discharging Fullriver AGM batteries

ldiorio · July 2015

hello forum
need to get some feed back on level of discharge om my 48 volt Fullriver 415AH battery bank
battery voltage fully charged is 51.4 volts
the default setting in the Magnum inverter (LBCO is 40 volts)
am looking for some input on a reasonable/practical level of discharge for my system to prolong the batteries life
if i lose power for and extended period of time i can use my standby genny to help charge the batteries

Lou

Magnum 48volt inverter,Midnite e-panel, 8- 415AH AGM batteries, magnum remote, 6- 255 watt Koycera panels
Future more panels, a battery monitor and a magnum AGS

westbranch · July 2015

ldiorio wrote: »

if i lose power for and extended period of time i can use my standby genny to help charge the batteries

Why would you lose power for an extended period, with those 6 - 255W panels?

ldiorio · July 2015

we live in the north east and get many cloudy days --guess will have to see how it goes--not looking to go complely off grid
just want batteries in case of a grid problem(am kind of a prepper)--will power some ckts from solar off a subpanel with battery at night--don't want to discharge batteries too much--will use my generator to supplement the panels--
getting panels this week

vtmaps · July 2015

ldiorio wrote: »

the default setting in the Magnum inverter (LBCO is 40 volts)
am looking for some input on a reasonable/practical level of discharge for my system to prolong the batteries life
if i lose power for and extended period of time i can use my standby genny to help charge the batteries

Try not to ever let the batteries get below 50% SOC, and if you do get that low they must be charged immediately.

The LBCO of 40 volts is too low for those batteries. The Magnum shuts down at 40 volts to protect itself, not to protect the batteries.

A resting voltage of approx 48 volts represents a 50% SOC for your batteries. With any sort of load on the batteries the actual voltage will be lower than the resting voltage. If you set the LBCO to 48 volts you will never go below 50% SOC, but if you have a large load the voltage may sag below 48 volts even though the batteries are above 50% SOC.

--vtMaps

ldiorio · July 2015

thanks for the response-that was the info i need-one spec i saw said 44 volts but i will diffently set the LBCO to 48 as you recomend-SOC at 50% sounds good to me
i tried my 240 volt well pump yesterday and the inverter handled it ok

thanks again
Lou

BB. · July 2015

If you cannot set time limits for LBCO (i.e., 5 minute and 1 hour LBCO), you might be better off with LBCO~46 volts (11.5 volts for 12 volt battery bank)... That will allow for heavy loads when starting the pump.

I worry that your pump starting may cause blackouts during bad weather/as batteries age.

If you can set time limits... LBCO~48 volts for 1 hour and LBCO~46 volts for 1-5 minutes (or set these as a generator start).

-Bill

ldiorio · July 2015

hi BB
thanks for the info -greatly appreciate all info you guys provide
i dont know if i can split the LBCO as you suggested but i am planning to use my 20KW auto generator to charge the batteries when needed but have to decide on a gen start module

Magnum has a AGS unit and the MagWeb internet monitor
kit which incl a AGS module

Would like any input as to the AGS unit that would be good for me-the Generac generator has Smart technology(with auto voltage regulation) if that makes a diff

lou

westbranch · July 2015

Well as long as you're not powering any appliances you will not be using very much out of those batteries other than the tare rate for the inverter...
FYI my 1120Watts powers the fridge and internet + laptop, all day till sundown and hits float by noon right now, waiting for winter...

ldiorio · August 2015

thanks all
i rec'd some voltages in an email from the battery manufacturue but they seem to be way off compared to general voltages and SOC for AGM's on the net --and from info you guys have provided. have sent him a request for clarification but he hasnt responded yet(he told me that 50% as 44.4V and 80% was 46.2 V)-maybe he was reading off the wrong table?????

Based on what i have read here (i can't split the times for LBCO voltages)
so if i understand all your info

am thinking am going to set the LBCO to 46.0 volts
and gen start or switch back to the grid to 48V(which vtmaps said is 50% SOC for my batteries)

one question i have if i am in a power outage and the generator doesnt start for some reason will the LBCO @46V damage the batteries

you guys have been great to help me understand and get me out of this frustarting exercise

BB. · August 2015

Remember that battery voltage drops with load... So 44.6 volts (11.15 volts @ 12 volts) is under heavy load...

leaf wrote: »

Am trying to upload the charts I am using...

Attachment not found.Attachment not found.

I believe those charts are from Home Power #36, August- September 1993. Lead-Acid Battery State of Charge vs. Voltage ©1993 Richard Perez.
Here is a link: http://www.scubaengineer.com/documen...ing_graphs.pdf

vtMaps

-Bill

discharging Fullriver AGM batteries

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