FireFly Battery Operational User Notes

[sogin]

Originally Posted by Nicholson58

Are you sure you trust your meters?

I trust my meters reading AC voltage and 12 volt DC but have no idea or way to really know if it is accurate above 12 volts.

[sailorboy1]

You need to get a handheld voltmeter

[sogin]

Originally Posted by sailorboy1

You need to get a handheld voltmeter

The 18 volt readings were with a hand held digital meter. I'll look around for another meter in the lab and report back

[sogin]

Originally Posted by sailorboy1

You need to get a handheld voltmeter

The 18 volt readings were with a hand held digital meter. I'll look around for another meter in the lab and report back

[sailorboy1]

It sounds to me you are getting a lot of voltage drop between your battery and the DC panel under load. Try measuring voltage at both at same time. But it could just be that the battery voltage is jumping up, as expected, after the loads are gone. But it shouldn't jump as much as you indicated without some type of wiring issue.

[sogin]

Originally Posted by sailorboy1

You need to get a handheld voltmeter

Another professional level handheld gave correct readings that perfectly matched the onboard meters and monitors.
My handheld meter was out of calibration but after inserting a new battery it works correctly. So thank you for suggesting a proper solution.
I'm still not sure how to drain the battery to 10.5 volts. I rigged up a 100 watt DC light bulb and plugged it into a cig receptical after the voltage dropped to low for the inverter to operate. The DC bulb continued to draw down the battery but it eventually dimmed and went out because of low voltage (9.5 volts) yet the unloaded battery voltage was close to 11. I could leave other lights and the freezer and frighted on but it would take forever to reach 10.5 volts without load. Perhaps 9.5 volts under a 15 amp hour load is good enough?

[sailorboy1]

Originally Posted by sogin

Another professional level handheld gave correct readings that perfectly matched the onboard meters and monitors.
My handheld meter was out of calibration but after inserting a new battery it works correctly. So thank you for suggesting a proper solution.
I'm still not sure how to drain the battery to 10.5 volts. I rigged up a 100 watt DC light bulb and plugged it into a cig receptical after the voltage dropped to low for the inverter to operate. The DC bulb continued to draw down the battery but it eventually dimmed and went out because of low voltage (9.5 volts) yet the unloaded battery voltage was close to 11. I could leave other lights and the freezer and frighted on but it would take forever to reach 10.5 volts without load. Perhaps 9.5 volts under a 15 amp hour load is good enough?

IMO that is more than close enough and you are now trying to kill your batteries. Charge those babies back up!!!!!!

[RickG]

That 18V reading is worrisome. Do you have solar with programmable solar controllers? 60C seems quite high, if accurate. Where is the heat coming from, are the batteries in the engine room? Something funny is going on.

Ah, I see it was a meter problem. Good!

Cheers, RickG

[sogin]

Originally Posted by sailorboy1

IMO that is more than close enough and you are now trying to kill your batteries. Charge those babies back up!!!!!!

I was just following directions from OceanPlanet but I agree it is kind of scary to push the voltage to such a low SOC. They are currently at the end of absorption - about to enter float where they must remain for at least 24 hours. I think everything is ok. Ocean Planet suggests that under certain patterns of use, this procedure should be followed very 30 days but I think few would take the time to repeat this every month. These batteries have performed extremely well and I would not want to "kill" them. I only wish my Prosine could put out more than 105amp hours when charging. That would eliminate the need to divide the house bank during the conditioning charge.

[sailorboy1]

I turned off my battery charger yesterday so the loads could operate in cruising mode and I could check I have everything set correctly.

This morning at 85% SOC the batteries were 12.68V and -65AH. That is pretty much as high as my FLA would ever be when 100% when they were new.

I ran my engine to verify that my regulator settings appeared good and my new alternator temp sensor was working. At close to 90% SOC the 4-G31s were talking about all the alternator could supply them at 80 amps. The battery voltage didn't get above 14.1V the 20 minutes I ran the engine while at that SOC the FLA would have been 14.6V due to internal resistance. I am now a little concerned that I programed my 14.4V bulk and absorption times too long and am checking with FF to see if holding the 14.4V way beyond that 100% SOC 0.5A/ea will cause damage. (they said that if way too long it will eventually dry out the battery, but 3-4 hours should be OK as long as they are still accepting current)

It currently is a little hazy out and my 640W of solar is putting out 230W with 12.4A @ 13.8V going into the batteries at -20AH out (96% SOC).

I set my charge efficiency to 90% and it is currently reading within 1% of SOC what the math would say based on -AH.

