Hi, Wrenchies~ I've been remiss in failing to send "props" to Larry Crutcher regarding his clarification on how battery charge regulation really works. See his post copied below. I see my error in that current is not directly reduced by the charge device, but the controller pulses get shorter and shorter to keep from exceeding the absorption voltage as the battery's internal resistance rises. The internal resistance presents a sort of "back pressure" so the amperage does diminish, but the reduced amperage is more of an effect than a cause.
I'll try to reprogram my remarks along those lines in future. I'm sorry for any mis-explaining from my side. Thanks, Larry, & again I say: The Wrench List is the Bomb! Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 ---------- Forwarded message ---------- From: "Larry Crutcher, Starlight Solar Power Systems" <larry@ starlightsolar.com> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> Cc: Date: Mon, 15 Oct 2012 16:56:40 -0700 Subject: Re: [RE-wrenches] Off-grid non-inverter battery charger recommendations? Hi MIck, I often see your explanation for absorption charge phase. Consider this: While charging, current is applied without voltage regulation (CC). At the charge set point, PWM control (CV) takes place to regulate voltage. There is no control over current as the battery internal resistance dictates this. For example, if you have a pure DC source at a constant voltage attached to a battery, once the battery reaches that voltage, charge current will naturally start to decrease. I find it interesting that many people, including some manufacturers, believe a PV charge controller or AC battery charger is adjusting or tapering the current supplied to a battery when it is the other way around. Larry Crutcher Starlight Solar Power Systems (928) 342-9103
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