Dear Members
I am a fellow enthusiast of RC cars.
I come from India and hobby cars are not very popular here because (a) they are expensive & (b) until few years back it was almost impossible to buy them. I am telling you this because even the shop owners have extremely limited knowledge about the products they are selling, making it all the more risky.
I have just bought a Thunder Tiger MT4 G3 monster truck with
1. 4 cell lipo battery 4000 mah
2. IMAX B6AC charger
Now, I have a few questions and I will be greatful if you can educate me a little bit.

1. The motor says 2000 kv on it. What does this mean?
2. The lipo battery is 4000 mah and reading at many places in this forum I understand that I should charge it at 1C per 1000 mah. 4A in my case. Excuse my ignorance, but I just need some clarification. .... 1C = 1A or 1C = 0.1 A?????
I ask this because the shop people set up the charger for me at 0.4 A, but after reading extensively, I feel that it is wrong.
Now, this charger is capable of charging 6 cell batteries also, but has current rating of 0.1 to 5 A. So that means it cannot charge a lipo 6 cell at 1C.
3. How long should a lipo battery take to charge normally?
4. If on fast charge, what really changes in the charger that enables it to charge the battery faster?
5. Is it okay to balance charge the battery each and every time?
6. If you know this charger, kindly clearly tell me if it auto cuts the charging after reaching the optimal voltage level in the battery?
7. Finally, I will be able to use my RC only weekly, so should I keep the battery on 'Storage Mode' all the time, or is it okay to just leave it discharged for a week? I ask this because my reading tells me tht it is not a good idea to leave the battery charged.
I really hope someone can help me.

Thank you for your support and suggestions.
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welcome to RCU
You are making a better start than most! Good purchases thus far.

And you pretty much have things right. You can charge at 1c, meaning 4amps for your 4000mah lipos. If you balance charge them, this will take alittle under 1 hour usually.
Fast charging means it will not balance the cells. Doing so takes extra time. While its not nessesary to balance charge most packs every time, it wont hurt them if you choose do. I personally always balance charge mine.

KV means revolutions per volt. So a 2000kv motor on 7.4v should turn about 14,800 rpms (this rating is with no load on the motor of course.)

Larger and heavier models usually use a lower KV motor, as lower KV equates to more torque. To get the top speed, more voltage is added (in your case 14.8 or 4s)

The thunder you bought is reported to be a tough truck.
many RCU'ers use the imex b6, Ive had one and they are awsome for the money. And yes, it cannot charge above 5amps, so a 6cell lipo it can not charge at a full 1c.
That charger will beep loudly when charging is done and stop on its own.
Lipos can hold a full charge for a good long time. there is no need to keep them on the charger in storage mode. I dont leave mine fully drained for more than a week. But when fully charged I may not use them for a couple of weeks.

If you do not yet have a lipo sack, its a good idea to get one. Tho lipo issues are very rare, a lipo CAN (threw a faulty charger or user error) burst into flames. A lipo sack is a fire "resistant" sack that you put the lipo into when chargering. It can give you time to throw the lipo out of the house before it catches anything else on fire. Again, its VERY RARE, but always best to spend the $12 on the extra protection than to risk it.

Thank You 'ejc34710'<div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">And Thank You 'Nitrosportsandrunner'</span></div><div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469);">For your replies.</span></div><div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469);">The information you both provided has helped to understand the technology and usability of my RC much better.</span></div><div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469);">Of course I am sure that with time I will learn more And will be able to help people as you have helped me.</span></div><div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469);">Thank you once again for your support.</span></div><div><span style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469);">
</span></div>

First of all thank you. I researched heavily before making the purchase so I hope the decision turns out to be good and it is actually as tough as people say it is.
Anyway, so if the battery charges in about 1 hour, Does that means that i once I drain it after running the RC for about 15-20 minutes, I can immediately put it on charge for about an hour and then reuse it immediately !!!!?
That sounds to good to be true.. That's a very short charging time in my opinion.
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If the battery is warm, let it cool down a little before recharging. Best off to just let the battery sit for a few minutes before you recharge it. Other than that, yea. Play, charge for an hour, play, etc.

Correct me if i'm wrong, but he said the charger specs were .1-5.0 amp charge rate @ 1-6s lipo. That means it can very well charge a 6s lipo at 1c as long as the capacity is below 5000mah....

Seems you are right. ..I mixed up mAh rating with the no. Of cells. . Probably someone will second that. .
Cheers! .
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Here's a post I wrote many moons ago about Electric, it should give you some additional background...

quote:ORIGINAL: Foxy

Electric guidelines:

Motor

Motors come in 2 basic varieties; brushed and brushless. Brushed motors are older technology and are only really used still in classes that dictate you must use a brushed motor, and other applications that require very smooth throttle response and low speed control, such as Crawling and Drifting. Brushed motors need maintenance every so often, changing the brushes when they wear down and sometimes shaving a layer of metal off the commutator (using a 'comm lathe') to provide a better surface for the brushes.

