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ilove599xx
2015.02.21, 12:41 AM
Dear all,

I tried my first time to play whole day in the club yesterday.

I found out my 5 set of batteries were not enough. my basic battery charger is just too slow to charge my battieries.

I wanna get a charger is really for my RC hobby.

As a newbie I saw my club has something called CHARGING TRAY and it's connected to a machine. Can anyone tell me what that machine is?

besides, one guy told me it's better not charge the batteries on the same day, is that correct?

sorry to ask this stupid question, I kinda didnt wanna ask my club owner cos he would push me to buy one right away lol

DMALMAD
2015.02.21, 01:47 AM
check out the maha powerex or the new orion aaa chargers. They are pretty affordable and do not require power supply assuming that is what he was pushing for you to buy because to use a charging tray you then need a charger and a power supply. Which IMO is overkill. Just look for a aaa charger that will do .7 - 1 amp which is the powerex and orion. hitec/skyrc make a bluetooth one that is cool and has some added features but is not really worth the extra 40$

mleemor60
2015.02.21, 07:45 AM
There are a couple of units from Accu-power that are listed on the bay for under $30 shipped. One looks a lot like the Power-X and the other looks a lot like the Lacrosse unit. One of them even does internal resistance checks. I have been using both of them for about a year and have had no issues with either. As a beginner these are suitable and affordable so you can keep three or four chargers operating at all times while you are at the track. I would recommend that while you are charging batteries that you keep a small fan blowing air across the battery chargers. Since most of the chargers we use for the hobby have a built in thermal cut off(128*) so keeping the batteries a little cooler allows them to charge to a slightly higher voltage and helps protect against false peaking.

You will learn that NIMH batteries will perform better on their second charge of the day but then will fall off on subsequent charges so it is best(from a performance standpoint) not to use any set more than twice in a 24 hour period. You will also learn that the higher the MAH rating of the battery the less performance(punch or power) it has but it will provide very smooth operation and longer run times. The lower MAH rated batteries will provide more performance but take a bit more attention during the charging process since they tend to build heat quicker at the higher charge rates(1A and above) and can "vent" during charging which may allow battery chemicals to leak into your charger and damage it.

There is a lot to learn about battery charging so just start slow and be careful. The biggest power gains you can make for your car are in the batteries and charging techniques.

ilove599xx
2015.02.21, 08:08 AM
thank you, i've checked the maha powerx on ebay,

PowerEx MH-C9000 and PowerEx MH-C800S 8 Cell

which would be better for mini-z?

they are not cheap for a charger though (compare to normal one)

ilove599xx
2015.02.21, 08:17 AM
There are a couple of units from Accu-power that are listed on the bay for under $30 shipped. One looks a lot like the Power-X and the other looks a lot like the Lacrosse unit. One of them even does internal resistance checks. I have been using both of them for about a year and have had no issues with either. As a beginner these are suitable and affordable so you can keep three or four chargers operating at all times while you are at the track. I would recommend that while you are charging batteries that you keep a small fan blowing air across the battery chargers. Since most of the chargers we use for the hobby have a built in thermal cut off(128*) so keeping the batteries a little cooler allows them to charge to a slightly higher voltage and helps protect against false peaking.

You will learn that NIMH batteries will perform better on their second charge of the day but then will fall off on subsequent charges so it is best(from a performance standpoint) not to use any set more than twice in a 24 hour period. You will also learn that the higher the MAH rating of the battery the less performance(punch or power) it has but it will provide very smooth operation and longer run times. The lower MAH rated batteries will provide more performance but take a bit more attention during the charging process since they tend to build heat quicker at the higher charge rates(1A and above) and can "vent" during charging which may allow battery chemicals to leak into your charger and damage it.

There is a lot to learn about battery charging so just start slow and be careful. The biggest power gains you can make for your car are in the batteries and charging techniques.

very useful message, and very easy to understand for me. I never though that much about mAH but now I know. about the accu-power, could you share any link? they are a bit confusing for me when I checked ebay

arch2b
2015.02.21, 09:34 AM
As with other topics, there are differing opinions with what is necessary for club or competitive racing. You can spend $400 or $40 and any number in between on solutions that varry greatly. It really boils down to how much do you want to invest to meet an expectation level desired.

Most of the locals in my area are running inexpensive cells to great effect but maintain them well.

ilove599xx
2015.02.21, 01:31 PM
May I ask another question?

