they use those? Cool, so a common connector. should be easy to find thenPaulT said:I shoulda checked my Arduino kit.
Paul
they use those? Cool, so a common connector. should be easy to find thenPaulT said:I shoulda checked my Arduino kit.
Paul
BrianW said:Here is a good write up on using a battery monitor, and how NOT to just believe what it says. Written for sailors, so info is a little more critical halfway across the Pacific Ocean, but still applies. The author is a highly respected person in his field. Also links to a "new" kind of battery monitor that has just light gauge connections to pos and neg battery terminals, way more accurate, and no user input required. Interesting.
http://www.pbase.com/mainecruising/programming_a_battery_monitor
Great info here BrianW!craig333 said:Given that what my battery claims is the ah rating is likely optimistic I could just lower the setting but, what if I go to far? Ex. my battery is rated at 220 and I set the meter at 200 but its really higher than that? Whats that do to my charging algorithm?
Indeed it does. Or you can KISS and just buy new batteries more often.BrianW said:Vic,
That was pretty much my "take away" from the article. The battery voltage is the number to watch, not the SOC. I have an early Victron monitor in a boat and will be using it a little differently now. Just knowing that the SOC reading can be off is valuable.
Gets all very complicated, no?
cheers
Craig, are you using AGM batteries or flooded cell? If you are using FLA batteries, the BEST way to measure SOC is still measuring specific gravity.craig333 said:What would you think of using voltage only for the guy who has very low electrical needs (no fridge) a single camper battery and doesn't mind replacing a cheapie every other year?
Many of us started that way. Volt meter, small solar panel, hoping the chinese controller does a decent job.
Craig,craig333 said:Of course I had to recheck Bogart Engineerings site to see if they had any updates and I noticed what they had to say regarding Peukert compensation. Much different. It'd be nice if the experts all agreed on this stuff.
Charged.... ooh.. punny!BrianW said:Lol, "much like aircraft...aficionados". Ok, boats and planes... guilty as charged !
That was total accident I swear!!Vic Harder said:Charged.... ooh.. punny!
This is fundamentally untrue. You actually get fewer joules out of a battery at higher discharge rates as the internal resistance of the battery is higher under high discharge rates. Anyone who has used a battery under high discharge rates will know that they get quite warm, that heat is wasted energy you won't get from the battery as electrical power. You can easily convince yourself of this by doing the same experiment but using electrolyte gravity as the 'end point' instead of cell voltage - Peukert will still apply.Simply put, the reason you get less amp hours out when the amps are higher is that the higher amps drag down the volts more than a lower amp load, so the 10.5 volts endpoint is reached sooner. It is not because some of the electrons in the battery get lost or wasted when you draw current out faster.
Vic Harder said:Craig,
Thanks for the tip on the Bogart info - is this the article you read?
I'm not so sure that the experts are disagreeing so much as taking a different approach to how they think people will use their equipment. The Bogart stuff has an extremely practical feel to it.
Sometimes not so fine I guess. So the Bogart paper maybe be in error on the physics. Do you think that it is also misleading? From my read their point on the difficulties of trying to predict future loads that might be impacted by a Peukert exponent calculation is worth thinking about.rando said:There is a fine line between physics and marketing.