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What Novak system for my e-revo running on 7 cell nimns?
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martin34
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What Novak system for my e-revo running on 7 cell nimns? - 05.26.2009, 05:10 AM

Hi guys i am waiting for my brushed e-revo to be delivered.I want to go brushless in the future and from what i have been seeing on other forums is that quite a few people run ninms with there novak systems where as nobody runs them with the mmm because it eats them.I know i will get told to go lipo but i cant and have to stay on ninms.I am a nitro and gas guy so i know nothing about electric but i am reading up as much as i can but it can frazzle your brain not fully understanding what you are reading.On youtube the 4.5t seems quite popular but i see you can get a 5.5 and a 6.5 aswell.The batteries i will use will be 3700 7cell 8.4v for the time being and what would be a safe gearing to use so that i dont fry it the first time i use it?Like i say this is going to be in the future when funds allow.Thanks for any info.
   
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JThiessen
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05.26.2009, 08:49 AM

You can run any of them in the Revo. I've had good success with the 4.5's. You'll get more speed out of the 4.5, but you'll need to dial in your gearing to keep heat down.
FWIW, I would stick with 6 cell. I have seen quite a few guys burn up their 7 cell packs with the HV systems. Not sure why, but it seemed to be a trend. Are you interested in a used system? I have one that needs to be returned to Novak to get the motor replaced....I think my nephew ran it on the wrong gearing, and it overheated and demagged the rotor.


Losi 8T 1.0, Savage Flux - XL style, LST XXL, Muggy, 3.3 E-Revo Conversion and sitting outside 425hp, 831 Tq Dodge Ram Turbo Diesel. It SMOKES
   
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TexasSP
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05.26.2009, 09:39 AM

Why can't you go with lipo? Good lipo can be had for the same price as nimh and performance is much better.


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martin34
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05.26.2009, 10:31 AM

I wander why 7cells burn up but not the 6cell?Thanks for the offer of the Novak but cant afford anything at the mo.Buying the Revo has used up all my cash.When i do go brushless what would be a good safe starting point with the gearing?I cant go lipo because i live in a small flat and dont have anywhere safe to charge them.I know Lipo is alot safer now that it used to be but i realy dont want to take the risk.Also i am new to electric and i realy dont understand all the discharge and cut off stuff.Its very confusing for an electric newbie.
   
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TexasSP
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05.26.2009, 10:46 AM

Lipo do not just spontaneously combust sitting around. Handling them is no different than any other battery. There is actually more potential for nimh to cause fire than lipo as nimh heat up quite a bit when charging while lipo stay almost at ambient temps. The cutoff is easy, all you do is set the ESC to cutoff for whatever voltage is correct. This is usually 3.0 to 3.2 volts per cell.

Don't let lipo scare you, the horror stories are mostly from stupidty. Take your time and don't rush getting into this. This forum is a great place to learn and you are better off buying once the right way than multiple times the wrong way out of fear of the unkown.


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martin34
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05.26.2009, 10:54 AM

Thanks mate and for the advice i see what you are saying.I might go lipo in the future once i have learnt a bit more about it.Say i set the cut off point to 3.0 or 3.2 like you say does the car cut out when the batteries get to that voltage?(i gather they do)then do i just recharge them again like i would with nimhs?
   
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JThiessen
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05.26.2009, 11:23 AM

You would charge and balance them. And yes, lipo cutoff's will cause the car/truck to stutter and stall.

Going lipo right off is a much steeper cost, since you'll also need a charger that can do lipos. I understand the fund limitation. Nothing wrong with taking small steps into this. There does tend to be some amount of arrogance on forums relating to "go 100% into it, or dont bother"....if you only have so much $$$, dont put yourself in debt due to some guy on a forum telling you what to do. Tex was correct that there is one brand of Lipo that can be had at Nimh Cell cost (Zippy), and quite a few of us run them. There is a sizable performance advantage to them also.

