Welcome to the webpage of the Halifax RC Park. Below this introduction you’ll find the most recent blog posts of all sorts of RC car happenings in and around HRM, including the activities at the free-to-use Halifax RC Park. The menus at the very top of the page give some more static information about who we are and how you can help, what the RC park is, how you can get into the hobby, and what local groups and clubs are there to share your fun, and when they meet and where. RC cars come in all shapes, sizes, speeds, complexity, and prices so there really is a vehicle for everyone.
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.
Just an handful of updates concerning Halifax Radio Control Park:
Maintenance: The track and surrounding area was given a full trim last night so the weeds and grass are short and it’s ready to go. Apologies to the two guys with the Traxxas Slash’s that we kicked off when we arrived with the mower and weed wacker – Hope you come back again soon.
Drivers Stand: The drivers stand saga looks to be over – and not in a good way. The requirements placed upon us by the city (HRM) has made the prospect of getting a true vandal-proof drivers stand installed at the park pretty much impossible. A wooden deck-like construction is vulnerable to fire and general abuse so was never really an option for us. Our hope was to re-purpose some metal pallet racking, but unless it’s installed with engineers calculations and sign-off, then it’s not allowed, and the liability assumed by that engineer makes it a hard sell from a professional standpoint. Plus we’d have to pay some ongoing fee to HRM on the square-footage of any structure placed on the site. Unfortunately we’ll have to make do with the bleachers we have, and the drivers mound that is in place. Personally I’d recommend bringing a step-stool for the top of the drivers mound for a better perspective.
However, the city have said that they’d help us with signage and mowing the park, even if the maintenance of the track itself remains the committee’s/community’s responsibility. We’re still waiting on the first mow and wack though! And some official signs will help ensure that park is being used in an appropriate way.
Regional Racing: To those of you thinking of attending some organised racing, there’s another round at Cap Pele this Saturday (23rd Sept) about 2.5hrs from Halifax. George puts on a great event and there’s classes for all types of R/C and drivers of all skill levels are accommodated. Locally it’s not often that you get to run with a full timing system which shows you how you’re improving. More details on the facebook link above.
We’re normally very much Halifax/Dartmouth R/C focused on halifaxrcpark.com, but for those of you interested in R/C racing slightly further afield, here’s a little report on last weekends race at Cap Pele Revolution Raceway in NB that a couple of us from your committee attended.
The race series at Cap Pele runs from May until October about once a month and draws drivers from all over the region. George puts on a great event, with Mylaps/AMB timing system (with loaner transponders for those without their own), times uploaded to LiveRC, and classes for pretty much everything out there from 1/16 electric to 1/8 nitro buggies. The track George has built in his yard is quite a challenge for the drivers with some very interesting sections that are in his own words – “made to be difficult”. There’s some bumpy washboard, a couple of sets of double-jumps, a 90° tabletop plus a neat section of moguls that when taken exactly right mean you can cut the last corner by leaping clean over the track marking.
Personally I entered 2WD electric buggy, 4WD electric Short Course Truck (SCT) and 1/8 electric buggy. After just over a 2.5hr drive, we had time for a handful of practice laps before the qualifying rounds started at about 10am. Each qualifier lasts 5min and drivers start at 1 second intervals to allow for maximum qualifying pace. Here you’re looking to complete the most laps you can in the 5min period. Making few mistakes is important as consistency is king. And it’s important to let quicker cars past as cleanly as quickly as possible. The results from the qualifiers for each class seed your start position for the finals.
Both the 2WD buggy, and 4WD SCT had enough drivers for a couple of qualifying races, and then for both a B-main (second tier) and A-main finals race. I was fortunate to qualify in 7th for both classes which meant I only had to race in the A-main. Those qualifying 8th and below, raced in the B-main with the top three from that race taking a ‘bump-up’ into the A-main. 1/8 Electric buggy had just under 10 drivers so a single A-main covered everyone. My final qualifier in 1/8 E-buggy went well and I qualified 3rd on the grid for the finals.
2WD buggies are hard to drive cleanly. They under-steer like crazy when on the throttle, and then quickly turn to over-steer under breaking as the weight transfers forward making them the most difficult to drive cleanly. After a terrible start where I dropped to the back of the field, I managed to claw my way back up to 7th before the end of the 7min long final.
