Battery Monitor - Advice & Recommendations

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RonHurd

Newbie
Joined
Aug 10, 2017
Messages
4
Location
USA
Vessel Name
Shangri La
Vessel Make
Cheoy Lee 46 Trawler
I was reading a related thread on battery testers and wanted to switch the discussion to battery monitoring.

We have a house bank (8-6 volt series) and 2 starter banks (2-12 volt parallel) on our Cheoy Lee 46 Trawler. I recently changed all the batteries and want to install a monitoring system that will allow me to know the % of discharge, reserve and to monitor actual amp draw.

I would appreciate any advice or recommendations as anything having to do with electricity is like black magic to me.

Thanks,

Ron Hurd
M/V Shangri La
46 Cheoy Lee Trawler
 
Try doing a search on this forum, there are many threads in which this is discussed. You may not get a complete set of answers here since it has been a repeated subject. Do you have an inverter? How are you charging these batteries?
 
For SoC nothing is more accurate today than Merlin SmartGauge, supported in the NA market by Balmar.

Also by far the easiest to install configure and use, part of why so accurate. Only works with lead banks.

Out of the plethora of AH counting BMs, needed for LFP, my choice would be Victron 712-BMV.

Many owners install both, but if that seems nuts to you, a decent AH counter - not full BM quality - can be had from well under $100.

CMS uses a Xantrex LinkPRO.

Read these three articles at his site

https://www.google.com/search?q=site:marinehowto.com+battery+monitor
 
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There really isn't a need to monitor a starting bank, only a house bank. If set up with proper charging circuits a starting bank will never go below 99% SOC.


Pick one of the monitors discussed above and install it on your house bank.


David
 
I agree with John61ct. I would use the Balmar Smart Gauge. I don’t have one but will be installing one at some point. I have an amp counter, and it works fine, but doesn’t give me as accurate SOC% for my house bank as the Smart Gauge would.
 
The problem of course is evaluating its ongoing accuracy. Trailing amps while charging is always the best way to benchmark 100% SoC, and for lead, 10.5V is zero. Just the points in between are rough, always a guesstimate as usage patterns and SoH (%residual AH capacity) change over time.

Would be great if one could rent a SmartGauge by the month to help calibrate the SoH, Charge Efficiency and Peukert adjustments periodically required by coulomb-counting BMs.
 
Nothing to do with the Gibbo's original SmartGauge technology, except the fact Balmar's trying to duplicate / reverse-engineer it for that side of its operation.

Also **very** interesting integrating also with a coulomb-counter, especially trying to estimate SoC on the fly - that would be unique.

Note no AH display, even though used internally.

Definitely worth keeping an eye on, but way too early days yet to say whether they're succeeding or not,

but they are looking for alpha testers.

http://www.cruisersforum.com/forums/f14/balmar-sg-200-battery-monitor-209056.html

​Manual http://www.balmar.net/wp-content/uploads/2018/09/SUP-0250_RS.pdf
 
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After reviewing what was available in 2015, I went with the Victron SOC guage. While it offers a number of features, I primarily use the amps in / out display, and percentage of full charge. The gauge appears to be extremely accurate and has a self zeroing feature. After there is essentially no flow of amps in at full charge for a number of minutes, it resets the gauge valve to 100%. I would guess I have in excess of 300 cruising days since 2016 where the house bank was discharged between 5 and 25% and then recharged the next day. The Victron gauge has tracked it flawlessly. If it quit tomorrow, I'd buy another one.

Ted
 
The simplest way to monitor Start batts is to have a volt meter that goes on with the key.

When cranking there will be a usual volt drop , as the start gets older and weaker the cranking voltage will be seen lower.

For house batts while supreme accuracy might have some advantage sometime , to someone, simply being close will save the batts from too much discharge .

Weather you drop to 55% SOC or 45% SOC is meaningless , that you recharge soon and fully is what counts.
 
It is very easy with AH counters for the inaccuracy to quickly drift a **lot** more than 10%. Most owners do not know, must guess their bank SoH % as it ages.

The 100% resets should be very frequent, and

usually should be done manually, or

at least periodically verify that the automatic reset feature continues to be accurate, corresponding with the mfg endAmps spec.

It is very common for charge sources to drop to Float (stop charging) prematurely.
 
john61ct said:
It is very common for charge sources to drop to Float (stop charging) prematurely.
Click to expand...

Are you referring to a standard engine alternator? Or are you implying that multi stage externally regulated engine alternators and multi stage shore power battery chargers do that?

If the latter, could you link a reference showing that it's "very common ".

Ted
 
Yes, please..... And don't stop with one random test....
 
FF said:
The simplest way to monitor Start batts is to have a volt meter that goes on with the key.
Click to expand...
I think the simplest way to monitor all batteries on your boat is to install a Low cost SOC in each battery circuit. (On Amazon for about $9 each.) Simply walking through your boat will tell you the SOC at a glance. (12.7v is fully charged.)

