|Accu-Cycle Elite Dual Output Charger/Discharger/Cycler:|
|battery types supported:||Nickel Cadmium, Nickel Metal Hydride, Lithium-Ion, Lithium-Polymer|
|cell counts suppored:||NiCd/NiMH: 1 to 10 cells Li-Ion/Li-Poly: 1 to 3 cells|
|fast charge current range:||50 mA to 2.0A in 50 mA increments|
|trickle charge current range:||0 mA to 200 mA in 10 mA increments for nickel batteries only|
|discharge current range:||50 mA to 2.0A in 50 mA increments|
|discharge cutoff values:||0.8 to 1.2V per cell for nickel batteries. Fixed at 3.0V per cell for lithium batteries|
|input power required:||11-14.5V DC, minimum of 5A for simultaneous full charge|
|Available From:||Available online at Tower Hobbies|
Once upon a time maintaining one’s radio system batteries was pretty straightforward – the batteries were all NiCds and, except for special purpose receiver batteries, they were all pretty much made up of AA sized cells with 500-600 mAh capacities. So, a cycler that drained these batteries at one fixed rate, to a fixed cutoff level, was all you needed to periodically check and exercise them. A classic example of a charger/cycler that worked well for this purpose for many years is the Ace Digipace.
But now things are more complicated. We have NiCd and NiMH transmitter batteries with typical capacities from 600 mAh to three times that. Some transmitters have other than the usual 8 cells (notably Multiplex with their six-cell batteries). We have tiny micro receiver packs and giant scale receiver packs, and everything in between. Some lithium-based batteries are being used as receiver batteries. We have turbine engine control units and starters and their batteries. And of course we have drive batteries for a huge variety of electric powered models from indoor and light park flyers up to giant scale models. And in these latter applications, NiCds and NiMH batteries are being rapidly supplanted by lithium-based batteries (primarily lithium-polymer) as well.
So, the simple Digipace and similar devices just aren’t enough any more.
Aware of this, Hobbico has recently released a programmable charger/cycler for radio system and small electric drive batteries that covers a wide range of capacities and both nickel and lithium-based chemistries. The Hobbico Accu-Cycle Elite is actually two identical charger/cyclers in one small box, sharing a common power supply and user interface of display and control buttons. Each of these is capable of charging batteries of up to 10 nickel-based cells at up to 2A and up to three lithium-based cells at the same current, using appropriate charge methods for each battery type. Each output can also discharge the same range of batteries at 50ma to 2A. Nickel-based batteries can also be automatically cycled up to 5 times, and the results of each cycle are available on the display at the end of the process.
The Accu-Cycle Elite operates from 12V DC power (actually 11-14.5V), so it can be used as a field charger. It comes with a 15W AC power supply that allows either output to be used at its maximum capability, or both outputs to charge at a reduced rate (depending on the voltage of the batteries involved) while used simultaneously. Full simultaneous capability on both outputs is available when running the unit on a more powerful power supply or from a field battery that can provide at least 5A while holding above 12V.
And, the unit has 10 memories in which you can store the battery type, capacity, number of cells, desired fast charge, and discharge rates, and for nickel batteries a trickle-charge rate and the desired number of cycles when cycling. There are also provisions for a temperature probe for each output that can be used to monitor a battery under charge or discharge and terminate the operation based on temperature. There is also a “manual” mode for charging or discharging a battery for which the specifics (chemistry, cell count, capacity) are not stored in one of the memory locations. This mode basically has you override the settings of the chosen memory without storing them.
All of this sounds pretty flexible and capable and should cover most any battery used in a fuel-powered model (glow, gas or turbine) and small electrics as well. Let’s take a closer look at it.
You can use the unit straight out of the box or you can customize the ten memory locations, depending on what you want to charge or cycle and how you want to do it.
