shunt charge controllers

[Trebor English]

> I have lead acid so I set it to 14.6 volts in winter, 14.3 in summer.  

For temp compensation or for some usage that varies with the seasons?

I do that for temperature compensation.  The cheapest solar charge controllers don't provide that.  Those numbers cause the battery to use 20 to 30 ml of water per month per cell and the hydrometer indicates full charge.  The first summer I noticed water use went up to 50 to 60 ml of water.  

Doesn't everybody keep track of how much water their battery uses?

 

[frater secessus]

I track it acoustically, using one of those fill jugs that bloops while it fills the cell:

A couple of bloops == minimal outgassing over the period.  Lots of bloops == thirsty.  All my batteries are used or leftover from previous experiments so they're all thirsty to one degree or another. 

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totally unrelated:  while writing that out I realized I dreamed last night about charge controller setpoints and cell water levels.  I may not be entirely normal. 

 

[tx2sturgis]

totally unrelated:  while writing that out I realized I dreamed last night about charge controller setpoints and cell water levels.  I may not be entirely normal. 

Normal is a setting on a dryer....

So, bask in your weirdness...  

 

[tripper]

The same design is sold under a bunch of names, but they have three buttons and an LCD screen.  Two USB ports which do work.    Often labeled PWM but they are Shunt.  Trebor has played with similar models.
Bought a 10A one for $8 shipped on the slow boat.  Cheapest I see right now is $9.10 shipped.  

The first button cycles through the display.  Long-pressing it on a setpoint (wrench icon appears at bottom center) allows you to change it.  2nd and 3rd buttons are UP/DOWN.    Pressing the first button after adjustment locks the setting in.
BTW, there are only three setpoints not four.  Charging OFF, LOAD LVD, LOAD LVR. 

I have the same controller on a 100 watt panel, strange that mine has two setpoints,  a 14.4 fixed bulk/absorb (the manual calls it equalize) and a settable float.