micro_Amps
Forum Replies Created
-
AuthorPosts
-
The guys at bit_charg_oz are doing an excellent job. We should support the local guys that are having a go. Work out the $$ conversion on the cost of a BCG or accessory before you buy off ebay and compare it with these guys prices first.
Happy customer :approve:
Yep.:)duracells can be, energisers are probably the same too. They charge up to about 2/3 of the previous charge. So if you got 10 hours out of a new battery, then charged it, youd get about 6 hours the next time, four hours the next time, maybe two hours the next time….. then youd thro them away.
:clown:uA
I wouldnt mind knowing
:question:uAQuote:the only bad thing about the batts is that they are alikines not recharges
:smiley2:uAQuote:i reckon that it would draw well over 1A current. I dunno whether the output fets/transistors will handle it. May need a turbo mod, i.e. stacked fets/transistors.Might take a little investigating, but I’m sure its possible. Maybe a shunt transister to switch the main drive current.
Quote:i dont use lube inside the motor Jamie, i just use it on the axle. i hate using WD40, biggest mistake ever, i still am regretting it, way way way to much debris gets caughtTamiya make an excellent ‘ceramic grease’ designed for plasic gearing. It makes the gears run really smooth and quiet. You only use the tiniest bit, a tube will last years, and if you dont use too much it doesnt pick up fluff & stuff :smiley16:uA
Quote:24 hoursI think a scaled down car deserves a scaled down Le Mans:) Since they are scaling down the drag strip what would the time on a proprotionally (roughly) scaled down Le Mans be???If lemans is 24 hrs, then 24 hrs x 60 mins = 1440 minutes in total (full scale)
If our cars are roughly 1/64 scale, then 1440/64 = 22.5 minutes. We would be able to do the race time in one charge on a 150mAH battery. But I suppose the object is the furthest distance isnt it. So the modified cars would probably run 3.5 or 3.8 motors, high gears, and would need two, maybe three charges to finish.
I get carried away with things when I get sleepy
uAJamie, Yes, Yes and Yes. Your last three posts are spot on.
LM317K is perfect for small battery charging. With a pot instead of resister charge time (voltage) can be varied.
Re peak charger: you could install a micro on/off sw to take the Rx out of circuit, but 1.2v 50-150mAH is too tiny to worry about peak charging. I see you also share my dislike of batt-batt charging.
24 Hr race (LOL) Id like to see how many drivers finish, the cars would probably go the distance.
Has anyone ever done distance trials anywhere in the world???:DuASorry to rain on your parade but it wouldnt charge, because the drive transistors (even if turned on) wont conduct on reverse polarity.
If the motor was directly wired to the battery it would tho, but then you would have no start/stop control when the battery is full.
The back emf will only ‘brake’ the motor if it is shorted accross a resistance. When you let ‘forward’ go, the time that the motor takes to slow down really depends on what gear set you have in and how much friction is in the drive train.
Sorry, I just cant resist these techo issues:dead:
even if they are in the wrong section:shock:You might find that these problems are related to the battery. Try swapping the batteries between the cars to find the faulty ones. Then replace them.
OR
if you have a motor you say has slowed, change just the motor to another car that runs well and see what is causing the problem, battey or motorHow bout a triple cell running twin 3.8s feeding KIT gears….outa control. :dead:
A booster chassis would allow you to keep control around corners at lower speed.
I think I read somewhere about a 4.0 or 4.2 motor too, has anybody else heard anything about these :question::question::question:I’d be interested to know if the hot swppable wheels are available localy (Australia) Is anyone running these on their BGC err BCG
uAWho’s a smart Panda then :smiley2:
The lower Ohmage the better, oh yeh, but only if you have something that draws more current than the battery is able to put out, which is not a micro B motor
uAIsnt this supposed to be in the techo section :smiley2:
As far as I know the armature of the motor is not shorted when forward or reverse is let released. If it was the wheels would lock and skid when you let the button go. The reason I say this is I saw a mod on a site somewhere that puts ‘engine braking’ on when you let go. The reason it stops so quickly is because of the high gearing. I wouldnt worry about fitting the mod, I cant see it adding to handling, performance or enjoyment for that matter
uAThey look excellent. I love exotic cars, lets hope they come out with more choices in future.
