My new 1200 watt pure sine wave inverter arrived yesterday. I just hooked it up to a new group 27 deep cycle. the LED read 12.9 volts. I then plugged a fan into it and turned it on. Voltage immediately dropped to 12.6. I then plugged in a 60 watt light bulb and it dropped to 12.4. Five minutes later, it was 12.3. My understanding is that at 11.9 volts I am 60% discharged and should disconnect the draw and recharge battery.Do my volt readings seem low or is the LED reading on my converter most likely inaccurate.In a previous thread, I was told to get a volt meter. Would a dedicated volt meter be more accurate?

battery will 'ALWAYS' read lower with a load, than when at no load restingnoway to know how accurate the inverter meter isuntil you compare it to another meterwhat does the inverter show when you remove the loadsbatteries ..even new ones.. should be fully charged before doing any testing

You need to “rest” the battery for an accurate volt reading. 27s average 90 amp hours. Kinda small. Trojan T1275s are 12 volts and 150 AHs.

mrad wrote:My new 1200 watt pure sine wave inverter arrived yesterday. I just hooked it up to a new group 27 deep cycle. the LED read 12.9 volts. I then plugged a fan into it and turned it on. Voltage immediately dropped to 12.6. I then plugged in a 60 watt light bulb and it dropped to 12.4. Five minutes later, it was 12.3. My understanding is that at 11.9 volts I am 60% discharged and should disconnect the draw and recharge battery.Do my volt readings seem low or is the LED reading on my converter most likely inaccurate.In a previous thread, I was told to get a volt meter. Would a dedicated volt meter be more accurate?Your battery voltage drops as the inverter 120v load increases. Called "loaded voltage" Not to be confused with "resting voltage" which is what you use for estimating battery state of charge.If you have more battery AH in the bank, the loaded voltage will not drop so much. The idea is to be able to run your loads and keep loaded voltage above the inverter's low voltage alarm setting, perhaps 11 volts. The inverter keeps running the load but makes a noise until voltage falls to 10.5 and it shuts right down.

A digital multi meter (DMM), especially one with a built in "amp clamp" is a very usefule thing to have. Many to choose from on Amazon for less than $50 (check the Uni-T brand). These should be more accurate then the built in meter, but probably not by much. Maybe +/- 0.1V-0.2VI would not trust those little, cheap Chinese volt meters that you find on eBay for under $10.FYI - There is no such thing as a TRUE "deep cycle" Group 27 battery. What you have is a dual purpose battery. Depending on your requirements (size of your load and how long you want to run it), you may be better off with TWO 6v golf cart batteries. These are TRUE deep cycle. You can discharge them more and they will last through more charg/discharge cycles than dual purpose batteries.

MrWizard wrote:battery will 'ALWAYS' read lower with a load, than when at no load restingnoway to know how accurate the inverter meter isuntil you compare it to another meterwhat does the inverter show when you remove the loadsbatteries ..even new ones.. should be fully charged before doing any testingWhen turned off it reads 12.6Put load back on and it reads 12.2It has had a load on for about 20 minutes. inverter LED is showing 140 watt loadBattery was put on charger this morning. With in 2 minutes, charcher said full charge

Question on new inverter reading | Good Sam Community

36 Replies

3_tons
Explorer III
Dec 03, 2018
I see no real problem here, just many solutions in search of a problem...Time to exit the Rabbit Hole.
RJsfishin
Explorer
Dec 02, 2018
shastagary wrote:
i am using a xantrex prosine 2.0 it is adjustable for the battery alarm i have it set to 10.8v but the batteries recover from that quickly under a lighter load there is a separate setting for the actual shutdown voltage
10.1 is low i agree there may be a warning on yours before the actual shutdown at 10.1v

Maybe keep in mind that the 10.1 low voltage alarm setting is on the inverter, not at the battery. The actual battery voltage under a heavy load could easily be a 1/2 volt higher than the 10.1 at the inverter, depending on the wiring size and length.
Quit trying to broke what ain't fixed !! :@
Boon_Docker
Explorer III
Dec 02, 2018
The AGM have the automotive posts, but the flooded have wingnut terminals.
Ed_Gee
Explorer II
Dec 02, 2018
Boon Docker wrote:
theoldwizard1 wrote:
Ed_Gee wrote:
theoldwizard1 wrote:

FYI - There is no such thing as a TRUE "deep cycle" Group 27 battery. What you have is a dual purpose battery. .

Really? A True deep cycle Grp 27 battery

Thank you for correcting me !

I should change my statement to "true deep cycle Group 27 batteries are typically only available through specialty store".

Trojan also makes a deep cycle Grp 27.

So they say, but those Trojan Grp 27 AGM batteries have vehicle starting battery posts on them which strongly indicate dual purpose......and dual purpose means compromise.
shastagary
Explorer
Dec 02, 2018
i am using a xantrex prosine 2.0 it is adjustable for the battery alarm i have it set to 10.8v but the batteries recover from that quickly under a lighter load there is a separate setting for the actual shutdown voltage
10.1 is low i agree there may be a warning on yours before the actual shutdown at 10.1v
mrad
Explorer II
Dec 02, 2018
shastagary wrote:
i have run my microwave off my inverter many times until the low voltage alarm has gone off on the inverter.
when i shut the inverter off the voltage on the battery recovers and i can run my lights and tv for hours after that before the battery is truly discharged i have a automatic 10a battery charger that float charges my 2 12v house batteries any time i am not using this camper van and they also charge as i drive it.
i easily get up to 7 years out of a set of batteries so just because the alarm goes off on the inverter under load does not mean the batteries are totally discharged.

When does your alarm go off?

My manual says mine goes off at 10.1 volts. That seems to way to low to be of any bennefit.
shastagary
Explorer
Dec 02, 2018
i think your main concern is going to be how to get a truly good charge on your batteries before you use them.
i do not like the automatic battery chargers that totally shut off when they think the battery is charged i would rather see the charger maintain the charge than have it totally shut off unless your just going to charge them up and let them sit for a while.
shastagary
Explorer
Dec 02, 2018
i have run my microwave off my inverter many times until the low voltage alarm has gone off on the inverter.
when i shut the inverter off the voltage on the battery recovers and i can run my lights and tv for hours after that before the battery is truly discharged i have a automatic 10a battery charger that float charges my 2 12v house batteries any time i am not using this camper van and they also charge as i drive it.
i easily get up to 7 years out of a set of batteries so just because the alarm goes off on the inverter under load does not mean the batteries are totally discharged.
2oldman
Explorer II
Dec 02, 2018
I would put a small load on it and keep checking the voltage every 10 minutes. If it drops but doesn't keep dropping, I'd consider that ok.
Boon_Docker
Explorer III
Dec 02, 2018
theoldwizard1 wrote:
Ed_Gee wrote:
theoldwizard1 wrote:

FYI - There is no such thing as a TRUE "deep cycle" Group 27 battery. What you have is a dual purpose battery. .

Really? A True deep cycle Grp 27 battery

Thank you for correcting me !

I should change my statement to "true deep cycle Group 27 batteries are typically only available through specialty store".

Trojan also makes a deep cycle Grp 27.