MGM controller do I go for amperage or cell count??

[Purplefade]

OK here's the question, I'm in the process of puting together my Savage and am "concerned" with using an ESC to its bleeding edge... My Savage will likely be in the 12 to 15 pound range loaded with cells and ready to run and I'm planning on a 10\12XL for the near future and upgrading to a Nue 1515(not sure which one yet) when cash permits. My target voltage would be 19.8 (6s A123) to 26.4 (8s A123), do I go with the MGM 22418 or the MGM 16024??? I realize with higher voltage and the right motor you effectivly pull fewer amps, load to load, hum... which one to buy??

I also thought about saving myself some green and going with the MGM 16018. Not to mention this solution puts me closer to my NUE!! My concern with the MGM 16018 is that it's only rated to 6s, can I sneak by using 8s A123s with it, anyone know?

Figured I'd poll the cumulative brain power on here before making an expensive mistake :-) :-)

Thanks!!
purp

[BrianG]

For reliability and warrenty (should you need it) reasons, I would select the model that matches the voltage you plan to use. The 16018 might be able to handle 8s A123's, but would be pushing it.

As far as the current rating is concerned, I would think the 16024 would be the way to go. At 8s A123 and 160A, that's over 4,000w (~5.6Hp)! Besides, I think the A123 cells will be the limiting factor current-wise.

[Finnster]

You should just be able to do 7S A123, but 8S is one cell over. Remember that A123s charge to 3.65V, while the controller is rated @ 25.5V max IIRC.

If I was choosing between the two, I would always go for higher V if its an doable option. w/ that hvy a truck w/ and XL motor, you will find you will be fighting motor heat before you hit those current limits. In fact I don't really see the point of the 224/18 controller w/ A123s. Even in 2p they recc no more than 140A max. I would aim for ~120A peak. With 7S A123s, that should be good for over 2300W. If you get a high eff motor, like a neu, that translates to alot of power to the ground. If you go to 9S2P (if you could even fit that on :) ) you have ~3000W. 18cells is alot of frickin cells tho. After a certain power level the batt just starts getting huge.

ZPB has a 7S2P A123 with a neu on his maxx and seems like a very strong setup. Perhaps he could shed some light.

Edit: Kinda contradicted myself there, but point is, more v is always better than amps (224A is silly imo, other than to keep a very cool controller) but you will be practically limited by the A123s if you go too high a cell count with still healthy amp draw. ~14cells is the practical limit else I'd be looking at hi end lipos. ==> 16018 would prolly fit the bill, unless you wanted to really push it to 8-9S on the 16024. How much power do you really want?

[crazyjr]

I agree with BrianG. All those numbers on voltage are theoretical, till you plug in and see if you get smoke . At 3.65v, thats close enough to the nominal 3.7 of the LIPO's to consider the S count similar

[Purplefade]

QUOTE: (BrianG:
For reliability and warrenty (should you need it) reasons, I would select the model that matches the voltage you plan to use. The 16018 might be able to handle 8s A123's, but would be pushing it.

As far as the current rating is concerned, I would think the 16024 would be the way to go. At 8s A123 and 160A, that's over 4,000w (~5.6Hp)! Besides, I think the A123 cells will be the limiting factor current-wise.)

- Thanks BrianG. I think I get the point, lol, I hadn’t considered the A123s to be the limiting factor, but it does make since as their discharge (amp) rate is less than a higher quality li-po.

QUOTE: (Finnster:
You should just be able to do 7S A123, but 8S is one cell over. Remember that A123s charge to 3.65V, while the controller is rated @ 25.5V max IIRC.

If I was choosing between the two, I would always go for higher V if its an doable option. w/ that hvy a truck w/ and XL motor, you will find you will be fighting motor heat before you hit those current limits. In fact I don't really see the point of the 224/18 controller w/ A123s. Even in 2p they recc no more than 140A max. I would aim for ~120A peak. With 7S A123s, that should be good for over 2300W. If you get a high eff motor, like a neu, that translates to alot of power to the ground. If you go to 9S2P (if you could even fit that on :) ) you have ~3000W. 18cells is alot of frickin cells tho. After a certain power level the batt just starts getting huge.

ZPB has a 7S2P A123 with a neu on his maxx and seems like a very strong setup. Perhaps he could shed some light.

Edit: Kinda contradicted myself there, but point is, more v is always better than amps (224A is silly imo, other than to keep a very cool controller) but you will be practically limited by the A123s if you go too high a cell count with still healthy amp draw. ~14cells is the practical limit else I'd be looking at hi end lipos. ==> 16018 would prolly fit the bill, unless you wanted to really push it to 8-9S on the 16024. How much power do you really want?)

