WAHHHH! (a how-not-to guide)
 

Well, i wanted to do this mode, but was too lazy to do it right, so i took a controllert i dont need (was for a bit pcb to zz car mod) and wired it so t4eh batteryies go stright to the charger, then plopped by recently tuene NiMH booster on it.....about 10-12 mins later i smell burning :( turns out hte chassis melted and warped around hte charger :O

well needless to say, im gonna buy another booster, and thank god hte pcb is swappable, so im prolly gonna place it on to another chassis (my rx-7 is screaming for a bit o boost).

My NiMH battery didnt fare so well, it was on the berge of bursting, the nipple on the positive end popped off 2 mins later with a loud pop......it was hatter than all hell too.


after thinking about it, i was feeding 3 volts into the ppoor thing...i should wire the batteries in parralell instead of series.......oh well live and learn.

jesus man! you only need to charge the nihm batteries for about 1 - 3 minutes, not no 12 minutes.

Re: Rayovac charger worked!
 

Clint,

Great idea, man! :D
I tried it with my Radio Shack charger. It discharges the batts first then charges.

It worked but....
I have to charge 2 batteries at the same time, it won't do single cells.
It took forever to charge. It still wasn't done charging 30 min. later! :mad: The batts never got warm though.
So, I took the car off the charger and ran it. I had about 30 min. continuous running time.

Good run time, but NOT worth the charge time! :rolleyes:

So Clint, what model Rayovac charger did you use? Please tell us! ;)

Barebones charger
 

I made a crude but effective charger out of 2 C cells and some resistors. I just switch resistor banks to vary the charge current.
I tried 75mA for half hour, (slow but safe approach) -- car ran for 15 mins or so, still has a good amount of charge in it too.
Next time I might try 100 or 150mA , and watch my digital voltmeter for the peak.

I also have a rayovac charger, but I think its peak detection is less than perfect ....(I dont trust it since it roasted some of my 1600mA AA cells!) It would probably blow my Z car to bits! :lol

it's the rayovac ps1 charger. the second time i charged the 50mA battery it took an hour to charge.(it must not have been drained all the way the first time).

it still lasted about 40 minutes. :)

i do have to make sure there is at least a pair of batteries in the charger for it to work..but i just throw in a normal aaa rechargable in the other slot.

I am thinking of trying...
 

this ==> http://www.allelectronics.com/cgi-bi...173&type=store

It says it can do 1.2 V at most any rate needed, plus it will automatically fully discharge the pack. Im not sure if it is a peak detecting charger though, otherwise I'll have to make up a quick timer for it. The charger looks good for other stuff, too. Ill put a charge jack in the transmitter with the 1900 mah NiMH AA's.

Question 1: So if the Rayovac PS1 charger works well and charges great at 2v 200mA per battery, then that means in theory you could find/make an AC/DC adapter with those specs and connect the wires straight to the charger pad? The main gripe I'd have with this mod is taking the batteries out of the car to charge them. You'd have to time it this way though.

Question 2: How would you alter that for a dual-cell car but charge them together with one AC adapter? Would you need 4v 200mA, 4v 400mA, 2v 400mA, or 4v 400mA? I'm assuming you'd have to double one or both of those numbers :)

Question 3: Has anyone tried using a 1-hour rapid NIMH charger? If it can charge a 1600+ mAh battery in one hour while the PS1 takes much longer, could it do a 1/3AAA in a fraction of the time, like 5 minutes or so instead of the ~40 for the PS1 charger? These chargers are only for NIMH and not NiCd.

Question 4: For those who don't have a peak charger, can we just start charging with our controller for like 10 cycles and expect the battery to hold it? Or do you have to charge slower than the controller does to fully charge without risking damaging the battery?

Answer some of those for me please!

Thanx for the NFO Clint, now I believe I know where I went wrong. Here are the pictures I took while doing this, unfortunately I have but one car and just the battery that came with it. So let me see if I have this right Clint, you took 2 50 mah NiCd batteries and placed them together in one bay, then took a AAA and placed it in the bay to the right or left of it? BTW thanx Ovgron for the url link I can't wait to see how that works. actofgod the only thing that I was thinking of doing was wiring a scrap charger post piece onto my PS1 that way I wouldn't have to bother with the way I have it wired now :rolleyes: Anyways, I hope this helps.
PS. that spring came out of an ordinary pen, had to stretch it a little though.

2nd photo

How about making jumper wires running from the charger to another car charging base? -- (never have to pull the batt from the car)

Could try to make a fake AA cell with wires attached, (so it easily fits in the charger), and then run the other end to the new charging base?

To make the fake aa cell, I actually took the end caps from a dead zinc carbon AA cell, and taped/glued them to a suitable sized cylinder. I have also used the whole aa cell (after having taken it apart and scraped out the "guts" ) --leaving a nice "shell" to attach wires to.

I went ahead and ordered the charger kit i posted about above. I should get it in about a week. Ill post if it does anything interesting.

That's really creative. I was looking for an AC adapter that put out 2v 200ma when there's 4 perfectly good ones sitting right next to me in one convenient unit :) Smart idea with the fake AA! Now we can still use the built-in charge protection circuitry without taking out the battery.

That answers my Question #1. As for #2, please try this on a dual-cell setup if you have one and see if it will charge it too (though taking longer) or if you'd need like 2 fake AA's connected to one charging pad.

This thread is great...

One question I was wondering about...if that rayovac charger can handle this little soldiers, I was wondering if anyone has played with the idea of using one of those "smart" intelligent chargers out there. I have thought about trying one of those, but have been unable to find a good spec sheet on them, and the "details" for most of them out there say that they can handle 1200 maH AAA's. But if they're really "smart" and detect voltage drop (I think the IC most of them use is the Maxim 712/713 chip), then would they be able to detect such a drop on these sized batteries?

Never had dual cells, (too chicken about blowing my motor I guess) But I think you'd need to get the voltage from 2 AA charging bays if the peak charger is to work properly. The thing is you need a charger that is the type that wants to charge 2 cells at a time. You'd need to find the terminals that actually have the voltage on them.

I just tried a test on my energizer nimh charger, put 2 AA's in (real ones) and then measured voltage from one charge bay to the other. It was about 3.3 volts (the batts had some charge already). My charger takes 4 cells, but only in 2 sets of 2 (you'd be able to charge 2 cars with dual cells with it). Need 2 fake AA's (you'd put your wires on them where the charger reads about 3 volts)

I tried to measure without any batteries in the charger, but the voltage was really high (17 volts, with almost no current) -that could be bad for your car if the batts have a loose connection inside your car. The car's receiver probably doesn't draw enough current on it's own to bring the voltage down to the usual battery levels.

To be totally safe about that, I'd put a few LED's across the voltage output (3 in series should do)-- that way, if your batteries in the car have a momentary loose connection, the led's will light up and clip the voltage down to about 5-6V (depending on the type of led)
Under normal conditions, these led's wouldn't light from just 2.5 to 3.5v from normal battery charging or if they did, it would be very dim, and shouldnt affect the charging much.

Led's only begin to glow at 1.6V, and usually operate at 2.1v (approximately). The 3 led's would begin to glow if 4.8v or more was present.

Has anyone found out conclusively if the super brain is safe to use or not? It looks like it has a single cell charge mode that would work. If it is ok to use, does anyone have any test data of charge time vs run time?