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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 05-24-2011, 02:47 AM   #1
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Default Voltman A123 batteries

I ordered six 2300 Mah A123 batteries from www.voltmanbatteries.com on 05-17-2011. The batteries just arrived by FedEx on 05-23-2011.
Web page http://www.voltmanbatteries.com/serv...1-dsh-A/Detail (This is what you will get if you specify tabs)

These batteries were received in a standard cardboard box, with a LOT of peanut packing material, and arrived in good shape. (Not so for my order of 24 A123's direct from China. Those batteries were LOOSE inside one of those plastic shipping bags. Zero packing.)

The Voltmanbatteries did cost more, $9.99 versus $8.00 direct from China. Add to that, $9.99 for shipping and handling. But, this company is located in Ohio, USA. Their website indicates that they have sold 210 A123 cells so far.

I requested and received "Tabs" on the batteries. These cells can also be ordered without tabs. These tabs are rather thin, checking out at 0.005 inches thick, and 3/8 inches wide. Each tab had eight spot welds connecting the tab to the battery. By actual test, the voltage drop on each tab was 1.05 millivolts per amp. This was measured from the cell terminal to the cell terminal, so the voltage drop of 1.05 mv/amp includes the spot welds. When soldering the tabs, one tab was cut off, then the adjacent tab was folded over the "Short Tab" and soldered with a 100 watt temperature regulated soldering iron. And as soon as the solder cooled off, the solder joint was hit with a piece of paper towel that had been wetted with alcohol to cool down the cell. It took less than 5 seconds to solder each cell.

So at the current level of 38 Amps to be used, that's 0.038 volts per strap, or 0.19 volts for the five straps on the battery pack. With a battery voltage of 20 volts, that's about one percent voltage loss. IMHO, that is acceptable.

If desired, these tabs can be cut off, and heavy duty straps could be soldered on top of the short tabs. But IMHO, not worth the effort.

These cells were plainly marked A123 cells. Voltmanbatteries main business appears to be a service shop that replaces the cells of the battery for any cordless power tool on the market. You just need to send in your old battery, and they will refurbish it.

Take a look at my 6S1P battery pack. The thin tabs allow "End to end" connections on the cells, something required to fit into my model. When soldering end to end, I placed a piece of heavy paper between the tab and the cell with the "Live" end, to eliminate any possibility of melting through the batteries shrink wrapping and shorting out the cell. The cover for the battery pack was made from a standard 12 ounce soda bottle, heat shrunk down with a standard heat gun.

Bottom line, it's nice to have an A123 supplier that's located in the USA.

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