- 3.65v, very true on those A123s, should have factored that into my equation, that said, don’t they level off rather quickly after a charge vs a li-po “holding” peak for a bit longer, if that’s the case that may give me some “safety margin” a quick heat up of the ESC at peak, followed by a leveling of current in the packs and a cooling off of the ESC (theoretically)… That’s kind of what I was thinking, take the higher voltage route of the 16024, keep the ESC VERY safe for the moment and then climb up, or be able to climb up in cell count (or convert to li-po) sometime in the future. As I need it\want it. For now I’m looking for a setup that will yield a solid 40 +\- mph out of my fat pig of a Savage I’m also hoping to be able to put the thing on a diet once it’s built and I determine where I can lose the weight, lol…

QUOTE: (Crazyjr:
I agree with BrianG. All those numbers on voltage are theoretical, till you plug in and see if you get smoke . At 3.65v, thats close enough to the nominal 3.7 of the LIPO's to consider the S count similar)

- Fingers crossed we get no smoke as long as I can control my urges for MORE POWER!!

All in all I’m getting the idea that if cash is a consideration I should go with the 16018 and keep my cell count to 7S2P with one of the NEUs. If cash is available then I should go with the 16024 and have room to grow You guys rock, thanks again for the solid input and keep me posted if anyone has any other GREAT ideas!!

ZPB – Anything you’d add?? Seeing Finnsters note on your Maxx I’d love to have your input here. – Thanks!

Thanks again,
purp

[aqwut]

I have two of the 24160 controllers.. I love them.. If it were me, I'd go with the MGM 24.160, and a 12XL... and run 8S A123 2300mAH or 9S A123 2300 mAH (that's still a lot of power) and should be lower amperage draw.. but if you are able to get a 14XL, I'd rather use that..

[Finnster]

The A123s do peak @ 3.65 on the charger, but fall pretty quickly down to ~3.3v/cell until they dump. Even my 5S packs are about 17.8V (~3.5V/cell) after they come off the charger and rest for a bit. That why I said 7 cells should be just fine w/ the 18, but if you are thinking of leaving headroom for higher voltages later than the 16024 is the safe bet. You should be able to hit 40 tho on the 7S I would think, unless it really is that fat :)

[Purplefade]

Originally Posted by Finnster

The A123s do peak @ 3.65 on the charger, but fall pretty quickly down to ~3.3v/cell until they dump. Even my 5S packs are about 17.8V (~3.5V/cell) after they come off the charger and rest for a bit. That why I said 7 cells should be just fine w/ the 18, but if you are thinking of leaving headroom for higher voltages later than the 16024 is the safe bet. You should be able to hit 40 tho on the 7S I would think, unless it really is that fat :)

Ahh, I gotcha now, 7S = about 25.6v +/- = no real worries for the ESC after they settle, speaking of the 16018 that is. All in all I think I like your idea of going with the 16024 and having the headroom to grow. Can't say for sure, but I'm looking at the Neu 1515 2.5d or the 1515 1y, leaning towards the 1515 1y on 7s or 8s. All in all I'd say 15 pounds for the Savage is probably high, I'm hoping for\thinking I can get it down to, maybe 13.5 pounds or so.

I've got a Revo 3.3 that I was setting up also, but just haven't been able to get the packs how I'd like them balanced and I can't stand the fact that I can't easily access the shocks after I mount the ESC over them... Guess I could look for other solutions for the ESC, just seemed a plate over the rear shocks, close to the motor, was the most simple. The Revo is 8XL with Quark 125, running dual A123 6S1P packs for 19.8v at 4600mah :-) Love your Revo by the way!!

[Patrick]

I think the 1515 1y would be a bit much on 7 and 8s, unless that's what your going for. I have the 1515 2.5d on 5s lipo in my e-maxx and it has a fair bit of power. It doesn't rev that high, but it has a lot of torque and I can vary the gearing a fair bit with out needing to worry about temps. This is it if you haven't seen it http://www.youtube.com/watch?v=ZMZeTJFA2f4 I don't know how much it weights, but it isn't exactly light.
Anyway I guess 6s A123 would be similar or slightly higher power (I don't have any experience with the A123's), so 7 and 8s would be crazy power. The 1y should be similar power on 4s lipo as the 2.5d on 5s lipo I think. So using the 1y on 8s A123 would VERY fast and probably pretty hard on the batteries, temps might be an issue as well.
If it was me I'd probably get the 2.5d for 6s and occasional 7 and 8s, but if your using 7 or 8s for most of your normal bashing I'd look at the 1.5y as well (1500kv), since you have heavy car. The 3d (1360kv) would be a lot of power as well on the higher voltages, but it depends on what you expect from it from your car I guess.

