MGM 12018-3 car and A123 cells

[gyn77]

I have this esc and I'm using it with 7 A123 cells that have a full charge voltage of 25,2 v and is the same of 6s lipo cells voltage, but I would like more volts.

Could this esc supports 8 A123 cells without going in smoke?
Has anybody tried that?

[potreinas]

very interesting question. I have a 1512 2y neu and a quark 125b with 6s a123, i don't want to put more than 6s a123 and don't want to smoke it with 6s lipos, but i have the 12018 mgm.. and if it supports the 8s a123... I'll give an opportunity.

I prefeer the quark with 6s a123 than the mgm because it has more POWER, I don't know why.

I want to know (like you gyn77) if someone uses it with 8s a123 and do not have problems. I have the dual heatsink and dual fan one :)

[tashpop]

are you using 7s1p or 7s2p? a123's voltage drop under load, and a 8s1p should be just fine, and you may get away with the 8s2p because of this drop.

[gyn77]

Sometimes I'm using 7s1p for light weight setup and sometimes 7s2p for high power setup.

My motor is a Neumotor 1515 1700 kv and with 7s2p my savage is a monster of power!!!!

I would like to add a cell if the MGM 12018 could accept 8s, but I don't want to fried my esc, so I must be sure if it is possible before trying.

Also I'm thinking to get a MGM 9032 for using 10s1p A123, but I don't know if my neumotor will be ok running about 50.000 rpm.

[othello]

@gyn77
8s A123 seems to be a bit risky with your ESC. A123 cells may come at 3,6-3,7V per cell from your charger but resting voltage drops quickly down to 3,5V as A123 cells don't want to stay at 3,6V. After a few seconds into your run the A123 cells quickly are droping down to 3,3V. Even at 3,3V your resting voltage is at 26,4V with 8s which is 1,2V higher than a freshly charged 6s lipo. When operating an ESC at its voltage limit there is no margin for voltage spikes which occur during regenerative braking where the ESC feeds the battery (It's comparable with recharching your battery with your charger. As soon as you apply current the voltage of your battery rises). When looking at my discharge graph of my 10s1p A123 pack the average voltage is only at 30V -> 3V per cell. Which would translate to 24V with an 8s A123 setup. You could risk it, but i don't think it's worth it (Think about shipping it back to Europe and the long wait until it will be sent back to you if you smoke it -> i guess you already saw the thread about 2 smoked MGMs on 6s lipos). If you only want to go faster, than gear higher if motor temperature is not critical.

The MGM 9032 is good up to 12s A123. Finnster here in this forum is using it with 10s1p A123 and a Neu 1515/2Y (1100kv). He even made some speed passes with 12s A123. But you would need a ubec as it is an opto ESc without BEC.

On the other hand your 1700kv motor would spin somewhat below 40000rpm with 8s. Although this motors have no problem with 40k rpm they do heat up quicker at this rpm levels. Normaly they still remain in check temperature wise. The more voltage you add the more agressive your motor will become when it comes to acceleration but i think this is where you want to go right? As you already wrote 7s2p A123 is monster of power. So what would be your benefit of running it with 8s A123? Beeing able to run only with 1p, dropping down ampere peaks, better gearing options?

But i wouldn't apply 10s A123 to your 1700kv motor unless you want to do short speed runs. For 10s1p A123 i would recommend either a 1515/2Y (1100kv) or atmost a 1515 3D (1360kv). I'm using the 1100kv version in my 11lbs truggy with 10s1p A123 and it has tons of power especially when i warm my cells up before driving. Unreal acceleration and wheelies although i'm using a center diff. Motor temperature stays uncritical, ESC and batteries are only warm to the touch and the motor only speeds up to 32000rpm under load. But at this power level i can deplete my battery pack in 8 minutes.

@potreinas
I used the Neu 1512/2Y too before i switched to the 1515/2Y (see video in my signature). On 10s1p the 1512/2Y is a real powerhouse which had no problem wheeling my 11lbs truggy. But it ran hotter than my 1515/2y in the same car geared for the same speed. In my lighter buggy the 1512/2y reached 43000rpm under load and in my truggy it reached 38000rpm. This translated to a very agressive setup.

But like i already wrote, i wouldn't try my chances on the ESC as to running it with 8s A123. Your motor will perform well up to 10s A123. If you want to run 10s A123 the MGM 9032 should be a good option.

[gyn77]

Many thanks Othello for all your preciousus informations.

I will remain with my 7s2p configuration!

[sleebus.jones]

Yep Othello, very thorough and well written. :)