Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 10-06-2013, 05:44   #46
Registered User
 
endoftheroad's Avatar

Join Date: Dec 2008
Location: Key West
Boat: Westsail 32 and Herreshoff 28
Posts: 1,159
noelex,
I was on the wrong track thanks for straightening me out.
__________________

__________________
endoftheroad is offline   Reply With Quote
Old 10-06-2013, 05:59   #47
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Battery monitor reviews wanted

Quote:
Originally Posted by endoftheroad View Post
noelex,
I was on the wrong track thanks for straightening me out.
It is simple to do a manual re-set:

#1 know your banks 20 hour Ah capacity, eg: 400Ah

#2 know what 2% of that is, eg: 8 amps

#3 Run the motor for about 5 minutes to clear any "in-rush" current.

#4 Make sure all DC/HOUSE loads are turned OFF

#5 Check the voltage screen to be sure your batteries are at 14.2 - 14.6V or so.

#6 Read the AMPS/CURRENT screen on your battery monitor

#7 If bank is taking less than or equal to 8A of charge current it is actually full enough to do a manual reset.

#8 It is important that this be done at your absorption voltage or above 14.2V when you make the reading. Float voltages can result in you seeing equal to or less than 2% before the bank is actually full...


Please keep in mind that just because a solar, wind, battery charger or alt regulator has gone into "float" mode that the batteries may not be full at all. Many of these charge algorithms are simply timed and do not know the size of your bank. Ideally your charge devices would not go into float until the bank was taking less than 2%, but this rarely happens.....

So, simply check your "accepted current" at absorption voltage, with no loads on, by using the engine alt... You could use a battery charger too...


Please keep in mind that 2% is not technically "full" but full enough on a cruising boat that you'll usually never get much beyond there. A full healthy battery bank will take well under 2% in charge current when truly 100% full..
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 10-06-2013, 06:35   #48
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Battery monitor reviews wanted

Quote:
As of yet my emails to Smart Gauge have gone unanswered as to whether this technology will work on LiFePO4. I would expect that it could but it instills little confidence when the company won't even answer an email with a simple yes or no answer.. Balmar, the US Importer, does not know the answer either...
SmartGauge as I understand it, ( and its the only way it can work) attempts to apply the dynamic voltage model versus SOC to a LA battery , The common wisdom is that battery voltage in a dynamic LA situation does not represent SOC, Thats only true at the simplest level, ie that there isnt a linear relationship

ie 2xSOC <> 2x f(V), where F(V) is a simple linear or near linear transfer function

however there is complex transfer function that does map battery voltage onto SOC and smartgauge attempts to model this, Now accurate it is nobody knows, but in theory that method is technically much better then current shunts.


Given the linear relationship in Li , It is entirely appropriate to use voltage as an indication of charge state. A current counter Monitor isnt needed other then to record charging parameters) in Li systems, as is witness by the many Li management ICs that just report charge vis cell voltage.

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 10-06-2013, 06:55   #49
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,583
Re: Battery monitor reviews wanted

Quote:
Originally Posted by goboatingnow View Post
SmartGauge as I understand it,......
ie 2xSOC <> 2x f(V), where F(V) is a simple linear or near linear transfer function

however there is complex transfer function that does map battery voltage onto SOC and smartgauge attempts to model this, Now accurate it is nobody knows, but in theory that method is technically much better then current shunts.
.....
Dave,
So how is that going to work when you have a continuing variable load(boat load), along with continuous charge (solar) on a cruising boat?
__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is online now   Reply With Quote
Old 10-06-2013, 07:05   #50
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Battery Monitor Reviews Wanted

Quote:
So how is that going to work when you have a continuing variable load(boat load), along with continuous charge (solar) on a cruising boat?
The terminal voltage of a large battery bank is almost totally determined by the battery voltage rather then any charge sources.

If you look at the research papers http://facta.junis.ni.ac.rs/eae/fu2k72/5mischie.pdf

Youll see that for a given load ( ie discharge) or charge source , there is a voltage relationship.

The trick is devising a software algorithm that models the curves with sufficient accuracy and also that the model copes with different battery capacities, etc

Hence the model accommodates a variable discharge load and variable re charge sources.

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 10-06-2013, 07:11   #51
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
YMMV, but SOC on FLA can be pretty accurately measured by bank voltage when the bank is at rest, or close to at rest. 12.8V is 100% and 12.0 is 50%. It's almost linear. You do need to top off weekly and check the specific gravity once a month and equalize if the cells get out of whack. Old worn out batteries seem to be about .1V less than this.