[Purplefade]

Originally Posted by Patrick

I think the 1515 1y would be a bit much on 7 and 8s, unless that's what your going for. I have the 1515 2.5d on 5s lipo in my e-maxx and it has a fair bit of power. It doesn't rev that high, but it has a lot of torque and I can vary the gearing a fair bit with out needing to worry about temps. This is it if you haven't seen it http://www.youtube.com/watch?v=ZMZeTJFA2f4 I don't know how much it weights, but it isn't exactly light.
Anyway I guess 6s A123 would be similar or slightly higher power (I don't have any experience with the A123's), so 7 and 8s would be crazy power. The 1y should be similar power on 4s lipo as the 2.5d on 5s lipo I think. So using the 1y on 8s A123 would VERY fast and probably pretty hard on the batteries, temps might be an issue as well.
If it was me I'd probably get the 2.5d for 6s and occasional 7 and 8s, but if your using 7 or 8s for most of your normal bashing I'd look at the 1.5y as well (1500kv), since you have heavy car. The 3d (1360kv) would be a lot of power as well on the higher voltages, but it depends on what you expect from it from your car I guess.

LOVE the Maxx video, man that thing goes like a rocket!! On the 1y, that was my err, I misstyped, I had meant the 1.5y @ 1500 Kv on 7\8s for about 38k rpm, pushing it slightly above the generally accepted 35k pom mark, but with the Neus (my ultimate goal motor) I figured probably wouldn't cause any issues.

Any chance you might be able to get the weight of your Maxx? I'd love to be able to compare it to my Savy and see where I might land power to performance wise?? I think my initial estimate of 15 pounds was probably grossly high, I'm leaning more towards 13 now as the assembled roller with all but batts and final mounting is just at 10 pounds

My thoughts:
13 pound Savy
3 spd
Neu 1515 1.5y
7s or 8s (A123 3.3\3.65v per cell - call it 3.5v nominal)
MGM 16024
gearing 16\47 (ish) pending final testing

My ultimate goal is to run at 40 mph aprox, with reliable power, "low" temps and solid performance that I don't have to let sit and cool for 30 minutes between runs...

Thanks,
purp

I've seen quite a few posts lately by newer guys asking questions about motor and battery choices. They are asking a lot of pertinent questions, but are passing over what has already been tried and proven.

I am far from being the resident pro on brushless conversions, but I have built about 8 of them so far, and have learned a few things from others and through trial and error.

I don't think that anyone would disagree with me when I say that there is sort of a formula for a successful truck conversion. 30,000 rpms is a good target to aim for with your motor and battery combo. There are also other considerations to keep in mind, like weight. Adding voltage is usually a good thing, but not at the expense of adding significant weight to your vehicle. A monster truck that handles like a boat is no fun to drive.

A couple of combos that come to mind that make winning setups in trucks are:

1. a Neu 1515/1y on 14.8v works very well and stays cool

2. a Neu 1515/2.5d on 14.8 or 18.5v also works very well and is very flexible

As for the A123 cells, I like them, but they do have their drawbacks. They are large and heavy and are limited in the amount of current that they can deliver in 1P configuration. I tried a pack of 5S1P A123 and although it ran OK, it really lacked the punch that I was hoping to get. For 5S, I think that a 2P configuration would really be needed. What I don't know is how much voltage you would have to run before the current demands are such that a 1P configuration would suffice.

You also have to keep in mind that the benefits of the added voltage will also diminish as more cells are added due to weight. The A123s weigh 70 grams each and are the size of a C cell battery.

If you just want to stick with A123s, I'd look into going with either a 5S2P or maybe even a 6S2P setup and get a motor that will get you around 30K rpms on your voltage.

Just keep in mind too that whatever voltage you do get, you'll need to charge it.

What I've said above is just my general opinion for off road trucks for extended running. Setups for specific purposes would probably deviate. I'm getting ready to start running a 1515/1.5d on 5S lipo for drag racing. Not very practical for off roading or extended running, but it's gonna haul butt.

[Purplefade]

Originally Posted by AAngel

I've seen quite a few posts lately by newer guys asking questions about motor and battery choices. They are asking a lot of pertinent questions, but are passing over what has already been tried and proven.

I am far from being the resident pro on brushless conversions, but I have built about 8 of them so far, and have learned a few things from others and through trial and error.

I don't think that anyone would disagree with me when I say that there is sort of a formula for a successful truck conversion. 30,000 rpms is a good target to aim for with your motor and battery combo. There are also other considerations to keep in mind, like weight. Adding voltage is usually a good thing, but not at the expense of adding significant weight to your vehicle. A monster truck that handles like a boat is no fun to drive.

