Victron 700

[medsailor1]

Two question please guys .
I just fitted a victron 702 BM , just before fitting I used shore power to get my batteries fully charge (4x6v T125) once the BM was fitted and setting checked I then Synchronised the BM , reading 100% soc .
Batteries capacity been set at 450AH just slightly below what they are .
Roll on 24 hours later .........
Solar panels have been use to charge the batteries but no shore power .
SoC 94% , voltages 12.50v . We used 44A BM tells me ,
although 6% of 450ah bank is 67A ?
Ever thing I read tell me that 12.5 is around 80% SOC ,
so the question is why is the BM reading SOC 94% stating a 12.6v fully charge batteries when the voltages is 12.50v
I understand to get a real reading the batteries have to be at rest for some time so the 12.50v is not a true valve .
Second question ....setting for charge voltage,
Manuel say set it .02/.03 below the float charge ? Mine is 13.50 so it should be set for 13.47 .
But if you watch their video it say if you have a solar array you need to set it .03 below the Absorption voltage, am I correct in thinking this is 14.82? In which case it should be set at 14.80 .

At the moment I set mine at 14.8 and I await your advise on that one .

[_andi_]

Hi,

use the charging voltages from the battery spec sheet.

I haven't used this BM but most need to actually drain the batteries to "synchronize". Maybe consult the manual for that.

Andi

[_andi_]

uh, too early, not enough coffee.

correction: the voltages set in the bm should be a bit lower than the voltages set in the charger (which should be the voltages from the battery spec sheet). This helps the BM to identify the state the charger is in. The reason the voltages are lower is because of measuring errors, cable losses, ... If the BM is not working correctly you might have to bump these values down a bit.

[medsailor1]

Hi the Manual says that it will auto sync when the batter fully charge , nothing about discharging it . It also state to set the charging voltage to .03 below Absorption , if there is solar panels fitted ,
Trojan spec don't show Absorption voltages , am I correct to say it bulk charge figure on the spec sheet above ?

[_andi_]

Manual (also note you're off by an order of magnitude with the voltage, 0.2V not 0.02V :

02. Charged Voltage
The battery voltage must be above this voltage level to consider the battery as fully
charged.
The charged-voltage-parameter should always be slightly below the end of charge voltage of the
charger (usually 0.2V or 0.3V below the ‘float’ voltage of the charger).
See section 3.7 for recommended settings.

In case of a 12V battery, the BMV resets to ‘fully charged’ when the
following ‘charged parameters’ are met: the voltage exceeds 13.2V and
simultaneously the (tail-) charge current is less than 4.0% of the total
battery capacity (e.g. 8A for a 200Ah battery) during 3 minutes.

[_andi_]

The BMV synchronizes too early
In solar systems or other applications with fluctuating charge currents, the
following measures can be taken to reduce the probability for the BMV to
reset prematurely to 100% state of charge:
a) Increase the “charged” voltage to only slightly below the absorption charge voltage (for
example: 14,2V in case of 14,4V absorption voltage).
b) Increase the “charged” detection time and/or decrease the tail current to prevent an early
reset due to to passing clouds.

... yeah, in this case bulk is the appropriate value. Here's another Datasheet stating bulk values.

https://cdn.taynabatteries.eu/datash...ata-Sheets.pdf

[swampbush]

This is my setup for the bmv700 with trojans. Took a bit of trial and error but seems ok now. Resets to zero as trailing amps drop down if voltage is high enough.

[smac999]

Your ah vrs % will vary due to perkurts. The victron does this.

Ie if you draw 44a for one hour. Or 1 amp for 44 hours. In both cases yiu have drawn 44ah. And the meter will show -44ah. But the battery % is not the same in both cases. The first one will be much lower. Because you have hammered the battery.

Because your total battery ah changes depending on load size. The number you enter is based on a single load size. (20h). Say at 44a the 450ah. Bank is only rated for 300ah. And at 1a load it's rated for 600ah. I'm making up numbers but that is the theory.

If your % is lower then the ah should calculate too . Then you have been discharging at a higher rate then a 20h load.