I see what you mean by no float/3rd stage. Indeed the MPPT500 just tapers off the amps once it reaches the "float" voltage.
The MPPT250 however does have an undocumented(?) mode where once it thinks the battery is thoroughly charged, it only puts a brief burst of charge into the battery when the voltage sags to something like 13.8V. The first time I encountered this I thought I had a bad controller. This really does represent a form of float charge.
-------- Original Message --------
Subject: Re: [RE-wrenches] BZ Products Charge Controllers
From: "Larry Crutcher, Starlight Solar Power Systems"
<la...@starlightsolar.com>
Date: Thu, April 11, 2013 11:47 am
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Just for clarification, there is no "float" mode in BZ controllers, even though that is what they call it in the manual. There are two stages only, Bulk and Absorb. Once the voltage setpoint is reached, it remains constant. There is no 3rd stage where the voltage is lowered.This means you must choose low charge set-point so you are not overcharging the battery too much after it is 100%. This also means slower charge rate so more PV power is necessary, compared to 3-stage chargers, to accomplish 100% charge. To the best of my knowledge, all battery manufacturers require 3-stage (IUoU), temperature compensated charging.USA made and customer support is great but some products are not as reliable as I demand for my customers.
Thank you,
Larry CrutcherStarlight Solar Power Systems
On Apr 11, 2013, at 4:06 AM, m...@hurshtown.com wrote:The float voltages are indeed adjustable, but with the MPPT500, they cannot be adjusted as high as the spec says they can.For a 12V unit, the upper limit is often 14.4V, where the spec says 15.5V.Mark
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