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Old 08-06-2013, 02:35   #16
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Re: Battery monitor reviews wanted

I have an older one of these..
DC Systems Monitor (DCSM)

Works OK, but the only way to know the state of charge for sure is one of these....

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Old 08-06-2013, 02:39   #17
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Re: Battery monitor reviews wanted

Hi Secrabtree I have used the BM1 for many years now and have worked out my system of use I think any you buy ( so long as it is reliable) you will get to understand what it is telling you !!!! remember you are not on a trip to the moon in a cylinder and you do not need infinite info after a while you will just look at the simple readings. I must say that in the early days of setting up your solar, wind and usage parallels you will spend a fair bit of time looking at the unit what ever you install good luck Cheers Jacko
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Old 08-06-2013, 04:38   #18
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Re: Battery monitor reviews wanted

I like my Victron BMV 6005 as per the maine sail link earlier. Easy install, works well. I wrote some details in another thread as per below. Not the installer didnt install it correctly initially as he didnt have all the wires to the shunt. I re ran a few wires and its fine now. A note regarding Battery Monitors BMV 6005 Victron
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Old 08-06-2013, 05:10   #19
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Re: Battery monitor reviews wanted

I have the Link20. It seems to accurately indicate the voltage and the amps in and out. But heck if I know if it's precises. It was useful when the last bank began going south I could see that they were not accepting much charge and then discharged fast.

I don't know how much detailed data I need. The time to discharge or whatever that is it can display seems to be unreliable and not of use to me.

The Link is much more helpful than an analogue voltage gauge. The install is pretty easy.
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Old 08-06-2013, 05:23   #20
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Re: Battery monitor reviews wanted

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Originally Posted by conachair View Post
.....but the only way to know the state of charge for sure is one of these....

This is another controversial subject in the “electrickery game”, so care needs to be taken when using Specific Gravity to measure SOC.

SG readings have been traditionally used to measure the state of charge, 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 about 1.265. 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 from undercharging; temperature compensation also has to be applied to all readings. A value of 30 points lower 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. Another major problem is the SG reading must only be taken when the charged battery has been allowed to rest with no charge or discharge for several hours. 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 then 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 very slightly.

So, if the state of charge is known to be at 100%, a lower SG reading than normal doesn’t only suggest that the battery is not fully charged, but it could also indicate that the battery has lost some of its Ah capacity.
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Old 08-06-2013, 05:43   #21
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Re: Battery monitor reviews wanted

I installed the NASA BM-1 battery monitor a couple of years ago. Shortly after I called the manufacturer in the UK for assistance. No help there. I tried their US distributor but was told there is ONLY one person knowledgeable enough to answer any questions and he was never available.
Nice display and seems to work well.
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Old 08-06-2013, 06:17   #22
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Re: Battery monitor reviews wanted

I have had a Victron 602, for about 5years , simple and reliable.
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Old 08-06-2013, 07:03   #23
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Re: Battery monitor reviews wanted

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Nobody knows!!!!! But the SmartGuage monitors the battery voltage 1100 times a second - if you were doing that you would get a pretty good idea what you batteries were doing! It learns you battery status and becomes more accurate the more it "learns".

There are many complicated reasons for the inaccuracies of shunt battery monitors.. The battery parameters have to be correctly input to the software on installation. The capacity of the bank has to be entered. Peukerts constant for the batteries being used has to be entered – sometimes this is not easy to find. Peukerts constant adjusts the actual used Ah values depending on the size of the discharge current - and very small changes can make a big difference to the Ah count!. Also an accurate charging Ah count is affected by the “efficiency” of the battery at accepting charge. Wet cells may be only 75% efficient whereas AGMs may be 98%. If all these values are not input correctly it will upset the Ah count accuracy.

The biggest inaccuracies happen because all of the these values change as the batteries age. Batteries also have a self-discharge up to about 10% per month which the battery monitor cannot detect. This can introduce large errors.

