- Feb 6, 1998
Until the charge source regulator sees the target voltage the charge source is putting out all it can, simple stuff. It is called constant current charging. If the charge soruce is only capable of supplying 5A then it will supply 5A until the battery voltage, or its "sensed voltage" tells it the "limit" voltage has been attained. At that point we begin "limiting voltage" to the pre-set limit point. Once voltage is held steady, constant voltage, the current begins to decline as the battery can only accept XX current at XX voltage and XX SOC...."
The answer is B. In the marine market all charge sources we use operate on CC/CV charging so bulk ends when the battery becomes voltage limited by controller, regulator or charger."
So your charging source is looking at charge current and supplying the needed voltage so the current stays at a constant value during bulk charging????
It is shocking to me how much the marketing mavens have made folks over-think something so darned simple. There is no magic. These devices simply work on CC/CV. Constant current until the absorption voltage is attained then CV. These are voltage regulated devices that is it.Pretty sure this is not how it works electrically. My understanding is the charge controler "does magical things" and determines that it needs to bulk charge and sets the voltage at the predetermined bulk charge voltage (probably 14.4).
If not at target voltage you are in BULK or CC
If at target voltage you are in ABSORPTION or CV (FLOAT and EQ are also CV stages)
Smart or so called "smart chargers" then try to determine the optimal absorption cycle based on either a super dumb egg timer or an algorithm that looks voltage rise and time.
Egg timer chargers work by starting a simple egg timer the minute the regulation sees the target voltage. Some are set at 1 hour, 2 hours 4 hours etc.. These are far from optimal and usually result in premature float.
Smarter charge regulation may use:
A Timer algorithm looking at;
Time to attain target voltage
*Sometimes % of field
*Sometimes power supply % current
*This can be tricked by domestic loads so charge sources may have other safeguards built in to not over absorb and some dumb ones can be tricked into remaining in absorption dock side, under domestic loads, which can be bad..
With these parameters they calculate the absorption time before dropping to float..
Keep in mind these are only used to determine how long to ABSORB the batteries. Ideally a battery would stay in absorption until the battery is full but using voltage as our reference this rarely happens and the chargers usually drop to float too early in favor of "safety".
Again bulk is not voltage limited despite some marketing departments insinuating it is to confuse people into thinking they are getting more than they really are.. If you are voltage limited you are in CV not CC/BULK....That in no way insures that charge current is constant. My experience is that the bank rapidly becomes (12 minutes) voltage limited and the current falls of mightly.
If you are witnessing a pause in current this is the charge controller dropping down to float or a second absorption voltage level. It is not thinking or processing. It is simply waiting for the battery voltage to decay naturally to the next voltage limit level, say from a 14.4V absorption to 13.6V float...The charge controler stops charging momentairly and does more "magical things" (like measure the "resting" voltage) and determines what charge regime to do for the next time period.
If the battery voltage is ever above the regulation set point the power supply or field is shut down until voltage comes back to the voltage limiting range where it will maintain the voltage level.
No it is not.It is really a puso resting voltage assessment of the SOC.
No constant current is constant current it does not care about anything until the battery terminal voltage reaches the "limiting voltage" then it begins holding the voltage to that point.If it really was CC charging then the regulator would need to know what the charging current was going into the batteries would it not?
No they are not. Chargers know nothing about SOC. They know at voltage or not at voltage. It is actually quite sad that someone with your quite decent level of electrical expertise has even succumbed to this marketing bamboozlement. If they can foll a guy like you it must be horrible for everyone else..They are using fixed voltage points when not charging to assess SOC and then determing which regime to do for the next time period.
Charging with CC/CV is really this simple:
Below Voltage - SUPPLY CONSTANT CURRENT
At Voltage - LIMIT/HOLD VOLTAGE TO PRE-SET LEVEL
Above Voltage -TURN OFF POWER SUPPLY, FIELD or PV and WAIT FOR VOLTAGE TO DROP
There is no charger I know of that assesses resting SOC based on voltage.Which brings up the observation that since they are using resting voltage to assess SOC and that is highly dependant on the state of health of the batteries (with old batteries taking a lot longer to settel down to resting voltage), a lot of the problem is that the charge controller is set up to over charge older batteries by its very (limited) design.
Sounds like you have a game of solar/alternator ping pong going on or a bad alternator regulator or a large load such as a fridge compressor coming on and adding load to the alt.. This is why solar should be set a .1V - .3V lower than the alt. If not we can get ping pong... When the alt comes on the current from that combined with solar is pushing the batteries into "absorption range" (limiting voltage) if the solar current, combined with alt current, pushes the voltage higher than the alt set point it shuts the alt down. Now with the alt shut down, we no longer have the current to maintain the voltage limit so the alt kicks back in and it ping pongs. These devices don't pause to check voltage it is all done on the fly. Some older really crappy MPPT controllers (and some cheap/sleazy Chinese controllers) did pause to check the max power point (unloaded voltage of array) I called this the old school "pause & observe" but these went the way of Dinosaur saddles many moons ago. Simple PWM charge sources, battery chargers, inverter/chargers, alternator regulators and solar controllers don't pause to check voltage this was only done very antiquated MPPT products as a way to track the max PV voltage.when I notice the lights slightly dimming and then brightning every 15 minutes or so while using the engine and this coorisponding to the engine sounding like it is taking up a load when the lights brighten and loosing load when they dim.......I'm pretty sure the controler is checking the "resting" battery voltage to determine what it needs to do next.