Parallax Converter

No, the Paralax is a dumb charger and will eventually boil the battery dry.
I learned this one the hard way! Boiled my battery dry and ruined it.
The only good thing about the 7300 series is the full current rating is available to charge the battery but only at 13.6V so it wont even do that very well.
Do what I did and replace it with the PDI you spoke of. Keeps batts happy during long storage periods.

The 7355 in our 2003 trailer still works just fine. It's 13.8v is good for a Float voltage except in hot weather. If hot out, just add water to the batts more often. No big deal.

If you want automatic temperature compensated Floating, you need a different sort of maintenance charger.

If you are off grid and want a fast recharge to keep generator time to a minimum, the 7355 won't do. You need a charger that will do over 14v ( 14.8v is best). I have a separate charger for that job, and use the 7355 for leaving the trailer plugged in at home.

7300 is a fixed 13.6 voltage converter. Fine in the Winter and mild days plugged in 24/7. Summer in TX you will need to check the water level more often. Also slow to charge if using a generator.

PD would be better in all conditions.

replace it with the prog. it,ll work just fine 24,7

OK... I ordered it. (sigh)

Since we will be boondocking and wanting to charge the battery faster...

Thanks everyone!


One thing I hadn't thought of - all the things I will be doing (and spending money on) a second time. :R

One thing I hadn't thought of - all the things I will be doing (and spending money on) a second time

Sell the things you pull for replacement. The cost differential will be covered by increased battery longevity.

Save the 7300 and reinstall before you trade again.

time2roll wrote:
Save the 7300 and reinstall before you trade again.

Good plan, but if the OP ordered a deck mount converter? Then IMO just leave the 7300 in place and put the deck mount as close to the batts as possible in the rig. Run a 120v receptacle to near there to plug in the deck mount converter.

There is one situation in which your Parallax 73XX converter can be an all-right charger/maintainer for a certain kind of RV battery:

Keep the Parallax .... and instead use the money you would have spent to replace your battery with one that is specified to require the same voltage for storing (floating) it as the single fixed voltage Parallax puts out - and will also charge good enough for many camping styles(ies) using only the single fixed voltage as the Parallax puts out.

i.e. We have had only a Parallax 7345 converter in our RV for over 10 1/2 years. But we changed to AGM batteries that are specified to be stored (floated) on 13.5 to 13.8 volts. In addition, since AGM batteries have much lower internal resistance than liquid acid batteries - they will also charge fast enough (for some camping styles) using only the Parallax's output voltage.

It was a no-brainer in our case because we wanted to change to AGM batteries anyway, for other reasons. We just had to look for AGM battery models that could be stored months at a time on around 13.6 volts without being damaged. We move a lot on our RV trips, so the engine alternator brings them up to full charge in just a few hours between camping spots if we have not been on hookups or generator power long enough at the last camping spot for the Parallax to fully charge them.

time2roll wrote:
Save the 7300 and reinstall before you trade again.

BFL13 wrote:
Good plan, but if the OP ordered a deck mount converter? Then IMO just leave the 7300 in place and put the deck mount as close to the batts as possible in the rig. Run a 120v receptacle to near there to plug in the deck mount converter.

X2. There's no need at all to even touch the Parallax ... just leave it where it is and turn it off. Since trailer batteries are most often mounted on the tongue the front pass through storage compartment that many trailers have is the perfect location for your new PD - out of the elements yet close to the batteries ... all you need is 120 vac to feed it and heavy gauge cable to run to the batteries. I'm doing precisely the same thing with my recently acquired CTEK Multi US 7002 charger which I'm using in place of the WFCO 8955 converter which never bulk charges as it should at 14.4 volts. I've just turned the WFCO off and use the CTEK instead ... when/if I sell the trailer I'll obviously keep the CTEK and simply turn the WFCO back on again ... a FAR better solution than physically replacing the converter. :B