View Full Version : discharging/charging AAA questions

2015.03.02, 02:54 PM
I have been discharging my wurks and orion batts at different rates and hva some questions.:rolleyes:

discharging at 3 amps is what is written on the wurks package.
I have been using the spintec batterypack manager wich discharges at 10 amp. with a special programm wich lets the batts cool. The batts keep relative cool.
Will this damage the batts? though?

The IR with this method is lowered by 25% i have noticed.

Another question is that with charging my wurks 990 with more than 800ma they will heat up to a extend that the charger shuts off at temp. The batts get too hot.
But reading this forum let me read values like 3 amp charge rates?? How can this be besides really wrong amp reading on the chargers(or mine ;)). The Orion 900 do the same. The batts have enough punch and speed though so its ok.

Seems odd though that i can`t charge higher amps without getting those high temps.

greetz JW

2015.03.02, 03:45 PM
Most of the older and widely accepted chargers will shut a cell down if it reaches 128*F during the charge process. I am not sure on the newer more expensive units. To keep the batteries cooler during charging I prefer to keep a 6" case fan(or your personal preference) blowing air across the charge ports to keep the air moving. I have never had a thermal shut down during charging but then again I don't charge a 3A either. As far as discharging I use the Atomic dischargers as they discharge at 2.5A. I usually discharge for a timed period to try to insure that the batteries drop to or a bit below the .9V threshold. This has always been good enough for my competition usage. When a set of batteries no longer perform in a matter that I like I either relegate them to practice status, modified class use or pass them off to a "noob" to help get them started. A new set of batteries is the cheapest performance part you can add to your car and it works every time.

Ask a hundred guy's and you will get a hundred answers. What works for you is the right way to do it.

2015.03.03, 12:51 PM
Ask a hundred guy's and you will get a hundred answers. What works for you is the right way to do it.

mleemor60 is right. There are countless opinions on charging, but the differences lie mostly in 'how fast' you are trying to charge your cells. If you are aiming for the quickest charge possible, without destroying your cells, then consult the manufacturer's information on the 'C' level of charge/discharge for that particular cell. Take that C value and multiply it by the mAh rating of the cell, and that should give you a number for the charge current your cell can sustain. However, if you are looking for a 'quality' charge, than a lower charge current is more ideal. If you have the time to wait, you can charge your cells at a level where heat isn't even an issue. Heat only becomes an issue when you're trying to push the envelope on a cell's 'C' value, which is unnecessary...in my opinion.

If you only have one or two sets of cells and you want to run your car for a long time, where you're recycling those 2 sets of cells, I could see why you would rather have a fast charge cycle, however if you have 'more' sets of cells and 'more' chargers, you could get away with charging at a lower current, and still have an available fresh set of cells when needed, and heat becomes a non-issue as it pertains to charging...

2015.03.03, 01:27 PM
I never take less than 20 sets of batteries and 5 chargers to the track whenever I go.

2015.03.03, 07:33 PM
Another thing worth noting about charging/discharging is that cells will net more charge cycles if stored discharged. Most people are inclined to immediately charge cells when dead, but unless you plan on using them 'soon' after the charge cycle, it is best to leave them at their lower voltage state.

2015.03.04, 01:37 PM
thanks guy`s for the info.

A`m having a great time racing, so all goes well.

2015.03.04, 02:37 PM
Another thing many people overlook is cell conditioning. Nimh cells like a schedule and perform better when you schedule your charge, discharge, and pre race cycle. Throughout my many tests when I used to run Nimh I found that a charge and then discharge of all racing cells the night before a race day and then charging and discharging once before I charge them to race them worked best for me. What this did was give them a conditioning the night before and made it so that when I went out for qualifiers and the main the next day they were on their second charge of the day. Personally this is where I found the cells to perform their best. And after I used them in the qualifier or main I put them away until the next week. This technique like any puts a good amount of stress on the cells so I sacrificed lifetime for perfomance and generally bought 4 sets of cells every month or couple weeks. I still have boxes and boxes of nimh that never saw the lght of day after a couple of months. Sometimes you really do get what you pay for. That is why I hate stock racing because to become competitive you have to spend a lot of money.

