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Difference between revisions of "E-Meter"

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* Gordon Stallings battery monitor with schematics
* Gordon Stallings battery monitor with schematics
* Smart Gauge (UK) Great technical info on how battery monitors work.
[[Category:BEV components]]
[[Category:BEV components]]

Revision as of 01:03, 29 January 2007

An E-meter measures the state of charge of batteries.

In a nutshell, it measures the current flow into and out of the battery pack. The thing is that the effective capacity of a lead-acid battery is dependent on the rate at which it's discharged. A simplified example:

A 100 Ah (amp-hour) battery can provide 1 amp for 100 hours, or 2 amps for 50 hours, or 5 amps for 20 hours. That's the theory. In actuality, the more current you draw, the lower the actual capacity you get out. So, you may get 1 amp for 100 hours, but 5 amps for only 19 hours, and instead of 50 amps for 2 hours, you'd only get 50 amps for 1 hour. This is known as the Wikipedia:Peukert's Law.

Anyhow, an e-meter not only measures the total amps that go into (charging) and out of (discharging) a battery, but takes into account the rate that it's used, and uses Peukert's empirical formula to calculate the effective charge, giving a more accurate indication of the battery's true state of charge (SOC).

Short version: Battery Fuel Gauge.

A commonly used E-Meter for electric vehicles it the Xantrex Link-10. The Link 10 is a state-of-the-art battery bank monitor that uses sophisticated microprocesor technology to report all significant battery information.

Xantrex also make the Link-20 and the XBM e-meters.