!!!

Oh, well 2s A123 will work yeah with internal BEC then I would think, fine.

You mean the Titans will get very hot? 10 cells A123 is the same weight as 12 cell NiMH, but larger. I might just run two packs then, just 5s1p packs and swap them up...

06.12.2007, 10:42 AM

Quote:

Originally Posted by zeropointbug

4s A123 no problem, even 5s would be A okay.

2s A123 is too much for BEC voltage, I have tried it, and it acts funny, receiver kept shutting down... etc. UBEC is best.

BTW, I just bought a Villian EX for myself, I plan to run 5s2p A123 pack in it. :017:

what do you mean 2s is too much voltage?

did you mean 6s a123?

brijar · 06.12.2007, 11:28 AM

I think he means if you plugged a 2s A123 directly into the Rx's Batt slot, it doesn't run it very well.
Doesn't the 5700 handle up to 12 NiMH cells? That is 14.4 volts. 4s A123 is only 3.3v*4 = 13.2v, which is less than the NiMH's rated voltage.
What I am probably going to do is cut the Dewalt pack up into two 2s packs and two 3s packs. I'll run a 3s pack mostly in the Rustler, and if it is safe, run a 4s setup every once in a while. For my boat, I'll put a 2s on the BEC side of the ESC, and probably a 2s on the other side too, but use a 3s on the non-BEC side when I need to race my neighbor's Villain EX (completely stock, 12 Radio Shack 3000 cells:005:). Theirs is fast, being new and all, but I have specially designed carbon fiber props, lower turn E-Maxx (non Marine) motors, more water cooling, better batteries, and more batteries. I should have no trouble beating them:027:.
@CPB, The Titans may get hot, so I would at least check them during the middle of a 2p run. I'm just going to do what you suggested, running 5s1p, then just switching that set out for the other set. If it is too hot, I'll let it cool some.
Does anyone know how A123's and water react? What if I were to flip my boat and some water gets in around the cells?

zeropointbug · 06.12.2007, 01:16 PM

Yeah, 2s on the esc's BEC should work great, better than a 7.2 pack.

I am going to run two packs as well then... and switch.

I thought the Villian EX was water proof? I think you can roll it, dunk, and dive it, at least that's what I thought.

So I think it should work great then, over volting it a little *Titans can handle it, in fact they are a couple turns more coils than the maxx Titans) but it will be lighter.

brijar · 06.12.2007, 04:42 PM

The Villain EX is NOT waterproof. It has foam floatation, so it won't sink, but it can get water in it. It has a waterproof box for the electronics (not batteries), but water can still get in if you flip it and it just sits there for a while. Here is what happens when you flip it.

The Titans can handle the voltage, the higher turn ones in your new one will handle it better probably, but their life will be shorter than if you just ran the recommended voltage.
I read somewhere that EVX's have different voltage limitations from ESC to ESC, and if you put too much voltage to it, it simply won't drive the motors. Then you can drop a cell or two and it works just fine. I heard of someone on the Traxxas board, rupert I think, who had one that could do up to 18 cells:036:. I haven't tested my EVX's voltage limit, so I don't know if it will do more than 7 cells. My packs would usually read about 9 volts when fully charged, so mine should be good for up to 18 volts, I hope.

zeropointbug · 06.12.2007, 04:47 PM

Well I better take it easy then...

Yeah, last year I had an on road 1/6 scale car, dual EVX's, dual dewalt 820 motors, I ran 6s A123, although, straight off the charger it would sometimes cut power, once the motors turned over for a few seconds the voltage came down enough for it to run fine.... and did it ever! :017: Prossibly 1000 watts from two brushed motors, they were very durable.

zeropointbug · 06.12.2007, 05:56 PM

Silly me, correction... 5s2p A123 is ~180 grams lighter than 12 cells NiMH.

So if 5s2p fits inside the boat, I might just go that route, I will see.

brijar · 06.16.2007, 07:52 PM

How hot do the M1 cells get? I just got back from the lake, running my Villain on 14 GP3300s, and those cells get way too hot to touch after a hard run. Of course, the batteries aren't exactly spring chickens, being about a year old (the 19th will be their birthday:cool:), and being run a lot in my used-to-be-brushless Maxx, the batteries didn't have an easy life, so they could have developed some resistance that will make them get hotter than they should.
I just don't want the M1 cells to melt a hole in my boat and sink the whole thing:036:. I read about them a bit in the newest issue of Popular Science, and it tells how they work and everything, also saying they can withstand heat up to like 400* without being damaged, so durability doesn't seem to be an issue.

Thanx,
Brijar!!!

06.16.2007, 09:12 PM

I don't know. If I were running something and weight was a real consideration, I think I'd have to go Lipo.

BrianG · 06.16.2007, 10:08 PM

Lipos sound like a good bet, but since boats tend to be more of a constant load (as opposed to peaky loads in cars), I'd make sure the constant current rating is at least 50% higher than you think you are going to run.

zeropointbug · 06.17.2007, 12:32 AM

I took my Villian EX with 5s A123 pack, with a UBEC in it for 6v for servo.

Boats are fun! Wow, it was a blast running that thing, with the 16.5v, and less than half the weight of 12 cells, it was fast! I would guess 25mph, I got about 20 mins of runtime. The titans at about 10 mins were 50c, and at the end of the run they were 78c, which isn't overly hot, but not cool.