2015.03.06, 01:44 PM
...That is why I hate stock racing because to become competitive you have to spend a lot of money.
i have to respectfully disagree with this statement and personally find it ludicrous. our stock club series is very competitive and some of the fastest drivers in the club spend no more time/money on their cells than i do, which is very basic maintenance of cycling cells. sure, you are always going to have the group that use sophisticated equipment, spend crazy $$'s on expensive matched cells but in the end, it's not going to guarantee you your going to be any better than the next guys with more skill, patience, luck or what have you. in principal, i completely disagree with the notion one must spend a fortune to be competitive. i've witnessed some of the best drivers whoop up me and others with basic equipped/tuned cars countless times over the years. it's more psychological in my opinion than reality as most will look to purchase something in an effort to achieve more immediate improvement in performance than could be achieved with additional patience, skill. i see high $$$ cars getting beat all the time locally and at regional events by cars worth far less $ invested. invested time is another story though...

2015.03.06, 02:38 PM
Be very careful R. Don't get him fired up(see post 11 in the X-power IMT thread) He will have to tell you ,as well, how great he is and how much he knows. Don't make him come to town and show all of you how it's done.

2015.03.06, 02:40 PM
It has been my experience as well, that practice, proper tuning/setup, and good driving will win the race over the amount of $ spent in stock classes... At least it has for me in Fast electric "stock" boat racing. I'm sure the same is true for car racing as well.

I won the national championship in the P-Limited Sport Hydro plane class with a $45 Tactic Transmitter, and middle of the road lipo packs.

Here's a video of last years National race where I went from 3rd at the start to win it against guys that had MUCH more $$ invested in their boats and equipment than me.


Stock classes force you to practice and tune better IMHO.

2015.03.06, 09:21 PM
I agree with Arch, We don't spend much money in stock class. Mainly 1 or 2 sets of tires per season. I have batteries that are a few years old and still going strong. The only reason I bought some new batteries is that my son is racing too and he likes to run different cars so he goes through 10 sets of batteries on race day.

2015.04.10, 02:18 PM
You can find those old Turbo Cell Matchers for cheap now anyways. If your that serious, you can find them for about $65

Cell matching does help, but unless your a Marc Rheinhard of mini-z, I don't think that will make a big difference in winning a race.

2015.04.10, 09:44 PM
Cell matching does help, but unless your a Marc Rheinhard of mini-z, I don't think that will make a big difference in winning a race.

I beg to differ. In a competitve racing environment when using stock motors batteries are the MOST IMPORTANT edge. Having matched batteries is a very valuable asset. Whether you are matching them or paying for someone to match them (better option as usually if somebody is selling matched batteries they have more batteries to match and thus the cells are closer to one another). Matched batteries that are cycled by charging and discharging are the quickest and most effective way to pick up time, and yes sometimes the difference can be .5 seconds which is a lot:eek: Every racer can notice the difference of having quality matched batteries over regular batteries so then the question becomes: Would you rather be faster or slower than everyone else? I always thought that stock class racing was the most expensive form of racing. When power is limited by the motor generally people look to batteries and other speed secrets for advantages.