The Accu-Cycle Elite stores data for ten batteries, defining the battery chemistry, cell count, capacity, fast charge and discharge rate for all batteries it can handle. For nickel-based batteries only you can also store a trickle charge rate, desired peak voltage sensitivity, selected cutoff voltage for discharges (from 0.8 to 1.2V per cell) and a desired number of cycles (from one to five) when using the cycling function. Rather than forcing you to define this for each memory (numbered from zero through nine) before you use the unit, it comes pre-configured with a mixture of default nickel and lithium battery profiles. Details on these pre-configured memories are shown on the top of page 9 in the manual. I’ve borrowed the table from the manual and reproduced it here:
If the settings you need for your batteries are already defined here, then the process is simple:
Using a Stored Memory Setting
The charger will do a quick check of the battery connections and with a two-tone signal, will start the selected process.
There are a wide range of settings predefined here – some that seem to me to be for radio system batteries, such as number 0 for a transmitter with an 8 cell pack of older AA-sized NiCds, memory number 4 for a 6-cell transmitter pack as you’d find in an older Multiplex transmitter, and memory number 5, for a moderate-sized receiver pack. The others all appear to be for small electric power drive batteries of various sorts, though memories 7 or 8 might be suitable for lithium-polymer-based receiver batteries.
All of the presets have rather conservative settings for charging and discharge rates suitable for simulating transmitter or receiver battery use. If you’re like me, you’ll want to modify these settings somewhat.
Changing one of these pre-configured memories to suit your own preferences involves selecting the desired memory, then stepping through a series of menus, setting each of the parameters. While this seems pretty straightforward on the surface, and there are pretty good step-by-step instructions in the manual, there are a couple things I need to point out.
First, you use the “Change” button to tell the unit you want to change a value and you press “Change” again to confirm the change, NOT “Enter”. Specifically you press “Change” to tell it you want to change, then use the “Up” or “Down” buttons to scroll to the desired choice, then press “Change” again to select the displayed choice. Then you press “Down” to go on to the next choice in the sequence and press “Change” again to edit that option. This confused me and made me wonder why there’s an “Enter” button at all. It turns out, by the way, that the enter button mainly is used to go into memory select mode and silence the process-complete chime when an operation is done.
Second, You MUST step through all the choices presented for charging, discharging and cycling, and after doing so return to the memory selection screen or the changes will NOT be stored. I found this rather irritating, especially if all I want to modify is one or two parameters. There is a note in the manual about needing to get to the final screen before changes are stored, but it could be more prominent. Basically you must use the “Down” key to get all the way back to the memory number screen before any changes are stored. And sometimes, for reasons I still haven’t been able to figure out, it still didn’t store my changes. They do supply two pages of flowcharts which help you figure out what the various memory options are and the flow between them. Even so, I did feel this was unncessarily frustrating.
You can temporarily modify one or a few parameters of a memory pretty simply – simply scroll to the desired parameter, press “Change”, scroll to the desired setting and press “Change” again to confirm it, then press “Charge”, “Discharge” or “Cycle” to initiate the desired process. You need not go through them all to be able to use the changed parameters, but once you either change memories or cycle the power then these temporary updates are lost. They also do not carry over to the other output.
During the parameter-setting process, once you’ve entered the battery chemistry, cell count and capacity, the Accu-Cycle Elite will calculate and propose a very conservative charge and discharge rate, and for nickel batteries a cutoff voltage. Hobbico calls this “Auto Smart Set”. If you’re mainly maintaining radio system batteries and are not in a hurry to get them charged, or simply don't wish to try to decide 'safe values' on your own, then using these automatic values would make sense. For my purposes I found them too conservative, much like the presets.
Once you have the memories set up the way you want them (and they give you a blank chart similar to the one shown above to fill in with your own information), using the Accu-Cycle Elite is pretty straightforward. As I mentioned at the beginning, the unit is essentially two separate charger/cyclers in one box, sharing a common display and controls.
First, the “Output Select” button chooses which of the two outputs to use. The LED to the left of the button will flash in yellow for a short time and a “1” in reverse video will show in the upper right-hand corner of the display if output one is selected. The right LED will flash yellow (and a reverse-video “2” will show on the display) if output two is selected. The memory location is selected by pressing “Enter”, then the “Up” or “Down” keys to get to the desired memory location. "Enter” is pressed again to confirm. Connect the battery you want to charge, discharge or cycle according to the memory’s parameters to the output you selected. Then, press and hold the appropriate button for a few seconds (“Cycle”, “Discharge” or “Charge”). You’ll get a confirming two-tone signal, and the display will say “checking battery and connections”, then as long as the connections are good the desired process will start. The color of the LED next to the output jack tells whether the output was just selected (flashing yellow), the battery is being charged (green) or being discharged (red). These LEDs display the state of the outputs regardless of which one is selected for the display.