I looked all my batteries. They all labeled Voltage: 1.2V

I found out there are batteries with 1.25v

Can I use 1.25v on my mini-z?

ilove599xx
2015.02.21, 01:47 PM
There are a couple of units from Accu-power that are listed on the bay for under $30 shipped. One looks a lot like the Power-X and the other looks a lot like the Lacrosse unit. One of them even does internal resistance checks. I have been using both of them for about a year and have had no issues with either. As a beginner these are suitable and affordable so you can keep three or four chargers operating at all times while you are at the track. I would recommend that while you are charging batteries that you keep a small fan blowing air across the battery chargers. Since most of the chargers we use for the hobby have a built in thermal cut off(128*) so keeping the batteries a little cooler allows them to charge to a slightly higher voltage and helps protect against false peaking.

You will learn that NIMH batteries will perform better on their second charge of the day but then will fall off on subsequent charges so it is best(from a performance standpoint) not to use any set more than twice in a 24 hour period. You will also learn that the higher the MAH rating of the battery the less performance(punch or power) it has but it will provide very smooth operation and longer run times. The lower MAH rated batteries will provide more performance but take a bit more attention during the charging process since they tend to build heat quicker at the higher charge rates(1A and above) and can "vent" during charging which may allow battery chemicals to leak into your charger and damage it.

There is a lot to learn about battery charging so just start slow and be careful. The biggest power gains you can make for your car are in the batteries and charging techniques.


what's the lowest mAh for mini-z? I have found 600mAh, 500mAh AAA battery online.

mleemor60
2015.02.21, 02:39 PM
Stay between 800 and 1000 MAH.

AM03GT
2015.02.21, 06:23 PM
The charging machine was a standard r/c battery charger. At this point for larger scales everything is LiPo batteries so some of the newer units are overkill or do not support as many NiMH features. You can get a lot of the older high end units made for NiMH cells at very good prices now even new I'm box due to it being older tech. Most of these charger output through a positive and negative wire with a high current plug or banana clips. For mini-z you just need a charging tray that connects four cells into one "pack" to charhlge with these type of chargers. The downside is you need to keep your cells in good condition and "matched" to get the most out of them. The good is these types of chargers can handle higher charge amp rates and even charging profiles which can get that last bit of speed out of your batteries.

I find my powerex is easier to use ona daily basis and for travel but a charger and tray combo usually gives me a stronger punchier charge.

Jshwaa
2015.02.21, 09:30 PM
Just my 2 cents..

Yea, with battery charging, peak current and temperature are the key factors to regulate.

If you have the time, it is always best to charge at low current (0.1C), but you should be able to charge at current levels of up to 1C. In other words, if you have 900mAh cells, it should not hurt to peak them at 900mAh until you start reaching full charge and ween off the current as you approach full charge, which chargers naturally do.

As far as heat goes, I don't take my cells off the charger until they are cool. As the cells reach full charge and draw less current, they begin to cool and will absorb a little more energy. You will get way more punch from a cell that comes off a charger cool than hot, no matter what the charge LED indicator is telling you. So the 'fast chargers' that charge batteries in 15 minutes are actually charging at such a high current that the cells heat up and lose a little capacity until they cool back down, thus mitigating the benefit of the fast charge, not to mention you get less charge cycles if you allow the chemistry to get too hot too often. The motor draw is bad enough during run-time, no sense in destroying them further by rushing the charge cycle.

The better alternative to faster chargers is just 'more' slow chargers. As long as you have a cool charged set when you need them, it shouldn't matter how fast a single charger charges.

ilove599xx
2015.02.22, 05:24 AM
May I ask another question?

I looked all my batteries. They all labeled Voltage: 1.2V

I found out there are batteries with 1.25v

Can I use 1.25v on my mini-z?

can anyone help me this question?

all my batteries are 1.2v

but I am thinking getting team orion 750 aaa and that's 1.25v

is that matter?

Mike Keely
2015.02.22, 08:53 AM
1.25V will not hurt the car in any way. I think that some of the manufacturers print the 1.25V in hopes that some people will buy them over a 1.2V printed cell. The 750 cells I use for stock 70 turn racing. I really like the DuraTrax 750 cells over all of the other 750 cells.

When I race the 50-32 turn motors I like the 900 cells. The 900 cells have a slightly lower voltage and the internal resistance is higher. These two factors smooth out the power of the motors in my opinion.

In my travels of cells the higher the voltage of the cell the lower the internal resistance inside of the cell.