2015.04.11, 12:57 AM
that plays heavily into what type of club you have in my opinion and what type of atmosphere surrounds it. it's certainly not that way in our area, and i have to say i am very thankful for that. in our area, most of the top guys are running the same $7 pack of batteries the bottom half are using. some are much more caring in how they prepare the batteries, some are not. i agree that it will make the difference in that 100th of a second when you have a tight group all needing that 100th of a second over 100 or so laps. and to point out, you don't even need the expensive equipment to per and service batteries. most just have a discharge tray and a decent, middle of the road charger.

my advice, don't get caught up in all that drama. do what you can, with the time and equipment you can and try to enjoy it. otherwise, why bother at all? you can be competitive and still have fun :) our group does so twice a month :cool:

2015.04.11, 07:17 AM
If anyone was to win by 0.01s, would they really be able to attribute it to how robust their cell pack is? I mean, isn't 0.01s kind of the difference between you taking one corner a little wide on one turn? Sounds like splitting hairs to me... If I win by 0.01s someday, I'm going to say that it was because I wound my motor better, or tuned my suspension, or that my car runs on a better frequency... :rolleyes:

2015.04.11, 08:47 AM
at top tier events, it happens. in average club racing, not so much and when it does, just as easy to attribute it to grazing a corner, take a few wide turns, etc. as you mentioned. again, it comes down to what type of club atmosphere your dealing with. i'm not in a club where everyone is going all out in terms of cash and tweaking cells to get that extra 100th of a second when keeping a clean and consistent line is by far the more advantageous strategy. clean and consistency wins 9 times out of 10.

2015.04.11, 11:37 AM
It is not 1/100th of a second but sometimes closer to 3/10th - 5/10th a lap:eek: In a 50 lap race that is up to 25 seconds:eek: Now that is usually the extreme as it is usually coser to 3/10th a lap I have noticed just on batteries. If nobody else is doing it than I agree it may not be neccesary but like I have said isn't nice to be faster than everyone else? I am not saying that if you are racing with a non-competitve crowd you will automatically see this difference because if you are a bad driver you cannot handle the extra speed but for someone who can drive a decent line the difference is noticable and justifiable. An edge is and edge, no matter how big or small. If someone has the money to do it why would you tell them otherwise if the only negativve aspect is money? Well I know why... you would prefer for everybody to not spend money so you don't have to either. It makes sense really... keep everyone in the stone ages so you can stick to your own budget and effort put into mini-z. I like the matched batteries, they made the racing closer and the performance more consistent and there were NO downsides. Spending time and money on batteries is a touchy subject because it takes time and money, but a few who would rather not spend that time or money should not tell others it is "not noticable" or not neccesary just for their selfish reasons. I have nothing to gain from anyone else matching batteries or putting lots of time into their batteries because I run lipo so why would I hide the truth? Just something to think about... Batteries are the quickest way to pick up speed and any serious racer should consider batteries an investment well worth their time and money.

Also, how did you come to the conclusion that matched batteries only gave that "1/100th" difference? Have you ever experienced driving with matched batteries? Do you own enough sets to come to an educated conclusion on the matter? It seems by your logic if you see it in use somewhere else or have a certain opinion on it you automatically become the expert on the subject matter. I am not trying to call anyone out but I have provided my INFORMED expereince not my guesstimate or opinion. If you never give anything a chance because you disregard it as miniscule or unnesscary you will never see any improvement or change. Would you feel the same about a software that mapped out the fastest lines on the track? This is theoretical of course but because it would go into the category of practice and driving clean lines by your logic that would be a valuable investment no matter the cost, despite the fact that it would simultaenously cheapen the racing and break the bank.

2015.04.11, 12:33 PM
If you feel the need to go to extremes to extract the last miniscule amount of energy out of a Nimh battery in order to gain an advantage then have at it. It is for that, among other reasons that people are or have moved to the small lipo's that are available. It provides a higher voltage and allows for more speed just for the sake of it and opens the door for those that do not have the skills to utilize the outdated technology that is needed to coax the nth degree out of the nickel's.

I have competed at Fairfax, Remnant, Railyard, Myrtle Beach, Miami Motorsports, Maj's and some others. I have visited Inside Line in Cupertino and a couple of other left coast tracks and I didn't or haven't yet found a single facility that has held a race that was for a specific number of laps as opposed to a specified time. Since the races are timed it kind of "lick's" the color off the notion of overall speed unless you are competing for most spectacular crash or highest number of broken parts. Sure. It's nice to be able to say "I ran a 9.00 flat lap" but the guy that runs a mean of 10.00 flat is likely to turn more laps in the given time for the race.

