How many monitors do I need

DannyLori · 05-27-2022, 10:18 PM

I have a battery bank with three lead acid batteries in parallel and would like to install a battery monitor. My question is will I need to purchase three separate monitors one for each battery or is there a way to Install one monitor for all three batteries.
I have been looking at a DC 100A multifunction Battery shunt monitor on Amazon for $20.99. Any recommendations would be appreciated. Thank you

chriscowles · 05-27-2022, 10:40 PM

Quote:

Originally Posted by DannyLori

I have a battery bank with three lead acid batteries in parallel and would like to install a battery monitor. My question is will I need to purchase three separate monitors one for each battery or is there a way to Install one monitor for all three batteries.

I have been looking at a DC 100A multifunction Battery shunt monitor on Amazon for $20.99. Any recommendations would be appreciated. Thank you

You need only one shunt monitor connected between the terminal negative pole of your battery bank, and the ground. NOTHING should be connected to that negative pole, except the monitor. All current must pass through it, to be accurate.

Can you provide a link to the monitor you're considering? I have a monitor that's not the popular, more expensive, Victron, but I'm skeptical about one that costs less than $25.

TacomaJoe · 05-27-2022, 10:52 PM

One monitor, as noted. I have the AiLi from Amazon and it works great. I have another (don't recall the name) but I found that it only measured current in one direction.

DannyLori · 05-27-2022, 11:26 PM

I hope this link works
DC Multifunction Battery Monitor Meter,0-200V,0-100A (Widely Applied to 12V/24V/48V RV/Car Battery) LCD Display Digital Current Voltage Solar Power Meter Multimeter Ammeter Voltmeter https://www.amazon.com/dp/B07T8GN61Z...RS6K93HTNEY0TR

chriscowles · 05-27-2022, 11:53 PM

I have no experience with that but the varied reviews make me skeptical. I have a QWork (same as AiLi) and am satisfied. But I have LFP batteries and you have flooded lead acid, for which Peukert's constant is relevant. If you aren't going to spend the extra money to get a Victron SmartShunt, which incorporates Peukert's constant, at least get the AiLi/QWork.

DannyLori · 05-28-2022, 02:04 AM

Thank you all for the advice. I did a little more research and thought this one may be a better choice. Any thoughts?
AiLi 500A Battery Monitor High Low Voltage and Low Capacity Programmable Alarm Compatible with 10-120V Lithium Sealed Gel Flooded Batteries Capacity up to 9999 Ah https://www.amazon.com/dp/B081SXH9TK...MQRPVP9HE89KE5

TacomaJoe · 05-28-2022, 08:19 AM

I too glanced at the reviews and it looks like it won't work for you. I have 2 of the AiLi monitors and have had great success with them. I have a bluetooth BMS on my lithium battery and it agrees with the AlLi numbers.

chriscowles · 05-28-2022, 09:42 AM

I have this monitor from QWork (Amazon). As far as I can tell, it's exactly the same as the AiLi. It works for me and seems accurate.

The differences between it and the next level up, a Victron SmartShunt, is (1) $82 ($130 vs $48), (2) the Victron is wireless (could be a big deal, depending on where you want to put the display) and (3) the Victron incorporates Peukert's law and temperature. (There may be other differences.)

Depending on the discharge rate (high or low) and the environment you're in, Peukert's constant and monitoring battery temperature may make a difference.

I used to recommend the AiLi/QWork as "good enough". I now recommend the SmartShunt because installation is far easier and you get the other benefits. That said, if being 2.7x the cost is too much to bear, I think you'll find wired monitor adequate.

Edit: I just looked at the one you linked. It's the same shunt as the one I have, with an improved monitor and audible alarm, at 50% higher cost. You may find those features worthwhile. I don't think you need a 500A charge/discharge rate but didn't find a smaller (but adequate) version. The AiLi brand 350A monitor that TacomaJoe references is a few bucks less than my QWork, at $44.

NavyLCDR · 05-28-2022, 12:16 PM

I have this one:
https://www.amazon.com/AiLi-Voltmete...dp/B07FGFFHC6/

I have 2x 6-volt GC batteries. I just used a hole saw (I think 2 1/8") to drill a hole in the top of the plastic battery box cover and mounted it right there with a bead of silicone sealant around the edge. Took about 10 minutes to install and completely happy with it so far.

DannyLori · 05-28-2022, 02:32 PM

Hey Tacomajoe
Which of these units won't work for me? I'm not sure if you saw both of the links I posted.

DannyLori · 06-02-2022, 09:44 PM

Quote:

Originally Posted by chriscowles

I have this monitor from QWork (Amazon). As far as I can tell, it's exactly the same as the AiLi. It works for me and seems accurate.

The differences between it and the next level up, a Victron SmartShunt, is (1) $82 ($130 vs $48), (2) the Victron is wireless (could be a big deal, depending on where you want to put the display) and (3) the Victron incorporates Peukert's law and temperature. (There may be other differences.)

Depending on the discharge rate (high or low) and the environment you're in, Peukert's constant and monitoring battery temperature may make a difference.

I used to recommend the AiLi/QWork as "good enough". I now recommend the SmartShunt because installation is far easier and you get the other benefits. That said, if being 2.7x the cost is too much to bear, I think you'll find wired monitor adequate.

Edit: I just looked at the one you linked. It's the same shunt as the one I have, with an improved monitor and audible alarm, at 50% higher cost. You may find those features worthwhile. I don't think you need a 500A charge/discharge rate but didn't find a smaller (but adequate) version. The AiLi brand 350A monitor that TacomaJoe references is a few bucks less than my QWork, at $44.

I looked at this one on Amazon and really like it. Very affordable so I may go for it. Thanks for your recommendation.

chriscowles · 06-02-2022, 10:56 PM

Quote:

Originally Posted by DannyLori

I looked at this one on Amazon and really like it. Very affordable so I may go for it. Thanks for your recommendation.

Do consider the Smartshunt to get Peukert's law included in the SOC calculations. It will be more accurate for lead-acid, in particular, and is easier to install. But, it is >2.5x the cost of the AiLi/QWork monitors. The latter may be a more effective use of your money.

Edit: there exists a 26' connector wire (Amazon) for this monitor. That may be of use to you, depending on where you put the monitor control. Note, though, that it's a replacement for, not an addition to, the standard 13' wire. You can always join the long one to the standard one with butt connectors or solder, but that's a lot of wire.

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