Tweet
Hello again guys my question today is what volt to cut off the battery system I'm going to use. I am using 2 12v in a 24v configuration and I have to set up the charge controller it has a lvd setting from 24.6 down to22.2 what woulyou guys recommend
-
-
24v is between 45 and 55% DOD and is considered as deep of discharge as you should go w/o risking permanent damage to your bank. setting your LVD to 24v or higher is recommended -
I set the rebulk on my 24 volt Trojan L16 battery bank at 24.5 volts, and the lvd @24.3, could be a tad high, but I do not want a deep DOD.Last edited by citabria; 03-31-2017, 12:08 PM.Comment
-
Hold the bus. The controller LVD is not going to do you any good because you DO NOT USE the LOAD OUTPUT TERMINAL on the Controller. The Output Load Terminal provided on some cheap Controllers is for very low power to used on something like LED Lights. They cannot be used for larger loads like an Inverter. Your Inverter is connected directly to the battery Term Post. Only way it can be used is to operate an external relay the connects the battery to the Inverter. Otherwise you program the Inverter LVD cut-off voltage, not the Controller. Most cheap Inverters do not allow you to pick a voltage and are hard set at 10.5, 21, and 42 volts.
OK having said all that you set the voltage to 11, 22, or 44 volts under load. Set i tany higher and you will have false nuisance trips.
MSEE, PEComment
-
If you are discharging until LVD (which you should NOT do - see below) set it as high as possible - 24V isn't a bad setting. Go lower only if you cannot get enough run time out of your system. I would not go lower than about 23 volts with such a system.
Observe current limits on that output - as SK said do not connect inverters to it.
In general you should NOT be relying on voltage based LVD's for stopping discharge; that should happen because you have properly designed your system to ensure that you do not pull the battery below about 50%. You should see an LVD event once in a blue moon, and it should be a signal that you should immediately start your generator (or run an extension cord, or start your car, or whatever alternative charge source you have) and recharge to prevent battery damage. If you have configured your system this way - AND you have the ability to immediately recharge - you can go lower in LVD.
Comment
-
Jeff I do not disagree with your advice IF the battery is sized properly to the Inverter size but you and I know that is rarely the case with DIT types as they are ignorant. How many come here with a 12 volt 100 AH battery and a 1000 watt Inverter? They have no clue a 12 volt 100 AH battery can only handle a 200 watt Inverter.
By setting the Inverter LVD at 12, 24, or 48 volts as you suggest with a undersized battery is prone to false nuisance trips. I can easily make an Inverter trip on a brand new fully charged battery. 11, 22, and 44 volts give them a bit of room to operate, and with more than likely undersized wire between battery and Inverter ends up being close to 12, 24, and 48 volts on the battery terminals. A Pb battery is fully discharged under load at 1.75 vpc or 10.5, 21, and 42 volts which are default inverter LVD cut-off voltages.
Last edited by Sunking; 03-31-2017, 02:09 PM.MSEE, PEComment
-
Hi guys thank you I appreciate constructive critisim I should have come to this site right from the start but you get that ....I am using a morningstar 60a Tristar charge controller with a magna-sine ms4124e inverter charger with 6 strings of 210w 47.7v 5.25a panels in parellel I only have ( yes you are right ) 12v 100ah batteries but are going shopping soon. Being a novice but giving it a go what batteries would you recommend for this set up and it also seems strange that Morningstar have a whole chapter on lvd shutdown and what it can be set at ( I set it for 22.2 but will now change it to 24 ) again thanks guysComment
-
Comment
Comment