A couple of combos that come to mind that make winning setups in trucks are:

1. a Neu 1515/1y on 14.8v works very well and stays cool

2. a Neu 1515/2.5d on 14.8 or 18.5v also works very well and is very flexible

As for the A123 cells, I like them, but they do have their drawbacks. They are large and heavy and are limited in the amount of current that they can deliver in 1P configuration. I tried a pack of 5S1P A123 and although it ran OK, it really lacked the punch that I was hoping to get. For 5S, I think that a 2P configuration would really be needed. What I don't know is how much voltage you would have to run before the current demands are such that a 1P configuration would suffice.

You also have to keep in mind that the benefits of the added voltage will also diminish as more cells are added due to weight. The A123s weigh 70 grams each and are the size of a C cell battery.

If you just want to stick with A123s, I'd look into going with either a 5S2P or maybe even a 6S2P setup and get a motor that will get you around 30K rpms on your voltage.

Just keep in mind too that whatever voltage you do get, you'll need to charge it.

What I've said above is just my general opinion for off road trucks for extended running. Setups for specific purposes would probably deviate. I'm getting ready to start running a 1515/1.5d on 5S lipo for drag racing. Not very practical for off roading or extended running, but it's gonna haul butt.

AAngel, couldn't agree more, it takes too much time and too much money to reinvent the wheel :-) :-) I guess I could have simply expanded on Serums details from the "Brushless General" notes from the top of the forum and been at a decent starting point.

I've always liked, not loved, my Maxxs running HVs and stepped into an initial Savage running an 8XL on 14.8v but it got so blasted hot that I wanted to flip to something lighter and more "controllable" when it came to temps and cooling off. Running my Revo also on the 8XL with a Quark has proven to be lots of fun, but I miss my Savage :-( Not seeing tons of info in the Savage forum and having it weigh CONSIDERABLY more than my Revo, I "lost my way" in planning.

That said, I should have been more clear on my A123 situation, lol, all my packs will be XS2P (X being number of cells) realizing that they pull down about 60\70 amps in 1P config scared me when I started looking at the weight of my Savage and the Savage lends itself nicely to dual packs, one on each side and also allows you to tend them to the front of rear for weight transfer if need be, which I like. My Revo ran all 12 cells down one side, which didn't bother me greatly, but it did make for one large pack vs the weight and balance of the motor, esc and electronics on the other side, lol...

For charging I'll be hitting these with the TC1010 from Thunder Power, I LOVE the charger and it has always treated me good in return :-) Question though, the 2.5d on 14.8 seems a bit "low" for RPM vs the weight of a larger MT? Pushing it to 18.5 takes it right to the sweet spot, but I was always under the impression and I know we're splitting hairs here, that you wanted to see about 35k rpm out of the motor and with the Neus maybe just a hair more?

Hum, considering your thoughts, and my trucks weight, maybe the "perfect" setup for my Savage would be:

Dual 6S1P A123s
Neu 1515 2.5d - 37k (ish) @ peak charge
MGM 16018

My only concern again is weight; believe me I've even thought of dropping to a 1500 kv motor or going to a 1521 and taking the cell count up and going with the 16024... Ohhhh what to do, lol

What I want is a truck that runs well, stays cool and doesn't handle like a boat

GREATLY appreciate everyones input, if I didn't have total faith in you guys I wouldn't have asked.

Thanks again,
purp

[BrianG]

The Neus are less sensitive to higher/lower rpm and load than your typical XL. I've run my 1512 2d (2600kv) Neu on 4s and 2s (for kicks) geared high and geared low and it seems to run cool no matter what...

IMO, the 1515 series will be PLENTY for a Savage. I would shoot for a kv/voltage combo that hits around 40k rpm and gear accordingly for the speed desired.

purp,

I'm only using the 30K as a reference. From personal experience, that has been a good number to shoot for. Running my 1515/2.5d in my 8ight T on 5S is nuts. It has lots of power, but then on 4S, geared at about 15/48 or so, is a good race setup and does well for bashing too, without the insane power. Of all of my motors, the 1515/2.5d is my favorite.

Oh, and not to be presumptuous or anything, but if you've only messed with Feigao motors, you really can't anticipate what the performance of the Neu motors will be based on your experince with the Feigaos. If you set your system up right, heat will not be an issue with the Nue motors. I don't even take a temp gun with me any longer when I go out and run.

[aqwut]

maybe the 4 pole motor has so much more torque at the start than the 2 pole motors.... maybe that's why they run cooler?.. just a thought... I've noticed using a 4 pole motor doesn't really cog...