19th Battery Charger Re-Hash

[nedjinski]

not that this is an over worked topic or anything . . . . but I haven't heard any reviews or comments about the Battery Sentinel which looks like a better unit than the others (Battery Tender, Battery Minder, etc.

 

any opinions?

 

http://www.battery-sentinel.com/compare_battery_chargers.html

[RFW]

not that this is an over worked topic or anything . . . . but I haven't heard any reviews or comments about the Battery Sentinel which looks like a better unit than the others (Battery Tender, Battery Minder, etc.

 

any opinions?

These are nothing special. The proper way to charge and maintain a lead acid battery is using a 4-stage charging algorithm as follows...

 

1. Bulk charge. Here, the charger is in constant current mode, and charges at a constant (high) current that remains unchanged (i.e. does not taper off) until the battery is about 80 to 90% charged. This is why some charger companies make a big deal about how the battery is charged in half the normal time. Hardly rocket science! An el-cheapo 10-amp (let's say) charger, will only output 10 amps when the battery is completely flat. As it begins to charge, charging current constantly falls to a much lower value. Using a constant current bulk charge, results is the charger pumping that 10 Amps continuously, until the battery is close to full charge. Obviously, the bulk charge will therefore take less time than if the current kept dropping. But again, it ain;t exactly rocket science!

 

2. Taper charge. Upon reaching a specified voltage, the charger switches from constant current mode to constant voltage mode. The voltage is maintained at this constant value, and as a result, charging current tapes gradually off as the battery reaches close to 100% charge.

 

3. Controlled overcharge. This is also a constant voltage mode, but the voltage is maintained at a slightly elevated value as the charger's current tapers off, for a specific time (typically less than an hour). A controlled overcharge is manditory for two reasons. First, it results in a 100% charge. Second, and most importantly, it ensures that ALL cells are equalized. If this is not done, the result can be that eventually (over may charges) one or more cells have a reduced capacity.

 

4. Float. Finally, the charger's voltage set point is reduced to a precise value that will neither overcharge the battery, nor allow its capacity to drop over time. This is essentially a VERY tightly controlled trickle charge, that can be maintained indefinitely without damage to the battery, or water loss.

 

ANY charger that accurately impliments the above algorithm will result in extended battery life and a happy battery. These types of chargers are common in the marine marlket, but every once in a while some two-bit company makes a big deal about their "revolutionary" product that is doing what other companies have done for years.

 

Bob.