Should I Change My WFCO Converter?
Opinions have often been expressed, both on this and other RV forums, that most stock RV converters are inadequate to properly charge and maintain batteries and are often of poor quality. It is frequ...
Forum Discussion
jrnymn7 wrote:
Mike, just keep in mind, it's what's happening at the batteries that counts. You must adjust the power supply (up) for voltage loss across the wiring, from power supply to batteries. Therefore, the shorter and heavier the cable, the better. And the higher the amps, the greater the voltage loss. So, when charging, compare voltage at the power supply's output with that at the batteries, and you'll see there is a drop in voltage across the wiring. In my particular case, I saw .07v drop over 4' of 4ga at 40a.
I've been going thru some notes, and using a 45 amper on a 215Ah bank, amps were down to 40a, at 14.8v(at batteries), at about 84% soc, (at ~65F). Your bank is slightly larger, so you should see the MegaWatt's amperage maxed out 'til at least 85% soc, I would think. This means two things, essentially, 1) using a 40 amper on a less than 85% soc 225Ah bank means less Ah's replaced than is possible with a higher amp unit, within the same time frame, and 2) if you only charge the bank from 85% soc and above, a higher amp unit would be of no benefit. Nevertheless, you will be able to do a 50-85% in 2 hours, at 40 amps, and an 85-97% in about another hour, amps tapering. When amps taper to somewhere around 30a, at 14.8v at batteries, you'll know you're in the 90% soc range.
If you have a good idea how many Ah's you've used, you can easily estimate the time it will take to replace them. For example, at 40 amps, that's 40a/60minutes, during the 50-85% range on your size bank. That's .66a/min. So, if you're at say 75% soc (which is -56Ah's on a 225Ah bank), you can do a 75-85% (-56Ah to -34Ah, thus replacing ~22Ah)in about 35 minutes (diff of 22Ah / .666Ah/min. = 33 min.). So, a 75-97% would take about an hour and a half. The final 3% will likely take another hour, or more. And this is why many part time boondockers do 50-80's with as large a charger as they can, while on gen power, and then do a good 80-97% followed by a 97-100% top charge immediately after getting home.
Not doing a proper top charge, (and if indicated by SG readings, a proper EQ), after a week or two of doing 50-80's, will inevitably result in premature battery failure.
Thanks for this and all the other info from you and others. I'm going back through the posts on this thread and printing out those that are especially helpful.
I hope the Megawatt comes with some good instructions.
Mike
