Progressive Dynamics Intelli-Power 4600 charger upgrade module
Greetings fellow Airstreamers. The last week has been filled with learning about and researching products related to power in an RV. I ended up buying new batteries (lead-acid 24DC) and bought a replacement charger for the converter.
I read through the threads about the batteries - AGM, 6 Volt, Deep Cycle, etc. I shopped batteries too and was taken back by some really high prices and not so good warranties. I realized that a high amp-hour rating with a two-year free replacement is not too bad, especially for $99 each. So, lead-acid won.
As others have mentioned, it does little good to buy batteries if all that will happen is overcharging and premature failure due to lack of care in charging. That lead to a long ordeal of shopping for a new type of converter- the built-in charger that activates when you plug the trailer in to shore power. What I found is a plethora of information on battery maintenance. It seems that batteries overall do best with higher charging volts as it stirs up the chemicals, etc. Too hot for too long though ruins them. Add to that, many chargers hold too high a voltage on the battery for a sustained time when not in charge mode but in maintenance mode, which, I found was to be 13.2-13.5 or so volts. Finally, I found a study where batteries were wired in parallel and had potential issues with overcharge if equalization was not performed from time to time at a nominal charge rate. Make sense?
So, I looked at my stock Parallax 7300. OK, one rate of charge - 13.8 volts period. Not good. Battery does not get the conditioning part of a higher charge for a short time AND worse, the voltage at storage is too high. Ah, so that's what all these people meant when they called it a battery eater! In the parallel battery study they mentioned the importance of being able to interrupt an automatic charger's cycling - more on that later.
So, what I found was interesting. Some converters were all over the place with voltage charging based on temperature. Others had no interrupt feature. Then I found a solution. Progressive Dynamics' PD4655V 55amp converter upgrade for Parallax 7300 owners (and other brands too). Supposedly it just slides in as a direct replacement for my current unit's lower part of the power box. My total cost? $220. The unit has four stages Boost (14.4V/2-3 hours); Normal (13.6V/Absorption); Storage (13.2V); Equilization (14.4V every 21 hours/15 min then 13.2V). On top of this info, there is a cycle indicator and manual override built into the unit (what used to be on a "pendant" option) to interrupt cycles as in the case of absorption cycle in some cases. I will share my install experience.