A MUCH better charger!

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    • #8953
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      I measured the current my remote was charging the battery with and it was about 300mA and went up and down like it was cycling it or something. I also measured 2.7 volts without the car charging and dropped to 1.9V when charging so I decided to make a better charger. 300mA seemed like a lot to come from 2 AA batteries. I also noticed when I put it on the charger for the second time (not running the car at all) it took about the same amount of current again. This means the battery is capable of storing a lot more energy.

      OK, here it is. I took a 3V 700mA transformer power supply (Radio Shack #273-1756 with a 5.5mmOD, 2.5mm ID tip) and hooked it up directly to my battery. The voltage was perfect 2.1V. The current was 400mA (the batter will only draw what it needs so don?t worry about the rating on the transformer being high). I watched the current for over 2 minutes and it never dropped below 250mA. I didn?t want to charge any longer so I took it off and WOW. It sure stayed peppy for a long time. You know how on a single charge it?s peppy for about 30 seconds. This was peppy for 1.5 minutes and lasted 10 minutes driving with throttle on constantly and 2.2 motor. So, time to make a nice charger. I used 2/56 very small screws and nuts sticking out of a plastic project box from radio shack. Just drilled the holes the right distance apart and used nuts to hold them however high I wanted. Then I made another hole for a jack (Radio Shack 274-1576) to plug the transformer in. I put a Blue 5V LED (Radio Shack # 276-311) in parallel with the terminals so I could determine if the car was charging. When the car is placed on the terminals the LED goes out since it drops the voltage down to 2.1V and when the car is off or not making good contact the LED is on since the transformer produces 3.6V when open. So, the LED is just there so I know I have a good connection to the car NOT AS A TIMER! I have to watch the time and take if off when I feel it?s ready (apron 1.5 minutes.). I also added a switch just to turn the light off without having to unplug it.

      Anyway, the charger works great, give it a try!

      http://www.geocities.com/pfabersac/bitcharger.html

    • #13773
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      Thx for the info. Is it too much to ask for a pic of the inside of it?

    • #13957
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      Not sure I follow you… This is because I am not technically inclined. hehe.

      So your new charger charges at 400ma now, versus the stock controllers at 300ma right? So does this make the charger more powerful or quicker? You mentioned the runtime was extended right? Are you using a stock battery? Couldyou replicate your results using the stock controller and charging twice i.e. 1.5 mins as well?

      Sorry if you have answered any of my questions in the post above. I just may not have understood it well. 😉

      deejay40

    • #14636
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      This is a favourite topic of mine – battery charging !!

      A common misconception with these micro cars appears to be that they can only be charged one or two times in succession before using it. NOT TRUE…..

      I will explain:

      When reaching a full charge Ni-Cads start to convert the energy going into them into heat – this means that the battery has taken all of the charge it is going to take – and is converting that un wanted energy into heat. This is when the battery is fully charged – NOT before.

      Charging the Bit Char G fully can take 3to 5 consecutive charges before the battery starts to get warm, depending on the condition of the transmitter batteries.

      You are not damaging the battery by getting it slightly warm – in fact you are doing it a favour – you are ensuring that the battery has a FULL charge.

      I regularly get over 18 minutes with a 2.2 motor on my garage floor – longer on my kitchen floor (because it offers less resistance)…..

      Another important factor in charging – is in fact ensuring that you DISCHARGE your battery fully before the next use……this reduces the chances of the battery getting the dreaded “memory effect” which causes the cell to gradually detoriate in a short period of time.

      Dont be afraid to charge your car twice or three times in a row – always checking the temperature of the battery using the “lip test” ;)….. (put your lip on the bottom of the car – and see if there is a slight warmth where the battery is located)…….then go on charging until the battery gets slightly warm.

      Give this method a try – you will be very surprised at the length of run time you get out of the car.

      I am currently trying to source some nickel metal hydride batteries for the Bit Char G – to allow even longer run times ! Charging NIMH batteries though is a whole different story.

      Just my two cents on the matter – I hope you all find this helpfull.

      On a side note – I will be adding a micro section to my website shortly – as I am growing more and more fascinated by these fantastic little cars !!

      If any of you would like to add some content to this section – please feel free to email me and we can chat !

      Cheers

      Darryn

      http://www.darrynsretrorc.rtox.com

    • #14641
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      whats a good way of fully discharging the battery? sometimes i stop playing witht he car after it stops moving, but then i try to see if it’ll move again like 10 minutes later, and it still can.

    • #14643
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      Ni-Cad cells will always “regenerate” to adegree – as the chemicals inside are always “volatile”.

      The simplist way is to ensure that you lift the car off its wheels and runit till the wheels dont turn any more.

      I have another method which is a little more tedious – and not really essential:

      I use a small LED light and hook iotup to the contacts on the bottom of the chassis……..When the light goes out – it is as dicharged as itis going to get.

      I hit a new record just now for run time – 35 minutes with a 1.0 motor !!

      Cheers

      Darryn

      http://www.darrynsretrorc.rtox.com

    • #14655
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      Tell me about NIMH batteries? I might be able to get some the right size – what battery stats am I looking for? Didn’t someone say the OEM bullets have NIMH batteries??

      I have a peak detect charger at home that can handle between 1 and 12 cells with auto cut-off. I thought I might give that a try. Perhaps rig up little charging stand from Bullet parts.

      Nick

    • #14693
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      Quote:
      Originally posted by darrynsretrorc on 24July2002

      I am currently trying to source some nickel metal hydride batteries for the Bit Char G – to allow even longer run times ! Charging NIMH batteries though is a whole different story.

      Hi.

      Please could you explain how you charge Ni-MH batteries? I got two from:

      http://www.overlander.co.uk/detail.asp?SubCategoryID=NickelMetalHydride&ID=53

      (Don’t know if that’s any help to you as a source)

      I’ve not yet tried them. Can you still use the controller as it is to charge a Bit Char-G with one of those Ni-MH cells in?

      Any information, greatly appreciated ;o)

    • #14697
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      I have a How-To article on making a plug-in charger:

      Here’s the whole site: Bit Cal-B

      And here’s the charger page: Bit Char-G-er

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