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Cadex C7400ER-C Battery Analyser Review by Nicholas Vinen This versatile unit can automatically charge, discharge, test, analyse and recondition virtually any type of battery pack. Up to four batteries can be connected at a time and many different types of connector are available, both for specific batteries and universal adaptors. The unit will quickly tell you whether an attached battery is good and if not, it will attempt to bring it back to full capacity. T he C7400ER-C is an automated battery charging, testing, analysing and exercising system. Each of its four bays can be filled with various kinds of interfaces to connect to battery packs for power tools, laptops, mobile phones and many other devices. It can handle batteries up to 36V, 24Ah with a maximum charge or discharge rate of 6A per battery. Lead-acid, Nicad, NiMH, Li-ion, Li-po or LiFePO4 batteries in any combination can be charged/analysed. All four connected batteries can be charged/discharged/tested simultaneously (within the unit’s total power limits). Who needs it? We would envisage using a device such as this in one of two types of situation. First, by organisations or individuals who use a lot of batteries and need to keep them all charged and in top condition, ready for use. Second, it could be used by those repairing, servicing or manufacturing batteries or siliconchip.com.au battery-powered products. This unit will give you confidence that every battery going out the door is fully charged and functioning properly, with documentation to back that up. It will keep track of how a given battery’s performance varies over time, with use. It’s also a quick (and reliable) way to eliminate a dodgy battery as being the source of an equipment fault before a repair. This unit is ideal for jobs like these since it can be configured for many different types of battery with minimal effort and can automatically determine whether a battery just needs to be charged or needs a more intense workout such as multi-cycle re-conditioning. The C7400ER-C can be used as a standalone unit, controlled either manually on a per-battery basis or automatically, by simply plugging a battery into one of its adaptors. When set up for automated use, personnel with minimal training can connect a battery and the unit will let them know when it is ready for them to use, or if it needs replacement. In this type of situation, the settings can be locked out so that users can’t cause a malfunction or use the wrong charging profile for a battery. There are two security levels; one lets users select a profile to use for a given battery but not change any settings, while the higher password-protected security setting locks users into a particular profile for each adaptor/battery so they can’t choose the wrong one. This Battery Analyser can also be connected to a computer for more advanced diagnostics. In fact the software can handle over 100 units simultaneously for managing a large organisation which deals with a lot of batteries. It performs extensive logging to allow users to check the health of the organisation’s batteries and also go back and look at when a given battery was serviced and what its condition was at the time. Battery adaptors The unit’s four bays can be fitted with various adaptors to handle different battery types or they can all be the same, if your organisation only deals with one type. March 2014  63 Some of the adaptors can be Our test setup with a “universal” types which can be Makita cordless used to connect to a variety of drill battery in different types with a quick recon- the first bay figuration. Having said that, there (off-unit). are over 1000 custom adaptors available for just about any battery type imaginable. Our photo shows the unit with a Makita power tool connector in its first bay, a general purpose banana plug/alligator clip interface with temperature sensor in its second bay (good for batteries with exposed tabs or terminals) and “RigidArm” and ”FlexArm” adaptors in the other two bays. These latter adaptors are used for rectangular or near-rectangular battery packs where the connectors are lands (ie, small rectangular for later analysis. This could be very useful pads), such as mobile phone batteries. For for large organisations. these, it’s simply a matter of using the supAlternatively, technicians can take a more plied magnetic brackets or spring-loaded slot interactive approach and alter parameters for to clamp the battery down onto the baseplate each battery that is connected, if required. and then lower the spring-loaded arms down This would be more typical in a service or into contact with the battery terminals. repair situation. Since the locations of the lands will vary While running the service program, the depending on battery type, there are multiple “Run” LED associated with that bay lights degrees of freedom which allows the probes up and the LCD displays some information on the arms to be moved so that they will regarding what it is currently doing, the batcontact the correct lands. The RigidArm has tery voltage and charge/discharge current. less degrees of freedom but because of this, Once finished, it beeps and lights up either it’s easier and quicker to switch between bat- “Ready” or “Fail” depending on whether the teries of the same type; the FlexArm probes battery is OK or not. Further information such must be positioned individually each time. as more specific details on the battery state However, both types are quite simple to set can then be displayed. up and use. So if you want to simply find out whether a Larger battery packs can be placed atop battery is any good, and check that it’s ready the units and the FlexArm can be arranged to go, this can be done at a glance. to have the arms pointed backwards to reach Modes & features their terminals. The unit can service batteries in a number Battery service profiles Each adaptor can be programmed with up to ten profiles (called “C-Codes”), which determine the battery chemistry, voltage, capacity, charge and discharge rates, termination voltages, test modes and so on. One of these profiles is set as the default and if a battery is connected to that adaptor, the unit will immediately prompt the user as to whether they want to start running that program. So once it’s set up, the unit is pretty easy to use; it’s just a matter of plugging a battery in and pressing ‘go’. You can set it up to bypass this step and just start operation if desired. It can also be set up to ask for an ID when a battery is inserted and it will then select an appropriate profile. When used in conjunction with a PC, it will also log the battery ID along with the servicing details 64  Silicon Chip of different modes. “Charge” mode just does a basic fast charge. “Auto” mode charges the battery and then does a quick discharge test. If this reveals that the battery is not performing as it should, it is then “reconditioned” with one or more discharge/ charge cycles. If that fails to improve the capacity, the unit flags the battery as having failed. “Prime” mode conditions a battery with repeated discharge/charge cycles. It stops when the batter y capacity no longer improves. The “QuickSort”/”QuickTest” modes estimates the condition of a battery in a very short time (around 30 seconds) based on a stored