Sturmhauptfuhrer

Hey there fellow tankers,

I'm looking to replace the 7.2v 2000Mah Nimh battery pack in my Tiger with a Lipo 7.4 10000Mah battery pack. My question is.......can this be done without hurting the electronics? Will the .2 volt difference make a difference in the functioning of the motors, electronics, radio receiver, ect.....? Have any of you done this without any problems? Will I have to install an ESC? A few questions I need answers to I guess.

Sturm

ausf

I'm not sure what a fully charged NiMH or NiCad is rated, but a lipo is 8.4 full. That said, it doesn't make a difference to typical set up, I use lipos in my Kettenkrad for space consideration and the ElMod is 7.2 just like everything else we use. Certain things like the Benedini are rated much higher since they are used in a variety of vehicles.

The biggest reason they're not widely used in tanks is there's no weight issues to deal with to justify the trade off of battery safety/maintenance. You'd be hard pressed to kill a NiMH, but run a lipo too low and it's toast. Then there's the fire issue too., which is real. I've personally had 1s' go up on me on two occassions and just last week a 850 2s in the shop. Things get ugly quick with them. I still use them, but only when there's a real advantage. If there's a short or puncture in a bouncing tank, it'll be over before you can get to it.

Imex-Erik

You will need some type of low voltage alarm or low voltage cutoff (aka LVA or LVC) to watch the voltage for you. They watch the individual cells and will either sound an alarm or cut off the voltage. I prefer the LVA myself, they are usually very loud and I can use mine for the quadcopters as well. I included a few pictures of two of our LVA's at IMEXRC. I run a 4000mAh in my show tank at our shows and get almost half a day of demo's with it. I have the LVA set at 3.3V per cell, so when the battery drops to 6.6V I get an alarm letting me know it is time to change it out.
Also as ausf mentioned there is a puncture risk. Make sure you run a hard case battery and try to obtain a battery tray from a RC car. You can always have one 3d printed as well for dirt cheap if you have a friend with one. Please note though, this does ruin your warranty for pretty much every manufacturer as no one provides tanks with lipo yet.

The first picture is just two of my favorites, the left having a huge 10mm LED for flight or lighting up your RC car. The one on the right doesnt have the LED light, but has a brighter display. The next three pictures are typical of every LVA; total voltage, cell 1 voltage, cell 2 voltage, etc. The one of the left is up to a 6 cell while the one of the right does 7. These things are your best friend if you run any type of lipo.

flyinwalenda

My Feedback: (5)

Just speaking on the battery issue. Your fully charged NiMh pack will be close to 9v off of the charger so not much difference compared to the LiPo. As stated the NiMh can be run down to 0v and still bounce back when charged, If you run a lipo down to below 3v per cell you can and usually will damage them. Sometimes you can resurrect them sometimes not. That's where the ESC comes in as it will cut-off the connection between the motor and the LiPo when the LiPo gets close to low voltage cut-off...usually 3.6 -3.5v per cell. Shouldn't let a LiPo drop to below 3.5v per cell on a regular basis as that's when they get stressed and can puff and shorten the lifespan.
I would install a LiPo esc that will work with the brushed motor and a hard cased LiPo pack to help protect it.

Jeff489

My Feedback: (12)

It would be helpful if the OP would identify what brand of tank they've got. I assume it is some sort of Heng Long?

tomhugill

I've got two 10ah lipos on order. There's no reason why you can't use them without a low voltage alarm!

Imex-Erik

I run mine a bit lower as most of the time the tank is just sitting there running with smoke and sound. However, for higher demand like flight I do set it a bit higher to the 3.6ish settings as burst with 4 motors can be a big draw or running dual 550 motors. The boss did just get me a new eFlight 6 cell with a 96A continuous rating, now I just have to find something to put it in haha. It all depends on your batteries I guess, I discharge my batteries way lower all the time (I test battery chargers, meters, and more) and my Onyx brand batteries are all still 95% after a year of hard abuse.

flyinwalenda

My Feedback: (5)

Yes, a beeper alarm plugged into the balance plug would work too .

ausf

There's no reason regarding runnng the tank, yes, since it's not going to be damaged in anyway or fall from the sky when power drops.