At this point, if you want to use the other output on the same memory settings, all you need to do is use the “Output Select” to select the other output, connect up the battery and push and hold the appropriate function.
Once started, it will display (for the selected output) the sort of data expected from a digital charger such as elapsed time, charge (or discharge) current, total capacity in (or out), and the current pack voltage. It also shows the battery type and what it’s doing (charge or discharge). All of this won’t fit on the display at one time so it alternates back and forth between two displays. A reverse video number in the upper left hand corner of the display shows which output is selected at all times. By the way, I crosschecked the voltage, current and capacity with my new Medusa Power Analyzer Plus and the numbers matched exactly...as you can see.
During a cycling program the unit pauses for 10 minutes between stages to let the battery cool. During this pause the LED for the output goes out altogether. There is a 10-minute wait between the discharge and the charge for a cycle, and between the charge and the next discharge in the case of multiple cycles.
If there is a problem with the battery connections when a process is started, the unit emits warning tones and a message on the display to that effect. If there is not a good connection, for example, it provides a message to check it. I discovered this by having one output selected and the battery I wanted to charge on the other one when I pressed “Charge”.
On page 8 the manual says “It is not possible to have one output use one memory location and have the other output use a different memory location at the same time.” I have found that this not quite true. It IS true that if neither output is in use, changing the selected memory location affects both outputs regardless of which one is currently selected and indicated on the display. However, if one of the outputs is already in use, it is possible to select the other output, then select a different memory location. You can then start a charge, discharge or cycle process on this second output without affecting the one that’s already in use. I was even able to have a NiMH battery in the middle of cycling four times on one output while charging a lithium-polymer battery on the other output at the same time, with both processes proceeding as expected.
The key to using different memory locations simultaneously is to get one of them in use and the process running before selecting the other output, then choosing the desired memory location for that output and launching another process. To change the current output to a different memory while the other one is occupied, select the other memory. Then press “Enter”, then “Change” twice, then “Enter” again. Now the memory location number will be flashing in the display and you can use “Up” or “Down” to scroll to another one, then press “Enter” yet again to select it. You can do this at any time that a process is running on the other output.
If the other output is not in the midst of a program, then the new memory location choice will be applied to BOTH of them.
When the charge, discharge or cycling is complete, the unit plays a short little tune (and it’s distinct for the two outputs so if you have two things running you can tell which one is done by ear). By the way this is one of the most pleasant “I’m finished” tones I’ve ever encountered in a charger. After a charge or a discharge then the display shows the sort of information you’d expect – time, total energy in or out, ending voltage – that sort of thing. This information remains until you press the “Enter” button or cycle the power switch. If you did one or more cycles then you can page through the charge/discharge data for each of the cycles with the "Change" and the “Up” or “Down” buttons. There are two screens of data for each cycle and they alternate on the display.
If it has completed a charge (or cycle) of a nickel-based battery it will trickle charge the pack until you disconnect it – there appears to be no time out. I left one battery on overnight just to see if it timed out and it did not. If you’re charging a lithium-based battery there is NO trickle charge. Once the end-of-charge is reached, it stops altogether. During NiCd's trickle charge the output’s LED will flash green.
There has been much discussion lately about lithium battery fires on the Internet and in print publications. Just about all agree that the surest way to ruin a lithium battery and, in the worst case have a lithium fire, is to start to charge a battery of a given cell count on a charger set for a higher count, then go do something else. So I was very curious to see if the Accu-Cycle Elite had any protection against this most-common cause of lithium battery damage.
