Interpreting the program instructions to setup Trimetric

[RC Pilot Jim]

RyanObrian1 PM'd me asking how the P 1-3 settings tell the Trimetric that battery has reached 100% full . This process has been fuzzy for me too. I re-read the procedures again (9th or 10th time) and saw an example that I understand so decided to share it with the experts to see if I'm correct.

Example
Re reading page 5 of the Trimetric "Install Instructions" in the very small Font paragraph above the bold heading " How to Determine value for program item P1"...There is a small paragraph titled
The purpose of P1-3 numbers. so inserting my numbers, paragraph reads as follows:

The numbers P1 (14.0 volts) and P2 (1.6 which is 2% my P3 reading (80 amps) tell the meter when my battery has been charged...That is when the battery voltage goes above P1 (14 volts) and the charging AMPS go BELOW P2 ( 1.6 amps). Then the meter will reset the "percent full to 100%". the "amp hours" to 00.0 and your "days since re-charge" to zero.

Yesterday I connected my new yet to be installed 150 watt RIGID panel to my "back wall" connector...Then reading Volts - 14.1. amps 4.0. % of full 89%. Disconnected panel.
Turned on compressor fridge (ours draws 2.5 amps) and the fan on full 2,5 amps = 5 amp discharge. Turned them off.
Re-connected solar panel. Turned fan and fridge on. Volts dropped to 13.6. Amps 1.0 charging (replacing the 5 amp discharge plus 1 amp charge battery) = 6 amps charging.
20 minutes later voltage at 14.3. ...Amps (point) .5 ...Percent of full jumped from 92% to 100%.

 

[photohc]

Jim, your interpretation of P1, P2 and P3 is correct. Those values determine when the battery is considered to be charged. The Trimetric will monitor the amps in/out and voltage at all times and determine the state of the battery based on those values. As long as the battery is above the P1 value voltage and the below the P2 current value, it will indicate a 100% charge value. Once you draw down amperage more than what the solar panel is able to send to the battery, it will correspondingly reduce the % of charge value. Since you've indicated the capacity of the battery in AH in P3, the Trimetric will calculate the remaining charge based on the amperage drawn out of the battery.

So as an example, if the battery is at 14.3v and the charge amperage going into the battery is now below 2 amps, the Trimetric will show 100%. Once you turn on appliances/etc and start to draw amps out of the battery, the Trimetric will measure the amount of amps per hour and recalculate the % of battery remaining. So if you draw 10 amps for 2 hours, thats a reduction of 20AH. That will leave you with 60AH remaining or 75%. (The 10 amps draw is net of the solar panel. If the panel is putting out 5 amps but your appliances are drawing 15 amps, your net out of the battery is 10 amps)

Well at least that is how it is suppose to work.

Harv

 

[DrJ]

The charging of lead acid batteries is not a linear relationship when you are considering amps and volts.

Early in the charging cycle, lots of amps can be pushed in at a lower voltage.
My system would often show 12.8 volts and 15-18 amps when it is charging after previously being discharged.
As it is more fully charged, it takes more voltage to completely charge it.
So at 80-90% full I would see something like 14.0 volts and 5-8 amps.
The last 10% takes lots of voltage to completely fill the battery. Like 14.4 volts with 1-2 amps or less amps as you near the end.

The trimetric lets you determine where you would essentially reach 100% by setting the P1 and P2 values. If you battery is at 14.4 volts and less than 1 amp of charge is likely you are 99% of completed charge. That last 1% is very hard to complete without lots of power.

You could set you values to something lower to reach 100% but it would not be as accurate.
14.4 volts and less than 1 amp is great if you've reached that with your solar system.