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Apr 06, 2010, 12:03 AM
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Mini-Review

Battman B6-80W Balance Charger/Discharger


1. Overview

I recently had the opportunity to do some evaluation testing of the Battman B6-80W balance charger/discharger. If you're not familiar with this charger, it's sold by OKHOBBY (http://www.okhobby.hk/), a relatively new Hong Kong RC web store. Basic information on this charger can be found on their web site (http://www.okhobby.hk/product.php?id_product=1075) and more in-depth information in the product manual attached below. In a nutshell, this is an 80W balancing charger that can charge the most common battery chemistries used in RC today. It can handle up to 6S lipos. It can also do limited discharge and charge-discharge cycling and has several different modes specific for lithium batteries. I'll give my observations in using this charger, but won't repeat all of the chargers features since you can read about them in the sources linked above.

The case is all aluminum, nicely finished and finned for cooling, and barely larger than the palm of your hand. The physical packaging, bright backlit 2-line LCD display, fan, and button arrangement all look indentical to several other chargers sold with other brand names on the case. Even the manual and programming functions look identical. Whether or not this is an OEM version being sold under the BATTMAN label or a clever copy is unknown. My first inclination was to have a look inside. The board layout is spacious with nicely soldered components.

My evaluation charger came with a power connector that is terminated with two small, long-nose alligator clips for connecting to a DC power supply. I thought these would present a problem connecting to my home power supply which has female banana plug outputs, but the slim nose of the clips fit nicely inside the plugs and clamped very securely. I also thought connecting to my car battery in the field would be a problem, but again the clips got a good bite on the battery cable clamp bolts, and worked well. The 18 in. power cable is a bit on the short side for my taste when connecting to a car battery.

The charger came with several battery main plug extensions, including Deans-style T-connector, JST, and Futaba-style servo connector for RX packs. Lithium cells are charged through their main power plug, not through the tap plug on packs so equipped.

There are 5 user-defined memory buffers for storing commonly used battery charging/discharging configurations.

2. Lithium Cell Charging/Discharging

It's necessary to first set up a specific lithium chemistry (Lipo, Li-Ion, or LiFe) in the charger set-up memory. I did not have any Li-Ion of LiFe packs, so my testing was done with Lipo packs. Once set, the lithium charging options will only show appropriate settings for that specific lithium chemistry. The user still must select the correct number of cells and charging current before starting a charge cycle. The charger will display the user selected cell count along with it's detected cell count, and the user must press a button to confirm they match before the charge cycle will start. There are a number of safety checks for pack and individual cell voltage (when the tap plug is connected), as well as for proper polarity and various charger functional tests. I did not test for these.

The charger has a 7 pin connector for balance taps, and several adaptor cables are available for the commonly used tap plugs. None were included with my evaluation charger, however, and the only way to balance charge was to connect the tap plug directly to the 7 pin charger port. This is NOT recommended, however, because the tap plug has to be precisely located in the extreme right side of that 7 pin port, with the negative wire of the pack to the right. Although the port is well marked with the correct cell tap alignment, it is EXTREMELY easy to inadvertently connect the plug offset one or more pins to the left, or with the + and - sides of the tap reversed. And some taps plugs won't work, with the wrong pin spacing (e.g. Thunderpower) or with the tap wires not all on adjacent pins (e.g. Polyquest). There is a warning and picture in the manual claiming damage will occur if the balance tap is plugged in wrong, but the picture does not have enough clarity to tell which way is correct! I did an ill-advised test and plugged a pack into the port offset one pin to the left to see what would happen if I initiated a charge (it was a complimentary evaluation charger after all!). Happily, the charger saw the problem, displayed an error message, and aborted the charge sequence with no apparent damage done. Even if you can connect the pack tap plug correctly to the charger port, it fits so tight within the case opening that I could not get hold of the plug to extract it. I had to resort to pulling on the tap wires! Do yourself a favor and get an appropriate balance tap adaptor cable to eliminate these problems.

The charger can handle up to 5 amps and 6 cells in series when charging, but the discharge amp capability is quite limited (more on that later). The two line display main screen shows the pack voltage, charge (or discharge) current, mAH in (or out), and elapsed time.

Although not documented in the manual, it is possible to charge two identical 3S lipos simultaneously when they are properly connected in series with power and tap cable adaptors that make the two 3S packs appear as one 6s pack to the charger. Since the manual does not recommend this, I won't go into detail here, but it is possible and does work.

