Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-02-2015, 15:48   #1
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
What is Midpoint Voltage and it it important?

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.
__________________

__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 03-02-2015, 20:27   #2
Marine Service Provider

Join Date: Oct 2011
Posts: 1,205
Re: What is Midpoint Voltage and it it important?

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



Quote:
Originally Posted by Snore View Post
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 is offline   Reply With Quote
Old 04-02-2015, 01:36   #3
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by Snore View Post
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
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 04-02-2015, 04:22   #4
Registered User
 
bill good's Avatar

Join Date: Oct 2006
Location: Brisbane Australia
Boat: sold
Posts: 721
Re: What is Midpoint Voltage and it it important?

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
__________________
bill good is offline   Reply With Quote
Old 04-02-2015, 04:34   #5
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by Snore View Post
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
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 04-02-2015, 05:23   #6
Registered User
 
ErikFinn's Avatar

Join Date: Feb 2011
Location: Malaysia, Thailand
Boat: Beneteau Oceanis 430
Posts: 832
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by Snore View Post
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,
__________________
ErikFinn is offline   Reply With Quote
Old 04-02-2015, 05:32   #7
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,038
Images: 4
Re: What is Midpoint Voltage and it it important?

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

Just sayin'....

Bill
__________________
btrayfors is offline   Reply With Quote
Old 04-02-2015, 05:35   #8
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by btrayfors View Post
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!!!!
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 04-02-2015, 05:39   #9
Registered User

Join Date: Jun 2007
Location: SW Florida
Boat: FP Belize, 43' - Dot Dun
Posts: 3,425
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by goboatingnow View Post
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!
__________________
DotDun is offline   Reply With Quote
Old 04-02-2015, 11:32   #10
Registered User

Join Date: Sep 2009
Posts: 64
Re: What is Midpoint Voltage and it it important?

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
__________________
clyde is offline   Reply With Quote
Old 04-02-2015, 11:49   #11
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by clyde View Post
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
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 04-02-2015, 14:57   #12
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Re: What is Midpoint Voltage and it it important?

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
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 04-02-2015, 17:52   #13
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: What is Midpoint Voltage and it it important?

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
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 04-02-2015, 18:50   #14
Registered User
 
Snore's Avatar

Join Date: Jan 2011
Location: www.USCGMaster.com
Boat: Tartan 33
Posts: 1,881
Re: What is Midpoint Voltage and it it important?

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.
__________________
"Whenever...it requires a strong moral principle to prevent me from deliberately stepping into the street, and methodically knocking people's hats off- then, I account it high time to get to sea..." Ismael ---- NEW website! www.USCGMaster.com
Snore is offline   Reply With Quote
Old 04-02-2015, 21:32   #15
Marine Service Provider

Join Date: Sep 2008
Location: Victoria B.C.
Boat: CS27
Posts: 1,727
Re: What is Midpoint Voltage and it it important?

Quote:
Originally Posted by Snore View Post

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.
__________________

__________________
mitiempo is online now   Reply With Quote
Reply

Tags
import

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Toilets and Shower More Important Than Sailing Capabilities ? Zonker Multihull Sailboats 40 11-04-2012 16:07
Important information for monohul sailors cat man do Monohull Sailboats 7 25-11-2006 18:38
Major important Breaking news. Alan Wheeler Off Topic Forum 6 12-10-2006 12:59
Most Important Advancement to Sailing? GordMay General Sailing Forum 24 19-08-2005 06:06
Important Discovery ! GordMay Electrical: Batteries, Generators & Solar 3 30-06-2005 14:48



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.