crashmaster said:
After reading the articles I felt that accurately programing a battery monitor was so complex that there is no way I would get it correct and would be better for me just to use a voltmeter!
Any wisdom you folks have about the Smartgauge vs. Victron BMV-712?
Thanks!
Whew, just read those two looong articles. I've read stuff by RC before, and he seems legit. He certainly has some very cool testing gear, and I learned a thing or two as well.
As for wisdom... I dunno, but here are my two cents:
First off, yes, that Smartguage sounds very cool.
Next, a voltmeter is a definite step DOWN from a Victron, as per the articles themselves.
Finally, the Victron will give you great results, even if set to defaults and never adjusted/programmed.
Why? As the article says
1) Folks used to just use voltmeters, and grossly mistreated their batteries, resulting in 2-3 year replacement cycles. Scan the forums, and you will see that a lot of folks here have been in this boat.
2) Folks used to use voltmeters, and assumed that some (nearly random) voltage indicated their batteries were full, when it merely meant the batteries had reached a certain (unknown) SOC that looked healthier to them. As, in my batteries are dead at 12.0 volts and fully charged at 13.0 volts. That resulted in both discharging too deep, and not charging fully later.
RC says that simply using a SOC meter with a shunt like Victron will mean that most folks are getting a MUCH better idea of what is going on, and
will get 4-6 years out of their batteries instead of just 2-3.
Can you get more out of them if you use an even better battery monitor and/or regularly test and recalibrate your Victron? Sure. But lets imagine that a good 150AH battery bank deteriorates 10% per year. After 6 years the capacity is only 80AH.
If you typically use 50 AH a day, when new the batteries will be at 67%. After 6 years they will be at 37%, and dying fast. In fact, to not kill the batteries super fast, we should be trying to avoid discharging them more than 50%. In our example of a 150AH battery, that happens after 4 years, when the capacity of the bank has naturally degraded to 98 AH.
That would mean it was time for new batteries anyway, as they bank no longer has enough AH for what you intend to use daily.
The bits that I took out of the articles that I wanted to note:
1) This unit will not work on LiFePo batteries
2) I need to reconfigure my charge efficiency number, since I rarely discharge my batteries below 80% and the charge efficiency drops the higher the SOC
3) I will reconfigure my batteries to 10% less AH capacity annually.
4) As a result of these tweaks, I might get another year or two out of my batteries, and have a better idea of the SOC they are really in.
Thanks for the articles!
Here is the relevant section from the articles:
Smarter Use of Your Battery Monitor
“But RC I have heard you say many times battery monitors generally lead folks to longer battery life, how can that be?”
That is correct and I still actually stand by that statement despite a lack of accurate programming. Let me share some reasons why I can say this…
Reason #1
Prior to having battery monitors many of my customers had simple analog volt meters. Most of these analog volt meters were quite inaccurate and many owners often discharged to well below 12.0V before recharging. They were in essence taking their battery to 70-80% DOD with each cycle.. Battery life for many was the typical 2-3 years we see with abused batteries.
Along comes the Ah counting battery monitor and all of a sudden the owner has a screen to watch, buttons to press and has some insight into the battery that never before existed. A good portion of these customers now started to be really careful about battery depth of discharge (DOD). The 50% DOD they assumed previously, which was really closer to 70 or 80% DOD, now became “Wow I am at 65% SOC I think I will recharge.” Human attention was brought to batteries that never had such a fan base.
Reason #2
Previous to the Ah counting battery monitor most owners had not a clue as to what their alternator or charging systems were doing. They watched voltage and when it got to 14.4V or so they stopped charging. With the battery monitor they could at least hold off until a good portion of the -Ah’s had been returned. Is this accurate? No, not at all, but it resulted in batteries getting to a higher SOC than the owners previously & regularly attained thus leading to overall healthier batteries.
