Hi guys, I admitted defeat on TC10 since my chassis won't allow me to connect any real bodywork to it (I know I give up too easy), so instead I decided that I wanted to try and reverse engineer gsia16's citroen saxo rally car!

However, with the regular 9v non rechargeable battery pack, the motor will go for a short amount of time and then just slow down or stop completely, inching forward a millimeter at a time and straining the battery.

I wanted to ask if this is the fault of the battery box not giving enough power, or the motor just being "old" (it's part of the 8287 set) I've searched around but can't find an answer (perhaps im not using the right search terms or something)

anyways, if it is the battery, could I use a 7.2v NiMH from a RC car? (for example one of these)

if so, that could provide a lot more power to it (more than the 9v lego pack could) and make for an interesting ride, provided it won't fry the receiver (that's my other worry about it)

What do you guys think? would the buggy motor get a new lease of life, and would it still be able to power an M motor for steering?

Thanks,

-ender

I don't know the price of that lipo, but p Sbrick is better investment, then disable battery block thermo overload protection. Do you have small AAA battery block or Lego lipo? You need shunt it - that is easy. That will be enough for small car with one buggy motor.

Edited August 28, 20168 yr by rm8

Hi rm8, thanks for replying!

I already own that NiMH plazma battery since I own a few RC cars. I only own this lego pack:

, and the light grey and red variant from the buggy motor set (both seem to have the same issue)

that lego Lipo is very expensive. The sBrick is very cool, but again, a bit too much to spend at the moment.

Is that thermo overload protection why it won't work? If I connected the lipo to a receiver, would that still be in place?

Also, what does "shunting it" mean?

Sorry for all the questions, i'm not very knowledgeable on stuff like this

Thanks for your reply

-ender

The battery box doesn't has anything to do, my Aspire was working on a non modified one,you need to get better batteries, with good ones ( I used Varta) it works normal, now I have cheap ones and the same problem happens, so investing in good batteries solves the problem.

Edited August 28, 20168 yr by LXF

Ah, I see, that's good to know! My batteries were pretty cheap (came in a 100 pack) - so that's worth looking into

As far as using that NiMH is concerned, will that work in place of the battery pack without destroying the receiver? (means I don't have to go out and buy better AA batteries)

Thanks guys!

Sure you can, I tried a 2000mah racing one and the receiver is OK

ahh, I see, i'll give it a shot.

Thanks for your help guys!!

Also, what does "shunting it" mean?

-ender

I can answer this. Shunt basically means an electrical conductor joining two points of a circuit. In this picture below is the Battery Box "Shunt" modification also known as the Philo Mod. If you look at the R2 spot on the circuit you can see a wire that bypasses the resistor.

But Fair warning, if you do this Battery Modification, you could also wind up melting the battery terminals like I did here. If the motor pulls enough amount of Current.

As far as using that NiMH is concerned, will that work in place of the battery pack without destroying the receiver? (means I don't have to go out and buy better AA batteries)

I know it been answered but Yes, the 7.2v NiMh 6 cell battery pack can power the 9v Lego IR receiver just fine. You can even power the IR receiver with a 9.6v NiMh 8 cell battery pack but a full charge 8 cell NiMh battery pack at 12v might be more voltage then the IR receiver can tolerate.

I tried connecting that battery to one of my older receivers (the wire had a bad connection to the brick connector thing), and I think it must have fried it. it didn't seem to work anymore. I have one more left, but I daren't try it again in case the same happens!

Is it because it's the v1 receiver or does that have nothing to do with it?

-ender

I don't know how you fried it, maybe because your battery is more powerful than mine... My receiver is also a v1 and works fine on 2000 mah battery.

Are you sure it no longer works?

Edited August 30, 20168 yr by LXF

I tried connecting that battery to one of my older receivers (the wire had a bad connection to the brick connector thing), and I think it must have fried it. it didn't seem to work anymore. I have one more left, but I daren't try it again in case the same happens!

Is it because it's the v1 receiver or does that have nothing to do with it?

-ender

We would need to see how you connected up the battery to the receiver to determine if you fried the receiver. It should work fine if everything is properly connected up. Quick question did you release the magic smoke from the Lego receiver after you connected up the battery if so then you have fried it.

Well, I tested it with the lego battery pack afterwards and no cigar - it smelled like a blown capacitor or something. There was definitely some smoke emanating from where I connected it up, probably burnt the plastic. The battery is designed for use in one of these, and it's a pretty powerful little car. Perhaps it's just too much for the humble lego receiver to handle!

-ender

Edited September 2, 20168 yr by EvilEnderman

The 7.2v NiMh battery you used the Lego Ir receiver can certainly handle it as long as you don't go above the 9-10 volts for the battery. From what I can tell. The 7.2v NiMh Battery should have worked if you connected it up right with the IR receiver. But from what is possible you could (a) have connect the battery backwards or (b) there was something wrong with the IR receiver to begin with. If the Capacitor Blew up inside It could have been the battery that Blew it up by being connected backwards or the Capacitor was connected up backwards to begin with...

That RC battery gives you less power than normal LEGO battery box filled with non-rechargeable batteries actually. It's benefit - longer running time before your model consume all its charge.

Smoke and stuff. It is probably due to short cut. I would suggest disassembling IR receiver to check what went wrong before fixing it. Did you use a switch or was receiver powered directly by RC battery?