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Peanut006

The Frog battery question

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Hello!
I bought broken Frog from fleamarket. I have been fixing it and now it mainly works.
I'm thinking of buying LIPO battery to it (currently I have tested it using normal recharable batteries 1.2v x 6).
It would be great if you could help me with these questions:
1. What is the maximum current that the standard motor can consume?
2. Can the battery have too much current (breaks the motor or something else)?
Here is some pics:
Forgot to take proper 'before' pic, but here is something:
Washed parts and fixed some part using clue:
Ready :)
Thanks!
- Timo
P.S.
I'm total RC car newbie..
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Welcome to TC, Timo! :)

The car looks great, seemingly it was a great purchase.

However the gearbox of the Frog is not too resistant -the gears strip easily. If the car was mine I would not try anthing more powerful than a tuned motor.

Again, that Frog looks really nice!

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Hi Noob!! Yes we have all been there....

The standard motor (what we call the 'silvercan'...) is a 27 turn motor which is rated at 7.2V max. There is no current limit, as the motor will consume only the current it needs. So if you were to use a 7.2V battery rated at 1500mah versus a 5000mah, the only difference would be in run times, there would be no speed increase or more wear on the motor. So no you cant damage the motor with a battery with too much current.

BUT you can damage a motor with too much voltage. If you were to use an 8.4V battery then the car would be faster but you would wear out the motor much faster. Hope that helps!

As Mongoose has pointed out, the Frog transmission is kinda weak, so you should stick to a motor with 20 turns or more (the lower the turns, the faster the motor). But there will always be people on here to stick some crazy brushless setup in there, just be warned, nice car!!

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Thanks!!


It was a good find I think, because it costed 6€ :) Even tough I already bought front suspension spare parts and need to buy some spare parts to the rear also,

because the clue isn't holding..


I was looking some LiPos, seems like those are mainly 7.4V. I'm hoping that the 0.2V difference isn't fatal. Or do you think that it is bad idea?


If found meabye the motor specs [http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_540sh]. If I understood the specs correctly, is the motor maximum efficient current ~70. So if I want to be able get max power from the motor, the battery should be able to give that ~70 current out.


When using those assumptions following battery might be ok with that motor?




- Timo

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Can't say much about the electronics you mention but 6€ !!! Man, that was a FANTASTIC purchase! The car is in great shape, congrats! :)

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Loll you cant go wrong for that price, nice deal!!

Now on to your questions: LiPo batteries require special handling and charging because they can be quite dangerous. But they do offer longer run times, are lighter than Nicad or NiMH and also have slightly more voltage than regular 7.2V batteries. 2s LiPos are 7.4V and odds are you wont damage your stock motor and it will be slightly faster than stock. I only run brushless motors on LiPos so I cant comment on how safe 7,4V is on a stock silvercan but I think it should be fine. The battery in your link is a hardcase LiPo which will fit in the Frog but you will have to add some washers to the side plates as the battery is slightly longer than a regular Nicad battery which the Frog was designed for. If you decide to go LiPo make sure to get a hardcase one as the battery is exposed on the Frog, if it gets punctured you could have some nice fireworks (type LiPo fire in Youtube...). You will also need a charger capable of charging LiPo batteries. Also a good idea to replace the Tamiya battery connectors with Dean's or other high quality battery connectors.

NimH batteries are cheaper and require less maintenance than LiPos and fit perfectly in the Frog. Whatever battery you go for, the current it supplies to the motor is more than enough for the silvercan you are using.

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Loll you cant go wrong for that price, nice deal!!

Now on to your questions: LiPo batteries require special handling and charging because they can be quite dangerous. But they do offer longer run times, are lighter than Nicad or NiMH and also have slightly more voltage than regular 7.2V batteries. 2s LiPos are 7.4V and odds are you wont damage your stock motor and it will be slightly faster than stock. I only run brushless motors on LiPos so I cant comment on how safe 7,4V is on a stock silvercan but I think it should be fine. The battery in your link is a hardcase LiPo which will fit in the Frog but you will have to add some washers to the side plates as the battery is slightly longer than a regular Nicad battery which the Frog was designed for. If you decide to go LiPo make sure to get a hardcase one as the battery is exposed on the Frog, if it gets punctured you could have some nice fireworks (type LiPo fire in Youtube...). You will also need a charger capable of charging LiPo batteries. Also a good idea to replace the Tamiya battery connectors with Dean's or other high quality battery connectors.

NimH batteries are cheaper and require less maintenance than LiPos and fit perfectly in the Frog. Whatever battery you go for, the current it supplies to the motor is more than enough for the silvercan you are using.

Thanks for the info!

I've been thinking about going LIPO for my Frog to save weight, but I'm cautious... In my other hobby, we avoid LIPO...

Terry

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Thanks everyone!

I think I'll try that LiPo because I already have a LiPo capable charger.

I'll post some video after I have all things running.

-Timo

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