Vintage465 wrote:
4. Maybe there is a good link to send me to that has "battery monitors 101"?
Perhaps not a 101, but good info. There is lots of good applicable info to rv electrical on this site.
https://marinehowto.com/installing-a-battery-monitor/
https://marinehowto.com/programming-a-battery-monitor/
I have a 500 amp 50mv deltec shunt, monitored by a BlueSky IPN pro remote battery monitor which also controls the settings on my blue sky sb2512i solar controller.
It has been a great learning tool, but part of the learning has been to know when to reset it when it is not reading correctly, meaning resetting it when one achieves a true full charge, and not to blindly trust it to be accurate always.
Lots of people let a green light on a 'smart' charger tell them when full charge is reached, but an ammeter a voltmeter and a hydrometer will almost say otherwise on batteries that deep cycle for a living. Lots of people believe the battery monitor with complete faith, while their batteries get chronically undercharged and sulfate and lose their capacity very prematurely.
So one needs to be smarter than both their charger and their battery monitor, yet, when one is capable of doing this achieving and determining when the battery(s) are truly fully charged, then the battery monitor itself becomes less useful.
I ignore the % remaining screen
I use the amp hours from full, knowing that the capacity I programmed initially was likely accurate but has declined with age.
I'm not worried about that, as if I reset it and it has counted 25 amp hours from full, and under x amount of load and holding 12.x volts, then that is expected and all is well, enough. when mine says 50% or half my programmed amp hours have been removed, I am usually still reading over 12.2v once the DC fridge compressor shuts off.
It's when I see either higher or lower voltage for that AH removed that i don't think something is wrong with the battery, but the battery monitor has drifted and is no longer accurate and I then need to achieve a true full charge and reset it.
The battery monitors ammeter has been very useful, in that I have seen higher readings than expected then turned everything off until I determined what the extra load was. For example If I have my doors open but all the map/dome lights turned off, there is still a 0.3 amp load from some time delay relay under the dash. I would have remained blissfully unaware of this significant parasitic load, with out the ammeter on the monitor, and that rotating my headlamp switch all the way clockwise eliminates this load.
Honestly, having watched my battery monitor through many batteries over the last 12 years I could watch a voltmeter and an ammeter, and estimate state of charge within 5%, but the Ah from full screen, especially after a recent reset is still valuable data.
Mine has issues when the battery(s) still accepts a fair amount when held at float voltage, it goes above zero, and I need to remove several amp hours before it starts reading 1 or more amp hours from full.
My current AGM battery is end of life and amps never taper to where they should be considered full, they stop tapering well above this and then start rising when held at the same voltage. Programming absorption duration and the amperage threshold in order to drop to float and reset it to 0 AH from full, has been a mark I have missed and don't really care about anymore, as voltage alone is enough for me, and I actually use my only battery for engine starting too, having shed all the extra battery capacity I never needed anyway.
I call the amperage refusal to keep tapering but stop then start rising,' the bounce' and I try to reset shortly after the bounce. but honestly even setting the charge efficiency factor as bad as allowed, it drifts so far pretty quickly that I view the Ah from full with great suspicion with this aged battery.
I have a hall effect ammeter too, but its not an amp hour counter. It tends to fluctuate several tenths of an amp up or down when the engine is running, while the shunt based ammeter does not. But both read within 0.5 to 3% of each other, closest in the 5 to 50 amp range.
I have no experience with wifi or bluetooth enabled monitors, so no comment. I was weary of Bluetooth stereo but have had one for 8 months now and can't imagine going back to using the 3.5mm stereo mini plug each time.
I have seen lots of much less expensive monitors on Ebay and Amazon lately, but no experience with them either, though I do have interest in them as many people who ask me to set up a DC system for them simply need a % screen as their eyes glaze over trying to explain the relationship between voltage and amperage as a battery discharges, and I wind up saying, when you see 12.2v and nothing big is running on the battery, it is likely time to stop the load and recharge or know that one should do that soon. I'm not a 50% rule Nazi. My existing AGM has hundreds of cycles down to 20 and 30% range and over 1300 deep cycles total. The key is a prompt and full recharge.
If you want to make your new batteries last, monitoring the state of discharge, is not nearly as important as figuring out how to truly fully recharge them.
An ammeter, a voltmeter, a hydrometer and a charging source which can hold absorption voltage until these tools indicate full charge, are needed to achieve true full charge and thus long battery life. A battery monitor provides only two of those tools, the voltmeter and ammeter, and honestly My battery monitor ammeter and voltmeter read only one decimal place.
I have some 3 decimal place, 3 wire voltmeters that can be calibrated, and watching that thousandths of a volt number move in relationship to load as the battery discharges, and with experience in knowing how big the load is, is very enlightening as to battery state of charge and battery state of health, and makes it obvious when something is not right, or battery performance starts tanking.
