Do I really need a $200 Battery Monitor??

IMO it is useful for monitoring how the solar is producing, that's what I use mine for 90 percent of the time. Handy to be sitting in my chair outside and be able to see how the sun/cloud is effecting the panels. I also like to see how many amps an individual item is drawing but that could be done with a multimeter too.

Again it's not necessary but I can afford it and RV'ing is my only vice lol so I don't mind spending a few bucks even for the entertainment value... yes I'm easily entertained.

time2roll wrote:

SCVJeff wrote:
Probably not needed, but the problem with just a voltmeter is that you need to measure things at rest to reflect the charts mentioned above. Once I got used to and confident in my SOC readings, that's now all I use

The chart that shows 10.5 volts as dead is actually while the battery in under moderate load.
Kinda get used to it. Monitor is accurate within maybe 5 percent and the voltmeter probably 10 percent. The 10 percent is fine for most usage IMO.

Yeah but getting there is where the SOC comes in handy. Its looking at voltage, current, and matches it against charging history, battery capacity (a config item), and has a rough idea where "dead" is based on aggregated AH draw throughout the discharge. 10.5 may be dead at 180A draw for late night popcorn, but what did you pull out of the remaining cap once you're back down to a 15A load and the battery recovers given the current state of the batteries, age, etc? I bought the BMK module for the Magnum because I wanted significantly better resolution for V&C; how I did it before the SOC calculation. Not needed but its a wonderful thing.

DiploStrat wrote:
Before one can answer the original poster's question, we have to ask another question(s), "What do you want the meter to tell you, and why?"

Good question. I've just spent several hundred upgrading my battery bank and adding 200 watts of solar and an MPPT charge controller. My primary concern would be not letting my batteries get below 50%. An alarm/warning of some kind would be nice when they get close to 50%.

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And our lights are back on....

Matt

SCVJeff wrote:
Probably not needed, but the problem with just a voltmeter is that you need to measure things at rest to reflect the charts mentioned above. Once I got used to and confident in my SOC readings, that's now all I use

The chart that shows 10.5 volts as dead is actually while the battery in under moderate load.
Kinda get used to it. Monitor is accurate within maybe 5 percent and the voltmeter probably 10 percent. The 10 percent is fine for most usage IMO.