Conan_the_Hungarian

Hello everyone,

First let me say that RCTanks is truly awesome! This is my first post.

My question is about new batteries for RC tanks. I know this has been covered before. However, there is not a lot I've found that is recent. What is your favorite type of main battery, based on brand reliability, performance, safety, etc.? I'm very interested in Lithium-Ion/ polymer, but welcome your thoughts and experience regarding Metal Hydride and other possible chemistries.

Thanks,

John

Crius

I use 2s lipos in the majority of of my tanks, and for tanks with limited space I like the Turnigy nanotech 2.2, and if I have enough room for any battery I want I usually run a zippy 5000 mah. Some guys get batteries as big as 6800 mah but I found the extra run time gets pretty expensive when you get up that high. I can catch the Zippy's on sale for about $15 each, and the nanotech usually runs about $10 a piece. I get a lot of batteries from HobbyKing, but chinahobbyline is also a good source. And don't forget the low voltage alarms.

Conan_the_Hungarian

Thank you Crius!

JREEVES

My Feedback: (2)

I've used lipos for years in RC planes, the power density vs weight makes them essential. I'm pretty new to tanks too, but considering the relatively low amp draw from most tanks and the fact that extra weight may be a benefit I consider nimh's about perfect. Plus they don't require the dedicated balancing chargers you should use and extra care during charging and discharging with lipos. I've been buying 5300 mah 7.2 nimhs on ebay for less than $20 apiece.

Lotuswins

I use both LiPo, and NiMh depending on the needs. I find NiMh the easiest to charge, and not worry about over discharging. They are larger, mostly, and cheap. I use LiPo's in tanks that have space considerations since you can get shorty's and even smaller. So my Luchs and 38t light tanks have the LiPo's, and my larger Taigen Heavies and TD's have the NiMh. If you are putting Open Panzer TCBs in your tank, which require sound cards and motor controllers, you may need LiPo's to fit it all in.

jerry

maillemaker

This forum scared me off of LiPos. People charge them in special cases and stuff in case there is a fire. I just use 3000 mah NiMh batteries. I get bored before they give out.

Rad_Schuhart

If you read in the forums, maybe you find my old myself recommending Lipos.

Now I say I was completelly wrong. I never had any lipo exploding, but a couple puffed quite a bit.

Also is what other guys say here, you dont need light batteries for the tank, and you dont need a lot of amps draw neither.
But the biggest drawback is the use of them. In a Lipo, I have to leave them half charged, or it damages itself in the self. That means when I pick the tank I have to fully charge it, or to run with the battery half charged, having risk of overdischarge and setting the entire tank and my house in flames.

I preffer to fully charge the tank, and dont caring about the use. When it stops moving, charge it again, and done. You can do that with a nimh, not with a lipo.

Lipos are for planes, drones, helis or things like that.

maillemaker

I'm also not disciplined enough to follow convoluted battery charging practices. The NiMh batteries are relatively cheap - even cheaper if you buy individual cells off of ebay and make your own. But anyway I have one of those Venom 2 chargers - I just plug 'em in and charge 'em - I have 3 battery packs and one is always ready to go for 15 minutes of tanking when I feel like it.

Steve

Crius

For me the main advantage to lipos is the size. If you ever tried to get a full-sized Nimh into a StuG 3 you know what I mean. I've never had any trouble with them, never had one puff or explode, and I leave them fully charged. So far it hasn't hurt anything and I haven't lost any batteries from doing it that way. If you use your tanks often enough that shouldn't be a problem. Storage voltage is when you think the battery is going to sit idle for three months or more.

I think it's mostly a matter of personal preference. If you like lipos, use them. If you don't, don't. I happen to like them a lot, mainly for the size. I can get a battery less than half the size with twice the runtime if I use a lipo.

Shabbernigdo

Ive always just used NiMh in my tank. 5000 mah lasts for hours on something that draws so little power and its not like they really have high peak current draws that need a lot of punch so never seen the need for a lipo as long as size limitations are not an issue.

tankme

I'm experimenting with some 12V 18650 cell packs for use with my Open Panzer TCB based tanks. Same battery type that are used in a lot of vaping devices. The packs came with a cheapo wall charger. Seems to work well.

heavyaslead

I use NiMH around the 3000-4000mah range and found Tenergy brand as maintaining charge over 5 years.

