Time for a new battery charger

For many years I have used Tekin BC112c AC/DC chargers to charge my NiCd and NiMH battery packs.

I own four of these chargers.  They have all been upgraded to the latest firmware (H31) by Tekin in order to support charging NiMH batteries in addition to NiCds.  Since I deal with mostly vintage cars, I still have not moved to LiPo or even brushless motors.

As for the BC112c, I really like the features and functionality it provides.  Variable charge currents are selectable in 10mA increments between 0.1 and 10A and from 1 to 12 (NiCd/NiMH) cells.  Trickle charge current is is also programmable.  Multiple charge modes including re-peak for just before a run and timed charge mode are available.  Last year, however, I had two chargers out of four fail on me for unknown reasons.  They were working perfectly and then suddenly they freaked out with power issues. 

With the two failures and doubts about the remaining two chargers, I decided it was time to buy a new charger (or two).  I knew I wanted a charger that could be powered via AC rather than just DC.  Yes, I know; if I bought a DC-only charger and an AC to DC power supply, I could keep using the AC power supply going forward no matter what charger I decided to buy in the future.  But I did not want to have to lug around two pieces of equipment and I wanted to buy enough chargers to allow up to four batteries to be charged simultaneously.  One AC power supply might not be enough juice to power multiple chargers at once.  Maybe someday in the future I will break down (again) and buy an AC power supply and DC chargers, but this time I wanted a charger that was AC powered.

My requirements were:

• AC powered
• Suport for 2 or more batteries fast charged simultaneously
• NiCd, NiMH and LiPo support

It's a pretty short list.  I purposely kept it short and simple because otherwise I'd have to look at chargers that were either DC-only or extremely expensive.

There are tons of chargers out there today.  The selection is quite broad, but with my short list of requirements I narrowed it down to just a few different makes and models.  It really boiled down to which chargers were considered good quality and had favorable reviews by people that actually used them (instead of just relying on the press reviews). 

In the end, I purchased two Duratrax Onyx 245 chargers.  I mostly decided on the Onyx 245 based on the fact that it won reader's choice awards in RC Car Action magazine multiple times.  I figured the people that use them every day would know what charger is good.

The Onyx 245 charger comes with Tamiya, Deans and Traxxas charge leads which is a nice plus.  Since I use Deans plugs in all my cars, I did not need to purchase any extra connectors.

After using the Onyx 245 for a while now, I have to say it is simple to use and appears to charge well, but it really is one of the most basic chargers out there.  By basic, I mean that there isn't one feature they could remove from its functionality and get away with it.  It has the absolute bare minimum of features and functionality in order to perform its function and nothing more.

Some of my complaints and wish-list items (not in any particular order) are listed below.  Many of these things I knew about before I purchased the charger, but I still think they are valid:

• Trickle charge is not available until after fast charging has completed.  A battery cannot be trickle charged just by plugging it in.  I wish trickle charge was available for NiCd and NiMH types independent of fast charge having been used or not.
• Charge currents are limited to 0.5A, 1.5A, 3.0A and 5.0A.  Nothing else.  I wish the fast charge currents could be configurable in 0.1A increments.
• Trickle currents are hard-programmed based on the fast charge current and cannot be changed.  I wish the trickle charge currents could be configurable in 0.01A increments.
• Settings are not saved so every time the charger is plugged in you must select the battery type and fast charge current (unless you like to use the default LiPo and 5A settings).  I wish the charger saved the last selected battery type and charge current for next power-up.
• Beeping and alarms are always on and cannot be turned off, nor is there a volume control.  I wish there was a way to turn down the volume and choose a different beep tone/style including a setting of 'off'.
• DC input plugs (alligators) are hard-wired.  I wish they were banana plugs like the battery outputs so they could be unplugged to reduce clutter.  The dangling wires and clips are always getting in the way.
• The AC cord is too short.  I wish the cord was two feet longer.
• The LCD display does not hold still while charging.  What I mean is that during a fast charge the display is constantly switching between battery voltage and charge current every 4 seconds or so.  Pressing the Data button repeatedly will allow you to cycle through battery voltage, charge current, total mAH charged to battery so far and charge timer.  But after a couple of seconds, it switches from whatever it was displaying back to battery voltage and charge current again.  This is annoying.  I wish the LCD display would stay on whatever screen was selected via the Data button.
• This problem is by far my biggest complaint:  Plugging in a battery while the other side is fast-charging a pack will often cause the whole unit to reset.  The small spark of current that sometimes occurs when plugging in a discharged battery (NiCD or NiMH) can cause the whole charger to reboot.  There is insufficient power supply and/or surge current separation between the two "independent" charging circuits and the main power supply.  The reboot is extremely annoying if there is a battery being fast-charged on the other side of the charger at the time.  Some type of electrical noise/surge suppression should have been designed into the charging circuits or shared power supply to prevent this behavior.  It happens often enough (50% of the time) that I refrain from plugging a second battery into the charger if one side is fast-charging.  I wait until the fast-charge cycle is complete before plugging in the second battery.  I've never seen this happen if neither side is fast-charging.  Both of my chargers do this, so it isn't a "one-off" problem with one unit; it's a design problem.

One other minor manufacturing/design nit:

• Quality Assurance failed to notice that on one of my units the fan was rattling quite noisily during fast charging.  After opening the charger up I discovered the molded fan mounts were simply too loose and allowed the fan to vibrate in the mount.  Two tiny slips of paper solved that issue by holding the fan securely in the slots.  Easy fix, but shows that it is a cheap design.

Of course many of the items I complain about above are available on higher-end chargers and even the new soon-to-be-released Onyx 225 has many of these features, although it can only charge one battery at a time.  Maybe that's a good thing, though, considering the problems I have when plugging in batteries into these Onyx 245 units when they are already fast-charging another pack.

As for charging performance, the Onyx 245 does a good job of charging NiCd and NiMH battery packs, even old ones like I have.  As for LiPo, I cannot say because I do not own any LiPo batteries that could utilize this charger yet.

Would I recommend the Onyx 245?  I suppose I would, but only if you are looking for a basic charger with no bells and whistles and you want to charge two packs at once and can deal with its limitations.  Frankly, I expected a little more from a US $120 charger.  It's a workhorse charger and works fine for what it does which I suppose is why it keeps winning the reader's choice awards. I'd say go for a higher-end charger like the soon-to-be released Onyx 225 if you are looking for more features and finesse, however.  I may end up doing just that.