A couple of weekends back we had a very good reception as part of the Youth Expo held in Brookfield NS. The Youth Expo is a large event aimed at youngsters with the particular focus on ‘hands-on’ activities. The organisers found us online and invited us to come and promote the hobby of R/C vehicles to the public. As those of you that check-in regularly, you know that there is an important distinction between Toy Grade and Hobby Grade R/C vehicles (we talk all about it on our beginners pages).
We had a few tables displaying a wide variety of R/C vehicles, and a foam R/C track setup on which people could spend a few minutes driving a pair of 1:27 micro scale racers. The cars held up well to continuous use, but alas it was the return spring on the steering wheel transmitters that gave out an hour before the end of the show (they’re still on my work-bench awaiting further investigation!). Don’t ask how many AAA batteries we went through!
We handed out a lot of information cards with links to this website so I hope there’s a few new readers. If so, Hi!
I didn’t get much opportunity to investigate the rest of the show but there looked to be lots of interesting things to see and try. I did take a couple of photos toward the end of the day though. There looked to be Laser Tag, Scotia Speedworld, Archery, Excavators, MotoCross etc. and there was even a competing R/C car track!
We hope to be invited back this year, and we’ve learned a lot about the shows setup. Maybe next year you’ll find us outside with bigger cars and a bigger track!
We all had a great time this weekend promoting radio controlled cars and trucks to everyone who visited the Shearwater Spring Hobby Show. Sunday was particularly fun as we had a large demonstration area and a few of our visitors were lucky enough to get the opportunity to drive a few cars on our throwdown track. Or even build a coil-over shock and spring from a kit r/c car. Sometimes there were ten different cars on track at a time. I didn’t have the chance to take a lot of photos as I was too busy letting everyone know how amazing and wholesome the hobby of R/C cars is, but what I do have is shown below.
Although we might not get the big area for next year’s hobby show, we’ve already got a few ideas about how best to demonstrate how R/C crawlers work!
And remember, our Fundraising Raffle is still going on. We’ve sold just over 140 tickets of 200 and the draw will happen at one of the the Halifax R/C Park maintenance events in Beaver Bank sometime in April or May (even if we don’t sell all the tickets!)
There’s no guarantee of a good weather weekend coming up, but there is guarantee of a fun, interesting and exciting time at the Shearwater Hobby Show. This post is just a reminder that we’ll be at the show promoting R/C cars of all types from 10am-4pm at the SeaKing Club on Shearwater Base. If you can choose a day, then aim for Sunday 8th April as we’ll have a bigger display, with some hands on R/C parts construction for you to try. More details in our original post here.
This will be the 4th year we’ve been part of the Shearwater Spring Hobby Show and new this year is a stand location upgrade for us as the show that allows us to demonstrate R/C cars, and to show the more detailed technical aspects of the hobby (for the Sunday anyway).
On Saturday 7th, you’ll see our usual show stand where you can talk to us about the hobby of R/C cars, but on Sunday 8th we’ll have a carpet track setup to demonstrate some cars, plus an area where you can try your hand at building a component of a car, and watch and talk with members of the R/C community who are maintaining their vehicles in-front of your eyes. Our advice, if R/C cars is a big reason for you to come to the show, then make sure you come on Sunday 8th April!
When: Saturday 7th April and Sunday 8th April 2018, 10am- 4pm both days
How Much: $5 per person or $12 for a family. Tickets also give you access to the Aviation Museum which is a great walk around for kids of all ages.
Where: The show is located at the SeaKing Club (15 Squadron Crescent) within Shearwater Forces Base just down the road from the Aviation Museum. You’ll need ID to get through the main security gates on Bonaventure Street. Exact Google maps location of the SeaKing club is here (click) and shown in the image below. Be warned that the Google Navigation directions don’t take you though the gate on Bonaventure St and you have to come in that way.