Are there gains to be made from hyper vigilance of your battery charging idiosyncracies? Certainly. You can learn discipline and patience. Is it necessary? Well, different strokes as they say. The best driver with a well tuned and set up chassis is still going to "Kiss the Queen" even if he is running alkaline's.

2015.04.11, 02:23 PM
Yes, I once bought into the notion I 'had' to do this or that to be competitive and spent the money and the time but I happen to run into some really fast, really intuitive drivers over the years that opened my eyes so to speak. I'm not nocking the efforts in question, they will make a difference, which no one questioned. It really doesn't take a lot of money to do it either. It's time consuming for sure but doesn't have to be really expensive.
As I've said over and over, it really depends on the atmosphere you compete in. Thankfully ours is both competitive, challenging and geared toward enjoyment. I'm far more happy with where we are at as a club now than ever before. I certainly hope it is the same for others irregardless of the differences in club culture. If your motivation takes you in a particular direction, follow. I know racers that enjoy the preparation, battery care, etc. just as much as racing. I know some that just take the stuff out of a box once or twice a month for thrill of the race and still do very well. I don't portray the facts as anything but as they are. You don't need to spend a fortune to be competitive, challenging and enjoy the sport. It's really that simple and nothing more to it that that. The rest is group think and club culture.

2016.01.27, 03:39 AM
Sorry Guy's for replying to a " old" post,
But I agree with arch2b `s answer and think its spot on.:p
This miniz racing is the best racing class ever. It will get us new contenders in RC racing, wich we need, because it doesn`t matter what you spend, experience is what counts. Just one car with 4 sets batts and a charge/discarge rig is all you need. Fun though for me is tingling with the countless options that are available and the Bling Bling.:)

Though racing 8th class onroad nitro in the summer Nationals its Always good/nice to start with miniz racing.

But DMALMAd has a point though. It is not what we generally tell newcommers though because its really difficult to get that last tenth of a second and only experienced and DEDICATED drivers manage to do.

But i have respect for these guys who do manage.

2016.08.08, 03:06 PM
I am late to an old post as well... but I will say that when I was racing regularly, I stopped racing stock due to the amount of NiMH maintenance required to be competitive locally.

You had to match cells, and go through 6-10 motors to find the one that had the best power curve for the layout... These 70t cars would outpace many 50t cars with a standard charge and drive approach. People would discharge their cells, and hold them at low voltage for the entire week, which required multiple dischargers... it was really a week long process to get the cells to the point that they were going to give you enough power to race competitively.

After a small hiatius, I returned to the track to run a 70t class, bought brand new cells which were good, got on the track, ran perfect laps.... and was being passed on the straight like I was standing still. My general driving style was momentum oriented, and I typically excelled in stock over mod, but there was no way to keep up.

Its what happens when competitive racers use every trick in the book to race a stock class. Its fast, but the expense is just too high, and why I mostly raced mod classes, since you didn't need the best batteries, a good motor choice would give you all of the speed that you needed. The standard battery maintenance was all that was required. Once LiPo was introduced at the track, it was so much easier to go back to charge and drive status.

My AAA battery care was Much More CTX-D2 5a linear discharge to .2v per cell, with a 700mah charge on LaCrosse BC700. On the MM discharger, you can see the average voltage, and seconds that it took for the cell to discharge, so you can match that way and weed out the ill performing cells. And with a 5a discharge, there is much more voltage sag than a lower amperage discharge, so the .2v per cell doesnt damage the cell. Typically, damage occurs when discharging unmatched cells in a pack, when the lower capacity cell dumps, polarity reverses and damage is inflicted.

