Looking for a battery monitor

[thezenvan]

Working on setting up my electrical system and I'm looking to get a battery monitor, I've been searching and I saw 2 monitors that seem to be pretty similar (feature-wise) but the prices are way different.

The first is Victron BMV-702 Battery Monitor at $206 and the second is the bayite DC 6.5-100V 0-100A Meter at $19.

I don't know much about this subject but from reading the specs on both the products it seems like the Victron one has a larger shunt (500A vs 100A) and is round instead of rectangular
I'm not planning on running anything that would draw anywhere close to 100A (the bayite limit) so I'm thinking about going with the bayite one, is there something I'm missing or is the Victron just that much better?

Thanks

 

[John61CT]

Yes Victron is more accurate, featureful and robust.

Check out PKSYS and Alan at Bay Marine for best pricing.


The SmartGauge marketed by Balmar is simpler and more user friendly, no shunt, no AH counting, but best for accurate SoC.

 

[John61CT]

Detailed howto's

​http://www.pbase.com/mainecruising/battery_monitor

http://www.pbase.com/mainecruising/programming_a_battery_monitor

 

[Trebor English]

The Bayite tells you the amps, volts, amp hours etc.  Just the facts.  It's up to you to figure out the state of the battery.  The hydrometer is your friend.  

The Victron calculates the effect of the discharge rate based on the Peukert coefficient to estimate the actual state of charge.  Taking 10 amp hours  in 6 minutes at a 100 amp rate has a different effect than taking one amp for 10 hours.  It also tells you the Bayite facts.  

Compare hamburgers to filet mignon.  Putting bacon on a burger makes a tasty treat but it is not filet mignon.

 

[Optimistic Paranoid]

Actually, there's a bit of a problem here none of the other's have alluded to.

A battery monitor SIMULTANEOUSLY measures all power going out of the battery to run your lights, fans, fridge, etc.  While also measuring how much power is going back INTO the battery from solar panels, the engine alternator, shore power, etc.  At any time that you look at it, it will tell you (more-or-less *) how much power your battery holds.

The bayite meter will measure one or the other.  If it is wired to measure power out, it will tell you NOTHING about how much power came in.  And if it's wired to measure power in, it won't tell you a damn thing about how much power you've used.

I suppose you could get two of them, wire them to measure both parameters, then compare their readings and do the math your self every time you want to check on your batteries state of charge.  Bit of a PITA, actually.

(* more-or-less:  because battery chemistry changes a bit with age and number of charge-discharge cycles, it needs to be recalibrated against the battery monitor from time to time in order for the monitor to be REALLY accurate when it tells you that you're at 100%, or 80%, or whatever.)

 

[John61CT]

Ooh now I'm hungry! Can I put bacon on my filet?

 

[thezenvan]

Would all the additional information that the Victron monitor provides be useful if I were to go with a Lithium battery instead of a SLA Deep Cycle battery? From my understanding the Lithium battery can be fully discharged without any long term issues.

p.s.
I know this is veering a little from the original topic but I'm currently looking into getting a LifePo4 battery instead of an AGM one, hence the question

Thanks

 

[John61CT]

Yes.

SmartGauge, no.

"Fully discharged" is a question of definition, arbitrarily defined by your BMS.

My preference would be an initial LVD set at 12V to isolate from the higher-amp non-critical loads, then the low-amp critical stuff at say 11.5V.

Drop-dead belt and suspenders full isolation at 11 means real systems failure, should never be triggered except real emergency.

If you do literally flatten the bare cells to zero short-circuit, the whole bank goes to recycling, will not recover. In fact likely not worth using well before that.

Those setpoints are much lower in a huge-current EV context, where banks only last a few years.

 

[John61CT]

A battery monitor SIMULTANEOUSLY measures all power going out of the battery to run your lights, fans, fridge, etc.  While also measuring how much power is going back INTO the battery from solar panels, the engine alternator, shore power, etc. 

All depends where the coulomb-counter's shunt is placed.

Put Anderson plugs on it with matching ones at strategic points in charging or load circuits, you can measure whatever you like with however many monitors you like.

It is only a "bank monitor" when all currents in and out go through the one shunt.

