cdcorpe wrote:
Per request I just finished my 1 hour test. I said it was a power max boondocker, but in fact it is just a power max 75 For the 1st 15 minutes, the volts were 13.2 (give or take .1) the amps were 74 (+- .5) after 15 minutes the volts were 13.5 & amps dropped to 35 every 5 minutes they drooped 1 or 2 amps volts stayed at 13.1 or 13.2 at the end of 60 minutes amps were 24.5 , no change in volts.
On its label, does it say PM3-75 or PM4-75? Very important!
Also the one hour test was with the batteries at what SOC to start with, and how did you measure/calculate that?
You say the battery voltage rose from 13.2 to 13.5 in fifteen minutes with constant 74 amps, then suddenly the amps dropped to 35 amps and tapered slowly after that?
That would suggest the batteries were around 75% SOC when you started and the converter acted as designed. If only you had four batteries instead of just the two so the charging rate would be lower, then you would no doubt (IMO) see how it actually works.
In fact it looks like your two batts are not up to their rated capacity so the charging rate with the 75 is even higher, making it hit Vabs at a lower SOC than expected. Are the batts sulfated at all? have they been equalized/desulfated recently?
Note that if you get a different converter with similar amps to the 75, it will still hit the Absorption voltage and start tapering the amps at the same battery SOC near 70% with the two batteries.
If you had a PD converter, you would need its Charge Wizard to keep the Vabs up for the four hours. Note also the PD9280 needs a 20a circuit, but the PM 75 has power factor correction so it can run on the 15a circuit, and also with a Honda 2000. if you are staying with two batteries, and do get a PD, perhaps a 60 amper would be better. The charging time difference between a 60 and an 80 is about ten minutes of generator time to do a "50-90"
