Motor for a small dynamo

Help & Support Robot Parts
1

Hi, I’m looking for a small (and cheap) motor that can be used as a dynamo to make DC electricity in a small hydroelectric central with my students. So it need to be a DC motor, easy to turn with just a small amount of water (like an opened 5 gallon of water), and create enough current to light a couple of DELs. I suppose it is better to use a 12v motor to have more voltage at low speed (not a lot of water)… My students will have to make their own central so I need to order 40 motors. So witch motor do you recommend me?

Thanks,

Philippe

Bonjour,
Je veux faire un projet de centrale hydroélectrique avec mes élèves. La centrale est petite, l’eau proviendra d’un 4 gallons qui se videra dans un bac. Je me demande quel moteur je devrais commander pour produire l’électricité. Comme le débit d’eau sera petit, j’ai supposé qu’un moteur 12 v serait plus adapté pour produire de l’électricité à basse vitesse. Quel moteur permet de produire le plus de courant avec un faible débit d’eau? J’ai 40 moteurs à commander donc je cherche quelque chose de peu coûteux.

Merci!

Philippe

2

At this time we only have one hydroelectric generator. The other bushed DC motors can be used to generate electricity, but are really not created for this and the efficiency will be quite low.

3

Thanks for your answer. But I cannot use this type of prebuilded generator. I need a simple DC motor because the students have to build gears or polley to optimize the speed of the motor. So I need only ingenering advise about witch dc motor is better for this type of project. In other words, I need a motor that produce enought voltage (say between 3 and 6v) when it spins relatively low because there’s not a lot of water flowing… only a big bottle that emptying freely. Is it better to take a very small cheap motor like this (I don’t know which speed is enough to produce 3v):
robotshop.com/ca/fr/moteur-c … -dagu.html

or it is better for me to take a 6 or even 12 volt motor to produce more voltage at low speed. But I don’t know if those are hard to turn with just a bottle of water that flows out… So maybe you have a motor that produce a good voltage when it spins lower that it is supposed to:
robotshop.com/ca/fr/moteur-d … 250ma.html

or this one
robotshop.com/ca/fr/moteur-b … 9-rpm.html

Thanks for your advice,
Phil

4

We understand what you mean. None of the DC brushed motors we carry, including the three you referenced, have any information at all regarding being back-driven, so we cannot provide any information about the voltage curve vs RPM or the efficiency at which they will operate. You’ll simply need to test a few models and see if they are suitable. Regarding the voltage of the motor, we are honestly not sure how it applies to using a normal DC motor as a generator - in all likelihood, you will not get the voltage out (a 6V motor can actually be operated over a range of voltages). It’s quite experimental at this point since these are not purpose-built.