4WD short course trucks are big beasts but take the bumps well. I managed to put together a handful of successive clean laps to claw my way up the field from 7th to 4th place within three laps. Some tight racing followed for a few laps after a mistake from the driver in front found me up in 3rd. I was quickly catching the racer in 2nd but a big mistake a couple of laps from the end meant I fell another 10 seconds back – not quite far enough to be caught before the end of the race. But I’d managed to secure 3rd on the podium overall which felt great. You can see the entire race details here on Live RC: http://cappelerevelutionraceway.liverc.com/results/?p=view_race_result&id=959310
1/8 E-buggy are quicker still than the SCT races, but starting high on the grid made for a less eventful first lap and keeping it clean (or at least cleaner than the guys that followed) means I didn’t even pass or become-passed by anyone for the entire race. Check out my amazingly consistent position tracker from Live RC:
Overall, I was both happy and surprised at my performance. Obviously getting some R/C practice in at Halifax R/C Park has paid off a little over the years, and I’d encourage you all to do the same. We hope to be able to put on events like this in the coming years, but its dependent on keeping the track in good condition (which is always a challenge). We need more jumps and bumps though!
It seems like every weekend this summer has had some rain. So certain we were that we’d have rain at the weekend, we actually scheduled a bit of track maintenance for a weekday. So yesterday, a Monday – so guaranteed no rain right (And to make our theory valid it rained a lot on Saturday and some on Sunday!), I got the lawn tractor, drag-rake, and roller loaded into a U-haul trailer and out to Halifax RC Park. Along with mower and whipper-snipper work by two more of your hard working committee we spent the day refreshing the track. The rake did a good job of pulling up some of the weeds, smoothing some bumps and loosening some stones from the surface generally leaving the track surface looking like it had just hosted an entire weekend of 1/8 buggy/truggy racing. A quick roll packed down the loose dirt. And wipper-snipping around the BigO track marking and final mow of the track on the lowest setting gives a usable and race-able surface.
The track surface certainly isn’t vegetation-free like it was back in 2015, and over time you’ll see the surface resemble a grass-track. But that isn’t a bad thing for a public R/C facility. Grass tracks are popular in Europe, keep the dust down, the R/C cars cleaner and are easier for the small HRCP committee to maintain with a couple of mows and whipper-snipping sessions a week. The grass helps hold the dirt together so the surface remains smoother and consistent over time, and rocks aren’t so easily exposed or dug up.
We ran a couple of Short Course Trucks around the track yesterday afternoon and it was much much better than before. There’s still a couple of sections with bumps that we’ll need to rectify – by making a small bump into a bigger jump!
We’re hoping for success in this long-term plan and one of the great ways to keep the weeds down is to use the track. So have at er!
So our successes rate of planned track maintenance vs. actual maintenance this season hasn’t been very good. We’ve had more rained-off work parties than actual work parties. We’ll continue to work on the track throughout the season, and if anyone is feeling enthusiastic then adding features or making repairs yourself can be carried out at any time. But the track is most certainly open and ready to use. You’ll find it a little bumpy in places, but as time goes on, and we carry out more maintenance, that should improve.
EDIT: We’ve added a weather widget to the website to give you the current weather at Halifax RC Park. Should be just over there on the right –>
The ground was still too wet last Sunday to get machinery to assist with building jumps on the race track at Halifax R/C Park, so all the progress was made by hand. A jump has been built on the outer loop, but this weekend (Saturday 17th 9am-noon) we’ll be back on track with machinery to make some more jumps. If anyone is around to help out then you’re welcome to come along – we’ll even have tools for those without any.
A local drone pilot (@JoeMiddleroad) took a great photo of the new 2017 layout at Halifax R/C Park a few weeks back. Since the photo we’ve been hard at work removing weeds and will shortly be building jumps (tomorrow, Sat 10th June 1-3pm) to give the track that real off-road feel.
The new layout has 3 possible tracks:
- A novice loop (green) for slower vehicles and less experienced drivers
- An advanced loop (orange) for the quicker cars
- A full circuit (blue) using a combination of the two loops
- If you find yourself alone at the circuit, feel free to use whichever layout you prefer. But do try to accommodate other users if they arrive while you are there.
- Always remember to be considerate of other users of the R/C track
- R/C cars can be dangerous, so make sure you don’t stand on the track when driving