Where I went to college, we had no electives. We all took the same courses – and had to pass them all. In simple terms, that meant that my classmates where in serious jeopardy of bodily harm if they had to work “juice” (electrical engineering) labs with me. There was something ominous about standing on a steel plate and handling all those volts and amps. I have had my reservations about electrics ever since – even though I did pass!
Having said all that, I might not understand exactly why all that I am going to tell you works, but I find that it does.
4 or 5
The RC Laser comes with a standard battery case for the boat that holds 4 batteries. To my knowledge, there is no such thing as a case that will hold 5 batteries (at least I have never seen one). So who would want 5 batteries anyway?
The best answer that I can muster is that you add the voltage of each cell in the system. So a four pack would have 4 times the voltage of one battery. So far so good. If you put standard ol’ Alkaline batteries in your system, you will find that each AA cell is rated at 1.5 volts. So 4 of them will be 6 volts total. (I had to pass all my math classes too!)
HOWEVER, if you move up to rechargeable batteries, guess what. AA rechargeables, whether NiCads or NiMh batteries, are only 1.2 volts apiece. So a 4 pack of rechargeables is only 4.8 volts.
Sooooo?, you ask. Well, the servos we use in our RC Lasers do better (stronger, faster) with a 6 volt system. Actually, the steering servo is not the problem, because it is working a small load and the gears turn the rudder as fast as necessary. But the big ol’ sail winch we have could definitely use the voltage.
So, the RC Laser sails just fine on 4 regular Alkaline batteries. If you don’t sail very much, then the “use and toss” program will work just fine. But if you plan to sail more regularly, the “use and toss” program gets a little expensive – and can be really frustrating to manage.
So here is one solution – At the Model Sailing Center we produce a 5 cell rechargeable pack for the boat. Five rechargeable batteries are soldered and glued together side-by-side, and shrink wrapped. This pack comes with the same plug used in your boat, so it is interchangeable with the 4 battery case. Too heavy? Not really, the RC Laser can carry the weight of an extra AA battery with no problem. AND, you still have the 4 battery case to use with alkalines as a back up if you run your rechargeables down (hard to do).
Last note – Some say Alkalines MAY last a little longer – but it is hard to prove. You should count on 4-5 hours sailing time on your batteries, alkaline or rechargeable.
Let’s say that you have opted to have a rechargeable battery system in your boat. If you buy the Power Pack from Model Sailing Center it will come with a matched trickle charger. This charger has two charging circuits with two separate leads – one plugs into your boat’s 5 pack (6 volts), and one lead plugs into your transmitter (9.6 volts- 8 ea 1.2 volt batteries). And there is no way to screw this up because the fittings are not the same at all. So relax.
Using this two lead charger is very simple, even I can use it safely!!! Just plug it in when you finish sailing and unplug it the next time you go sailing. It’s my kind of idiot-proof charger.
Note: The most common battery failure is getting the batteries in backwards or upside down! That’s the best part of our recommended system. You never remove the batteries, they are charged in place!
So what’s the catch? – A trickle charger is just that. It can take up to 18 hours to get a good charge on completely flat batteries. But realistically, you can thump a pretty good charge on your boat just overnight.
How about Memory?
Well, mine is gone! But what about this pesky problem with NiCad batteries having a memory. Theoretically, when you recharge a NiCad that is not completely discharged, you decrease the charge it will accept. Thus you lose a little longevity on each cycle. That’s the bad news! The good news is that whatever this memory thing is all about, it is not so much a factor with the newer NiCad batteries. In fact, some of us see no evidence of memory problems at all with our new NiCads. But if you worry about it, just completely discharge your batteries every now and then and the problem is solved.
On the other hand, Nickel Metal Hydride batteries (NiMH), do not have a memory problem at all.
You will get such good service out of both of these types of rechargeable batteries that I do not push one over the other. They are both great and will get you through a 4-5 hour day of sailing. By that time your brain is fried anyway.
How many charge cycles?
I have not personally lived through a rechargeable battery life. NiMH tout that they are good for around 500 charging cycles. NiCads claim they can go as high as 1000 cycles. The new rechargeable Alkaline batteries are supposedly very good except they will only make it through 50 cycles. Let’s say you get NiCads or NiMh batteries – and they cycle only 500 times. That is 500 days of sailing you have enjoyed – wouldn’t that be a good investment?? That’s less than 1.2 cents per day!
This article was written by Steve Lang of SailRC.com.