House, Engines & Genny
 

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Most of the coulomb counting monitors work pretty well for a few cycles and are in my mind preferable to voltage only monitors. That being said they all drift. Consult the manual from the manufacturer of your battery bank for an indication of fully charged. Usually .005C in amps. Once you hit that with your charger you should be fully charged. I’ve run three of he mentioned meters in this thread and my current preference is the victron but the new BMI 760. The Bluetooth interface actually allows you check and set almost everything with your iPhone from most anywhere onboard the boat. I usually do a capacity test every fall just to keep everyone honest. This year I found a liar.
 
Codger2 said:
I think the simplest way to monitor all batteries on your boat is to install a Low cost SOC in each battery circuit. (On Amazon for about $9 each.) Simply walking through your boat will tell you the SOC at a glance. (12.7v is fully charged.)

House, Engines & Genny
Click to expand...

And don't you just love those Label Makers! Our daughter and son-in-law gave me one when we bought our boat - EVERYTHING in our boat will be labeled :thumb::thumb:
 
"Install an SoC" is meaningless word salad.

Voltage level has very little to do with SoC if you are looking for accuracy.

My statement about most charge source regulators dropping to float prematurely is very easily verified with your own equipment, just requires an accurate ammeter at the bank to measure trailing amps, and a bit of patience.

Yes also true for very expensive fully adjustable gear, shore chargers, solar controllers etc, most people just leave at the defaults.

I don't want to argue about it, but if anyone asks for howto details I'm sure they'll get an answer.
 
cafesport said:
Usually .005C in amps. Once you hit that with your charger you should be fully charged.
Click to expand...
It does vary by batt model, but that's a good default if you can't find the spec.

> I’ve run three of he mentioned meters in this thread and my current preference is the victron but the new BMI 760.

I can't find that, the 712-BMV was my reco.

And yes actually running a 20-hour load test is the only accurate measure for SoC. Bit of a pain to get set up, but after that just tedious.
 
john61ct said:
"Install an SoC" is meaningless word salad.

Voltage level has very little to do with SoC if you are looking for accuracy.
Click to expand...
I have a Maretron SOC system that tells me anything I want to know about my battery banks. The little SOC meters in the various circuits alert me to more serious problems.(At a glance!)
 

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I have the Maretron DC monitor on the house bank and have been super happy with it. I also have basic volt/amp displays on the panel. I love that I can check on battery SOC from almost every area of the boat as i have maretron displays in most of them. Also now have the system setup to email/text me if SOC gets too low.
On the starter batteries I just have simple amp/volt displays.
 
Arthurc said:
I have the Maretron DC monitor on the house bank and have been super happy with it. I also have basic volt/amp displays on the panel. I love that I can check on battery SOC from almost every area of the boat as i have maretron displays in most of them. Also now have the system setup to email/text me if SOC gets too low.
On the starter batteries I just have simple amp/volt displays.
Click to expand...
I couldn't agree more! :thumb::Thanx::popcorn:
 
Voltage does not correspond to SoC without an **isolated** resting period, often 24hrs but sometimes 72.

Even then the correspondence table is different for different types and even models by the same mfg.

And it changes over time as the bank ages, as does residual AH capacity.

I understand most don't care about accuracy, but for those that do, voltage is near useless.
 
BruceK said:
And please do find a publication to regurgitate....
Click to expand...

Don't you just love all the links and citing that are noted in today's internet world. Makes one an instant expert without even owning a boat where electrical things constantly don't behave!
 
john61ct said:
I understand most don't care about accuracy, but for those that do, voltage is near useless.
Click to expand...

And yet, that is all the Balmar SOC meter uses.

If you are technically naive and wish to stay that way, then an SOC meter will be your friend. CMS' main argument for them is on that basis. Armed with a bit of knowledge, an amp counter gives you much more information about what is happening with your system and batteries. The SOC meter is a guess, not a measurement, and says little about the condition of the batteries. New batteries will be 100% when fully charged and 50% when half discharged. Old batteries will be 100% when fully charged, and 50% when half discharged. What did I learn from that?

I have two amp counters (Mastervolt and Blue Sky) and they track quite accurately for a number of charge/discharge cycles. After 10 or so they are beginning to get off by a few percent, but with AGMs (and certainly on a power boat) they will and should be fully charged by then, which resets the integrator.

In a different system, I have a Magnum amp counter, I disconnected and abandon it as it was quite inaccurate. Often you get what you pay for.
 
I had a brain fart on that victron sensor model, it’s actually a BMV 712 Smart sensor. As I mentioned earlier my capacity testing revealed a bad battery. First thing I did was charge it fully then disconnect it for 30 hours. The Resting OC Voltage was in spec but it was the SOC behavior and recharge amp numbers indicated that something was wrong. Remember as John points out those voltage soc charts supplied by battery manufacturers are for open circuit (no load), resting voltage at standard temperature (68F). The victron is a cheap simple solution that works better than most and is very programmable. I removed a linksys put the Balmar on the dink and never even look at the screens for the mastervolt or magnum. With an iPhone can see and program the bmv from anywhere on the boat.
 
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