Jarlath

I'm converted to all Lipos.
You do not need anything more than a 20C 2S Lipo battery for these tanks. Just always get an LV alarm if your tank does not have built in Lipo LVC (Low Voltage Cutoff).
Lipo batteries will ALWAYS puff out at some point. It is the electrolyte decomposition between the Cathode and Anode parts of the battery. It is always occurring, but is usually minimal. But it is greatly increased by excessive heat generation.
Excess heat is caused by over discharging (current draw) or by charging too fast/from mininimal voltages.
Great info on Lipo puffing here : Puffed Lipo Battery: Why they swell and what to do about it ? LearningRC

The current draw of our tanks is under 15A (Tamiya Connector limit) so heat due to overdraw is rarely the issue. Draining a Lipo below minimum voltages is an issue as that minimal Voltage
5000MAh 7.2 V will run my son's HL King Tiger for 5+ hours of usage (I have heat sinks on the gearbox motors and a fan over the Clark board FETS). Lipos are good for several hundred full cycles of use if cared for properly (In tanks that is 1000+ hours of drive time)

Videos of people's RC cars catching fire is from excess current draw. AKA putting a cheap 5000MAh 20C Lipo in a car that should be running 40C minimum (most Car ESC are rated for current draws. Aka an ESC 160A 4-6S battery. The simple rule is battery Discharge rate * AH, but it is that , simple. 5000MAh = 5Ah, times 20C = 100A draw capacity) This is why the hard case lipos are gaining popularity. When the case cracks on the seam, they replace the battery.

Now that being said, I've seen people go on the cheap and want to run PUFFY Lipos that are almost round from swelling...
Simple Lipo Rules.

1. Buy a GOOD charger... (One that can also monitor internal cell resistance for Lipos). Use of a Lipo bag/box is always optional, but a good thing in case of charger malfunctions/surges/etc...)
2. Use LVC ESCs or LV alarms... (Most automatic chargers will not even attempt to charge a Lipo that is drained below a certain voltage).
3. Use the right battery for the application... (Discharge rates are important for current draws, but 1/16th RC tanks can easily work with 20C)
4. Do not expect the Lipo to last forever... They will ALL puff from electrolyte decomposition.

I have nearly 4 dozen RC's which range from 2S 20C Lipo for tanks to 6S 75C for boats... Probably 20 or so Lipos, and have disposed of 3 in the last three years due to puffiness (The 3 were used when I got them). Not one smoking, nor flaming battery among them.
They do require more maintenance than NiMH.

Conan_the_Hungarian

Thanks everyone for the continued replies! Appreciate everyone's input. The detail on Lipo's is especially helpful.

I've used NiMH in the past. Have some experience with Lipo's from use with UAVs. Details Jarlath provided are extremely important for Li-polymer.

Has anyone here ever tried using LiFeP? They have much greater stability and longevity than the LiCo chemistry found in typical present day Li-polymer batteries. However, they come in 3.3V units, so 2S seem to be too little, and 3S seems to be too much.

Jarlath

LiFe vs Lipo.

LiFe Voltage range (3.3V Nominal per cell), 3.6V Upper, 2.5V LVC limit.
Pro: Way more cycle life (5x that of LiPo), Less susceptible to over discharge/over charge issues (You can flatline a LiFe. aka 0V)
Con: Heavier (10-30% heavier), Actual MAh is 90% of listed, Most LVC's set for LiPO (3.4V), Less output V, Harder to find high discharge versions (C rating)

LiPo Voltage range (3.7V Nominal per cell), 4.2V Upper, 3.4V LVC limit.
Pro: Less mass for same MAh @ higher V.Actual MAh is 90% of listed, Most LVC's set for LiPO (3.4V), Easy to find high discharge versions, High V output.
Con: Lower life cycle (300-400), Very susceptible to over discharge/over charge issues

For an RC Tank, LiFe batteries are decent replacements for NiMH. A typical NiMH, while it starts at ~7.0V quickly degrades to 6.5V down to 5.5V over 75% of MAh Capacity (New, properly charged battery). Mass is not usually an issue either...
LiFe is usually a good transmitter option.

Jeff489

My Feedback: (12)

I noticed that the OP didn't mention their brand of tanks, or how they use them (backyard bashing or organized battle events). It makes a difference. Some electronics systems can handle up to 12v (like an IBU equipped tank), while others need lower voltages only.

I run Tamiya electronics mostly, and some Clark electronics. I use LiFe batteries primarily, and like them because they are environmentally responsible, are much safer than Li Po's, and hold a full charge for weeks. I am currently running Hyperion 2s LiFePO4 batteries with good results. Been using LiFe batteries in all my tanks for about 6 years now.

As to the above Pros vs. Cons analysis, I agree with much of it, but have observed that a high discharge rating (while desirable for faster buggies, trucks or truggies) seems irrelevant for RC tanks because I don't have any that pull more than 7 or 8 amps (even my 21 pound ones). Most pull about 5 amps max.

I've also experienced the unfortunate incident of a tank left on for months, and the consequential full discharge on a LiFe battery usually destroys it (puffs up, and will take no charge).

I haven't experienced any of the 90% charge (10% lower than stated capacity) capacity issues. My LiFe batteries all charge up to or exceed their rated mili-amps.

Of course, others may have different personal experience, to each their own.