For AAA mod racing, I typically use lower voltage cells with more capacity... for stock, I use highest average voltage cell with minimum of about 600mah capacity.

2016.08.09, 01:42 PM
:eek:wow glad I get into this argument :D

2016.08.10, 11:18 AM
TBH it is really a mute point now though. The guys still running AAA around me don't mess with their cells the same way people used to. The last vestige of nimh racing is 90mm and some stock racing and everything else seems to have moved towards lipo so the racers that want everything to be about pure performance and driving skill have more power than they can shake a stick at (I recently tried 10000 kv with lipo in my Atomic chassis and its just crazy ballistic :p) and the stock class and fun classes are slow and just that... strictly fun.

2016.08.10, 11:27 AM
'fast' is a relative term. for those that are not exposed to lipo outlaw/mod class platforms, a well tuned 70T or 50T is plenty fast. i can understand why they would seem slow if lipo is the predominate class in your area but where it's not, 'fast' has a different frame of reference :)

2016.08.11, 01:15 AM
We still use NiMH pretty much exclusively at our local meets. There is a pretty big difference in performance in the same class (we run a 70T class and "open") when using inexpensive NiMHs/Chargers and good batteries and quality chargers. I've never gotten around to investing in a good quality charger for my Mini-Zs mostly because the atmosphere at our club is pretty casual so you don't need it to have fun and be fairly competitive. I use Eneloops and a basic multi-chemistry cheap-o charger. Works fine for what I need it for though admittedly, those at our meets who use good chargers/batteries together tend to have the quickest cars by quite a margin. I'm also fairly sure your batteries last a lot longer (get more cycles) when charged with good chargers versus cheapies like mine.

2016.08.11, 06:29 AM
sounds a lot like our group :p competitive but fun. we have some who have good chargers, better battery care practices and while most still tend to use inexpensive batteries, they are indeed faster however it also has to do with their skills being high as well. i don't begrudge them at all though. I personally use it as a motivator to better my skills on the track so that i can get even closer with what i'm using. a fast car without the means to control it on the track is futile.
most of our club runs duratrax cells which are sold inexpensively at the LHS we race in. i happen to have eneloop's myself but i got a batch on sale so price wasn't much more overall. i've been running this batch for almost 2 years now.

For AAA mod racing, I typically use lower voltage cells with more capacity... for stock, I use highest average voltage cell with minimum of about 600mah capacity.
this is pretty common at our group as well for those that have analyzed their cells.

2016.08.11, 01:17 PM
I'll chime in with what I do. Recently I changed my charging/discharging practices and have noticed a good difference. Due to time availability I used to discharge the day prior to charging and charge the day before racing. My batteries were always "alright". I used a Hitec X4 AC/DC charger and PN discharge trays.

The recent changes I have made are to use my other Hitec X4 DC only charger and connect it to a good power supply I bought with my iCharger. Just the addition of the separate power supply made a very noticeable difference in the top speed and power of the batteries and my car. Since then I changed to discharging and and charging the same night before racing. I wish I could charge the day of racing but don't have the time.

My equipment used is a Hitec X4 DC charger, Generic 75 amp power supply, PN charging and discharging trays, Homemade charge leads (14ga), and Peak 900 AAA batteries.

My method is to discharge till the lights go out or more. Charge at 1.5amps, .5mv delta peak with the cutoff at 900 mah. Most packs will cutoff at 860-900mah and seem to have good power.

I wish I had the time and energy to put into squeezing every ounce of performance out of batteries and motors for stock racing but I dont and probably wouldnt race if I had to. My advice to most would be to spend that time practicing and running laps to make yourself faster instead of making the car faster.

2016.08.11, 03:00 PM
That last sentence is sage advice, indeed.

2016.08.12, 08:42 AM
I agree as well. Don't have the time myself to prep batteries like I used to. Matching batteries does make a difference but if you are just starting out in this hobby, concentrate on driving and car set up first.