ARC 50 - End Amps questions

[JoshuaCanada]

Hi:

I hope post finds everyone well. I have a question about ending amps for absorption time.

System parameters below:

Here is my question. I have my absorption time set based on a specification from Surrette (T=.42 x (428aH/42A) = 4.2. I recently extended it a bit to get the SPG up. Will the the ME ARC 50 support having two Absorption ending parameters or will it only function based on one. I have it set as time but I would like to put in an end amp setting as well. I don't know if it supports having an absorption time and an end amp setting.

Does any one know if it will look at ending amps if it has yet to reach the absorption timer?



MS PAE Magnum 4448 Inverter
-ME ARC 50 Controller
-Magnum E Panel
-Magnum BMK
-Magnum Mag Web N
- 2 Classic 150 charge controllers incase one fails
-12 x 260 watt solar panels. 6 on each controller.
-8 x S550 batteries in Series
- Cummins Propane Generator
-Magnum Auto Start N

Current Setting:

- Absorb 60.0v
- Float 54.0v
- Absorb time calculated using
-T= .42 x 428 /42 = 4.2 hrs
-Therefore: absorb time 4.2hrs
- Charging amps at 10% of C20 = 42 amps
- Inverter is 60amps DC output. Currently set at 70% max charge rate (70% of 60amps is 42amps) with a max charge current set at 40. The options go in groups of 10 so the next option was 50 which is over 10% of the C20 rate.
- We currently do not have a lot of sun and so the generator is set to take the batteries to float.

- AGS parmeters:
- Start voltage is at 46.8
- Stop voltage is at Float

- BMK parmeters:
- Bank efficiency is at 80%
- Amp hour rating of batteries is 420aH. --BMK manual states to set it below the actual bank size. Goes in increments of 10.

-Generator:
- Magnum stats to set the AC in amps as what is available on only 1 lag of the generator. In this case it's a double pole 30 amp breaker which means the AC in amps would be set to 30 for 1 lag and 30 on the other.

Classic 150 Settings:

- Absorb 60.0v
- Float 54.0v
- Absorb Time 4.2hrs
- Classic 150s are linked in follow me.so they share charging phases at the same time.
- Also sharing ground fault and battery temperature sensor so that they compensate as one.

[Mike90250]

AS batteries age, the ending amps increase, You have to babysit the batteries one day and monitor them with no loads, to discover what the end amps are, Then set your controller Absorb time to match the amount of time it took to reach end amps.

[Sunking]

Absorb is not a timed event. Absorb is Current Saturation event based on the battery capacity. I know Rolls and others have calculations for time in the event your charger cannot terminate when charge current tapers to a specified level of roughly 3% of C.

With solar there is not enough hours in a day to fully charge a battery unless you have a significantly over sized panel wattage. Absorb can take 6 to 10 hours to saturate a Pb battery.

[inetdog]

Absorb is not a timed event. Absorb is Current Saturation event based on the battery capacity. I know Rolls and others have calculations for time in the event your charger cannot terminate when charge current tapers to a specified level of roughly 3% of C.

With solar there is not enough hours in a day to fully charge a battery unless you have a significantly over sized panel wattage. Absorb can take 6 to 10 hours to saturate a Pb battery.

And to properly end the Absorb stage based on End Amps current, you really need to have a shunt that measures current into the battery and not just current out of the CC, some of which will probably be going to a load.
Some CCs, Midnight Classic for one, have provisions for a shunt right on the negative battery terminal. Optional extra of course.

[Mike90250]

Absorb is not a timed event. Absorb is Current Saturation event based on the battery capacity. I know Rolls and others have calculations for time in the event your charger cannot terminate when charge current tapers to a specified level of roughly 3% of C.
With solar there is not enough hours in a day to fully charge a battery unless you have a significantly over sized panel wattage. Absorb can take 6 to 10 hours to saturate a Pb battery.

i was trying to present a low tech method to approximate the Absorb Time, and neither grossly over or under charge the batteries. Every system is different, and if a current sensor and method to calculate charging from it, is not installed, you can come close with simple meters and stopwatches

[Sunking]

Mike I was not disputing what you said. Hope you did not take it that way.

Rolls user manual is out of date vs say Trojan who has updated charging algorithms from an avalanche of warranty claims by solar users. Three Stage chargers which most solar charge controllers do not work with solar. Ironic as that seems there is just not enough hours in a day to fully charge a battery from solar. 3-Stage is fine if you use a commercial AC power charger with unlimited time and power. So what Trojan and a few others have done is done away with 3-Stages. They turned to voltage up and call it DAILY CHARGE. Just a simple CC/CV voltage set point. No stages. Max Smoke for as long as the Sun shines. Even that will still requires weekly Generator runs, especially in winter.