What is Midpoint Voltage and it it important?

[Snore]

So after doing tons of research, reviewing my boats wiring, reading numerous posts and sketching the installation, I was ready to buy a Victron 700 and repurpose my existing volt meter to monitor the starting battery.

THEN I saw that the 702 could track mid-point voltage. Logically this would tell if one of the two house batteries was having an issue. Does anyone have a grasp of this feature? How important is it? Is it just marketing hype?


Thanks for the inputs.

[FlyingCloud1937]

It's important to Victron, because they can now sell you 1-2-3-4 more devices, to make yuo feel like you have total control.

It does not balance your bats, it seems to tell you you need to do something.

Lead acid, is very forgiving, just with an EQ, and most Flooded La's would better be served by a Hydrometer.

AGM's and Lith-ion could be served by such a system if it could be accurate.

But it's not.

The flat voltage curve of Lith... it won't be accurate....soooo what to do?

At US $193.00 per bat, it will defiantly make Victron happy.

The 700 series counts bat temp monitoring as something new, it's not, and it does nothing for Lith..., as far as determining SOC or for that matter charge parameters.

It is good for LA's in columb counting, and VOLTAGE REGULATION.

In the end it doesn't control the charge /discharge.

Lloyd

Originally Posted by Snore

So after doing tons of research, reviewing my boats wiring, reading numerous posts and sketching the installation, I was ready to buy a Victron 700 and repurpose my existing volt meter to monitor the starting battery.

THEN I saw that the 702 could track mid-point voltage. Logically this would tell if one of the two house batteries was having an issue. Does anyone have a grasp of this feature? How important is it? Is it just marketing hype?


Thanks for the inputs.

[Ex-Calif]

Originally Posted by Snore

So after doing tons of research, reviewing my boats wiring, reading numerous posts and sketching the installation, I was ready to buy a Victron 700 and repurpose my existing volt meter to monitor the starting battery.

THEN I saw that the 702 could track mid-point voltage. Logically this would tell if one of the two house batteries was having an issue. Does anyone have a grasp of this feature? How important is it? Is it just marketing hype?


Thanks for the inputs.

It looks like mid-point voltage is important for series or series/parallel installations.

it connects the "positive" of the total bank and the mid-point of the series negative connections - There is some tech data on the Victron site.

This link is general and schematic in nature.

My personal opinion is that we have lived a long time without this feature so why now? I would rather be monitoring the second (start) battery's voltage.

http://www.victronenergy.com/upload/...0x_part1_2.pdf

[bill good]

Just purchased a 700 to use with a 300a/h lifepo4 pack for the boat & I must admit to having a "bit" of trouble getting just how to set this unit up!! Once the double dutch was sorted on some of the settings that was needed it is able to set all the necessary charge & discharge to allow a 70% SOC. The default values are all good for lead acid. The idea of this midpoint voltage monitoring is to use the alarm functions to warn if some slow out of balance is commencing. I am sure it works & would save lead batteries where series/parrallel is used. It is just another safety layer.

There are cheaper copies but I am happy with Victron.

Regards Bill

[goboatingnow]

Originally Posted by Snore

So after doing tons of research, reviewing my boats wiring, reading numerous posts and sketching the installation, I was ready to buy a Victron 700 and repurpose my existing volt meter to monitor the starting battery.

THEN I saw that the 702 could track mid-point voltage. Logically this would tell if one of the two house batteries was having an issue. Does anyone have a grasp of this feature? How important is it? Is it just marketing hype?


Thanks for the inputs.

In a series string , its always useful to monitor individual cell or battery voltages, this is what is done as a matter of course in Lithiums installs. It prevents the charging system overcharging a series battery, especially if that battery has reduced capacity compared to its neighbours in the string, or perhaps it has a different SOC level ( age , different capacity etc).

In that regard the Victron is adding a useful monitoring facility, lead acid is however fairly forgiving as to overcharges, which is why we have " got away" without such monitoring in the past.

NOTE however , this is only useful where you have series strings, its of no use if you are simply making bank from 12V batteries for a 12V system. its useful if you are using 6V batteries or making a 24V system from 12V batteries

In that regard its a timely and useful addition to certain multi- battery configurations

The term uses normally is battery level monitoring or cell level monitoring as opposed to the rather confusing and idiosyncratic " mid point voltage " term

dave

[ErikFinn]

Originally Posted by Snore

So after doing tons of research, reviewing my boats wiring, reading numerous posts and sketching the installation, I was ready to buy a Victron 700 and repurpose my existing volt meter to monitor the starting battery.

THEN I saw that the 702 could track mid-point voltage. Logically this would tell if one of the two house batteries was having an issue. Does anyone have a grasp of this feature? How important is it? Is it just marketing hype?


Thanks for the inputs.

Unfortunately I can't help you with your question, but as I understand you did not yet purchase the battey monitor, let me suggest you read this first:

Smart Gauge Battery Monitoring Unit Photo Gallery by Compass Marine How To at pbase.com

Cheers,

[btrayfors]

ALL 12VDC and 6VDC batteries are series batteries, each battery consisting of either 6 or 3 individual 2VDC cells in series.

Just sayin'....

Bill

[goboatingnow]

Originally Posted by btrayfors

ALL 12VDC and 6VDC batteries are series batteries, each battery consisting of either 6 or 3 individual 2VDC cells in series.

Just sayin'....

Bill

Indeed, but thats much use to the OP, what with all that casing between him and the cells!!!!

[DotDun]

Originally Posted by goboatingnow

Indeed, but thats much use to the OP, what with all that casing between him and the cells!!!!

Drive a self-tapping screw midway between cells, you'll get the midpoint voltages!

[clyde]

in all my reading, etc, talking to engineers, my cousin was an electrical one, the botom line on our boat is, 12.2 volts is the 50% level [lead/acid batts] go below that, and the life of the batt is reduced! over the last 30+ years, the average life of our batts is 10 yrs...clyde

[goboatingnow]

Originally Posted by clyde

in all my reading, etc, talking to engineers, my cousin was an electrical one, the botom line on our boat is, 12.2 volts is the 50% level [lead/acid batts] go below that, and the life of the batt is reduced! over the last 30+ years, the average life of our batts is 10 yrs...clyde

Note the issue here, the victron system is for monitoring series strings of batteries not one battery

[Snore]

Guys

Once again the CF brain trust comes through!


Based on the inputs. I am still not seeing the value of midpoint voltage on two AGMs. Looks like the 700 it is!

Based on MaineSail's comments I am going to trust my "persnicketiness" to ensure all is wired correctly and remains so-- thereby negating the need for a smartguage.

Cheers!

Bill

[Ex-Calif]

The 702 has value if you want to monitor voltage on a second battery - i.e. starter battery. The 700 only measures one battery/bank.

http://www.victronenergy.com/upload/...-series-EN.pdf

[Snore]

Ex-Cali,

I am going to repurpose the existing voltmeter that currently measures voltage on the live bus to just monitor the starting battery.

$50 that I save, should cover the needed rewiring for the shunt.

[mitiempo]

Originally Posted by Snore

Looks like the 700 it is!

Based on MaineSail's comments I am going to trust my "persnicketiness" to ensure all is wired correctly and remains so-- thereby negating the need for a smartguage.

Cheers!

Bill

Wiring it correctly and keeping it so is good. But keep in mind that all amp counting monitors get out of sync over time. They also don't take into account the declining capacity of the bank.

Smartgauge is unique and gets more accurate over time, not less accurate.

The Victron is a good monitor of its type.