I have been badmouthing preinstalled converters for a while now but I was always just regurgitating other things I have read and a bit of my own experience as well but I didn't have any real data to back it up.
We were camping this weekend and had shore power and we were in a very shady spot so after our batteries got ran down a fair ways I turned our converter back on and took some notes. Until this trip our converter has been turned off to let the solar maintain the batteries.
We have two 6 volt Rolls Surrette batteries installed with 220Ah of battery capacity for reference.
The batteries were discharged down to 76% when I turned on the converter.
I turned the converter on at 3pm.
17 amps initially and 13.4 volts. Never went into bulk charge. Float voltage right away.....
Anyone know how low your batteries have to get for the converter to go into bulk charging mode?
@ 3:08 pm down to 11 amps and up to 77% charge
@3:35 pm 9.8 amps 79% charge
@ 4:31 8.5 amps 83%
@ 7:02 5 amps and 90%
@ 7:55 4.3 amps and 92%
@ 11pm 2.1 amps and 96%
@ 2am 1 amp and 98%
@ 8am 0.2 amps and 99%
@ 8:10am finally reached 100% charge
17 hours to charge the battery while on shore power.
Keep in mind that if your battery is at 90% you are actually down 20% of your usable battery capacity if you follow the 50% rule. And you have more power available from 90-100% than you do at 50-60% as the voltage is higher so you will draw less amps to do the same work.
I also checked the voltage from our tow vehicle and found a dismal 12.9 volts with the truck running. You need volts to charge a battery. The converter float charge of 13.4 to 13.6 took 17 hours to charge. Charging from my tow vehicle would take a lot longer. Comparatively our installed solar that is programmed to charge at 14.7 volts can easily charge our batteries in a day. And that is only 300 watts of panels.
So for those of you who think running a generator for a couple hours a day is keeping your batteries charged it's not. And I used to be one of them as well. Or plugging in and running your tow vehicle for an hour or two. That won't do it either.
Flooded batteries like to be fully
charged regularly for best life and capacity. Running them from 50% to 80% is not good for their long term health. And this is probably the range that a lot of people are using from their batteries.
Another side note is that I am using a Trimetric TM 2030 with a current shunt and it keeps track of amps in and out to measure battery levels which is much more accurate than using voltage to measure your state of charge.
Hope this helps someone get a little more life out of their battery.