The simplest of all motor controllers (besides a beeline on/off switch) is the contactor controller. I advised this contactor ambassador for use in my electric scooter project. It is based about three 12V relays, two 12V batteries, two switches and of advance a motor. Having no silicon to “fry”, it is absolutely reliable and robust. A contactor ambassador works by rearranging the two (or more) accumulation batteries amid alternation and parallel. This gives the motor a apathetic acceleration (batteries in parallel, accepted adds) and a fast acceleration (batteries in series, voltage adds). This assures that both batteries are absolved equally. When the ambit is “at rest”, the batteries are affiliated in parallel, which allows accessible recharging.
Notes
1. S1 closes K3 and appropriately causes M1 to operate. S2 activates K1 and K2, reconfiguring the batteries for alternation operation and appropriately causes M1 to accomplish at “fast” speed.
2. B1 and B2 should be called based on the accepted requirements of M1. Often, closed lead-acid blazon batteries are accessible at bounded suppliers for decidedly low prices. These batteries are ideal for things such as scooters, go-karts, etc.
3. The relays are accepted automotive blazon relays, accessible cheaply from any auto genitalia store.
4. Your motor will depend on your requirements. 12V motors will commonly run accomplished at 24V, and carnality versa.
5. You will apprehension that in alternation mode, all three relays alone cull ability from B2. This is because the relays accept 12V coils, and it is absurd to about-face the batteries from alternation to alongside and accumulate ability to the coils at the aforementioned time. This does, however, beggarly that B2 is absolved slighty afore B1. This should commonly not be an affair unless the batteries are actuality drained absolutely “dead”. Draining a array asleep is not acceptable for it in any situation, and should be avoided. If you wish, you can use a baby 12V array to run the relays separately.
6. You can add two added speeds to this ambassador application the schematic below. It connects at credibility A and B apparent aloft on the ambassador schematic.
Parts
Part Total Qty. Description Substitutions
K1, K2, K3 3 12V 30A SPDT Relay (See Notes)
S1, S2 2 SPST Switch or Button
B1, B2 2 12V Battery (See Notes)
M1 1 12V or 24V Motor (See Notes)
MISC 1 Case, Wire, etc.
source=http://www.aaroncake.net/circuits/cntctcon.asp