At first I thought that there was no protection for incorrect lithium battery cell counts, since there’s no mention of such a function in the manual or the ads for the unit I’ve seen. But after some correspondence with Hobbico in which I told them this lack was a serious drawback, they asked me to take another look. I put a partially depleted 2-cell pack in my fire-resistant charging container, set the charger for three cells and started a charge cycle. What I saw was interesting: Instead of ramping the charge rate up to the selected value (in this case 1.0 Amp) over about one minute as it normally does, the charge rate stayed very low – 0.1A or so – for a total of 5 minutes. At the end of 5 minutes the unit shut down with a “voltage too low” error message and chime. The chime sounds until you press “Enter”, it doesn’t stop after a few cycles as the end-of-charge indication does. After this, I switched the output back to 2 cells and restarted the charge, and it proceeded normally. I tried it again with a similar 2s pack that was nearly full (initial voltage of 8.32V) with the same result.
I am told that the Accu-Cycle Elite uses a battery voltage slope detection algorithm – that is, it watches how fast the voltage of the battery under charge changes – and it decides if the battery is healthy, or in this case if it has the correct cell count selected, based on the rate of voltage change.
I also tried a single cell on a two-cell setting and got the “voltage too low” error message immediately. I did not try charging a 3-cell pack on a 2-cell setting, as this error is benign.
So, the Accu-Cycle Elite does protect against charging lithiums with the wrong cell count selected. This is good news as I simply cannot recommend a lithium charger that doesn’t protect against this simple error now that this capability is available in a number of chargers.
For added insurance you can use the new Electrifly LiPoly packs, which have a safety circuit in them to prevent overcharge. But if the unit performs as it did with the unprotected packs (and it did so with the one Electrifly pack I tried) the voltage will not get to a level where the protection circuit “kicks in”. I do not know how the Accu-Cycle Elite will get along with the separate Kokam Safety Guard, the PolyQuest PCM Guard, or the protection circuit built into some recently-made Thunderpower packs. However, since it seems to work safely with unprotected packs, I expect it will be fine with protected ones from any vendor.
While the Accucycle Elite has protection to avoid attempting to charge at too high a cell count, it is important to note that NO multi-chemistry charger on the market, including this one, can stop you from trying to charge a lithium battery on a nickel setting. ONE mistake, if not caught in tim,e will lead to a lithium battery fire. For this reason I personally strongly recommend dedicated chargers for lithium batteries.
For that matter, making the opposite error – charging a nickel battery on a lithium setting – could also lead to a destroyed battery and a big mess if the lithium cell count setting is high enough that the nickel battery is overcharged. When set for lithium, the charger is not looking for a peak, but rather a specific voltage that might never be reached.
The Accu-Cycle Elite itself is a very compact unit, in a rugged aluminum case measuring 6-1/8" by 3-7/8" by 1-1/2" (15.6cm x 9.8cm x 3.8cm). It has DC input power leads exiting from the right side near the back that are 36" (91cm) long and ending in standard banana plugs. Supplied with the unit is a pair of big alligator clips that have banana sockets on them so they can be put on the ends of the input lead – a clever touch. The input leads are of sufficient wire gage to handle the maximum input current the unit could demand easily. There is a power on/off switch on the back at the right end next to the power input leads.
The two outputs are pairs of banana jacks located near the front outer corners on the top panel. No charge leads are supplied – I used a pair of Schulze leads I also use with my isl 6-636+. In the upper left on the top panel is the two-line LCD display. The “Enter”, “Up”, “Down” and “Change” buttons are to the right of the display. The “Charge”, “Discharge” and “Cycle” buttons are below the display and the “output select” button and the two LEDs are between the pairs of output jacks toward the bottom of the top panel. On the front panel are jacks for the connection of temperature probes for each of the two outputs. These are an optional extra. The ones that are sold for use with the Triton charger also work with the Accu-Cycle Elite.
There are cooling vents on the sides and back. The unit is passively cooled – there is no fan. I only noted it getting moderately warm during discharging packs, so the cooling seems to be adequate. There are substantial rubber feet on the bottom, supporting the unit about a quarter inch off of a hard surface. This aids cooling and also makes the unit less likely to slide around if you accidentally tug on a lead.
The provided AC power supply is a rather large affair for a 15W unit – for those of you who remember the old Commodore 64 computers it’s about the same size as the power supply for one of those. It has a standard two-conductor AC input cord that’s a little over four feet four inches (130 cm) long emerging from one end and two banana jacks on the opposite end into which the banana plugs of the Accu-Cycle Elite are plugged to use the unit on AC. The power supply only gets slightly warm during use.