profile of a known good battery. This is stored in the adaptor itself so can be customised to the type of battery inserted. There are also several advanced modes that include self-discharge measurement, destructive testing to determine the number of charge/discharge cycles a battery will withstand, internal resistance measurement, battery runtime under various load conditions, residual capacity measurement (discharge testing), an extended “Prime” mode, and low-battery recovery (“Boost” mode). Custom modes can also be programmed. The C7400ER-C can be connected to a Dymo label printer, and after testing can print a label indicating the state of a battery, which can then be affixed to it. This is a quick way for users to keep track of which batteries are good. If connected to a PC, a comprehensive report can be printed on a regular printer. Oh, in case you have already seen the article on the Nicad/NiMH “Burp” Charger in this issue (starting on page 66) and are Between the FlexArm (left) and the RigidArm (right) most battery types can be accommodated. There is also a range of specific battery connectors available. siliconchip.com.au For more in-depth analysis and/or to keep a permanent record of battery states, the unit can be connected to a PC and various software run to really tell you how your batteries are performing. wondering: yes, this unit also supports this type of charging. They call it “Reverse Load” charging and it is enabled for Nicad & NiMH batteries it by default. The ratio of charge/ discharge can be set in the battery profile. Our experience We started out using the C7400ER-C in stand-alone mode, ie, without hooking it up to a computer. In general, the unit is easy to drive. It automatically recognises when a battery is connected and prompts you to select its chemistry, voltage, capacity, what mode to use and so on. Once you have input this information, you press enter and it begins to charge/discharge/test the battery immediately. By default, the display shows the status of each of the four bays. You can then press the large button under each bay, labelled with its number, to get more detailed information about what’s going on with that battery. As well as showing the current action, terminal voltage and charge/discharge current this also shows the battery pack impedance (if measured) and its temperature. When set to automatic mode and a battery is connected, the unit does what it thinks is required to bring it up to full charge and capacity. Master Instruments provided us with a 12V Nicad replacement pack for Makita power tools (which they make in-house) and when we popped it on the Analyser, it did a quick charge and discharge test and confirmed it was in good condition and no further action was required. We also tried connecting some Li-po cells that had been lying around (for quite a while...), also in Auto mode, and it behaved somewhat differently, subjecting them to more thorough testing and in the case of the obviously more poorly cells, attempted to re-condition them with a full discharge and recharge. This sort of re-conditioning is most likely to succeed for older battery siliconchip.com.au technologies such as Nicad and NiMH, which are still in fairly common use, however it may be beneficial for Litihium-based cells too. One thing it took us a while to figure out (even with the user manual handy) was how to abort battery servicing. It turns out to be pretty simple – press the Alt key and then the associated battery bay button. This then gives you the option to restart the currently running program, which then allows you to change the profile settings or abort entirely. It’s a good idea to use this method to disconnect a battery during a test since simply yanking the battery out risks arcing which could damage the contacts of either the battery or the unit itself. However if the battery is disconnected while being serviced, the unit will sense this and stop whatever it is doing. If the battery is quickly re-connected, the previously running program will automatically resume, otherwise it aborts the program. Performance As stated earlier, the unit can handle batteries up to 36V and charge or discharge at up to 6A, however there is a limit of 75W per bay/battery, ie, with higher terminal voltages, the maximum current is reduced. Also, there is a total limit of 170W for charging and 200W for discharging across the four bays. If this would be exceeded, the unit will either reduce the charge/discharge current or pause action on one or more batteries until others finish. In practice though, you wouldn’t commonly need full power on all bays simultaneously. Accuracy is specified as ±1% for voltages and ±2% for currents which is good enough for most purposes. There is a procedure to re-calibrate the unit if necessary and you can also re-calibrate the individual adaptors, as the unit measures and stores their internal resistance to allow for more accurate battery voltage and impedance measurements. Advanced features If your organisation uses a lot of similar batteries, the unit can ‘learn’ how a good example behaves. Other batteries of the same type can then be tested against this model for a very quick assessment of their state (“Excellent”, “Good”, “Marginal” or “Poor”). Custom tests and procedures can be programmed, eg, if a battery needs to be ‘exercised’ periodically in a specific way, the unit can be programmed to do this without the need for user interaction. The optional “BatteryShop” software can be used not only to manage and track multiple Battery Analysers can also produce graphs of the performance of a specific battery over time, including how capacity and impedance vary each time a battery is connected to the unit (including date stamps). Reports can be printed of the state of a given battery each time it is serviced or charged. For really advanced battery analysis, the BatteryShop software can also produce a graph showing how the battery voltage, internal resistance and temperature vary over time during charge and discharge, in comparison to the current flow (see screenshot). The unit(s) connect to the PC via USB. Overall, we would have to say that this Analyser is has a very comprehensive set of features and is quite easy to use. It can handle most rechargable batteries in use today. Using one of these units to manage a large set of batteries would be far better than having a hodge-podge of different chargers, especially given that some battery chargers don’t always do the best job and can in fact lead to a shortened battery service life (eg, due to overcharging). Where from? The Cadex C7400ER-C Battery Analyser is available from Master Instruments. Their range of Cadex products can be viewed at www.master-instruments. com.au/category/Cadex_Battery_Analyser_Charger_Conditioner/1232 You can also call them at one of the following numbers: NSW/ACT – (02) 9519 1200, Vic/Tas – (03) 9872 6422, Qld – (07) 5546 1676 or WA/SA/ NT – (08) 9302 5444. Or e-mail info<at> master-instruments.com.au for more information. In addition to the more common types of battery adaptors, they also stock the C7400-C, which is a similar instrument to the C7400ER-C but has a more limited range of voltage and current (up to 16V, 4A). Or if your needs are more modest, you could consider C7200-C which is a two-bay version of the C7400-C. SC March 2014  65