new power max converter, problems

[shane102]

Replaced wfco 8955 converter with power max pm4b-55-mba converter. I put the new PM in today and followed the testing directions.

Step 1. With only shore power hooked up and all DC fuses pulled and battery disconnected (No load): voltage reads 14.74 on output side and no noise from converter. Directions say it should read 13.6 +/- .2

Step 2. with fuses in and battery hooked up and shore power on: voltage reads 12.54 on output side and the converter starts humming. Nothing in rv is turned on. Voltage at batteries read 12.54. Directions say voltage should be the same or close.

shut down all power at this time.

Voltage at disconnected batteries read 12.48.

first question is: the PM converter wires that hook to output side of fuse panel (DC side) are white and blue and both are 10 awg. I hooked blue wire to positive connector and white to negative. Is that correct?

Not sure why at step 1 the voltage is reading 14.74 with zero load? And not sure why at step 2 the converter is humming with nothing on?

I will be calling best converters in mourning. Any help, please.

[BFL13]

Voltage drop is proportionate to the amps flowing. Your batts are full so there are no amps flowing and so no voltage drop.

The converter appears to be working properly. It is the path from converter to battery that has such high resistance right now that is screwing things up for being off-grid. The high R could be too long, too thin wire, loose connections, or some of each.

[shane102]

Ok, I am not getting voltage drop anymore and the converter is not humming anymore. I have to get on my knees and put ear next to converter to hear it.

So, I unplugged shore power let it sit for couple hrs. Plugged back to shore power and now the converter is very quiet and at converter the volts read 14.7 and at batteries read 14.6. And now every time I check voltage there is only .1 difference between bats and converter (currently, con is 13.6 and bats 13.5

Did the converter "burn" itself in as Randy said it would and now it is performing correctly. Waiting for him to call back.

[CJW8]

Be careful about using jumper cables as BFL13 suggests. Some use very thick insulation with #6 or smaller wire. The thickness of the insulation gives you the impression that you have thick wire. (Plastic is cheaper than copper) Better jumper cables have at least #4 wire.

[shane102]

1600 generator: It is a coleman powermate 1600 sport and it is rated at 1300 and surge at 1600. I have 2 RV deep cycle les schwab batteries and they are brand new.

I left trailer on shore power all last night and today with no load. volts at batteries and converter are 13.17.

[time2roll]

shane102 wrote:
I will be using generator for charging most of the time. Small gen is a 1600 watt and big gen is a 3500 watt. I will be using 1600 mostly and using 3500 when I need air conditioner.

What changes do I need to do for charging with generator.

Is the 1600 rated or surge? Honda 2000? 1600 rated Honda will drive the 55 amps but 1600 surge might be 1200 rated and possibly overload.

How many batteries again?

I honestly think you would be better with a PD or IOTA close to the battery. PowerMax is better IMO for mostly pedestal hopping.

[BFL13]

with the batteries at 12.1 at start, the converter should have gone back to 14.6 after the 15 minute thing, and stayed at 14.6 for some time before dropping to 13.6. As it is, you might as well have kept the WFCO! 😞

To prove the PowerMax is working right, if it were me, I would haul it out, use shorter cables close to the batteries (probably with a set of ordinary jumper cables, and on low batteries, make sure it does some time at 14.6 past the 15 minute point. Right now the numbers are confusing, but could be due to voltage drop, don't know.

For generator charging, you need to stay at 14.x once the batts get that high. I like the adjustable voltage PowerMax for that to the highest amps you can run with the generator. Note that the 75 is PF corrected so it draws the same as the non-PF 60. Might be ok with the 1600 if that is VA not watts (A Honda 2000 is 1600 VA).

For generator charging on the 1600, you should set the converter up near the batts same as above, and get some time at the 14.6 volts till it drops to 13.6. If that is close to 80% SOC (hard to tell without a Trimetric)then IMO adopt 50-80s as your off-grid procedure till you can get shore power and "recover" the batteries.

If you don't mind using the 3500, then you could get a 100 amper and use both for a 155 amp fast recharge in Bulk

[shane102]

i did not read your posts before leaving and pulling the batteries down. Batteries are brand new and fully charged

So, here is another voltage test (probably getting boring).

The batteries are now at 12.14 volts. Turned on shore power and volts at output are 14.48 and at batteries 13.38. fan kicked on at about 4 mins and ran for about 1 min then shut off and volts at output read 13.6 and read 13.3 at battery.

Things seem to be working fine, I think. Other than the voltage drop.

I will be using generator for charging most of the time. Small gen is a 1600 watt and big gen is a 3500 watt. I will be using 1600 mostly and using 3500 when I need air conditioner.

What changes do I need to do for charging with generator.

[time2roll]

No further testing is needed. No need to cycle the batteries.
Just leave it plugged in. You are ready to camp.

If you plan to charge on generator would be the reason to make changes.

[MEXICOWANDERER]

Can somone send down an exocist to pull the evil out of my Whiffco after running at 13.6 for nearly a year?

[BFL13]

Not clear what state the batteries are in. Need SGs or a resting voltage before you drain them down again. If the batts are indeed full, the converter must be running the loads at 13.2 Float without being kicked back to 13.6.

I don't know what it takes to get them back to 13.6 with that converter. (or why it would be necessary if it is running the loads ok) ISTR WFCO or PD blurbs do say that running loads will bring their converter back to 13.6 from 13.2 Float.

[shane102]

Ok. as of now, after running lights and heater for almost 4 hrs this mourning and hooked to shore power, the voltage reads 13.08 at converter and 13.04 at batteries. This voltage has basically stay the same for the 4 hrs.

When I unplugged from shore power the voltage read 12.65 at converter and 12.73 at the battery.

I will now drain the batteries for a few hrs and see what voltage does.

Any other ideas need doing

[BFL13]

---OP, that 13.17 might be the 13.2 Float. It should go back to 13.6 if you run some loads if I understand that right.

I was trying to agree with RJ 🙂

If I couldn't have my adjustable voltage PowerMax, I would choose the PD with Charge Wizard. Iota does not have the PD's lame amps, but its IQ4 controller is not like the Charge Wizard in that you cannot make the IQ4 controller change which "stage" (voltage level) it is in. It would not help that situation where the controller is too far from the batts like the CW can.

[shane102]

This mourning the voltage at output side of converter is 13.17 and at batteries voltage is 13.16.

I am assuming that when I start putting a load on batteries and battery charge goes down then I will still see the voltage drops (as I did last night) when converter is trying to charge.

The wire size from converter output to batteries are 6 gauge

I will check connections, wiring and etc for voltage drop.

[time2roll]

BFL13 wrote:
Yes, the PD with Charge Wizard helps when your converter is too far from the batts by letting you keep the 14.4 going. That does not cure the PD's lame amps though.

I have to agree with RJ on this one. PD will outperform Powermax in most generator use conditions and especially in the OP's situation.

As for lame amps... PD would be far higher from 15 to 240 minutes. Powermax might lead for the first 15 minutes only.


Even if both are right on the battery, the Powermax is dropping down at ~75% charge. PD continues well into the 90% zone.