Brushless motors are the newer technology, requiring no maintenance and delivering significantly more speed and power for the same ratings.

Both types of motor are rated in 'turns', with higher turns being more torque and less speed, and lower turns the opposite. Most brushless motors are also referred to as having a specific KV rating. This is a measure of their maximum rpm per volt. So, for example, if you see a brushless 10.5 turn 4000kv motor, it will turn 4000rpm for every volt supplied at maximum throttle. So the max speed (in rpm) of that motor on a 7.4v lipo battery will be 7.4*4000. In general consider that 3000kv or less is a fairly slow motor for high torque, and a 9000kv motor is a very fast, less torquey motor. The current a motor pulls on startup and under load (amps) goes up with the KV.

Speed controllers

Speed controllers also come in the brushed and brushless variety, indicating what kind of motor they can accept. There are many speed controls which can be switched or switch automatically between brushless and brushed operation. Running the wrong type of speed controller for the motor or running the wrong setting will destroy the speed controller and/or the motor in pretty short order.

The next things to look at on a speed controller are voltage and current ratings, which must not be exceeded. Often a speed controller (hereafter referred to as an ESC) will say first how many volts you can pump through it. Though this is often expressed in how many cells you can use (the number of cells your battery has). NimH old style batteries composed of a number of SubC cells are 1.2V per cell, and Lithium Polymer (lipo) batteries are rated at 3.7v per cell. You may see an ESC say '10 cell/3s max' This means 10 nimh cells (10*1.2=12v), or 3 lipo cells ('S' always refers to lipo cells) (3x3.7=11.1). Or the same speed controller may say 12v max. Once you have identified that the ESC can handle your batteries, you need to look at the current rating (maximum AMPS) and make sure your motor draw will not exceed that. Most motors will say how many amps they draw 'under load' and 'burst'. As long as those amps do not exceed the 'continuous' and 'burst' amp ratings of the ESC, you are good to go. As a general rule of thumb, 25A ESCs are for micro scale stuff, 40A ESCs will do for most 1/10th stuff, 60A ESCs are for the heavy duty (very high kv) 1/10th stuff, 80A for light duty 1/8th stuff, 120A for midrange 1/8th scale stuff, and 150-200A for the really big 1/8th scale stuff.

Batteries

Nimh batteries (made up of smaller 1.2v cells) need to be maintained. After a couple months being flat, they will rarely take a full charge again, at least not without careful resurrection using a complex cycling charger for many hours, apart from that, decent nimh cells should be fine for almost all your current needs, though cannot reach the performance of lipo.

Lipo batteries are a little more trouble, but overall lower maintenance. The thing about Lipos is that they could start a fire if mistreated. Mistreated means; overcharged, overdischarged, badly damaged. These batteries must never be allowed to drop below 2.9v per cell. If this happens, first of all there is the fire risk if high current is still being pulled through it, but also a battery overdischarged in this way will never take a full charge again, and may visibly 'swell'. Therefore it's critical when using lipo batteries to use a speed control that has an automatic lipo cutoff, ideally one which you can set. When I have the option, I always set my lipo cutoff to 3.0v per cell. (so when a 2s (2 cell) 7.4v battery reaches 6.0v, the ESC stops the power to prevent battery damage). These batteries also need to be regularly balanced to make sure that the batteries stay at the same voltage per cell so that the lipo cutoff works properly. The danger of an unbalanced battery, is that eventually, if one cell in the battery were to fall to 2.5v, yet the other was still at 3.6v, that wouldn't be low enough (combined=6.1v) to activate the cutoff, but the first cell is already damaged beyond repair, having dropped too low. Balancing your batteries prevents these voltage mismatches. Most lipo chargers include a balancing charge option, which will do this automatically.

The good thing about Lipos is that they charge fast (can be charged in an hour at the most, and many can be fully charged in half an hour), they do not lose much charge over time sitting around, they deliver incredible amounts of current, and last a very long time. Despite the extra care, these batteries are VASTLY superior to the other type, and I strongly recommend getting some and getting used to their idiosyncracies. Dont be put off by the extra care they require, follow these simple rules and they are very easy to own and will serve you well for many many charge cycles.

