Deep cycle battery charger

PowerMax is now shifting over to LKs, which have the ADJ feature besides the normal 3 stage feature, so the PMBC external knob ones will be special order only in the future.

Advantageous versus the power supplies that need compensatory adjustments. I like that. I'm getting ready to try out the settings on the 1500 which uses a totally different sensing circuit than the 350 or 400 watt units. Time to fiddle with damping caps.

I tried a test for that, but used "13.7" since that is what the batteries are at and full. If I jack up the voltage to 14.x, it will be forever till things settle and I could take readings.

RV sitting in yard plugged in at 13.7 with battery bank 450AH of AGMs full. Disconnected solar and all possible 12v loads. Disconnected 55 amp ADJ neg wire at charger's terminal.

So PowerMax 55 ADJ still plugged in but not connected to load, reading 13.68 on multi-meter at DC terminals and 13.7 on its own little meter. (Going back and forth 13.67/68 but got it to stay at 13.68--very sensitive knob, hard to get it to stay at any one second decimal place)

Trimetric says disconnected batteries are at 13.7 and have a draw of 00.2 amps (some of which would be the Trimetric itself)

Stuck the neg wire back into the converter's terminal. Trimetric says battery voltage still 13.7 but charging at 1.0 amps, tapering.
Voltage at converter terminals 13.68 and at the battery bank 13.66 (wiring zoo between converter and battery bank)

Waited till amps tapered to 00.1 on Trimetric. Voltage at converter terminals still 13.68, batteries back to being full at "13.7"

Asked another way.

Set voltage to say 14.45

When batteries are fully charged does the voltage read 14.45 or less? If less, how much less. There is a .15 volt discrepancy with power supplies. Let's say I fire up a Meanwell or a Megawatt and set voltage to 14.45 and the battery is right at fully charged to begin with. The voltage drops to 14.30 and stays there. The power supply can stay connected for a month and maintain 14.30. Disconnect the battery and it will rise to 14.45 <50mv ripple should answer that question.

This is called "slump" and it's important enough to ask if it exists.

Thank you.

"The PMBC Series ADJ – 12V looks like a good machine. But how close to the preset voltage does the unit get when charging? If it is set at 14.80 volts, does it end up at 14.80 volts?"

Not sure what is being asked, since Mex already knows what follows, but anyway----

The unit stays at the set 14.80 volts the whole time. (As set while not connected to a battery)

But when it is connected to the battery, the voltage on the connecting wires is lower, and rises as battery voltage rises with rising SOC.

Also once Absorption starts, the voltages seen at either end of the wires get closer together from the reducing voltage drop as amps taper.

At the end, in theory, with no amps flowing, the voltage on the wires would finally be 14.80 at each end. However, absorption never quite ends, but it could get to where it looks like 14.80 depending on the accuracy of the voltmeter.

I think that would be the same with any battery charger.

The PMBC Series ADJ – 12V looks like a good machine. But how close to the preset voltage does the unit get when charging? If it is set at 14.80 volts, does it end up at 14.80 volts?

The Meanwell I am rigging up maxxes at 138 amperes. I am force feeding it additional air for cooling. It has 11-preset voltage selections which covers just about everything imaginable. Including an on-on switch for .5 volt temperature biasing of all 11 settings. The RSP-1500-15 is a three hundred plus dollar unit but it isn't for amateurs. It uses "Hirose" connectors and even 25 AWG wire is large for the Hirose connector pins that get biased 0-2K with resistors to set voltage or a 0-2K pot which is easier. The 11-stage single deck switch was hard to find in mil-spec quality. I cannot recommend the Meanwell so I need an alternative to recommend and it looks like the Power Max PMBC Series ADJ – 12V is it.

I'm tickled to see that some of the more savvy vendors are recognizing that charging an off-grid battery is more than push a button then return to I Love Lucy.

My monster Belkor 400 amp 24 volt charger needs to have 2 wires swapped from terminal to terminal to adjust voltage. It's transformer is every bit as large as a 1,100-watt microwave oven tipped up on end. It has a lifting eye on top. It is obvious to the eye it is a ferro-resonant saturated transformer type charger. All I did was switch rectifiers to 5 pound each metal plating rectifiers and install an 8" diameter EBP Pabst 24 volt fan.