If you must do this in stages, you next purchase should be a decent charger than can also do lipo's, so you'll be set when you do go that route. The better chargers will also take better care of your Nimh's. Those cheap chargers are probably the biggest cause of Nimh cells going bad (IMHO).....A superbrain is probably one of the better entry level chargers around 100 bucks (I'm sure there are a few others) but it will need an external balancer when you go lipo, Hyperion is probably the best of the mid level ($200 and up) with built in balancers.


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nitrostarter
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05.26.2009, 11:29 AM

And as far as the Novak system goes, Why not get a MMM system if you do decide on Lipo's. There are almost the same price.

But to chime in, Lipo's are much much more safer now and technology in these packs are steadily improving and getting better and safer. Honestly, I have a shed outside where I have all my R/C and old toys. I charge my Lipo's in there. I normally set it and forget and go inside and watch TV or play on the computer when they are charging.(not recommended, but I trust them that much).


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lincpimp
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05.26.2009, 11:43 AM

You can run the castle system on nimhs, just gear it for around 35mph and you should be fine. Load will determine how many amps you draw, so less load will lighten the load on the nimhs. You can also set the punch control high, like 70+%, that will cut down the amp spikes from accelerating. I could not see wasting money on the outdated slovak system, considering the castle system is the same price. Plus when you do decide to go lipo, you will have a much better system to use.
   
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martin34
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05.26.2009, 02:10 PM

Thanks very much for the reply's and very usefull info.If i do go lipo i will do it properly but like said it isnt cheap and like i have been told aslong as you understand lipo you are ok if you dont it can be a bit dodgey which i dont understand yet.its like trying to read japanese
   
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lincpimp
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05.26.2009, 02:20 PM

Quote:
Originally Posted by martin34 View Post
Thanks very much for the reply's and very usefull info.If i do go lipo i will do it properly but like said it isnt cheap and like i have been told aslong as you understand lipo you are ok if you dont it can be a bit dodgey which i dont understand yet.its like trying to read japanese
Lipo is very simple. As long as you buy a good quality charger, and understand how to set it up correctly charging the lipos is very simple and does not require much if any attention. As far as running the lipos go, as long as the low voltage cutoff is set correctly on the speed control you will be fine.

Unlinke nimhs you do not need to cycle them to get best performance, and lipo does not loose voltage as quickly as nimhs do when they sit. Plus the discharge curve of lipo is very flat, meaning that they hold voltage well unitl they are empty, where nimhs experience voltage drop as soon as they are used and steadily fall. Plus you can charge lipos from partial charge without causing memory issues link nimhs have, and lipos will last longer than nimhs. The only benefit I can see nimhs having is that they are robust, however I think a decent hardcased lipo is just as good in that respect.
   
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alangsam
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05.26.2009, 03:42 PM

you should get a Castle system and run Lipos. Buying Nimh's at this point is just shortening your run time and requiring you to have multiple sets as they have to cool after they run. they get VERY HOT after a run and do not last as long as lipos. the list goes on and on.
   
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TexasSP
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05.26.2009, 06:56 PM

I am with JThiessen and do not think you have to go all in to go in for sure. Like he said beware of the snobs that push you that way. However I do believe it is best to take your time and have as much info as possible before purchasing a system. I also do not suggest listening too much to what most LHS's have to offer as most in my experience are about 5-10 years behind the curve on electric.


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Rebelgium
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05.26.2009, 09:55 PM

My opinion is you should read around for a week or so, learn as much as you can about lipo's. not that hard really.

As said above, all those fire stories are 99% user error. overcharging (impossible if you use a lipo charger), or charging after overdischarging (again, impossible with a lipo charger) , shooting them, ...

Once you've learned enough, buy some zippies and a charger from hobbycity. You'll be much cheaper off than buying nimhs and a nimh charger, and then switching to lipo in a couple of months... And you'll have a major performance increase over nimhs.
   
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shaunjohnson
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05.27.2009, 04:40 AM

uhhhh...try a castle creations MMM + 2200 combo...i THINK novak make them LOL


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