Charge and discharge rating... When you buy a lipo battery, as well as the number of cells (2S, 3S, 4S, etc, which determine the voltage, 7.4, 11.1, and 14.8 respectively), and the duration expressed in mAh (milliamp hours), you will also see a discharge rating, expressed in 'C', for example, '2s 7.4v 5000mAh 25C'. This means it is a 2 cell 7.4v battery which will last for 5000miliamp hours and the maximum discharge rate is 25C. The C rating is an expression of how much continuous current (Amps) the battery can deliver safely (exceeding this can damage the battery and/or the ESC). The C rating is calculated based on the capacity. So, 25C on a 5000mAh battery is 25x5 (remember 5000mA=5A), so this battery can deliver 125A of maximum continous current. A 40C battery of the same capacity would be able to deliver 200A of continuous current (40x5A=200A). Once again, it is important to match the battery to what your motor and ESC are capable of. To be honest, most batteries of 4000mAh or more at 20C or more are good enough for most applicatoins, it only starts to be a problem in the really high power 1/8th applications, where a 2650kv motor pulls say 150A regularly. You would need to make sure that the C rating of your battery multiplied by its capacity makes at least 150 in order not to risk damage to the battery and/or ESC

The same applies when charging. You may see a battery say it can be charged at 1C or 2C. Lets take the 5000mAh example again. 1C as we said=5A, 2C=10A etc. So a 'Charge at 2C' battery with 5000mAh capacity can be charged at 10A maximum.

you are right, got my numbers backwards. If it was a 6cell 6000mah, it wouldnt charge at 1c since the max charge rate is 5amps. but any battey 5000mah or below it can charge at 1c.

also, to Dounut0999:
I wanted to correct the charge time I mentioned earlier. My 2s 5000mah packs take 1 hour to charge. My 3s 5000mah pack takes alittle longer (more cells to keep balanced) and so your 4s 5000mah pack will take a bit more than that. But it still shouldnt be more than 1.5 hours tops.
Again, fast charging will take less time. But I wouldnt use fast charge unless you know the pack is only 50% drained. When a pack is fully used before being put on the charger, the chance is higher that the cells are out of balance. But if the pack still has 50% power, then the cells are most likely closer in voltage so fast charging wont hurt anything.

But you should find that your lipo will get you at least 25 minute runtimes....maybe even more. The runtimes we now get with our brushless/lipo combos is amazing. I remember when my old traxxas brushed models went 25mph top speed and only ran for 8 mins (and the nimh was wicked hot) and it was time to recharge the battery!
Now I run brushless 1/10 models on 2s 5000mah lipos and get 1/2 hour runtimes and speeds around 40mph.

<div>Thanks foxy for great info</div><div>Thanks nitrosportsandrunner </div><div>Having a great time with the thunder tiger. Battery takes about 75 minutes to balance charge and does give a run time of about 25 to 30 minutes. So you are spot on.</div><div>
</div><div>Now there is a new development. 2 of the 5 balance lead connectors have broken right off the battery. Some research shows that it's a fairly common problem. There is even a video on YouTube on how to repair it. </div><div>
</div><div>I hope I am not breaking any rules by adding the link.</div><div>
</div><div>Do you guys think that I should go ahead with such a repair. I am refraining from charging the battery until I sort it out.</div><div>
</div><div>Totally unrelated query: the hobby store guy told me to keep the battery covered in thin foam and tightly taped so that it doesn't swell up and is more safe. Is he right?</div><div>
</div><div>Thanks again for our help guys</div><div>
</div><div><span style="color: rgb(34, 34, 34); line-height: 20px; -webkit-tap-highlight-color: rgba(0, 0, 0, 0); font-family: HelveticaNeue, Arial, sans-serif; font-size: 15px; -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "><div><div style="border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(238, 238, 238); border-right-color: rgb(238, 238, 238); border-bottom-color: rgb(238, 238, 238); border-left-color: rgb(238, 238, 238); background-color: rgb(0, 0, 0); float: left; overflow-x: hidden; overflow-y: hidden; margin-top: 4px; position: relative; height: 65px; width: 116px; " class="th thb"><span style="position: absolute; top: -11px; " class="thc">[img][/img]</span><span style="bottom: 0px; font-size: 11px; font-weight: bold; padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; position: absolute; right: 0px; text-align: right; text-decoration: none; background-color: rgb(0, 0, 0); opacity: 0.7; " class="vdur thl thlb">► 9:41</span><span style="bottom: 0px; font-size: 11px; font-weight: bold; padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; position: absolute; right: 0px; text-align: right; text-decoration: none; color: rgb(255, 255, 255); " class="vdur thl thlt">► 9:41</span></div></div><div style="margin-left: 123px; "><div style="color: rgb(102, 102, 102); display: block; margin-bottom: 3px !important; margin-top: 3px; " class="f kv"><cite style="color: rgb(0, 153, 51); font-style: normal; ">www.youtube.com/watch?v=G0kBx8moZ94</cite></div><div style="color: rgb(102, 102, 102); display: block; margin-bottom: 3px !important; margin-top: 3px; " class="f slp">Jan 12, 2012 - Uploaded by RCINFORMER</div><span style="line-height: 1.24; " class="st">How to <em style="font-weight: bold; font-style: normal; color: rgb(0, 0, 0); ">repair[/i] your <em style="font-weight: bold; font-style: normal; color: rgb(0, 0, 0); ">LIPO Battery balance leads[/i] when they break off the battery. I had many of ...</span></div></span></div>

You are on the spot. Takes about 75-80 minutes to charge and gives a runtime of about 25-30 minutes.
Thanks again.
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Great information Foxy.

