Originally Posted by mitiempo
You state that the voltage rises slowly then rises quickly - that doesn't seem right. The batteries will accept less and less current as they approach full - this takes a long time.
What Mike is likely seeing is the wind
/ solar controller in bulk as the "slow rise" then the On/Off regulation once the bank has achieved the OFF point of approx 14.2V. The problem with On/Off regulation is that while fine for wind, it is horrible for a live-board cruiser an far less than ideal for solar.
An On/Off controller will never get his batteries anywhere close to full in a single
solar day. Heck getting to 100% SOC in a single
solar day is extremely difficult even with PWM or MPPT
& faster charging
By not getting full every day Mike's battery
capacity will gradually "walk down
" from continual PSOC (partial state of charge cycling).. On/Off regulation is necessary for wind, otherwise the unit would murder itself, but On/Off is really quite abysmal for solar which is great for "finish charging"...
Mike really needs a fully programmable PWM or MPPT
solar controller. Wind is a very good bulk charging source & solar is a good bulk and absorption source. Trying to use a one size fits all controller for both wind and solar really defeats the ability of solar to bring your batteries to the highest possible state each day.
Unfortunately Mike's controller will not let his solar array provide a proper absorption cycle because it does this: (voltages are approximate
On at 13.2V > Off at 14.2V > Battery Voltage Decay's Back to 13.2V > On at 13.2V > off at 14.2V > Repeat > Repeat > Repeat
With On/Off regulation voltage never held steady at an absorption level. A proper absorption cycle is quite critical for optimal battery health
especially in a daily deep cycling application.
A PWM or MPPT controller will bring the batteries to absorption level voltage then hold the absorption voltage steady
, at the desired set point voltage, and will yield significantly
faster & healthier charging during the day. For live-aboard cruisers who cycle daily a proper absorption charge and the correct voltage is absolutely critical to minimize cycling capacity "walk down
" and to minimize the effects of PSOC cycling and the resulting sulfation..
In short voltage is not held steady with On/Off regulation and instead of absorbing it can actually spend more time off
once it has brought the batteries to absorption voltage.
A pulse width modulating regulation (PWM or MPPT controller) never stops charging and holds voltage at the desired set voltage for the programmed duration until it drops to float. Even AGM
batteries, when basically brand new, still require as many as four plus hours of absorption charging, after bulk is over, at a constant voltage that is held steady. By ping-ponging off
the battery is essentially going straight from bulk to a "floatish" state which causes charging, after bulks ends, to be measured in terms of days not hours...