There's a big reason for it if you want to protect your battery. Large lipos aren't cheap, no reason to waste them by getting anywhere near 3 volts per cell. That's why even a cheap lipo esc has a LVA included.

Imex-Erik

Yea I would never use a Lipo on a non-lipo vehicle without an alarm. They are cheap, less than $15 for a nice one with lights. You can keep them until you break them and use them on multiple models. Unless you get free lipos, you SHOULD run them.
I will say the lipo make a big difference for torque for me at least

tomhugill

Sorry I meant to say not reason to use the whilst using a voltage alarm. Ie alway use an alarm!

flyinwalenda

My Feedback: (5)

The alarms work until you get a few guys running the same set-up ,then it's like five people in the room with the same cellphone ring tone when one gets a call! Probably best to install the proper ESC if it's something you are going to stick with.

tomhugill

Its not that simple with tanks. Most of the proper esc aren't made with lipos in mind so don't feature variable voltage cut offs an the the cut off they do have tend to be too low (ie 5v)

TheBennyB

Yea, I would like to know what electronics your using. Tamiya electronics can handle up to 14volts and I believe shut down at 6 so u can't kill a lipo. My tanks are too loud so the audible alarms are useless, and when u have 10-15 other loud tanks there's no way to hear an alarm unless it's next to you. Also if you drain a lipo cell below 3volts you can revive it by charging it as a Nicd at low amperage say .5 amps till it gets back to 3volts.

Sturmhauptfuhrer

I'm sorry..........It's a Taigen Tiger I, then there is the thought of putting them in a Mato Sherman, a WSN T34, and Heng Long T34. I'm looking for the longer run times and performance that I have heard that Lipo's can give.

I want to thank you all for your responses and your thoughts. I appreciate all input as I'm kinda new to the hobby, but Like Tim Allen...........I'm always looking for a better way! More POWER!! lol

city hunter

Once you go lipo you never go back. Easier charging, better run time and power. You will have no problems except more run time

YHR

Lipo's are a real fire hazard, and one should never forget that. You can buy 6800 maH NIMH batteries, and get very long run times if that is what you are after.

ausf

I agree completely Dan. They are great, but without proper respect, they are not worth it.

I personally had a tiny one cell burst into flames on the pavement about three seconds after I got it out if my pants pocket, literally seconds before I sat in my car to drive home. If it happened a minute later, I'd have a nice hole in my leg.

I know people who've lost thousands of dollars worth of planes to them and theres no shortage of photos of SUVs and cars burned out from lipos going up.

Not going to watch a $1000 model melt before my eyes because I wanted 90 minutes run time instead of 75. I'll save them for planes where the weight and discharge rate trade off are necessary.

And if you think that's over reacting, look at the manufacturer recommendations for fireproof charging bags and metal storage cases for lipos. There aren't any for NiMH or NiCads.

Tanque

Now I know I'm an old codger now because I get the willys every time I think about these but I just won't touch LiPo batteries with a 10
foot pole. So many horror stories regarding these things. Heck even Tesla isn't immune ( I know they're not quite the same)
but there's so much riding on such a thin fragile interface layer between 'plates' in those things. The dielectric separating the plates is
a flammable organic compound if memory serves.

I think some of the guys in the local clubs use packs made up with A123 Systems' Nanophosphate Lithium Iron Phosphate cells
which are supposed to be a lot more fault tolerant. These I still hope to try. But as all advanced batteries, they're not cheap.

They, LiPo types, just seem to be a problem waiting to happen. I've read a little about these things from a chemical composition and I just don't
want them around my models. Anything I have/ had that DOES / DID use them always seems to run hot; iPhone 3 ( now retired ), old company
issued laptop..even the toy $20 helicopter. I've seen a laptop go up an an impressive display due to one of these things.

