I recently bought a 6v 2000mAh NIMH battery to power around 4 or 5 micro servos. I’m just wondering if it is safe that I connect this battery directly to the solderless breadboard (provided by Arduino Starter kit) in parallel with each of these servos.
Thanks for the feedback. I’m a somewhat beginner to the world of electronics.
Four or 5 micro servos could draw a couple amps or so at peak, which seems kinda high for a temporary, 'friction-fastened' connection. It could work, or it could fail, depending on the quality of your breadboard and the size and type of wire plugged into it. Perhaps you could use the breadboard for connections to the control circuitry, but solder or use screw terminals for the power to the motors.
Ok, I will keep that in mind. The only problem is that I don’t have access to a Soldering kit. Il’l try it out. I won’t be keeping it on for too long or be putting too much load on the servos either way. Thanks!
Solder and irons are cheap. I recommend soldering as well as it is simply satisfying to solder. Most important starting accessory to an iron is a decent stand. I made mine out of a block of 2x2 wood and plywood with baling wire that I fashioned into a helix.
It may not be welding but still that tip will cause a rapid 3rd degree burn if mishandled. I've only been burned once, by the barrel, and lucky had water nearby.
According to one source I saw, even a micro servo can draw 800mA.
The figure you quote in mAh is the battery's capacity, not its practical current which is mA without the "h" on the end. If your requirement is for all those 5 servos to start moving at the same time, and thus all draw stall current simultaneously, can that battery provide 5x800mA, so 4A?
A 2000mAh NiMH battery can easily provide enough current for 4 or 5 micro-servos (most have a stall current of around 600-650mA).
Making the connections for such relatively high currents through a breadboard is more worrying. It may not only not work well but it can damage the connectors in the breadboard making that unreliable for future projects. For short tests even carefully twisting the power wires together may be preferable.
Steve
slipstick:
A 2000mAh NiMH battery can easily provide enough current for 4 or 5 micro-servos (most have a stall current of around 600-650mA).
Not doubting your word, but how does one know that a battery whose worth is quoted as capacity, can provide a certain current, in the absence of any other data?
The battery type is a very good indicator of the current they can produce.
Rechargeable batteries (like those NiMH ones) tend to be able to produce a lot of current, I wouldn't be surprised if such a pack produces 10-20A or even more when shorted (don't try, unless you're not interested in using those batteries again and take serious fire/explosion precautions).
LiPo batteries will produce enough current to easily set themselves on fire, which is why the good ones are equipped with short circuit (over current) protection.
Alkaline AA batteries are not too shabby either, they can produce 5-10A or so when shorted. This is why they're commonly used in small robots and so, the 1-2A small DC motors need is no problem for them.
On the other end of the spectrum, 3V button cells can produce something like 10-20 mA.
arduin_ologist:
Not doubting your word, but how does one know that a battery whose worth is quoted as capacity, can provide a certain current, in the absence of any other data?
In this case, experience. I've used a lot of NiMH batteries and I know how they behave.
I agree that it is a pain that basic battery "specifications" don't include the maximum current or a C-rating which allows you to calculate that current. But in many cases the manufacturers do provide detailed specifications if you put in the effort to search for them.
But you can't calculate maximum current from a basic voltage/capacity specification any more than you could calculate the top speed of a vehicle from engine power and fuel tank capacity.
Steve
Useful info thanks wvmarle and slipstick
wvmarle:
On the other end of the spectrum, 3V button cells can produce something like 10-20 mA.
Yeah my local supplier tests leds just by sticking a coin cell between the legs for a moment.
slipstick:
But you can't calculate maximum current from a basic voltage/capacity specification any more than you could calculate the top speed of a vehicle from engine power and fuel tank capacity.
Which is why I asked....
.... in the absence of any other data?
The most important data point when it comes to batteries was there: the battery type. As a rule, a larger capacity of the battery leads to a higher current delivering ability, and the capacity was given as well. Batteries come in a number of common sizes, type + capacity give this, but this is less important for current delivery ability.
After that of course the actual peak comes down to manufacturer, terminal connections, and other minor details. This is becoming quite irrelevant as the moment you're trying to use batteries at (nearly) their peak current you're probably doing something wrong. That button cell LED trick... well, that's just convenient 
So for this case: "a 6V NiMH 2000 mAh pack" is more than enough info to be able to say "that will happily run 4-5 microservos" (note how the current requirement of those was also not specified). The expected 2-3A total stall current for those servos, which will normally run at lower current, should be no problem for such a battery type. There are also numerous different solderless breadboards out there, but as a rule of thumb putting more than 500 mA through those rails is not a good thing to do.