I may consider getting a ferrari myself. Is the guy selling them privately too or only via auction on ebay??Thanks for the info Prez :smiley2:
LOL
uA
Good mods for going forward at various speeds, but i dont know if I’d sacrifice my reverse for another forward speed control or lights control.
On a single cell car, a standard ‘double charge’ will probably do (90 – 120 secs). A 3 battery external charger (4.5V) would charge in less time, just keep an eye on the temperature.
Can you tell me where you got the 160mAH 1/4AAAs?Crom, some answers to your questions……
If the battery being charged is not generating any heat then it is being charged VERY gently (and slowly). All NiCds and NiMHs generate heat when being quick charged. The Tomy controller starts to heat a standard N50AAA battery when you do a “double” charge. The heating is unavoidable in quick charging. So the answer to your first question is yes (when quick charging) if it is still cool it is not charged.A spare KIT battery is the original N50AAA NiCd. You wouldnt have to worry about controlling the charging current, the charging voltage determines this.The higher the charging voltage, the higher the current being forced into the battery. You are right tho, if you charge at a certain voltage for 1 min and the battery is VERY hot then this voltage is probably too high (warm is ok tho) At 3V charging the N50AAA will start to warm after about 90 to 120 secs. So I would think that charging at about 5V could charge the battery (and warm it) in about 1 min, but I’m guessing.
The NiMH will take longer to charge because of its increased capacity, so if you want to charge it fully in the same 1 minute time you would up the charging voltage(which ups the current), maybe 7V, again I’m guessing but you see (I hope)what I’m getting at……
more volts = less time to charge but more heat!! (and lots of heat is bad)so a compromise must be reached.
Having said all this, the hotter you go in charging, the less life span your battery will have but they can be charged quite quickly if your not concerned about longevity. Also be careful, this battery is charged in the car which is PLASTIC and prone to MELTING, you get my drift. Also if you are charging and warming the battery, the battery will hold a little heat from the previous charge, which may accumulate and again you end up with a molten BCG. I have seen large NiCd packs charged so quickly they hiss and when charged you can barely touch them, they go like stink, they just dont last very long.Let me know how you go, I’m planning on doing some “ideal charging figures” of my own for the various configurations of NiCd and NiMH cells. PM me or post the results or both.
P.S. Impreza, love the slot car track charging idea. Drive on when not quite fully flat, wait a minute or two, and zoom away…excellent.
You would probably need guide rails on both sides to direct the car to exactly the right spot over the charging rails. Oh, and dont park on the rails for too long, you’ll meltPPS Sorry about the huge posts, I rabbit on a bit.
The N50AAA are definitely 1/3AAA 50mAH NiCd batts
The ratings for both batteries are in mAH or milliAmp Hours. The higher mAH the better but capacity is limited by physical size.
The 1/3AAA batteries are about 15mm tall, a 1/4AAA is about 11mm tall. Both will do the job but 1/3AAAs NiMH are available up to 150mAH so these are prefered. NiMHs are also available in a 120mAH capacity, so the only way you can tell what you have got for sure is to measure them. If they are 1/4 size you may have to bend the contacts a little. Either way, at 120mAH capacity, the batteries you have got are definitely NiMH so you should get a good run time.Running a car whist on the charger will only result in less charge ending up in the battery. The controller charger can deliver more current than the motor uses whilst running, it wont make any difference to the battery. The battery will just be under charged
Crom a double charged battery is ‘zippier’ because it has been held at a higher voltage (or charged) for twice as long and once disconnected the output voltage is higher too and can push out more current because of this slightly higher voltage. In answer to your question, yes doubling these time figures will make for a better charge and therefore longer run time but how long do you want to waitfor it to charge. The best compromise for us is probably to do the NiMh battery mod and charge it for 2 mins at a time and get 15-20 mins run time out of it. You could double charge that too if you dont mind the wait.