Jesus, laughs and says I should buy twenty large panels and then plant twenty coconut palms. In ten years the palms will be lifted up into sunshine and the family will have solar power.

MEXICOWANDERER wrote:
I looked at the Power Max converters but so far have failed to see one with an external voltage control knob. Maybe BFL13 and others can help me find an image and spec page.

I believe this might be a bit custom for or by Randy.

http://www.bestconverter.com/Boondocker-BPCM-75-75-Amp-Adjustable-Power-ConverterCharger

Mex, here is one for the 100amp ADJ--the photo is of the 75 amper though (three fuses the 100 amper has four fuses.)

https://www.boatandrvaccessories.com/products/powermax-pmbc-100adj-charger

You can get these PMBC-ADJ in various amp sizes.

Some specs are available here--but they are not all accurate--eg, the 75 amper does not have PF correction as some ads claim. The 100 amper does for sure.

Here is the manual for the PMBC LK version which has the holes in the side. Ordinary LKs do not have the voltmeter and on/off switch on top like the PMBCs can have.
The voltage range using the ADJ is 16.5v down to around 12 ISTR. The early ones of these only went to 15.5, but that got changed.

http://powermaxconverters.com/wp-content/uploads/2018/05/PMBC-ADJ-Manual-2018.pdf

Para 10 applies to the ordinary LK too. If you twiddle the pot while it is switched to 3 stage it changes all the stage voltages. You can repair that by starting over and set 14.6 in ADJ mode and switch back to 3 stage mode.

Here is an ad for the 100amp LK

https://www.amazon.com/Powermax-PM3-100LK-Power-Supply-Light/dp/B01MS4F5QT/ref=sr_1_17_sspa?ie=UTF8&qid=1528030632&sr=8-17-spons&keywords=powermax+converter&psc=1

time2roll posted a link to the bestconverter version of the PMBC ADJ. Randy calls his "Boondockers"

The "boost" voltage of the 3 or 4 stage ones varies by model from 14.4 , 14.6, and I think a 14.8.

Some of the ADJ models have a 15 minute thing at the start where they do a higher voltage for 15 minutes then drop a volt. So you get 16.5v for 15 minutes, then it drops to 15.5. If you start with 14.6 it will drop to 13.6 after the first 15, so you have to crank it back to 14.6 and now it will stay there.

The 3 stage option in the LKs has a 30 minute initial boost no matter what ISTR. It will stay in boost longer if the batts still accept the amps. The PMs had that drop to 13.6 from 14.4 as soon as the batts hit 14.4, which was too soon. This 30 minute thing in the LKs is meant to address that--at least somewhat.

There are so many versions it is hard to keep track of what does what for specs.

AHA! Finally! It looks like PowerMax is going all in with the LKs. They have a new product line up here, but the photos are still showing the old PM3s. (You can spot an LK by the two holes in the side and by the lack of the external fan)

http://powermaxconverters.com/products/

The charger has to do "Top Charging". Know of any that does this? Hmmmmm? Hold 15 volts for a selectable amount of minutes?

Or a charger/converter/whatever that can deliver 5% of bank amp hour capacity with a 16.0 volt ceiling? Hmmmm?

The amperage throttle is attainable using 100 or 50 watt 12-volt light bulbs. Or an even cheaper aluminum enclosed power resistor. But voltage throttle is unattainable in anything but a power supply.

I looked at the Power Max converters but so far have failed to see one with an external voltage control knob. Maybe BFL13 and others can help me find an image and spec page.

Regardign PD converters and why when Mine failed after 12.5 years I put in a new one (Ok a Factory Refurb).

My Factory Original Interestes lasted NINE years and during that time they had severl "OPPS" discharges (To well below 50% State of charge) and they still lasted 9 Years with little maintenance thans to the PD converter taking care of 'em. Most batteriesk well cared for, last 7-10 years.