After experiencing some disappointing charging results for AA batteries that I use in digital cameras, I tried to figure out why I was getting such uneven results. I learned that charging "re-chargeable" batteries is not a fool-proof process. In fact, overcharging certain batteries can shorten the life of batteries or even ruin them.
In order to protect your batteries from damage, it is wise to use a "smart" charger to figure out the type of battery it is charging and then "do the right thing".
After doing a considerable amount of research, I concluded that the Rayovac PS 3 is such a "smart charger", and will take steps to achieve optimal results.
It has four independent charger bays, each holding two battery cells, and each bay can charge a different size battery (or pair of batteries).
The Rayovac PS 3 is also generally well made and modestly priced, making it a good value.
After using it for about a month and carefully measuring "before" and "after" voltages on several sets of batteries, including AA, C, and D cells, and both NiCAD and NiMH batteries, I am satisfied that the Rayovac PS 3 is doing a good job, and quietly working as it is supposed to work.
Product information
| Product Dimensions | 6 x 5 x 4 inches |
|---|---|
| Item Weight | 1.14 pounds |
| Manufacturer | Rayovac |
| ASIN | B00004W4XM |
| Item model number | PS3R |
| Customer Reviews |
3.8 out of 5 stars |
| Is Discontinued By Manufacturer | Yes |
| Date First Available | July 25, 2007 |
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Bulky, heavy, but surprisingly smart and versatile
[IMPORTANT NOTICE on Jan 1, 2010]: I've been informed (thanks to Domenico Perrella) that the item being shipped now is the 'PS3D', which is an inferior product compared to the 'PS3' described in my original review. If you have ordered the PS3 but received the PS3D instead, return it to Amazon for a full refund - on the ground that the product description does not match the product received. [Original Review follows] I already have at least half a dozen smart chargers in the house, including top-of-the-line models such as the La Crosse BC-900 and Maha C9000, but I still wanted this Rayovac Universal Battery Charger (PS3) for the following reasons: 1. It can accept C, D, and 9V batteries in additional to the standard AA and AAA cells. 2. It can handle rechargeable alkaline cells in addition to the standard NiMH or NiCd cells. 3. It has the potential to recharge up to 8 AA or AAA cells at once. So far, I'm very satisfied with this charger. Of course it is bulky and heavy. But that's to be expected for an unit that can accept four D-cells at the same time. For home use the size and weight is not an issue at all. I'm happy to report that this charger is a lot smarter than I previously imagined. Unlike a typical dumb charger in this price range (for example: the Energizer CHFCV Overnight Family Charger), the PS3 has four independent charging channels. That means I am free to charge different cell in any channel. Each channel comes with a status indicator LED, which goes out once the cell is fully charged. But most of all, this charger is smart enough to recognize the difference between NiMH cells and alkaline cell, and can pick the correct charging method accordingly. When an unknown cell is inserted into the PS3, the charger first starts off with a trickle current (800mA peak current at 10% duty cycle, or an average current of 80mA). Based on the voltage profile of this cell, the PS3 can determine whether this is an alkaline cell, or a NiMH cell. After two minutes, the duty cycle is increased to 60%, so the average current is now around 480mA. For a NiMH cell, charging will continue until a negative dV/dt is detected, in which case it switches back to trickle current again. But for an alkaline cell, charging current will gradually decrease with higher terminal voltage until it reached 1.65V. The Rayovac PS3 is designed to recharge the Rayovac 'Renewal' brand of rechargeable alkaline cells (which are now discontinued). The user manual warned against charging ordinary disposable alkaline cells, but I experimented with it anyway. So far, I have observed very good results with recharging Duracell alkaline AA cells [see warning below]. Of course, the capacity of a recharged alkaline cell is lower than that of a fresh cell, and it drops with each subsequent cycle. But since I can squeeze another half a dozen cycles out of an exhausted alkaline cell at no additional cost, I really should not complain. Back to the charger itself, I do have a complaint about its claim of "recharge up to 8 AA or AAA batteries". It turns out that each of the four charging channels can accept one to two AA or AAA cells, but the two cells are electrically connected in parallel. So in case somebody accidentally placed two cells of different battery chemistries (NiCd, NiMH, or alkaline) in the same channel, the one with lower voltage will discharge the other one. The charger may also get confused and fail to terminate correctly in such case. It is safer and faster to charge only one AA or AAA cells in each channel. [WARNINGS:] 1. Do NOT try to recharge alkaline cells that are completely exhausted (terminal voltage below 1V). It will not work. 2. Do NOT try to recharge Energizer alkaline cells. Four Energizer AA cells I tested completely dropped dead after just two discharge/charge cycles. Two D-cells started leaking electrolyte a few days after charging. Luckily they were left outside and not being used. [Update on Jan 26, 2009] Out of maybe one dozen Duracell AA alkaline cells I have recharged, two started leaking electrolyte a few weeks later. I must now officially advise AGAINST recharging disposable alkaline cells: do it at your own risk!
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