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Old 13-12-2013, 00:36   #16
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Re: Balmar SmartGuage

Originally Posted by btrayfors View Post
........I find that most clients don't have the knowledge or inclination to provide what is necessary to ensure that their battery monitors yield accurate information.....
This is an excellent reason for a SmartGauge.

BUT - it does have a huge range of alarms and a very long and detailed user manual for those who want to get the most out of it. It has a relay that can be activated by alarms, so it could start a generator or run an external alarm.

It can also be linked to the SmartBank battery combiner in a whole complicated number of ways. My big criticism is why can't SmartGauge/SmartBank tell when the second bank is fully charged and then disconnect it. A second SmartGauge on the second bank and the relay output could be configured to do this.

I forgot to add a second battery can also be connected to monitor battery voltage only.

I, like Maine Sail, have been in touch with Merlin but get no answers. Maybe Balmar have taken over as Merlin seem to be moving away from the yachting market to more lucrative UK/US Military markets. I know "Gibbo" who invented the SmartGauge is locked in a room with no external communications working on top secret "Stuff".

So the question that should be answered - are different SmartGauge settings for Lithium batteries or Lead Crystal batteries needed? Maybe Balmar can provide the answer.

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Old 13-12-2013, 03:53   #17
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Re: Balmar SmartGuage

Originally Posted by sailinglegend View Post
This is another controversial subject in the “electrickery game”, and is another good reason why SmartGauge is much simpler and much easy to use.

Measuring SG of an open wet lead acid battery accurately may be a difficult and time consuming procedure, but unless the battery is healthy they may not be the best method because the SG reading gets lower as the battery ages.

The SG of each cell at a 100% SOC should be 1.265 or higher. If the cells in the battery are not equal then an average of all cells has to be made. If individual cells are lower it means their Ah capacity is reduced due to sulfation. A value of 30 points between cells indicates that the battery should be equalized.

For accurate results the SG must only be taken when the cells have been topped up with distilled water and then only after the batteries have been charged, this stirs up the electrolyte to give a true SG reading for each cell. The SG reading must only be taken when the charged battery has been allowed to rest with no charge or discharge for several hours, the temperature of the battery must be measured and compensation has to be applied to all readings. All this is not very practical on a typical cruising boat, so the potential for errors can give poor results.

If the battery is known to be fully charged because it has been on shorepower for a couple of days the SG readings taken then will represent 100% charged. If these are all lower than the readings when the batteries were new that indicates they have lost some of their Ah capacity. Every time the battery is discharged and charged again these SG values will reduce slightly.

The only thing I find a hydrometer is really good for is to tell you when cells are out of balance and when to stop equalizing. Your resting voltage will tell you what the hydrometer does in terms of overall SOC.. Never seen it not agree, but the key is resting voltage.

I have seen many boat owners destroy their batteries thinking they need to check SG all the time. The elcheapo hydrometer they are using often resides in a drawer full of rusty tools & contaminates and each time it is inserted they are adding metals & other contamination to the electrolyte. The battery tops are also quite often filthy and loaded with contaminates.

It is not uncommon for me to see 1-2 year old batteries with cells gassing at float levels which is most likely due to metals contamination... When I ask to see the hydrometer, well, out comes this filthy tool dug from a drawer of rusty tools.......

If you own a hydrometer I have two words for storage, TUPPERWARE CONTAINER. Please give your hydrometer its OWN clean storage container. It also helps to flush it after use with distilled water....

I then ask the procedure the owners use and nine times out of ten they are doing it incorrectly. This also leads to erroneous readings and defeats the entire purpose of exposing the cells to potential contamination..

I no longer use a hydrometer as I find a sight refractomter far easier, less invasive, less electrolyte to use, and less clothing holes. It is also easier to read. After breaking my third fragile and very expensive Freas hydrometer I switched to a refractometer.

As Bill said an SG test tells you nothing about the current capacity of the bank. The only way to determine this is with an actual discharge capacity test. Waiting on a resting voltage reading will tell you the "SOC" but won't tell you individual cell balance..

I have seen plenty of batteries that can put up perfect SG readings after a proper charging yet they have almost no "capacity" left in them. I have two sitting in my shop right now where all cells are evenly balanced and after being charged they both show near perfect temp corrected SG yet the physical capacity is just not there anymore.

I use SG readings most often to tell me when the batteries are in need of an equalization and when to stop equalizing.

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Old 13-12-2013, 03:55   #18
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Re: Balmar SmartGauge

Originally Posted by Strait Shooter View Post
I have to say, I may buy one as well, and even though I really need to leave the house for work, I would love to hear about the feely interpretation approach to gauge reading.

Peace out
What I mean is that voltage has to be interpreted in light of a number of different factors to have any meaning -- you have to have a feel for what voltage does in your system under various loads, how fast it bounces back, etc.

Other clues I use: I watch the voltage during charging. I can tell how close the batts are to the SOC they will have at the end of the absorption phase (85%?) by how close the voltage is getting to the full absorption voltage.

You have to have a feel for when voltage is reflecting surface charge.

My battery bank is large enough (420 amp/hours @ 24v) that the voltage doesn't sag much under ordinary loads; it takes a big inverter load to pull the voltage down much. So under many circumstances -- say no big inverter loads lately and light loads on at the moment -- I can read the system voltage and figure I am not too far off the open circuit values for SOC. And any error will be to the side of conservatism. So it the system voltage under those circumstances would indicate say 70% SOC if it were an open circuit value, I know that I'm ok -- the real SOC is going to be somewhat more. If I always charge before the system shows 24.2v at a light load, I can be sure to never discharge them to more than 50%.

Here's a really interesting article on the subject:

Reading a battery voltmeter and turning that information
into a reliable assessment of the battery’s state of
charge is like tracking an animal by its footprints.
Tracking requires noticing small details and
extrapolating information from these details. A tracker
uses his knowledge of the animal’s habits. A tracker
considers the weather and season. A tracker’s
knowledge of his subject and its environment allows
him to predict the actions ofhis subject."
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Old 23-04-2014, 20:27   #19
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Re: Balmar SmartGuage

Today's Panbo feed has a nice plug for MaineSail's site in general, and his recent SmartGuage writeup in particular.

Seems like magic, but I'm sold. Anyone want to buy a slightly used Victron BMV-600S?
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Old 24-04-2014, 11:26   #20
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Re: Balmar SmartGuage

As sailinglegend noted in a previous post, Merlin (manufacturer of SmartGuage) also sells a battery combiner (VSR) system that interfaces with the SmartGuage. Not sure if the advantages over a plain vanilla VSR are terribly significant, but integration with the SmartGuage is pretty slick.

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