It took me a little time to figure out the differences in old style Turn Motors and newer Brushless motors. I had to do a lot of reading before I understood the conversion and your post helps to educate me further.

I just started to run Brushless motors this last year in my RC10T4 and 2RC10B4s all three were SEeditions with the Reedy 15 Turn motors.

I installed aDuratraxbranded Castle CreationsESC and3900Kv motor in each of these 3 R/Cs along with running Venom 7.4v500040C battery packs than can get about 40 minutes of run time out of this setup.From my understanding this setup is around a11.5 Turn motor and these went from about 25 mph to close to 35 to 40 Mph after I performed the conversions. Crazy fast and fun than almost uncontrollable if I attempt fullthrottle generallycanonly hit about half throttle on thelongest straight. Keep telling myself to gear them down withsmaller Pinion Gears but never do.

Here is a good link for you guys to help you understand more

http://www.rccaraction.com/blog/2011...-vs-kv-rating/

As arrogant as it may sound, I'd rather people listened to me than RC Car Action on the vast majority of topics.

i'd like to hear someone comment on op's query about taping a lipo so it doesn't puff. is this dangerous advice??

No, it just won't do anything except restrict the swelling a bit, the damage that causes the swelling is still occurring, just the tape is keeping the visual effect under control. In fact, it's arguably not a very smart thing to do as you may have a pack which without the tape would be like a football, but you think its fine, so you keep running it, then one day poof, sizzle, boom.

while your chargind it catching anything around it on fire


btw foxy why not just make that one basic electronic post a sticky already lol

It is actually. lol. It's the second post in the beginner's sticky in this forum.

I do need to reorganise a lot of the stickies, stuff is too spread out.

<span style="font-family: Verdana, Arial; font-size: 13px; background-color: rgb(251, 252, 255); ">It's the second post in the beginner's sticky in this forum.</span><font size="2" face="Verdana, Arial"></font>

So the ownership of the mt4 g3 has been quite eventful.<div>1. The balanced charge connector on the lipo got burnt. Had to open up the battery and solder on new one.</div><div>2. The pinion gear on the mt4 comes loose very often ( didn't realise that I should loctite it). The pinion slipped and shredded the teeth of the plastic spur gear.</div><div>3. As difficult as it is to find parts in India, I have replaced the spur gear with 46 teeth metal, instead of 50 teeth plastic. I don't understand the implications yet but the truck seems to pop wheelies now much more easily.</div><div>4. Now, some connecting pin ( hinge pin?) connecting the shaft from rear diff to the wheel, has broken from the wheel side.</div><div>5. Lastly, the groove nut inside one of the wheels is almost smooth, I used some sealant to make the shape of the nut until I can get my hands on new wheels.</div><div></div><div>If someone has any info on hinge pin replacement, kindly share</div>

As arrogant as it may sound, I'd rather people listened to me than RC Car Action on the vast majority of topics.
[/quote]

I do not find it arrogant when you can provide better information

I too like to read more information then what I just read in a magazine and like to do more research because you can never depend on one person's view on a subject. Most of the time before I answer a question I will look at different opinions and form my own after reading. While my opinion sometimesalsomay seem arrogant I formed it after reading different views on a subject. I admit I do not always have right answerand stand to be corrected whenI am wrong.

I have also found that batteries of all types need to be cycled once in awhile. They will go flat if you do not take them down to lowest voltage and bring them back up. NiMHare notorious for this and NiCads hold memory if you do not. LiPos are too knew to me and I know with a new battery pack it takes a few cycles to get a full charge and hold it. My Receivers setup for LiPo battery packs will perform the low voltage detection for me and shutdown my Electric R/Cs between 3.2V and 3.4V depending on the receiver.

What I do like about Receivers these days many have aLiPoLow Voltage Detection built into them for LiPo battery packs. It has done away with Fail Safe modules. While I never needed them with NiMH or NiCad hump packson my nitros because the signs of low voltage were obvious when runningthese batteries thenmany people bought into buying them.

We are all here to help each other to find the best solution to a problem