Power Converter Battery Charge Rate? Anyone?

[nmken]

[p]I've got a technical question about our power converter.  I'm trying to figure out the rate that it charges the battery.  I see in the manual it is an intelligent charge controller with 4 modes, but the manual says nothing about the charge rate - I'm hoping its at least an 8 amp charger but would love to hear from anyone that's already investigated.[/p][p]
[/p][p]Thanks[/p]

[daplumbr]

There's a bit of information on that in this thread. One measurement was 20A charging off the converter (in a 21RBS). 

http://livinlite.proboards.com/thread/265/trying-get-most-out-alternator

[charliem]

[font size="3"]nmken,

There's no set answer to your question. The PD intelligent charger found in the 21s is rated at 45 Amps max and I believe the same one is in the 16s. The converter is basically a constant voltage device so the current is dependent on the state of charge of the battery. If the battery is very low the converter will probably start out close to the 45 limit, but quickly drop as the battery voltage rises. The 14.4 boost level will be maintained until the voltage rises to a preset level or until 4 hours has elapsed. Then the voltage drops to 13.6 and maintains until the battery is fully charged. The current slowly decreases during this time and can take many hours depending on the initial state of charge. When the battery reaches full charge the voltage drops to 13.2 and remains there to maintain the 100% level. If left unattended the voltage will jump to 14.4 for 15 minutes every 21 hours for equalization.

So there's no fixed answer to how much current it charges with. It depends on state of charge, time, wire size, temperature, and lots more. Definitely more than 8 amps, but I'm not sure why you ask about this umber. Follow the above mentioned thread for more charging ideas.


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[daplumbr]

When I hook up my new batteries this spring, I'm going to investigate this further. The converter is rated for 45A maximum, but i assume that's total load and not just for battery charging. I doubt the 8 foot run of rather small wire from the converter to the battery could even deliver 45A. I seem to remember an oddly placed in-line fuse under the trailer in that wiring too, but there's deep snow under there right now, so that will have to remain a dim memory for a bit. I suspect the OP question was about the maximum possible charging rate, in hopes that it was at least 8 amps. 

[nmken]

[p]I think the wire connection at my battery is 16 gauge , which would be good up to maybe 10 amps of DC current.  Using this chart as reference[/p][p]
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[charliem]

[font size="3"]The Camplites are wired with #6 AWG  for the primary battery circuit. The NEC allows 55 Amps at 60C, but this is based on thermal and fire considerations. In low voltage circuits we are more concerned with voltage drop. Your chart allows about 12 feet at 45 amps, but this is based on 2% voltage drop. Note that this is the total round trip distance including both conductors so it's really 6 feet of two conductor wire.  At 12 volts this is 0.24 volt which is a lot in a battery charging circuit. However, all is not lost. The battery will only require 45 Amps for a very short time and only if very discharged. The current will quickly drop as the battery charges so the wire resistance will only add slightly to the required charging time. Most of the battery charging time will be spent in the 10-25 Amp range. The 45 Amp rating is the total from the converter including charging and any other loads on the system, but these loads are small by comparison to 45 Amps. Not a problem here. [/font][font size="3"]The Progressive Dynamics converter is a good 4 stage unit and #6 is adequate for the distance involved.
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[nmken]

I took a closer look at the wire and would agree it appears to be much larger than a 16 gauge wire.  Its a little tough to see the wire because of the jacket and I had used the yellow crimp on to equate it to 14-16 gauge - my bad.  So the good news is that the answer to my question of just how beneficial a solar charger would be - marginal since we have the Honda generator - won't run much to keep the batteries charged and we'll be using the generator anyways for other things (A/C, Microwave)