Solar help... Mppt or PWM
Hi.. I recently got a new solar panel from somewhere... fell off truck... lol I know mppt is the way to go im mysituation but am asking for advice... panel 250 watts volts 30v. Wh...
Forum Discussion
lawrosa wrote:
I though bulk and absorb voltage stayed the same at 14.8 ..
You thought right. Only in bulk it doesn't "stay" at 14.8, but rises slowly to 14.8 from 12.3 (or whatever it measured the beginning of charging).
And it's not "the same". It's different for different brands, that's why I linked Deka tech bulletin where it's a bit lower than 14.8.
Also, as Red noted, temp comp factor in Deka is different - it's 0.003V/C per 2V cell, not 0.005V/C like most others. Sounds odd, but I tend to trust published specs. This translates into 0.017V/10F per cell. So... Absorb at 67F should be 14.55+6*0.017=14.65V.
Not very useful info if this controller can't raise the 2nd stage above 14.5V anyway.
On the bright side, think how you were charging your batteries with truck alternator or unknown grade converter in trailer. Very likely, they were never close to Absorb voltage.