I have a BEP BM, and a SmartGuage.
The issues with a shunt are clear. Sampling a battery voltage at once every millisecond does not explain at all how this info can accurately be used to determine battery state of charge. On my boat there is always load on the house bank, plus it gets charged by 3 charge approaches, with low level solar on most of the day. The voltage is much more effected by the charge controllers and the charge consumers at any moment. I'd like to hear how this system is supposed to work, short of snake oil.
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Old 08-06-2013, 07:45   #24
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Re: Battery monitor reviews wanted

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The issues with a shunt are clear. Sampling a battery voltage at once every millisecond does not explain at all how this info can accurately be used to determine battery state of charge. On my boat there is always load on the house bank, plus it gets charged by 3 charge approaches, with low level solar on most of the day. The voltage is much more effected by the charge controllers and the charge consumers at any moment. I'd like to hear how this system is supposed to work, short of snake oil.
Their website only explains the weaknesses of the other systems.

SmartGauge Electronics - Products

What their system does, is not explained. It looks like a digital volt meter. Does it display current draw?
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Old 08-06-2013, 08:05   #25
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Re: Battery monitor reviews wanted

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.........I'd like to hear how this system is supposed to work, short of snake oil.
Everybody would - then they could make a million too!

This was developed in the UK and is now used extensively by the armed forces. They demanded more accurate battery monitors - so enter the SmartGuage.

Nobody believed it could work, including the boss at Merlin Equipment, but he finally bought the company. It has proven to be much more accurate than any shunt-based battery monitor.

They recently did some development work with Enersys Energy, the company who make Odyssey batteries, and SmarGuage was proven by Enersys to be 0.1% accurate. That's good enough for me!
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Old 08-06-2013, 08:07   #26
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Anyone tried quantum magnetism yet

http://batteryuniversity.com/learn/a...tate_of_charge
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Old 08-06-2013, 08:15   #27
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Everybody would - then they could make a million too!

This was developed in the UK and is now used extensively by the armed forces. They demanded more accurate battery monitors - so enter the SmartGuage.

Nobody believed it could work, including the boss at Merlin Equipment, but he finally bought the company. It has proven to be much more accurate than any shunt-based battery monitor.

They recently did some development work with Enersys Energy, the company who make Odyssey batteries, and SmarGuage was proven by Enersys to be 0.1% accurate. That's good enough for me!
Any links to data on how accuracy was determined or how the tests were done to show 0.1% accuracy when just getting that accuracy on soc seems so difficult ?

A few untrusting minds out here in web-land
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Old 08-06-2013, 08:22   #28
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Re: Battery monitor reviews wanted

If you feel that you need 0.1% accuracy on your boat for anything my prediction is that you are going go crazy in the end. After all most boat stuff into the "close enough" category.
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Old 08-06-2013, 09:05   #29
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Re: Battery monitor reviews wanted

Quote:
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Everybody would - then they could make a million too!

This was developed in the UK and is now used extensively by the armed forces. They demanded more accurate battery monitors - so enter the SmartGuage.

Nobody believed it could work, including the boss at Merlin Equipment, but he finally bought the company. It has proven to be much more accurate than any shunt-based battery monitor.

They recently did some development work with Enersys Energy, the company who make Odyssey batteries, and SmarGuage was proven by Enersys to be 0.1% accurate. That's good enough for me!
This doesn't answer my question. Does the meter give the user any information regarding current draw (Amperage) or is it just a fancy volt meter. I don't doubt the meter's accuracy, but if it doesn't display current draw it's of no use to me.
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Old 08-06-2013, 09:34   #30
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Re: Battery monitor reviews wanted

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This doesn't answer my question. Does the meter give the user any information regarding current draw (Amperage) or is it just a fancy volt meter. I don't doubt the meter's accuracy, but if it doesn't display current draw it's of no use to me.
No it does not display, or even measure current.

With a complicated algorithm it attempts to derive the SOC from voltage alone.

Some users install a cheap ammeter as well as the smart gauge.

My take, for what its worth, is that its better than a poorly installed and adjusted conventional battery monitor, but if you can install and set up a conventional battery monitor correctly, this is a better option.
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