There are 5 charge/discharge modes available, aptly named Charge, Balance, Fast, Storage, and Discharge, and they function as follows:
  • Charge Mode

    This mode simply charges without balancing. The balance tap does not need to be plugged in, but if it is, the display can be toggled to show the voltage of each cell even though no balancing is being done. This is a nice feature since the charge will normally go a little faster without balancing, and when the charge terminates the final voltage of each cell is saved in the display, so a decision can be made whether to finish off with a balance charge if desired. The charge cycle in this mode appears to stop when the charge current approaches 100 mA.
  • Balance Mode

    This mode requires a balance plug to be correctly attached, and will check, alarm, and abort the charge if this is not the case when the charge cycle is started. The maximum current drain for balancing is 300 mA/cell. I tested this mode with a 3S pack that has one bad cell that won't quite hold the full 4.2V when charging. The charger dutifully tried to balance it, going until the charger's time limit timed out (120 min. default) and stopped the charge. With decent packs charged at 1C, the charge terminated after about 1 hour and 15 minutes, with the pack resting voltage averaging about 12.43V (about 95% charged). This is several percent less charge put back in than my regular charger.
  • Fast Mode

    This mode simply stops the charge cycle sooner... it does not actually charge faster at a higher C rate. It will take less time but the battery will not receive as much charge. It will also balance during the charge if the tap plug is connected. Based on several tests, this mode appears to terminate the charge when the current level drops below 300 mA, taking about 50 minutes when balance charging at a 1C rate starting from a full discharged state, and leaving a pack with a resting voltage of about 12.3V (about 90% charged). Continuing the charge in the regular Balance mode afterwards resulting in charging for about another 17 min. on average.

  • Storage Mode

    This mode is intended to set the pack voltage for long term storage. The charger will also balance cells in this mode if the tap plug is connected, but it takes a lot longer (30+ minutes vs 15+ minutes in my tests with 1300 mAh 3S packs). The pack voltage setting is fixed by the charger and cannot be changed. For 3S packs used in my tests, the charger set an 11.4V target cut-off. The mode will work with the pack voltage either above or below the cut-off voltage, discharging or charging the pack (respectively) as needed based on the packs starting voltage. For a discharge cycle, the charger limited the current to .8A for the 3S packs in my tests, diminishing to about .1A as the pack voltage neared the target 11.4V. The resting voltage of my 3S packs was measured after a 20 minute rest period following both discharge and charge cycles in this mode to see what the relaxation storage voltage would be. I measured an average of 11.70V (approximately 60% charged) for a discharge cycle, but only 11.25V (approximately 25% charged) for a charge cycle, which is low by conventional standards.
  • Discharge Mode

    This mode will discharge lipos to 3V/cell. The LVC is fixed by the charger for each lithium battery chemistry and is not user selectable. The discharge current is likewise limited by the charger and cannot be changed. For the 3S packs used in my tests, the discharge current did not exceed .9A, even though the display showed a 2A (max.) rate. The discharge power capability of the charger is only 10 watts, and it limits the current accordingly. So this mode is not useful for things like testing for voltage under load. It's primary usefulness is for break-in cycling, but the 3V/cell is too low for today's higher C-rated lipos. Resting voltage after a discharge of my 3S lipos averaged about 10.8V.

3. NiMH/NiCad Charging/Discharging

I did do some brief tests with both NiMH and NiCad packs. The charging is as expected... worked well. The delta peak value can be changed by the user, but I used the default settings. I also tested the auto-cycling capability (up to 5 charge/discharge cycles). The time period between cycles can be user set (0 to 60 min.), but I used the default (10 min.). The amount of mAH in and out for each cycle is saved for later review... a nice feature.

4. Lead Cell Charging/Discharging

I did not have a proper connecting plug to test with a lead cell battery I had.

5. Miscellaneous

The charger has a port that will accept either an optional temperature probe or a PC USB interface. The temperature probe will monitor battery temperature during charging and terminate the charging if the set point (user selectable) is exceeded. The USB interface and it's supporting software reportedly can log and graph the charging and discharging variables (volts, amps, mAH in/out, etc.) for each cell. Neither of these optional accessories were included with my test charger so were not tested.

6. Conclusions

The Battman B6-80W balance charger/balancer is a compact, well-built unit with many nice features, capable of handling the common battery chemistries used in the RC model hobby. Although the 10W maximum power during discharging is a limitation and there are a couple of fixed function set points that could be tweaked to be more appropriate for today's Lipo cells, the charger pretty much performs as advertised and is a good value in it's price range.
Last edited by Tom Frank; Apr 06, 2010 at 12:15 AM. Reason: Formatting
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Jun 01, 2010, 06:43 PM
Registered User
Do you need an adapter for JST-XH balance leads for this charger or will they plug right into the side like on the Accucel-6 ?

Thanks
Jun 01, 2010, 08:09 PM
Dance the skies...
Tom Frank's Avatar
Quote:
Originally Posted by Tag1260
Do you need an adapter for JST-XH balance leads for this charger or will they plug right into the side like on the Accucel-6 ?

Thanks
They will plug right in, but as I mentioned in the review, they are hard to get out, especially if you push them all the way in. You can't get hold of the plug to remove them... you have to pull on the wires to get them off. So an extension cable is highly recommended.
Jun 01, 2010, 11:29 PM
Registered User
The below Turnigy 200w unit is a better deal at $39.

http://www.hobbyking.com/hobbyking/s...r_&_discharger


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