Double charging is worthwhile but just takes too long. Its a pity the battery is not removable and we could keep 1 or 2 on charge and put them in on a pit stop. One thing we could do tho, if you had an extra charger setup you could leave a car on charge, but it would need to have a mini on/off switch installed somewhere on the car to turn the radio receiver off when charging.
In order to determine ‘peak’ charge you would need a ‘smart’ or ‘switch mode’ charger which determines the batteries ability to accept current and charges accordingly. NiCds develop a memory, NiMHs not so much but a smart charger would sense charging current and charges the correct ammount. The way to fill a battery cell properly is to charge at 10 to 15% higher voltage than the cell voltage, monitor the current when cell is first connected to the charger, when charging current drops to about 1/10 of the original charging current the battery is ‘fully’charged. This may take hours tho, depending on the cell’s capacity (mAH) and is getting too technical for our situation. We use a charge voltage many times higher than the cell we are charging that is why it charges so quickly but it is detrimental to the cells ‘health’ but so what,… its quick.
But yes, double charging will store more power into a single cell (and give a longer run time) but because the charge voltage is so much higher than the cell voltage it will lead to an earlier demise for the cell being charged.If you are shopping for the NiMH batteries buy the 1/3AAA (10mm x 15mm) unless you go to the site I suggested, they are calling them 1/4AAA. They are the only site calling them 1/4
I apologise if I caused any confusion
So how come I am listed as a newbie with 10 posts and shypo has 400 on the NEW forum (when there arent 400 posts on the whole forum)??? On the old forum I was listed a 23 posts, do some posts carry over from the previous forum and some not??? Not that it really matters I was just wondering.
These are my thoughts on charging Bits.
Any DC power supply or battery pack can charge a Bit’s battery so long as its voltage is above the voltage of the battery you are going to charge, within reason. The standard bit for example charges at 2.8v @ 300mA for 45 seconds. You could charge the same battery at 1.6 volts (and much lower current) but it would take 16 hours. Alternatively, you could charge the same 1.2v battery at 5v (at approx 600mA) in half the time but this will heat up the battery and kill it quite quickly. The more you heat a rechargeable battery whilst charging, the fewer amount of recharges it will take. The ideal is low current, longer time charging but this is not the best for us, so a compromise must be reached.The way tomy designed the charger is not the absolute best for the battery, but it does a good enough job for a toy application.
If you take the charging figures from the original cell, you can expand it in to figures for 2 or 3 cells, eg
1 cell (1.2V NiCd) charged at 3v takes 45 secs (or lets say 1 minute.)
2 cells (2.4V NiCd) charged at 6V will take 1 min
3 cells (3.6V NiCd) charged at 9V will take 1 min the charging current should be the same in these 3 cases, all at about 300-400mA ,which is high for a standard application, but quick and that is what matters most to us.
But alot of us are using NiMH cells with a 150mAH rating and our rule of thumb has been to double charge (ie 2 X 45 secs) to charge these.
So going on that theory–
1 cell (1.2V NiMH)charged at 3v takes 90 secs (although 2 min makes for a better charge)
2 cells (2.4V NiMH) charges at 6V takes 90 secs
3 cells (3.6V NiMH) charges at 9V takes 90 secs
Again the charging current should be the same in the above 3 cases
NiMH cells ‘should’ be charged at lower currents than NiCds but it doesnt matter here.
So you can see a pattern of ‘multiples’ emerging that can be used as a guide to how to set up a custom charger. It is not necessarily the way a Nicad purist would do it, but then we arent sending shuttles to the moon here we are just trying to shove some electrons into a toy.If you wanted to charge quicker than above you could increase the charging voltage and shorten the time but if you go too high with charging voltage the cell will heat up, hiss and die.
So a dc power pack or charger (or a battery pack) with a voltage rating as above and a minimum current rating of about 500mA should do the trick.
You could build a multi charging station with 3V,6V and 9V selectable for 1,2,& 3 cell Bits and have a timer switch for 1 min or 2 mins depending on whether you have NiCd or NiMH cells in your car. That would cover all combinations of Bit charging, you would just need to mount the whole lot in a box or something. -
AuthorPosts