[sailorboy1]

Originally Posted by sogin

. I only wish my Prosine could put out more than 105amp hours when charging. That would eliminate the need to divide the house bank during the conditioning charge.

I figure if I ever want to do the recondition with the 0.4C current of the manual I would just wait for a sunny day and hit them with my battery charger + Alternator + solar all at once.For me that is in theory 43%. I bet time at 14.4V and 0.5A is more important that the high charge rate. But that may be my old brain applying FLA rules.

[a64pilot]

I think all of these numbers are ideal, but likely not often met real world.
Pretty sure the 10.5 comes from it being the accepted voltage that a 12V battery is “dead” as in 0% SOC and not a lab tested number.
Just as the charge rate being high, that’s across pretty much all AGM batteries that are good enough to write a manual, big chargers and high charge rates are ideal, but charging from Solar doesn’t kill them either, so take it with a grain of salt.
I know these aren’t Lifeline’s, but they are AGM and I feel sure there are similarities.
Download and read the Lifeline manual, it’s a lot longer and does a much better job of describing what’s going on and why you want to do this or that.

[RickG]

I re-read Mainesail's article on programming battery monitors. It is long, but worth the read - https://marinehowto.com/programming-a-battery-monitor/. The article leads me to believe that I will never know the true capacity of my house bank. But, I can know if the bank is fully charged if the charge acceptance rate goes to 0.5 amps per battery at absorption voltage. I have tweaked the settings of my Victron BMV-712 battery monitor based on this article.

I was having problems with the BMV auto-syncing to 100% SOC early. I believe this was due to having charged voltage set to 13.2V (Victron default) and the charge detection time set to 3 minutes. Solar charging with rain showers/clouds were triggering the autosync to 100% SOC early. The article recommends disabling autosync by setting parameters that cannon be met and doing a manual "known-full reset"; he set charged voltage above the bulk/absorption setting of the chargers. I am keeping that tactic in reserve. Victron recommends in the BMV-712 manual setting the charged voltage setting slightly below absorption voltage if premature autosync occurs.

The BMV configuration I am working with now is below. It has been cloudy for three days and I have not seen SOC above 90%. I have not seen an autosync. I'll report back how this works. My battery anxiety is back after reading these articles again!

Charger configurations:

• Bulk: 14.4V
• Absorption: 14.4V
• Float: 13.4V

Victron BMV-712 configuration:

• Battery capacity: 812ah (7*116ah)
• Charged voltage: 14.2V
• Discharge floor: 50%
• Tail current: 0.5% (7*0.5 or 3.5 amps is 0.43%, but 0.5% is the min setting)
• Charged detection time: 10 minutes
• Peukert exponent: 1.07 (20 hour rate)
• Charge efficiency factor: 90%
• Current threshold: 0.1 amps (Victron default)
• Time-to-go averaging: 3 minutes (Victron default)

This thread and sailorboy's 'Time It Takes To FULLY Charge Batteries' thread have been helpful in working through this. https://www.cruisersforum.com/forums...es-238875.html

Cheers, RickG

[sailorboy1]

I set mine to 14.4V, 0.5% (the min), and 10 minutes.

I also just changed my charge efficiency to 89%. The afternoon thunderstorm messed up my solar charge, but I could tell it was heading to 100% on the BM way before it got to 2A charge rate (4x0.5).

I see no problem with the batteries getting to 100% BEFORE the BM says so. I only see a problem with the BM getting to 100% and resetting before the batteries.

Another thing to consider would be to set the conditions so they could never be done. Like 15V and 0.5% and just manually reset once in a while when you see conditions have been met.

[RickG]

Originally Posted by sailorboy1

Another thing to consider would be to set the conditions so they could never be done. Like 15V and 0.5% and just manually reset once in a while when you see conditions have been met.

That's what Mainesail advocates in his 'Making Your Battery Monitor More Accurate' article. Read the full article to understand why. Quote:

"Disable the “auto-sync” feature and use manual “known-full” re-sets.

“Come on RC, what the heck is a known-full reset?”

The Known Full Reset:
#1 Turn all DC loads OFF

#2 Fire up battery charger or engine & allow to run 4-5 minutes

#3 Voltage should be at ABSORPTION level or 14.4V+ (GEL 14.1V)

#4 Net accepted charge current should be less than 1.5% -2% of Ah capacity

#5 Okay to MANUALLY reset to 100% SOC"

I am going to let my BMV setting soak for a while to see how that goes.

Cheers, RickG