If one was going to set this up as a piece of workshop equipment, finding a place to put that power supply will have to be a consideration. If it’s going to be on the workbench but also in the field box, the fact that you can leave the AC power supply at home and bring a compact and fairly light unit out to the field is probably a big plus.
For me, this unit mostly is very good. It does exactly what Hobbico says it will do, plus a pleasant bit more in that you can use the two outputs with separate memories with a little trickery, and that it protects against selecting the wrong cell count for lipos. It does all this accurately, quietly and with a reasonable user interface - with one exception. That one exception is the seemingly fussy process required to modify a memory location and have the modifications actually be remembered. It seems straightforward, but I’ve had changes not be remembered now more times than I’ve successfully got them stored, even when I thought I was following the instructions precisely. If I could choose programming functions, I’d much rather have a “save now” button or function for stored memory updates than the adjustable peak voltage threshold (beyond maybe one for NiCds and one for NiMHs).
From the perspective of someone who flies primarily fuel-powered models and needs a top-notch tool to charge and cycle radio system and accessory batteries, I think it is a fine piece of equipment and well worth considering. The fact that it can do two batteries at a time is a bonus, and two different batteries at the same time even more so! It'll take awhile to charge the biggest of the turbine ECU batteries (an hour and a half or more at the 2A maximum charge current), but it will do a good job.
From an electric flyer’s standpoint, it does a fine job with parkflyer-sized NiCd or NiMH drive batteries with that same advantage of being able to do two of them at once, as well as being able to automatically run several cycles to break-in such a battery or wake up one that’s been sitting awhile. And within its limitations it does do a proper job of lithium charging. (It is fairly limited as lithium chargers go, with a maximum of three series cells and 2A charge rates.) And, as with fuel-powered models, it does a great job on all the batteries one is likely to have in transmitters or, in large e-planes, for receivers.
In the end, I find I like it more than I thought I would just looking at the manual online – partly because the manual portrays it as more limited than it actually turns out to be. I do have several different transmitters to maintain, some of which have high-capacity NiMH batteries. And I still have a number of small NiMH electric drive batteries that are well within the Elite’s capabilities. Also, it will do small lithiums well, so I may use it, with great care to select the proper charge cycle, on the occasional park flyer lithium battery, even though I prefer to use dedicated lithium chargers. These are plenty of reasons to retire the old Digipace and keep the Accu-Cycle Elite around for a long time to come.
The Specification for the Accu-Cycle manual states:
Input Voltage 14.5 V @ 2.5 Amps
The AC Adapter that comes with the Accu Cyle provides an output that is full wave rectified with a zero to peak voltage of 20 volts no load. Loaded with 5.5 ohms the voltage drops to 17.6 volts. There is no filtering of consequence on the output. (rectified sine drops to zero at 180 deg)
My cheap meter (not RMS) is an average meter calibrated in RMS for sine waves, reads:
12.75 Vdc No Load
11.24 Vdc Loaded @ 11.24/5.5= 2.04 Amps
To convert zero to peak measurements to RMS multiple by 0.637
(RMS V = V/1.414)
I don't think the Accu Cyle is all that fussy about the supply as long as it will hold above 11 volts @ 2.5 Amps it should deliver the 2.0 amps charge current to any single output.
Your supplly is rated at 12 V @ 0.5 Amps. (12V x 0.5 Amps = 6 VA)
You will not be able to use the Accu Cycle at it's full capability and you may risk damage if you accidentally program a larger current than the charger can handle.
My Electrifly PolyCharge 4 does not like the Accu Cycle wall adapter at all because of the unfiltered output.
I knew Bernard was going to have a fine review of the Accu Cycle Elite when it started with "Once upon a time......"
Last edited by al_wa; Feb 04, 2008 at 08:57 PM.
If your 3S2P pack @ 2000mahr is made from six 1000mahr cells then:
The Accu Cycle Elite will charge that pack just fine using the supplied wall adapter if only one output is used. The max charge current per output if both outputs are used is 1.35 Amps. (would take longer but the battery won't mind at all)
If using an alternate input power source capable of supplying 5 amps at 12 volts you can achieve the full rated output of 2 amps on both outputs simultaneously.
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