So maybe you’ve just bought your first boat only to find you need to separately find yourself a transmitter? Or you just will get a new one?
The first thing you find when you google it, is that there are lots out there. On many occasions, you’ll land on a website only to discover that the seller splits the transmitters into “Air” or “Surface”. …. Baffling.
Before the modern wave of 2.4ghz radios it seems that it was thought better to help prevent signals on radio control race cars accidentally being picked up by a radio controlled plane overhead – and crashing them to the ground. So it was prudent to split frequencies – or at least I think that was the idea. To this day, you will see that MYA Entry Forms still ask for wavelength, a legacy of those days I guess – and we all fill in “2.4ghz”. Our radios all pair precisely to the receivers in our boats – no problems.
A manufacturer legacy of those days is still to classify their transmitters as either Air or Surface. You see that on seller websites a lot. Now before you immediately go and look at “Surface transmitters” as we sail on the surface…. Stop!! You want to look at “Air Transmitters”. We use airplane type transmitters for sailing.
It looks like “Surface” designs now tend to be pistol grips (rc cars?) and “Air” designs have the twin joysticks that radio sailors use.
So : You want to look for “Air” and “Mode 2”, the latter being about the way the joysticks are arranged. Mode 2 is rudder on the right. That’s what we use.
You might also come across the term “Open TX”. For now, just ignore this. This is the transmitter manufacturer equivalent of linux in the home computer world – free shared industry software for driving the transmitter as opposed to manufacturer proprietary software. There are pluses and minuses – and you’ll be wondering about those as you read. It should in theory make it all cheaper in the long run. At the present, Radiomaster, FrSky, Jumper and one or two others have adopted OpenTX.
I’ve only been radio sailing a short time, but I’ve already had five chargers in the house. Or is it six? My wife thinks I am/we are mad. However, it does give me a disproportionate amount of experience in the matter (ha!).
Let’s start with safety though. It appears that LIPO batteries in particular (see earlier articles) cause some safety concerns and prime among them is what happens if they leak, or overheat, or leak and overheat. There is honestly a lot of opinion written about this online. I feel my own summary is that your batteries can leak and become dangerous from three or four main reasons:-
physical damage, bumps, abrasions etc (check them visually regularly)
exposure to extremes of heat or cold (so don’t let it happen)
over charging (includes left on the charger overnight – my favourite)
amazingly, apparently letting the charge drain to nothing also can cause problems
What do you think? It seems to me that at least the first three above are high in my mind, but surely the most likely thing I am going to experience is over charging, or perhaps charging too fast (too high a current included).
So we have had five types of chargers here in just a few months. Let me deal with that. Firstly, rechargeable AA batteries for the transmitter. Well you could simply always carry a spare pack of duracells in your pocket, but I disposed of the first charger because it had no display or coloured light system too show when your AAs were fully recharged. So now, I use one with a display that shows you the state of charge in each cell, plus flashes at you once it hits full. It’s a pity they dont beep when full as well. From Amazon, not expensive, and great. It came with fresh AA’s I think. It can charge different sizes too, and variable battery numbers.
Now… on-board batteries ….. much more interesting….
You need to read up about balancer cables and balancer charges. Basically, if you just charge via the one main connector, in a two cell battery the first cell hits full before the second cell. It obviously leads to all sorts of inequality but notably the first cell will tend to over-charge and over-heat. So get a charger that supports balancer leads.
In my short time, I’ve had LIFE with JST connectors, LIFE and LIPO with XT connectors. The first charger I had for the JST batteries, was frighteningly crude. You plugged the battery in for hours, and it never seemed to charge fully. It had one red warning light. It was with the Club loan boat – I threw it out and bought them a new one.
My brand new IOM came with LIFE batteries XT60 connectors, …big ones. The charger had balancer leads (the little white things with three holes), progress lights in red and green, so somewhat more informative. It had no indication of applied current though. I think it did one battery at a time – I’d have to check. Then I got the Marblehead which came with XT30 connectors, …the mounting variations made my head hurt. I have a mix of LIFE and LIPO for that boat just so I can make my own comparisons.
So what to do?… Consult an expert…. I paid a visit to the fabulous TJD Models shop in Sutton at Hone, Kent. (near M25 and close to RC Yachts, home of the DF95) Not sailors, but drones, planes and race cars is their thing. They were magic. Seen it all before and knew the questions to ask.
First question was all about connectors, and the second big discussion was about charging current. He asked what m.a.h. batteries we use in sailing. I said (guessed) 1000mah to 1800mah. He said, always charge at 1 amp maximum else they get hot. His simple rule was to show me a 1500mah battery on his desk and cross out the last three digits and you get a “1”. Use 1 amp was his strong recommendation for both longer life and safety.
Then he asked about budget. I’m sure you can spend a fortune, but his product shelf went from basic to intelligent, and £25 to £50. What price safety? I know £50 is double £25, but honestly around here that’s about 6 cups of latte. With their help, I chose a charger model around £50 (a bit less I think). I bought the SKYRC 100 intelligent charger in the photo above. I bought two eventually – one for the loan boat and one for me.
For your £25 extra, what do you get?
-firstly it has separate charging regimes for LIPO LIFE and about three other battery types, I’d never heard of. So I share my one charger across all boats and batteries now.
-when you plug in, it checks the battery type and tells you what it thinks you have got, so the user can check for mistakes.
-you select the amps going in, the number of cells, the target volts you want, and it displays all this all the time during charging. You particularly see the current amps fall as “full” gets closer.
-when it detects “full” it turns off the current and beeps like hell at you to come and unplug everything. You can hear it from two rooms away. I love it. I disconnect straight away.
-it has balancer lead support and refuses to start unless you plug it in. Good.
-get this, it can charge two battery types! I have it set up to do XT60 in one socket, and XT30 in the other. (see photo). I’ve not thought, but it probably can charge two batteries at once (I’d have to check)
For my batteries with JST, the lovely TJD Models Shop made up an adapter lead while I waited. For XT30 (my marblehead) batteries I bought this little bag of adapters for about £5.50 on Amazon.
So there we are – do what you feel is right. I wanted to feel good about managing my risk, and for the moment this charger plus fire-proof bags seems as good as it gets. To charge I place the SKYRC unit inside the explosion proof bag (fits nicely) and charge inside there. The cable goes in through that little trap door flap in the side that you can see here. Easy…
Datchet Radio Sailing - Making It All Much Easier !! 