Question on new inverter reading

what size and length wire are you using to connect the battery to the inverter it makes a big difference because the inverter can draw a lot of current bringing the voltage down

MrWizard wrote:
battery will 'ALWAYS' read lower with a load, than when at no load resting

noway to know how accurate the inverter meter is
until you compare it to another meter

what does the inverter show when you remove the loads

batteries ..even new ones.. should be fully charged before doing any testing

When turned off it reads 12.6
Put load back on and it reads 12.2

It has had a load on for about 20 minutes. inverter LED is showing 140 watt load

Battery was put on charger this morning. With in 2 minutes, charcher said full charge

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-0.2V

I 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.

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.

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.

battery will 'ALWAYS' read lower with a load, than when at no load resting

noway to know how accurate the inverter meter is
until you compare it to another meter

what does the inverter show when you remove the loads

batteries ..even new ones.. should be fully charged before doing any testing