Charging stations

[HammerZ]

As long as it’s a newer Piranha it will work just fine. Try setting it for 3 cells and 0.3 amps to start keeping the peak sensitivity on the sensitive side. With the Epoch you will want a fairly fast charge so you can spend more time driving than charging, that’s why the 0.3 amp setting, but then you need to find a peak setting that cuts the charge off before the batteries get hot. Unfortunately with a stock Epoch the battery is not removable or even exposed so it’s hard to tell when it gets hot.

This was posted on MZR in the mini RC section. Figured I would start a thread here asking about charging stations for the cars. My Piranha is a programmable digital peak charger. I feel it may be too much for these tiny battery packs in these cars. I am looking to keep the batteries more or less stock for now.

[LBRC]

Since the stock epoch pack is a 3.6 volt 120 mAh NiMH three cell pack you want a digital peak charger that will handle a pack this small.

The Piranha’s specks are a good example:

• Battery Type: NiCd, NiMH - 1-8 cells
Good, the point here is that 3 NiMH cells falls nicely between “1-8 cells”• Charge Current: 0.1-5.0A
Again great, since 0.1 amps is less than 1C (120 milliamps)
• Battery Capacity: 50-5000mAh
This is the big one, along with the number of cells, 120 mAh is more than “50” where in there great.
• Peak Sensitivity: 3-20mV
Adjustable Peak Sensitivity as low as 3mV very good, if it was only 10-20mV it would be bad.
• Trickle Current: 0, 100, 200mA
The point here is that it can be set to “0” since unlike NiCad’s you do not want to trickle charge NiMH cells especially small ones, it shortens their life and degrades their performance. Note; advanced chargers have A monitored top-off charge setting that is sometimes labeled as a trickle charge this is a good thing since after the peak is detected a low current charge is applied until a very faint peak is detected and/or a time limit is reached (usually less than 2 minutes).

Key point is that the specs say the Piranha will charge 1-8 cell packs so 3 cells are ok, and it will go as low as 50mAh so it’s a go for the 120mAh Epoch pack. :)

However for someone looking for a micro car charger I recommend looking into something like the Duratrax Ice or Great Planes Triton. Yes they cost more ($115 to $125) and require a 12 volt power source, but you do get what you pay for (at least in this case) they have improved sensitivity and logic functions, including cut off safety timers just incase the charger misses the peak or something is wrong, optional thermal sensors, oh yea and they’ll do Lithium cells too.

Of course if you really want to fork out the big bucks there are some serious chargers out there. Although you have to be careful and pay attention to what the charger is actually targeted to do, and sometimes they are just a bit proud of them selves. For example the Futaba CDR-5000 is a pretty spiffy little charger and was quite revolutionary when it came out, but why no computer interface and software for the price, of course it could have been updated. In the last two year digital peak chargers have taken many great leaps forward. Shoot not that long ago if you showed up with a Piranha at a race or trade show it would have made the front page of RC world, things are advancing fast and today’s top chargers are being replaced daily.

[HammerZ]

I have been poking around the RS site looking for a connector that I hope will fit this cars charge jack. Here's the item I found. I posted it to see if the size is right. I did get an extra power switch and plug from the shop to check the fit outside the car to be sure.

Coax-Style DC Power Plug4.0x1.7mm
Model: 274-1532
Catalog #: 274-1532

Tip size: 4.0x1.7mm
Barrel length: 22.8±1.0mm
Solder terminal

I found out that above isn't the right one, this listed below is the one that fits the charge jack on the car.

Size H Coaxial DC Power Plug

Tip size: 3.4mm O.D.x1.3mm I.D.

Model: 274-1571
Catalog #: 274-1571

[HammerZ]

I cobbled up a connector to charge it up, and note the dirt on the tires it works. The big downside is with the Piranha, it takes over an hour to charge. Other than that it worked well thanks to the setup list above. I will have to come up with a better connector that is more solid than this stuck together hack.