 

[Weight]

That is the instruction. All the negatives go through the shunt then to the battery. Why have a quality battery monitor if you just measure items? They would only needs a $20 meter.
Victron is one of the better units. Buy from MaineSail and appreciate all Rod's great instruction. http://www.pbase.com/mainecruising/buy_a_battery_monitor

 

[John61CT]

Yes, wasn't saying my point pertained to one type or another.

 

[jonyjoe303]

For battery monitors all you really need is a 90 volt 30 amp combo meter, its an LED meter you can easily read in the daylight or nightime and its bidirectional, tells you amps in/out of battery. I have mine connected between controller and battery, it tells me how much my panel is putting out.(cost 20 dollars) Mine has been running 24/7 for 4 years straight. 

For more accuracy or to find how many amps something uses over a period of time I use a 15 dollar dc wattmeter. You can also monitor how many amps your panel produce in a day or how many amps you used during a day. I rarely use it except to test how much amps something uses.

I also have a LCD capacity meter I use in my lithium powerpacks, it's not really needed since you can more or less know battery condition by the voltage. These LCD meters can be program to run on a lead acid battery.

I recommend LED meters, so you can see them clearly in all conditions. The LCD even ones with backlights you have to be right next to it to read them. I can see the LED from 10 feet away. You can leave them running all night long, the power they use is insignificant. 
The combo meter is the only meter I rely on for the past 4 years, it tells me the condition of the battery instantly. I tried other meters that can keep track of battery capacity but I learned I never really use that feature.

 

[John61CT]

To me, the minimum definition of a BM shows State of Charge.

Accuracy in that number is paramount, again, to me.

Voltages and specific amp flow data can it is true, be provided by a range of other devices, at whatever circuits one likes.

 

[Hermes1]

My choice is the Morningstar Trimetric meters, they are top notch, easy to program, loads of configurations and perform brilliantly. I had the 2025 on my TT which we traded in on a truck camper and just installed the 2030 model in the TC.

 

[tx2sturgis]

Come over to the 'dark side'...we have cookies!




https://powerwerx.com/digital-meters

 

[Weight]

TriMetric are made by bogartengineering, not by Morningstar. Morningstar makes the best solar charge controllers.

 

[John61CT]

Morningstar Trimetric meters

Wut?

Morningstar has a Tristar line.

Trimetric BM is from Bogart, yes it is excellent, and has the ability to control two SC-2030s for max output of 62A.

They also make the Pentametric, but no SC integration.

 

[Hermes1]

TriMetric are made by bogartengineering, not by Morningstar. Morningstar makes the best solar charge controllers.

 

[Hermes1]

My bad you are indeed correct, I was confusing with the charge controllers made by Morningstar. So yes to be clear Bogart engineering makes the Tri-Metric meters and are excellent. Morningstar makes excellent charge controllers. Thanks for the correction, I was having a bad day when I posted.

 

[Spaceman Spiff]

Working on setting up my electrical system and I'm looking to get a battery monitor . . .
I don't know much about this subject but from reading the specs on both the products it seems like the Victron one has a larger shunt (500A vs 100A) and is round instead of rectangular
I'm not planning on running anything that would draw anywhere close to 100A . . .

Would all the additional information that the Victron monitor provides be useful if I were to go with a Lithium battery instead of a SLA Deep Cycle battery?

My 2¢

As a newby with solar charging batteries there are two pieces of information that are important:

1. State of charge (as a %), calibrated so you know it is accurate.  Yes you can calculate it based on amps in/amps out and battery voltage, but being new to this you wouldn't know how to do this and it is not an easy calculation.
2. Amps in and amps out.  Being new to solar charging this was the best way for me to learn my system.  Watching how many amps different appliances used, how much I used overnight, how much I could replace on a sunny or cloudy day, how shading effects output . . . 

I have a Trimetric 2030R and am happy I spent the money on it.  After three years I feel I know my system's limits pretty well.  You generally get what you pay for.

As to lithium batteries, any of the amp counter monitors should work.  The Balmer doesn't work with lithium (per MaineSail).  I would think with what you would invest in a LiFePO4 battery bank you would want the best monitoring you could get.

A 100 amp shunt will work as I don't think any of us use more than 100 amps.

 -- Spiff