For LFP, I'm planning to try and create both a voltage and current counter meter in conjunction with a battery monitor targeted for lithium. But there is very little voltage change in the 20-80% SOC range, so you need a very accurate voltmeter. Plus I don't know yet if a "new" cell will have different characteristics than an older cell. Only a slight change will make voltage alone pretty useless. I think LFP benefits from, and needs some sort of Ah counting meter as a guide.

But no monitor on any chemistry is really going to be able to have absolute accuracy if not "reset" occasionally at "full" charge since any tiny error, and they are impossible to eliminate, gets amplified over time.
__________________
ebaugh is offline   Reply With Quote
Old 10-06-2013, 07:21   #52
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Battery Monitor Reviews Wanted

Quote:
Originally Posted by ebaugh View Post

But no monitor on any chemistry is really going to be able to have absolute accuracy if not "reset" occasionally at "full" charge since any tiny error, and they are impossible to eliminate, gets amplified over time.
Well said..! Even with our LiFePO4 bank and a Peukert programmed for 1.01 I still do manual resets when the bank is "full". Force of habit I guess... Thus far, at a 1.01 Peukert, it has been spot on every time I have re-set it. Even the automatic re-sets have been accurate.

Having used battery monitors for over 20 years I have never relied on them automatically re-setting. In my experience they do a very poor job of this especially when you introduce solar or wind (with our LiFePO4 bank solar is turned off when we are not there).... Manual re-sets are easy...

I have one customer who was recently reading -162 Ah's on a 80Ah starting battery. Since that can't physically happen I still stand by; "battery monitors are only as smart as the people wiring, using and programming them."
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 10-06-2013, 07:24   #53
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: Battery Monitor Reviews Wanted

Quote:
Originally Posted by Maine Sail View Post
Since that can't physically happen I still stand by; "battery monitors are only as smart as the people wiring, using and programming them."
My problem in a nut shell!
__________________
Sandero is offline   Reply With Quote
Old 10-06-2013, 07:39   #54
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Battery Monitor Reviews Wanted

Technically voltage monitors like Smartgauge dont need resets to remain accurate BTW ( they dont monitor current anyway).

Current monitors need resets because of the fundamental issues with current monitoring, ie the inability to differentiate what the sources of current flows are from.

In reality a good battery monitor should separately measure charge currents and load currents and therefore could better tell what the battery is actually receiving, this could then auto reset on full far more accurately.

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 10-06-2013, 07:46   #55
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Boat: Outbound 44
Posts: 4,583
Re: Battery Monitor Reviews Wanted

Quote:
Originally Posted by goboatingnow View Post
The terminal voltage of a large battery bank is almost totally determined by the battery voltage rather then any charge sources.

If you look at the research papers http://facta.junis.ni.ac.rs/eae/fu2k72/5mischie.pdf

Youll see that for a given load ( ie discharge) or charge source , there is a voltage relationship.

The trick is devising a software algorithm that models the curves with sufficient accuracy and also that the model copes with different battery capacities, etc

Hence the model accommodates a variable discharge load and variable re charge sources.

dave
If I read this paper correctly, this applies to a fixed load or charge currents. Have you tried the Smartgauge? Does it work on a cruising boat type situation?
__________________
Paul L
http://svjeorgia.blogspot.com
Paul L is online now   Reply With Quote
Old 10-06-2013, 07:55   #56
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Battery Monitor Reviews Wanted

Quote:
Originally Posted by Paul L View Post
If I read this paper correctly, this applies to a fixed load or charge currents. Have you tried the Smartgauge? Does it work on a cruising boat type situation?

Yes it does, but it "seems" accurate but Ive no proper data.

Why I referenced the research paper, is to show you that using advanced battery modelling you can interpret SOC ( which is what you want to know) from terminal voltages , even in a dynamic situation

heres a simpler description of using voltage in a charge only situation http://www.scubaengineer.com/documen...ing_graphs.pdf

Heres a IEEE paper with a bit more depth for those so inclined

http://www.nuigalway.ie/power_electr...onics_2007.pdf

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 10-06-2013, 08:40   #57
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,312
Re: Battery Monitor Reviews Wanted

I asked a similar question a month ago about BM and SOC restting when using a solar panel. My Victron seems to be working well with a setting of 14.5 volts and a 2% current level. While it is possible to get the high voltage and low current if a cloud when over at just the right time, from what I'm been seeing it pretty much appears to have gotten pretty close to charged once the voltage even got to that level.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 10-06-2013, 10:32   #58
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 3,872
Images: 4
Re: Battery Monitor Reviews Wanted

(Re: How can "Smartgauge" accurately determine battery State of Charge with no current monitoring?)

