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Open Roads Forum  >  Tech Issues

 > What's a good battery level monitor?

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MrWizard

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Posted: 11/19/20 04:05pm Link  |  Quote  |  Print  |  Notify Moderator

Capacity is a matter chemistry and chemical reaction increases with temperature,
And I do my best to not go below 70% SOC,
This morning I was at 83% capacity,
Colder weather will mean more heater runtime and lower SOC in the mornings,
But like I said batteries are in the heated basement,
My capacity does Not shift very much because of temperature,
Any drift/shift is the Perkurk? Effect (chemical reaction ) from evening and morning MW use,
Which BTW is also/more so, on your use
So if I use 80 AmpHrs over night, its really more, when I do the charging,
When the monitor says full but the charge rate is 3amps, no problem I'm in the high 90s SOC,
I can stop if I want or keep going
If the charge rate is high , 10 amps or more then I know I should keep charging until the batteries are full, goes to float or at least tapers to the right value,
Monitor saying full capacity, means the measured discharge has been returned, Does Not mean batteries at saturation level
You and I are trying to achieve the same thing
But your doing math with too many variables
While I watch for my recharge rate to reach the correct threshold

BTW this monitor has more setting that I do Not know the use of, and have left the values at default, there is probably one for recharge compensation, but the instructions weren't much help with that

* This post was edited 11/19/20 04:12pm by MrWizard *


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deltabravo

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Posted: 11/19/20 06:01pm Link  |  Quote  |  Print  |  Notify Moderator

jornvango wrote:

What's a good monitor that I can install in my Casita to see the battery level throughout the day?


Victron BMV-712 like I installed


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3 tons

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Posted: 11/19/20 06:05pm Link  |  Quote  |  Print  |  Notify Moderator

The OP was asking about a “Good Monitor”....

Per FWC:

“It is not just theory. For many of us who don't plug in, you can get several partial charge cycles in a row (several days of non optimal solar for example) and as a result your SOC can be significantly off. Without plug ins, we also generally don't sit at float for hours upon hours to get your monitor back to 100%.

Yes you can make it work without these conveniences, but you have to remember when the last time you were on float for multiple hours, or try and check the battery voltage when you know things are at rest.

My point was that the good battery monitors deal with this, and you can be fairly sure when you glance at the display that the number is pretty close to reality. Cheaper monitors are a compromise.

I use lithium batteries, so the voltage doesn't tell me much about the SOC. However I have a good battery monitor that is correctly programmed for my batteries, and I can trust it. “

I can resoundingly second FWC’s off the grid experience, and the Victron 712 is also LiFePo4 compatible...It’s a matter of getting what you pay for...

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MrWizard

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Posted: 11/19/20 08:09pm Link  |  Quote  |  Print  |  Notify Moderator

"Without plug ins, we also generally don't sit at float for hours upon hours to get your monitor back to 100%."

Don't need to be on float for hours & hours
Batteries don't really need floating in an RV that's in use, floating is too keep an emergency battery service from self discharge
Once batteries reach float, they are full
It's not the monitor that needs to come to 100%
In many instances, The monitor will reach 100% before the batteries are full, watching the charge rate is what is necessary with lead acid batteries,
Since lithium batteries have very little compensation needs, just count AmpHrs in and out, I think the one I using would work quite well,
If l had the $$ for lifepo4 I would get whatever monitor I thought was best for the job, be it Victron or something else

time2roll

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Posted: 11/19/20 08:20pm Link  |  Quote  |  Print  |  Notify Moderator

My basic voltmeter resets to 100% every time. Never fails.


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MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 11/19/20 08:58pm Link  |  Quote  |  Print  |  Notify Moderator

Once the battery electrolyte achieves maximum density the batteries are fully charged. Analysis by dirivities is pure bull pucky. Analysis of sealed batteries is verified only by hyper-exaggeration of charge parameters. There is a difference between "apparent full charged" and "verified full charged" The verified mode is needed to accurately zero amp hour transactions. Unless of course battery capacity and life are of no concern.

Verification (zeroing) is not appropriate for every cycle but should be performed every few weeks.

Derivative assumption, is like referring to an employee's time clock ticket to determine production rather than check the loading dock.

3 tons

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Posted: 11/19/20 09:55pm Link  |  Quote  |  Print  |  Notify Moderator

“ Derivative assumption, is like referring to an employee's time clock ticket to determine production rather than check the loading dock.”

Ha,ha, truly a solid candidate for quote of the year Sir!!

3 tons

Itinerant1

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Posted: 11/20/20 04:56am Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

“ Derivative assumption, is like referring to an employee's time clock ticket to determine production rather than check the loading dock.”

Ha,ha, truly a solid candidate for quote of the year Sir!!

3 tons


I like that quote also. lol


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KMLsquared

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Posted: 11/20/20 07:33am Link  |  Quote  |  Print  |  Notify Moderator

I use a $30 dollar Bluetooth unit from eBay. BM2 is the model. It has no display and must be viewed on a phone. The best part is I can check my battery voltage without getting out of bed. It stores up to 30 days of data that gets downloaded to the phone when within range. provides really nice graphs as well.

">9cAAOSwVA5aMUMw]BM 2

I cant get the clicky to look right.


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sgfrye

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Posted: 11/20/20 12:27pm Link  |  Quote  |  Print  |  Notify Moderator

MrWizard wrote:

[image]
[image]Click For Full-Size Image.

Maybe something like this
ALL INFO IN ONE place on one screen


i have had this one for a couple of years. bought off ebay, works great

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