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BOAT wrote: - but on the boat - if you lose the battery there is no back up so I thought a meter would be nice.

That's where an independent start battery for the OB comes in, perhaps with a charge relay to the house batt(s), so they get second dibs on the OB charging current. Your OB has, I think, is a lot more charging output than my BF50 produces, by the way. Every other OB does, in fact.

Or a backup battery pack, which was already mentioned.

Those energy monitors are nice, but good ones are expensive. I don't know how they compensate for self-discharging, either, which batteries do faster as temperature goes up.

I went with the Blue Sea M2 1830 SOC meter 100% satisfied with it.

Here is a good Youtube video on electrical systems on boats. Check at 13:18 when he covers them.
https://youtu.be/bFA-qyJWn5A

And this one at 2:35
https://youtu.be/P7K6UD8zxbs

For what it's worth, I tucked one of these "zowaysoon PJH-RS-0377 Car Digital Voltmeter Dual USB 2 Port Power Socket Three Hole Panel, Black" into my pedestal, over the hole where a previous owner had had an old Raytheon autopilot unit. For just $9.99 with free shipping from "way yonder", it certainly looks and works well enough: gives you a voltage reading to tenths of a volt, a couple of USB plugs (1 and 2.1 Amps) and a handy ciggy-lighter-style power outlet, all on one neat little faceplate panel:



Wired through one of my two DC switchplates in the cabin (which also has a pair of ratty little integrated analog battery charge meters), sharing one of two "Instruments" circuits with my binnacle compass's littIe interior light, it's perfectly adequate for getting a general idea right in the cockpit of the state of charge of the battery or batteries. If you need to assess their quality, as to whether they'll hold a good charge, or if it might be time to replace them, then it's time to break out the hydrometer...for "old school" lead acid types like mine, anyhow.

Been contemplating same thing boat

This electrical stuff is all hocus pocus to me

Watched much Youtube stuff on it and still the lamp of understanding is very dimly lit

When one guy mentioned MOSFETS I almost went into the fetal position and started rocking in the corner

jimmy alonso wrote:I went with the Blue Sea M2 1830 SOC meter 100% satisfied with it.

Here is a good Youtube video on electrical systems on boats. Check at 13:18 when he covers them.
https://youtu.be/bFA-qyJWn5A

And this one at 2:35
https://youtu.be/P7K6UD8zxbs

I will 2nd the M2 1830 SOC meter as a good option. It will monitor 1 battery with current. Then will give you voltage of 3 batteries. With a small boat load,,, Ok back to post. With a small boat electrical load I changed out the shunt to a 100A to make the meter more accurate and less susceptible to interference. It has a low draw and you can configure it to any battery.

sailboatmike wrote:Been contemplating same thing boat

This electrical stuff is all hocus pocus to me

Watched much Youtube stuff on it and still the lamp of understanding is very dimly lit

When one guy mentioned MOSFETS I almost went into the fetal position and started rocking in the corner

Well now you have concurred that we can start on the inductor coils and buck boost

grady wrote:

jimmy alonso wrote:I went with the Blue Sea M2 1830 SOC meter 100% satisfied with it.

Here is a good Youtube video on electrical systems on boats. Check at 13:18 when he covers them.
https://youtu.be/bFA-qyJWn5A

And this one at 2:35
https://youtu.be/P7K6UD8zxbs

I will 2nd the M2 1830 SOC meter as a good option. It will monitor 1 battery with current. Then will give you voltage of 3 batteries. With a small boat load,,, Ok back to post. With a small boat electrical load I changed out the shunt to a 100A to make the meter more accurate and less susceptible to interference. It has a low draw and you can configure it to any battery.

What is this strange language you speak in????

Once installed a quick look tells you House Battery is at 92% and is getting 8 amps of charge. And start is 13.44 volts.

Boat that Blue Seas M2 looks sharp, but we have that ol Balmar cause it was so easy to hook up. Its only money, spend it and enjoy your boat.

jimmy alonso wrote:Once installed a quick look tells you House Battery is at 92% and is getting 8 amps of charge. And start is 13.44 volts.

Yes but what is it telling you cause that is is all over the place

At 13.36 volts the battery is full and should be on float constant voltage 13.3-13.7 no amps
At 92% the battery should be in absorb mode constant voltage 14.4-14.7 at low amps
At 8 amps that tells me the battery is in bulk mode but the voltage is too low.

looks like it does no better job than a $15 watt meter.

Agreed, from the little I know about these things it would be a concern if your sending 8amps into your battery when its basicly full, maybe the meter is just reporting whats happening, its regulator and charge controller I would be concerned about if its reporting correctly

kadet said

At 13.36 volts the battery is full and should be on float constant voltage 13.3-13.7 no amps
At 92% the battery should be in absorb mode constant voltage 14.4-14.7 at low amps
At 8 amps that tells me the battery is in bulk mode but the voltage is too low.

My limited understanding is that you get the 13-14 range readings when the battery is being charged by either the engine or a charger, but when you take the charger off, you get the 12.5- to 12.86 range readings that really tell you where your battery is in terms of actual charge and ultimately, its functionality. Could not explain it technically, but from a "manager" point of view (vs. tech), that is what I go on and seem to have reasonable success.

jimmy alonso wrote:Once installed a quick look tells you House Battery is at 92% and is getting 8 amps of charge. And start is 13.44 volts.

Knowing the quality of Blue Sea products I'd trust those readings. It is not the charge controller just reporting what is going on.

The 8 amps seems high but not sure if he is charging 1 battery or 2 or possibly 3. It would be interesting to know the charging source when the reading was taken,

Sumner

You guys are missing the point I have no doubt that the reading of Voltage and AMPs is accurate. It is the percentage full that is wrong as using voltage to guess the SOC is just that a guess.

And whether you have $15 or a $250 meter seems to make no different.

Those readings indicate to me a fairly heavily discharged battery in bulk mode I would expect the voltage to steadily rise to 14.4volts and the AMPs drop over a couple hours depending on type of charger and battery chemistry.

What I do know is it ain't 92% full

kadet wrote:You guys are missing the point I have no doubt that the reading of Voltage and AMPs is accurate. It is the percentage full that is wrong as using voltage to guess the SOC is just that a guess.

And whether you have $15 or a $250 meter seems to make no different.

Those readings indicate to me a fairly heavily discharged battery in bulk mode I would expect the voltage to steadily rise to 14.4volts and the AMPs drop over a couple hours depending on type of charger and battery chemistry.

What I do know is it ain't 92% full

If his meter is wire according to the instructions the amps to the battery on the meter also include any loads that are running at that time. So some of the 8 amps is going to recharging the battery and the rest is going to any loads that might be on at the time like say a laptop, fridge, lighting, etc.

Since the voltage was down in the 13+ volt range I'd guess that whatever was charging the batteries was in the absorption stage of charging. Was the charging source solar, the outboard, both or other?

The meter doesn't base SOC on the voltage. It bases it on the known amp/hr capacity of the battery and then calculates the SOC on following the amps that have gone out of the battery and into the battery and a few other parameters. You set up the meter for the specific battery bank you have.

It is a nice meter but I've had no real problem knowing the general state of charge with a volt meter (also have an amp meter). I generally look at the voltage in the morning with no loads on and before the solar kicks in. Is this totally accurate? No, but I probably know withing 5-10%, which is good enough for me,

Sumner

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1300 miles to the Bahamas and back -- 2015

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