Quote:
Originally Posted by goboatingnow View Post
The terminal voltage of a large battery bank is almost totally determined by the battery voltage rather then any charge sources.

If you look at the research papers http://facta.junis.ni.ac.rs/eae/fu2k72/5mischie.pdf

Youll see that for a given load ( ie discharge) or charge source , there is a voltage relationship.

The trick is devising a software algorithm that models the curves with sufficient accuracy and also that the model copes with different battery capacities, etc

Hence the model accommodates a variable discharge load and variable re charge sources.

dave
But this paper (and the ones you reference later) show that both battery voltage and current are needed to determine State of Charge. Terminal voltage alone is not sufficient, unless you somehow know, without measuring, the charge or discharge current.

Elsewhere you say:
Quote:
Originally Posted by goboatingnow
Why I referenced the research paper, is to show you that using advanced battery modelling you can interpret SOC ( which is what you want to know) from terminal voltages , even in a dynamic situation
Again, the papers tell me that the terminal voltage will depend on both SOC and current. And not just instantaneous current, but also the current averaged over some duration. The models in these and other papers use multiple layers of capacitors and series/shunt resistors to mimic this dynamic battery behavior.

So, I remain puzzled as to how accurate the Smartgauge can be without measuring current.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 10-06-2013, 11:21   #59
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Re: Battery Monitor Reviews Wanted

There is a documented, understandable relationship between battery voltage and SOC, even in dynamic situations, ie , where the discharge rate changes and there is a switching between discharge and recharge cycles.

The terminal voltage is an indication of discharge current, its just that deriving SOC from that isnt straightforward.

SmartGauge from what I can see, uses an iterative approach, building discharge maps to refine the underlying algorithm

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 10-06-2013, 12:22   #60
Registered User

Join Date: Jun 2013
Location: Antioch CA
Boat: Cal 39
Posts: 189
Re: Battery Monitor Reviews Wanted

From my reading of the SmartGuage info it appears that the definition of state of charge is the ratio between the amount of charge (energy?) in the battery compared with the amount of charge (energy?) that the battery could hold. This is an interesting number to me, but only out of curiosity. What I would like to know is the amount of energy that the battery holds and that is a completely different number than the ratio between what exists and what is possible. I haven't yet found any instrument that can instantaneously tell that. Battery voltage while at rest gives a fair indication, but that isn't perfect. The "percent of charge" reading of an Amp hour counter may not be an accurate reading of the percentage of charge, but it seems just as accurate of an indication of the amount of energy still available as a true "state of charge" meter like the SmartGuage. A new 100Ahr battery has a certain amount of available energy. At an SOC of 75% it has about 50%, realistically, of the original available energy. But as it gets older and, let's say, realistically has the capacity of a 50Ahr battery at a 100% SOC it will only have the same available energy as a new 100Ahr battery at 75% SOC. So SOC is a meaningless number unless one knows what the available amount of energy is when the SOC = 100%. And if one knows that then an Amp-hour counter will be perfectly fine.

In my case I would mainly use the Amps function (not on the SmartGuage) to help determin when to run the watermaker and/or refrigerator, the largest consumers of electricity on my boat. Negative charge and I must turn off one or both. The "Amp Hours Remaining" function I use only as an indication of when I must be careful and miserly about cabin lights and other discretionary uses of power. I have 210Ahr of battery capacity so I never want to use more than 105Ahr, and, to play safe, I try to keep it under 75Ahr. And, realistically, with my 6 solar panels I rarely get that low.
Now you know my reasoning behind my selection of an Ahr counter rather than a SmartGuage.
I have selected the TriMetric45 mainly on the recommendation of the Morningstar technition and not hearing anything bad about it. (Although Morningstar makde my TriStar 45 controller, and the similarity of the TriStar and TriMetric names, Morningstar does not make the TriMetric, Bogart Engineering does.
I guess my question has been answered about as well as it ever will be.
__________________

__________________
secrabtree is offline   Reply With Quote
Reply

Tags
battery, monitor, reviews, wanted

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
Golf cart batteries foggysail Electrical: Batteries, Generators & Solar 112 28-06-2017 00:28
Yanmar 3GM30 Starting Battery Size ? endoftheroad Engines and Propulsion Systems 37 14-01-2017 08:27
Need Help Setting up my Battery Monitor Jbaffoh Electrical: Batteries, Generators & Solar 46 07-11-2012 13:48
Battery Isolator with Battery Drain Bensigler Electrical: Batteries, Generators & Solar 83 28-11-2011 13:50
My Battery Keeps Fizzing antoche Electrical: Batteries, Generators & Solar 6 21-11-2011 04:07



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:20.


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.