What truly bothers me is that many problems I've read about are just spontaneous; no one did anything wrong; no damage, no nails through cells;
not dropped. I'll admit I'm not that fastidious with my pack maintenance; but these things have to be watched like a new-born until the day you retire a pack.
That just isn't me. I don't want my hobby to be maintaining batteries. I'll tuck my dogs and birds in for the night and even visiting children but not batteries.

The power they can deliver is extremely impressive, I have seen that. But to me it comes at a potentially too high a price. I once thought could use the power to drive the starters of my 1/10 tanks until it dawned on me that if I needed that much power I must be doing something wrong. I've read that you need a complex and costly very intelligent ( just how intelligent? , Mensa level? ) chargers to maintain these...

Nope I'll stick with my old NiMH batteries; a 5,000 MaH works in my Tamiyas, Heng Longs and others and serves as the aux power source for all my 1/10 scale
beasties. If it comes down to having to switch to LiPo packs I'll probably buy just one, maybe two and hope for the best.

Jerry

Imex-Erik

Lipo isn't really necessary in these tanks, that I will agree with. However, lithium batteries are getting harder and harder to ignore. Personally, I have always had good luck with my lipos. I charge between 2-10 batteries a day, with multiple cycles on each. I test all kinds of chargers, power supplies, motors, motherboards, etc and I have yet to have more than a spark. I am always very careful, I always change my battery connectors to either EC5 or Andersons just so I don't to worry about open connections touching something, I also always use battery bags even with NiMH batteries, I have a steel charging box (a tool box I hacked out to hold batteries and chargers) that I use when I charge, and a fire extinguisher within arm's reach of it all. That being said, you can never be too careful.

CountChocula

For small projects like my 250/9 HT and RRAC large heavy NiMH can't be used. I use small Lipo's mounted externally and they're awesome. I do use the fireproof bag when charging ($50 charger using balancing) them and so far so good. I have 1300mah and 1800mah packs using Tamiya electronics and can't seem to drain them down on the battlefield. I suspect part of that is due to the small motors/gearboxes plus not using the flash so I don't use as much juice per battle as most. Heck my RRAC uses a single FA-130 motor so it's a Prius running around the battlefield.

Anyhow, now that Santa brought me the new 1/16th Renaut FT and 38t, I'll continue using Lipo's out if necessity.

You guys having them burst into flames on you sure makes me more cautious though.

Dave

city hunter

I seriously dont know why anyone would bother with nimh these days, unless you are too cheap to upgrade to a lipo charger. You would have to be a complete moron to blow up a battery, and if you are really that scared, just buy a couple dollar lipo blow bag. I've been using lipo in everything I own for a few years now, and could never go back to a nimh setup. No more false peaks, or cell massaging. Lipos charge perfect every time. I've ran them under water many times, arc'ed the leads., smashed them into rocks with soft cel. Never any issues. They never get hot, put out more juice and keep the juice coming on until they are basically dead. A 5000 lipo will easily outlast a 5000 or the fake 6800 nimh packs.

YHR

I have a Lipo charger as Lipos are a necessity in some models, but I still us NiMH batteries in a tank. They work fine and there is little risk of fire. The stories of Lipos starting house fires are real. Just because it hasn't happened to you doesn't mean the hazard can be ignored. That is exactly when accidents happen. I am guessing when you say dead , you mean when they hit the low level cut-off.

It has nothing to do with being cheap and everything to do with risk assessment.

ausf

Took all of 5 seconds to grab those photos of the thousands out there.

Good luck collecting insurance after that too. I'm sure paying some a few grand to prove negligence is more attractive than paying for your house or car.

If you want to, by all means use them everywhere and anywhere, but please don't be casual about telling people new to the hobby that they're completely safe.

Tanque

Don't you just admire that rhetorical technique of having to insult others who don't agree with your position just to make a point?

I'm neither cheap or scared. Some one else summed it up quite well- it's all about risk assessment. LiPo batteries IMHO aren't worth the
potential hazards.

As some of you already stated if there's a good reason why I have to use them I will. I've been slowly getting into ( back into? ) RC Helis and
some of the best are electric. Little choice but to go LiPo there. Still not a fan....

Jerry