I try to explain electricity like your home garden hose. Voltage is like the pressure trying to push the water through the hose ( the type of work that the water could perform, more pressure more work ). Resistance is like the size of hose that you are using to get the water to the work that you want to perform. A 1/4 inch line X 50 foot of hose X 50 psi of pressure is not going to do a lot of work. A 3/4 inch line X 50 foot of hose X 50 psi would supply you with a lot more water to be able to do more work or a 1/2 inch line X 50 foot of hose X 75 psi would do better then the first scenario. So you can see the difference of increasing the voltage ( higher pressure ) or lowering the internal resistance of the cell ( bigger hose size ) will make your car faster. Remember that if you improve either of these 2 items times four cells that we run in our cars it will help a lot.

Now you see why people match their cells to get the best performance from their motors. If you take the four best cells out of all of your batteries you will notice a big performance increase. If you have ten 4 cell packs it is most likely that you have some good performing cells with some below average cells in each of those packs. The below average cells should be I you practice packs or in you Xbox controller at home.

If you go to a big race you will most likely find that each guy in the A Main is matching his batteries or getting someone to do it for him.

For people that are just starting out this step of matching batteries is not needed. But the info is now here for them to use after they improve their skills. Hope this helps

Jshwaa
2015.02.22, 10:39 AM
When I race the 50-32 turn motors I like the 900 cells. The 900 cells have a slightly lower voltage and the internal resistance is higher. These two factors smooth out the power of the motors in my opinion.

I like your analogy of ohms law and the garden hose, but the 900mAh having a higher internal resistance than say a 750mAh cell is where I beg to disagree. It is the nature of the higher output current rating (900mAh vs. 750mAh) that should be the first clue as to the 900mAh cell having a 'lower' internal resistance. If you wanted to find the 'exact' internal resistance (at a given temperature), place a load on the cell (1ohm power resistor) and monitor the current AND voltage of the cell at the same time. Divide the voltage by the current, and you have the instantaneous internal resistance of the cell.

So, a 1.2V, 750mAh rated cell will inherently have a 1.2/0.75 = 1.60 ohm average internal resistance.

A 1.2V, 900mAh rated cell will inherently have a 1.2/0.9 = 1.33 ohm average internal resistance.

These resistances change with temperature, and the ratings are more than likely at about 70 degrees, so any kind of current draw will cause heat and make this resistance go up. Hint, keep your cells cool.

In my travels of cells the higher the voltage of the cell the lower the internal resistance inside of the cell.

It depends on the chemistry. Take regular alkaline 1.5V cells for example. These cells obviously have a higher voltage than a standard NiMH cell (1.5V > 1.2V), however the alkaline chemistry was never designed or intended for a high current draw application. 1.5V alkalines are designed for high shelf life, so that you can put them in say a 'flashlight' and have a decent chance of them having power when you need it, or get more hours out of a low current draw device such as a calculator, or say the remote for your mini-z. I challenge anyone with the means to race like-mini-z's with NiMH vs. Alkalines. I'm sure many here will attest to the fact that alkalines are deceptively weak when it comes to output power, which is a direct function of internal resistance as a function of temperature.

ENERGIZER DATASHEET (http://data.energizer.com/PDFs/E92.pdf)

ENELOOP PRO DATASHEET (http://www.eneloop.eu/index.php?eID=tx_nawsecuredl&u=0&g=0&t=1424709157&hash=9bd08f5a24a2b1e14af0efcae2cf01b5cdc4c6cc&file=/fileadmin/web_data/Data-Sheets/BK-4HCC.pdf)

Mike Keely
2015.02.22, 06:15 PM
When I check my cells on a Turbo Matcher or a Check Mate charger with the same 2.5 amp load the IR numbers are 100% of the time lower numbers then the lower voltage cells would have. I never thought about how they come to their numbers on either of the two machines. I am sure that they take the average over the discharge of the cell.

I should have stated in my travels with rechargeable batteries that we use in RC car racing I guess? You are correct with the alkaline batteries. I was not thinking about them.

The 750 mAh vs the 900 mAh is a capacity of the cell. If you take a 1157 car light bulb and place it on each cell after charging both batteries the 750 battery will die before the 900 cell would. Same load on each cell but the 750 cell will make the light shine brighter then the 900 cell would.

Mike Keely
2015.02.22, 06:27 PM
The mAh capacity rating refers to the storage capacity available for a particular battery. A battery with a capacity rating of 1800 mAh could deliver a current of 1800mA for one hour. Higher mAh ratings for the same battery type will generally mean longer run times.

Jshwaa
2015.02.22, 08:39 PM
Same load on each cell but the 750 cell will make the light shine brighter then the 900 cell would.

Ah yes, which is the distinction between mAh rating and C discharge rating.

My apologies, but again I'm not sure that 'lower mAh' always equates to 'higher discharge'. Not that it really matters, as it is really the 'energy density' of the cell that really counts as it pertains to racing, and lithium polymers take that one by a long shot.

