when should a powermax pm4b drop into float mode

lol, o.k., 90 seconds.

You don't need all four screws. One each side at opposite corners is plenty :)

yep, or simply mod one of these:

http://www.adventurerv.net/powermax-amp-converter-power-max-pm355-p-28099.html

To be honest, I don't see the need to have the knob for quicker adjustments (compared with re- and re-'ing 4 screws and twiddling the pot; which only takes a total of about 2 minutes) For the most part, the unit will be 'set and forget', anyway. That said, as a portable charger, the knob makes real good sense. And I do see a benefit to the knob if the OP top charges to over 15v on a regular (say weekly) basis.

And one could very easily attach a 4 digit, 2 decimal place volt meter to the lid and wire it to the +/- outposts; for reading output voltages during both normal operation and while doing adjustments.

For the people that want manual control, without building it themselves... Instant gratification.

Manwell Charger by Randy at Best Converter

Yeah, that last one was a pretty hard & fast cycle. But it just shows these 6 volters can handle it. My next step is to top charge all 4 batts individually, then string them in series/parallel, and start using them as usual. (I haven't been staying in the camper for a while now, so they, and I, need to get back to our usual routine to see the full effects).

I also need to do a series of 50-85% cycles, then a full-on top charge to see how they respond to the typical boondocker strategy.

thanks guys.

Nice work jrny!

Another convert that has seen the light on a good top charge and Equalization routine. Don't worry about the slight voltage drop, all the cells are now pulling equal weight. Until the next time...

I tend to think that after the first equalize, if the batteries have been a bit neglected, take them down, now that they are equalized, to a 50% SOC with normal use, about 12.1 volts, at rest, no load. Do a full top charge and equalize session again. You should be able to get the next EQ done in an hour to 1.5 hours this time... watch the voltage, do you get to 8 volts per battery? You might be pleasantly surprised with the SG readings the second time around. I know I was, it was a good battery "tune up" in my case.

EQ Update:

The batts rested another 4 days, tied in series. Resting voltages were equal. I did a fast discharge at over 30a for about 2 1/2 hours, followed by a 14.8v charge with the pm4b, back up to near full. The next day I checked sg's:

Batt A: 1.280, 1.275, 1.275

Batt B: 1.275, 1.275, 1.275

I equalized two of my 6v gc's with the cps 1620.

Nice accurate toggling; coarse, fine, extra fine. You can adjust the voltage by the hundredths, tenths, singles, and tens of volts by simply pushing the adjuster knob to light up the digit range. Amps same thing, but to the tenths.

In series, after doing a top charge the previous evening, the batts were resting at 12.79v; individually at 6.40 (A) and 6.39 (B). I set the 1620 at 8v and 10.7a for a single 6v/215Ah battery, and did a 3 hour EQ on each separate battery.

Battery A:

Voltage rose rather quickly to 8v, with unit in c.c. mode. After a short while, amps began to taper, and unit switched to c.v. mode. About 2 hours in, amps began to rise back up, from about 8 amps, back to 10.7a (a thermal issue, I'm presuming?). Then voltage began to drop to 7.87v in c.c. mode, by the end of the 3 hour charge.

After resting a few hours, while the other 6v was being EQ'd, S.G. readings went from 1.290, 1.285, *1.275* (pre EQ) to 1.290, 1.280, *1.280*. After another hour and a half of EQ, and a three DAY rest, S.G. readings tightened up to 1.285, 1.280, *1.280*. But, as with every higher voltage charge I do, the resting voltage had dropped, in this case from 6.40v (pre EQ) to 6.36v? (And yes, I do realize there was still some surface charge, but please see comparison in last paragraph).

Battery B:

Basically the same profile, but the amps began to rise back up after only about one hour, to 10.7a, and 7.93v c.c. by the end of the charge. After a similar 3 hour rest period, the S.G. readings went from 1.280, 1.285, *1.265* (pre EQ) to 1.285, 1.285, *1.275*. After a similar, additional hour and a half EQ, followed by a 3 day rest, S.G. readings tightened up to 1.285, 1.280, *1.280*.

So, a rather successful EQ it seems. I will keep an eye on the *two* cells' s.g.'s to see if they slide back down.

The weird thing is, before doing these EQ cycles, battery A had always had lower s.g readings, and a slightly lower resting voltage than battery B, but had already started holding higher s.g.'s and resting voltages, after doing a few top charges with the pm4b and Peak. Now, after the EQ, both are holding similar S.G.'s and resting V's. :)

After the 3 day rest, both batts were holding steady at 6.36v, so I wired them back up in series. Today, a total of 6 days later, they're each holding their own, equally, but at an even lower resting V of 6.35?

One thing I have noticed, is the larger 430Ah bank seems to hold a higher resting voltage (12.78) than the two 215Ah banks (12.76), which in turn seem to hold a higher resting V than the individual 6v's (6.36 x 2 = 12.72).

wheee, indeed !