Classic 150 + Iota DLS-55IQ4 + MNBCM

[hemmjo]

I am heading down next week to the mission I work with to upgrade the system I installed last year, and install another one, almost identical, in a different set of buildings.

I understand the MNBCM uses battery voltage and time to determine if the batteries have received  a full charge. For flooded batteries it must reach 14.7v for 2 hours.  Here at home, in my garage, I have hooked up the charger, a used auto battery, and the MNBCM.  The battery is about 4 years old, from my daughters car. It is a group 24, 875amp battery.  It works, I took it out as I did not want her to be stranded someplace with an old battery. With this set up the MNBCM as never reached full charge status. I had it hooked up for a week. The jumper on the MNBCM is set to flooded.

The blinking of the IQ4 led on the DLS-55 indicates it is cycling though the Bulk, Absorb, and Float stages. I did not record the voltages for each stage, but the highest I saw in Bulk was in the range of 14.5v.

Thinking maybe the battery was not discharged enough for the charger to run through a full charging cycle.  I hooked up the inverter and used an 800 watt heat gun to pull the battery down to 11.6 volts,  then turned on the charger.

After doing this test I found the Iota document, "Charging Flooded Lead Acid Batteries for Long Life”. It shows “typical voltages” for each stage.  For a 12v system ,bulk = 14.8, absorb=14.2, float =13.6. Is this correct?  Seems like most of what I read is that bulk starts out lower V and higher A, then at the battery "fills up", voltage increases as amps drop off. Then at a certain set point is switches from Bulk to Absorb.

Perhaps the battery I am using for this test is too small, it will not allow the IQ4 to run correctly?

After reading the Iota document I am concerned that we have been undercharging the existing batteries for a year.  The staff has been reporting SG readings but they are suspect as I even have a difficult time with the Brady Hydrometer. I am taking them a MidNite Hydrovolt this trip.

This got to be rambling.  My questions are;

I see where to set Absorb, Float and Equalize on the CC150 but not bulk. It seems that it switches from Bulk to Absorb when the voltage gets to the Absorb set point.  If I set Absorb at 14.8v, that is contrary to the Iota suggestion of 14.2v.  Is the Absorb volts number where it switches from Bulk to Absorb or is that the voltage level the 150 maintains during absorb? What am I missing?

Thanks,

John

[Westbranch]

it switches from Bulk to Absorb when the voltage gets to the Absorb set point

Correct!

I set Absorb at 14.8v

This should be set as per the battery makers recommendations. 

Due to the inconsistent nature of Solar output, PV charging values are usually higher than those used when on mains power.

From the classic manual

Battery Charge Stages and Meanings
Bulk MPPT
This stage of the Classic means; that the Classic will be putting out as much current as it can to raise the battery voltage to the absorb voltage set point. This is also known as constant current mode.
Absorb
This stage means that the Classic will maintain the absorb set point voltage until the batteries are charged. This stage is terminated at the end of the Absorb time or the End Amps set point whichever is reached first. At this stage the classic is not putting out maximum current, as that would increase the battery voltage over the Absorb set point. This is also referred to as constant voltage mode.
The absorb time is proportional to the bulk time. (i.e. the time bulk takes to reach the absorb voltage.) The battery it’s considered “full” at the end of the absorb charge cycle.
Float
A Float cycle follows after the Absorb cycle is completed;
Float is displayed on the screen. Battery voltage is held at the float voltage set point

[Westbranch]

go to page 82 of 92 in this document... could not copy it... it is a good explanation...
http://legacy.outbackpower.com/pdf/manuals/mx60_pv_mppt.pdf

[boB]

Right.  "BULK" is not a voltage.  And, "Bulk Voltage"  is an oxymoron...

Typically, what happens is that "Absorb voltage"   is  what can be also called "Bulk termination voltage"

"Bulk voltage" as far as I know is left over from the old Trace Engineering days when the SW inverter
used this terminology for meaning bulk termination, or, absorb voltage.

The actual charging voltage depends on battery temperature.  The colder the battery is compared
with 25 degrees C, the higher the absorb voltage should be.  The higher the temperature,
the lower the charging absorb voltage should be.

But the values used in the MNBCM are based on 25 degrees C.  Typically, for a flooded lead acid
battery, if the voltage is too high (meaning that the battery temperature is less than 25C), then
you just have to watch the water level.

I'm not sure what the SG of an old car battery should be ?

boB

[CDN-VT]

In my take of the question from post 1 is , how do I get the MNBCM to read correctly ?

I have also just got one to the point of synced to the classic  after a long bit. The MNBCM needs it's own two wires to go right to the batterys or in no way would it see a voltage drop or dip , that will reset the hamsters & wheels . My one system would take a few weeks to look good , but during bad weather & usage it didn't look happy / green leds on the weeks . I rewired the system due to main batterys replacement & maintenance plus , and wired it straight to the output feed external of the battery box.  Within a week , good readings . I had the BCM just attached into the box where most easiest place was .

So if your looking for the correct readings it needs to see just the main as close to the battery feed as possible without a chance of a voltage bump or drop .

If at any hook up the BCM had a blip of voltage , I'm thinking that the internal clock would reset the hamsters again , having a great battery to BCM , the bcm would of reacted as it should.
It took me a while also .

VT