Has anyone tried a 2x2 series/parallel with the LiFE's yet? I wonder how that would fit...if it did, that would be the kind-daddy power source for mini-z's, imo...

DMALMAD
2015.02.22, 10:03 PM
Life are not as good because they are actually too light and upset the weight balance and when higher power is used they neither provide the runtime or the output neccesary for racing at a high level. (Based on experience at my local track which is very competitve and the standard is 32 turn motor and lipo batteries).

Jshwaa
2015.02.22, 10:51 PM
Life are not as good because they are actually too light and upset the weight balance and when higher power is used they neither provide the runtime or the output neccesary for racing at a high level. (Based on experience at my local track which is very competitve and the standard is 32 turn motor and lipo batteries).

I'm sorry, but I don't understand 'too light'. And as far as the power output goes, that is why I'd like to try the 2x2 series parallel. You would essentially be doubling the run-time and punch you'd get from just a straight 2x1 series. It would take some surgery to get it accomplished, but I bet such a setup would change your outlook on the Li-FE's. I ran a 2x2 series parallel on an xmod evo, with a 2x2 FET stack and a heat sink, and it was very powerful. Of course, by then I think it would be necessary to have AWD to be able to transfer all of that motor power to the ground, instead of the rear wheel get-ups that always lose the rear end.

cowboysir
2015.02.22, 11:06 PM
You're comparing a pig/brick (xmod) to a race car. The MR series of chassis are defined by their aaa layout and a finely balanced make at the specific weight of 4 x aaa. By adding more Li-Fe packs you negate the point and in the truest sense of 5-8 min heats it would be pointless to have that much capacity.

Back on topic, most high discharge aaa come in smaller mAh and can be charged ata higher rate. This gives then the ability to discharge at a higher rate as well giving more power to the motor. Great for 70T class.

Jshwaa
2015.02.23, 08:34 AM
You're comparing a pig/brick (xmod) to a race car. The MR series of chassis are defined by their aaa layout and a finely balanced make at the specific weight of 4 x aaa. By adding more Li-Fe packs you negate the point and in the truest sense of 5-8 min heats it would be pointless to have that much capacity.

Back on topic, most high discharge aaa come in smaller mAh and can be charged ata higher rate. This gives then the ability to discharge at a higher rate as well giving more power to the motor. Great for 70T class.

Although I will admit that the quality of the Kyosho Mini-Z is hands down better than xmods ever tried to be, I equated the 'hobby' of xmods to that of the 'hobby' of Mini-Z's in that with an xmod you were starting out with say a Dodge Neon tuner while the Mini-Z's were already starting with a Porsche. There's no doubt that on a track a Mini-Z would mince up even the most tuned xmods, but I've never really been in it to race on those itty bitty tracks. I never knew the topic of battery charging was so limited to '5-8 minute heats' and '70T class'. My bad.

Furthermore, it is widely known in the RC realm, as well as the engineers that introduced them to the hobby, that lithium polymers will give you more output power per mass than Ni-MH. This is why it is the cell composition of choice with RC aircraft, where energy density is most critical.

As far as 'balance', if you're symmetrical with your composition, then you're balanced. As long as you don't raise the height of your overall mass profile, your center of gravity should not be changed. 2 Li-Fe's does stand taller than 2 AAA's, so admittedly there would be a shift in center of gravity, but the gain in 'power to the motor' would theoretically be 37.5% greater with a 2x2 li-fe setup. I guess it would take 'trying it' to know for sure if the mod would be 'track worthy'.

Here's a little FYI...
A 4x1 Ni-MH setup (stock mini-z) will net 4.8V, at 900mAh (ie. eneloop pros)

A 2x2 lithium polymer setup will net 6.6V , at 900mAh (ie. Li-Fe, however I would choose a different li-po perhaps with more mAh).

So, there's the 'more power' part. Here's the 'less mass' part...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/DSCN2290.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/DSCN2290.jpg.html)

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/DSCN2289.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/DSCN2289.jpg.html)

I understand that the unhacked mini-z has the best chance at respect on these boards, but there really is some fun to be had in pushing limits. Sorry, but lap times just don't do it for me. If the hobby was limited to how proudly you can wiz around 8 in. radius turns, I would have been bored a long time ago. And if you got too much capacity for your race, so what? It is about power on demand. Go do some donuts in your victory lap if you have extra charge after the race.

KWT
2015.02.23, 09:54 AM
If you aren't racing, you can do what ever you want. But there are rules for racing that limits what you can or can't do with the car and also what power source and motors you can use.

