# full battery power

#### g8ysn

have 3 -120 amp batteries [in line ] = 320 amp but my mt-5 meter reads 200 amp which is the default setting,it states in the guide book [the modified data should be near or equal the real capacity] does this mean the battery settings should be 320 amp fld battery,will it charge all 3 batteries fully in this setting

#### Peter_n_Margaret

##### Free Member
The capacity setting will not affect the charging, it only assists in calculating the State of Charge display.

#### pappajohn

LIFE MEMBER
Battery monitors are not very clever gadgets.

You input the total battery capacity then it calculates know variables.

12.6v is fully charged nd 12.2v is fully discharged (for our purpose) regardless of AH capacity.

The monitor then knows the total capacity at 12,6v so simply calculates remaining capacity depending on the present voltage......12.4v = 50% discharged so remaining amp/hr is half the total usable capacity.

So.....as you have 360ah but the monitor only goes to 200ah set it to 180ah and double the resulting readout.....ie: if the reading is 90ah them you have 180ah remaining....which means time to recharge.

OP

#### g8ysn

thank u 4 your input have not had any issue,s yet just trying 2 understand the charging/display ,4 days away at lincoln charging ann,s mobility scooter/sleep apnia machine on at night,so as they say if it,s working leave it alone ,thanks again

#### Peter_n_Margaret

##### Free Member
Battery voltage can be a very misleading way to estimate state of charge. It is generally useless if there are any loads or charging happening at the same time.
It can be a rough guide if the battery has sat without ANY charge or discharge for at least an hour.

Rather than relying on voltage to estimate state of charge, better monitors will actually measure power used and deduct it from the total capacity, at the same time adding any charge going in. It will also allow for the efficiency losses that any charge/discharge involves.
But to do this they need to be wired and set correctly and even then will only give an approximation of charge state.
A battery monitor may be a stand alone unit, or it may be built into the solar regulator.

Cheers,
Peter

OP

#### g8ysn

as stated no issues just trying to understand the readout,s