This is a bit of a Public Service Announcement regarding Lithium Polymer (LiPo) batteries. Over the past year I’ve purchased a couple of used RC cars that came with LiPo batteries. I didn’t need the batteries per-se, but the condition of the batteries when they arrived has made me wonder whether people really know how to properly care for them.
On the beginners page of this very website we have a section on batteries, including LiPos. It gives some basic information but I thought it’d be worth highlighting some of the critical aspects, as LiPo fires are certainly possible without the correct care.
And since the detail below is a bit wordy, here’s a quick summary:
DISCHARGING ANY INDIVIDUAL CELL BELOW 3v WILL DAMAGE IT
CHARGING ANY INDIVIDUAL CELL ABOVE 4.2v WILL DAMAGE IT.
ALWAYS BALANCE CHARGE
CHARGE AT 1C (the capacity of the battery in Amp)
CHARGE IN A LIPO SACK/BAG AND NEVER LEAVE CHARGING BATTERIES UNATTENDED
SET YOUR ESCs LOW VOLTAGE CUTOFF (LVC) >3v/cell
(Optionally use a Low Voltage Alarm (LVA) plugged into the balance port set to >3v/cell)
RECHARGE TO 3.85v/CELL FOR STORAGE or
DISCHARGE A CHARGED PACK DOWN TO 3.85v/CELL FOR STORAGE
IF A BATTERY PUFFS UP, STOP USING IT
Overview of a LiPo
A LiPo pack is one built from ‘cells’. A single cell is nominally rated at 3.7v (volts) but operates between 3v and 4.2v depending upon state-of-charge. A LiPo pack made of a single cell is referred to as 1S. Therefore a 2S pack, is a battery, made of two 1S 3.7v cells totaling a battery pack of 7.4v. Likewise a 3S pack is made of three cells giving a total voltage of 11.1v.
The cables coming from the battery will include the main Positive (+ve) and negative (-ve) wires, but also a balance lead that links to the +ve and -ve terminals of each individual cell inside. For a 2S pack, that balance lead has 3 wires allowing you (or your charger) to measure the voltage of each cell.
Charging you LiPo
There’s is one mantra here – ALWAYS ALWAYS BALANCE CHARGE. That is when the voltage of each cell within a pack is monitored while charging. You’ll need to set your charger to the number of cells (1S-6S is typical) and to connect both the main connections, and the balance connector to your charger. The majority of the ‘juice’ is fed back into the battery via the main cables, but nearing the end of the charge, the charger carefully tops up each cell separately. A LiPo is fully charged when each of the cells within it reach 4.2v. CHARGING ANY INDIVIDUAL LIPO CELL ABOVE 4.2v WILL DAMAGE IT.
As far as the charging rate goes, unless you’re totally running out of time (i.e. between heats at an important event) then it’s always best to CHARGE YOUR LIPOs AT 1C. C is a measure of capacity so if your pack is a 5000mAh (milli Amp Hour) then you charge at 5000mA = 5A. The charger begins charging at that rate until the cell voltages get nearer 4.2v and then the charging rate slows to a crawl when the charger smartly charges only the cell that needs the power. Charging is completed when each cell in the battery pack has a voltage of 4.2v. CHARGING ANY INDIVIDUAL LIPO CELL ABOVE 4.2v WILL DAMAGE IT.
Pit Tip: Charge on a non-combustible/non-meltable surface. I use an old porcelain floor tile I had lying around. Saves your workbench/window-sill if something goes wrong.
Using your LiPo
DISCHARGING ANY INDIVIDUAL LIPO CELL BELOW 3v WILL DAMAGE IT.