Some of the stuff you say goes against the years of experience many people on here have. Just because it looks better on a data sheet doesn't always make it so in the real world.

cowboysir
2015.02.23, 10:50 AM
That is certainly some tech info to share but it is (again) entirely off the topic stated in this thread. The publisher wanted to know about aaa's since he is just starting out in racing. It is important to focus our attentions on info that'll be useful in his endevours of improving his knowledge base for his racing league instead of wasting space on how awesome it'd be to hack up the chassis to get more power.

Back on topic, I have a two tiered approach to my battery packs. I have 6 sets of race specific packs and quite a few practice packs. Before a race gtg I take the time to trickle charge my race packs to match the mAh with my Maha charger. I then discharge them the night before the meet and pack them away discharged

At the gtg the first thing I do when setting up is get my multi charger organized and set my race packs on a charge at their rated capacity. By the time the first heat is ready to start the matched cells are charged and being freshly charged and warm they are ready for a high discharge.

I try not to use the race packs more than twice at an event.

Once the race day is done I discharge all race packs to wait for the next gtg.

Practice cells just geta charge before the gtg... ready for use with no expectations.

Jshwaa
2015.02.23, 10:52 AM
If you aren't racing, you can do what ever you want. But there are rules for racing that limits what you can or can't do with the car and also what power source and motors you can use.

Some of the stuff you say goes against the years of experience many people on here have. Just because it looks better on a data sheet doesn't always make it so in the real world.

I hear you, and I try to refrain from using absolutes, which is why I say 'theoretical' a lot, meaning that it is implied that other factors can come in to the model and bring to light the 'experience' you mentioned.

I don't intend to go against the grain, or imply that a datasheet trumps experience. I know that what I say sometimes goes against the common knowledge of the avid 'racer' on this board, which is why I reference datasheets to try to back up what I say, and to also bring to light 'why' some of the things you guys do actually works. We're just looking at the potato from two different angles is all. It would only make sense that there is a community and a class of mini-z hobbyists exclusive to their own respective levels of knowledge, and I respect that. If there's a 'Mini-Z Engineering' forum, please point the way.

Oh, and I certainly don't mean to persuade anyone to the contrary of what the experts on this board has to say. You guys are actually the reason I'm here, as I have questions regarding the experienced side of things. Cheers!

arch2b
2015.02.23, 02:18 PM
Jshwaa also addresses an equal important faction of racers, those that don't place priority on fitting into class/spec formats. while it may not be specifically relevant to the exact question, it's good reading :cool: a few years back, this forum in general comprised mostly of this non-conforming faction at arguably the peak participation level of the forum. it has it's place, the current times are simply dominated by format racing. if i could make a recommendation, add to existing similar threads on the topic or start anew, there are interested parties out there ;) always have to remember, only a small portion of members participate, there are always many, many more that simply lurk. :p

Jshwaa
2015.02.23, 10:49 PM
Well, admittedly I did get carried away there. My bad. I will try to keep the feedback in perspective from now on. All I can really add is that I love these eneloop pros I got.

Anybody use the 'IntelliPeak ICE' charger with any luck?

LuckyDuc
2015.02.24, 09:20 AM
A very good and trusted source of information on charging AAA/AA NimH cells in the R/C soaring community is the information found here: http://www.hangtimes.com/rcbattery_faq.html

It addresses some of the common myths about AAA/AA NiMh charging techniques.

Hope you find it helpful.

mleemor60,
Thank you for the assistance in activating my user account so I could post.

Kind Regards,
Sean
Recent purchaser of 4 Mini Z Optima Buggys

Djiewie
2015.03.04, 03:39 PM
great info, thanks.

Since trying to get some knowledge about discharge rates and what/wich cells are the fastest and why, i`ve been testing several batts from fellow racers when they have clearly more punch on the track. The charger has a quick IR test option wich i use with full charged batts. So here are some results wich can vary some.

orion 750 ho between 30 and 35 mohms
orion 900 between 44 and 49 mohms
wurks 990 between 40 and 45 mohms
wurks 750 between 40 and 42 mohms
cheap lsd cells between 300 and 350 mohms.

The orions 750/wurks 750 have a little more punch but the wurks900 are almost the same but last longer.
Thats what i have experienced. Don`t know how some charge and at what rate but its likely about 800ma . IR rate and punch are related it seems:cool:

TheSteve
2015.03.04, 06:05 PM
IR rate and punch are related it seems:cool:

Absolutely they are!

The lower a cells Internal Resistance the more voltage it will maintain during load(acceleration).