You should always check that your Electronic Speed Control (ESC) has it’s LiPo Low Voltage Cutoff (LVC) enabled, and that it is set to some reasonable value exceeding 3v/cell if user-switchable. Although the ESC manufacturers are trying to be helpful by letting you set it to a value of a particular voltage/cell, the LVC is actually fairly dumb since it can only MEASURE VOLTAGE ACROSS THE WHOLE BATTERY (the balance leads aren’t connected to the ESC). So even though you set the LVC to 3.0v/cell, the ESC actually decides whether you’ve plugged a 2S, 3S or whatever pack into it, and then determines the multiple of 3.0v that it’s going to cutoff at. So when you connect a 2S battery, the ESC thinks “this battery has a voltage somewhere between 6 and 8.4v so it must be a 2S and I’ll therefore cut-off when the voltage drops to 2*the user-selected value = 6v (in this case)”. It’s trying to be smart, but you can imagine that if one of the cells in this 2S pack is going bad, then the ESC won’t see a problem even if one cell was dangerously low at 2.6v and the other was totally fine at 3.5v. The ESC just sees 2.6+3.5 = 6.1v and thinks everything is fine. It’s much safer to set the LVC to something like 3.4v/cell, where a 2S pack would be cutoff at 6.8v.
There’s also a small circuit board available for around $5 called a Low Voltage Alarm (LVA). It’s connected only into the balance lead on a battery pack and is small enough to leave in your vehicle while running. Basically it’s a voltmeter with a bloody loud alarm on it, and it’s CONTINUOUSLY MEASURING THE VOLTAGE OF EACH CELL. The voltage at which the alarm sounds it user selectable, but since you’re measuring the voltage of each cell you can set it to just over 3v/cell. It’s a great fail-safe and one that could save your battery.
Storing your LiPo
If you need to leave your LiPo unused for a few days, weeks or months (you know, because it’s wet out!) then putting them safely in a storage condition will keep them lasting longer. This is something lots of people overlook – myself included when I first started using LiPo batteries. STORAGE is when each cell in the battery pack is at 3.85v. It’s just above mid-way between a full charge of 4.2v/cell, and a used battery at 3v/cell. If you’ve run your battery down to 3v/cell then you’ll need to STORAGE CHARGE TO 3.85v/cell. Most chargers have a STORAGE option, which is just like balance charging but it stops at 3.85v/cell not 4.2v/cell.
If for some reason, you didn’t fully use a charged battery, say because you smashed the front corner off your car on a rock. Then you’ll need to DISCHARGE TO THE STORAGE VOLTAGE OF 3.85v/cell. Most chargers had a discharge setting, but it takes a really long time. The single most useful piece of equipment I’ve added to my battery maintenance is a cheap ($30max) 150watt DISCHARGER/BALANCER that takes your battery pack down to 3.85v/cell, or balances mismatched cells if you forgot to balance charge. There’s lots of similar looking devices out there on eBay/Amazon, but make sure you get the one with the light-bulbs on as that’s what gives you a reasonably quick discharge rate.
Store your LiPos disconnected from your vehicles, and in a sturdy container, so they can’t get damaged or punctured.
Pit Tip: I store my LiPos inside an ammo can, with some foam washing-up sponges cut to stop the batteries moving around and banging into one another. However, do take the rubber seal out of the lid to avoid creating a pressurized bomb if one of the batteries leaks/explodes inside the can.
Taking care of your LiPos will make them last longer and keep you safe
If you have any questions, or corrections then feel free to get in touch.
We had a great time at the Shearwater Hobby Show over the weekend. Thanks to those of you that came out to say Hi and for those of you who are only seeing this because you took one of our information cards, “welcome to our website, and welcome to the hobby of R/C cars”. Unfortunately we didn’t get the chance to put on a full demonstration on Sunday morning, but we’ve been promised that nice carpeted area for 2018. Look out for details of our plans for that area sometime in March 2018.
We’re getting near to the time when track maintenance can start in earnest out at Halifax RC Park in Beaverbank, so keep checking here for more details. Many hands make light work!
If you’re scratching around for something to do this weekend then how about coming along to the Shearwater Spring Hobby Show on Saturday 8th or Sunday 9th April (this coming weekend). We’ll be there with lots of cars and trucks to see, along with a few smaller ones to try for yourself. A few more details on our post from a few weeks back.