Parallax Converter

SoundGuy wrote:

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

Yeah... But - this is for our class B - absolutely no extra room anywhere. Not to worry - we plan on keeping this RV for a very long time. ;)

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.

SoundGuy wrote:
X2. There's no need at all to even touch the Parallax ... just leave it where it is and turn it off. sly keep the CTEK and simply turn the WFCO back on again ... a FAR better solution than physically replacing the converter. :B

pasusan wrote:
Yeah... But - this is for our class B - absolutely no extra room anywhere. Not to worry - we plan on keeping this RV for a very long time. ;)

Doesn't change my story ;) ... apparently you've already purchased the PD so I guess you're stuck with it but in your shoes, because your current Parallax is otherwise working just fine, I would have just left it as it and instead invested in CTEK or NOCO portable charger, any of which will have a much smaller footprint than any converter/charger and which can be used anywhere at any time and not require any modification of the RV itself. JMO. ;)

When I replaced my 7345 with a Progressive smart charger I kept the 7345, added a 120 volt cord/ plug to it and used it as a 20 amp power supply for my macerator. Easier than running wires 20 feet or so from the battery big enough to handle the 20 amps plus start up surge.

pnichols wrote:
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.

Phil, based on your postings of this over the years :) I recently grabbed a 7445 (deck mount version of a 7345) at a garage sale to run my new AGM in the truck camper.

Mex says don't fuss with temperature compensation for the AGM Float, so the fixed 13.7ish will do for when on shore power at home or when actually camping with shore power.

I don't have your alternator charging, so I will still use a portable charger that does 14.6ish if the AGM ever needs recharging from low SOC, and for the once a year zap at 15.5v it should get according to the tech at that AGM place.

Sound Guy, your advice is probably good in most cases. But in a Class B, there is no extra room for anything. You take along a battery charger, you have to leave something home.

OP you will be glad you are the changing to the PD.

Snowman9000 wrote:
Sound Guy, your advice is probably good in most cases. But in a Class B, there is no extra room for anything. You take along a battery charger, you have to leave something home.

"Sorry Hon, but I guess no more camping for you." :W

The particular CTEK charger I'm using measures a mere 8.5" x 3.5" x 1.875" ... somehow I think I could find a way to make this work. :p

BFL13 wrote:
Phil, based on your postings of this over the years I recently grabbed a 7445 (deck mount version of a 7345) at a garage sale to run my new AGM in the truck camper.

I'm curious ... is your particular AGM battery type specified to be floated at around 13.5-13.8 volts (at 77 degrees F)? I believe that some AGM batteries specify the normal liquid acid float voltage of 13.2 volts and I would hesitate to expose them to a 73XX converter for long periods as they might "dry out" (i.e. heat up enough internally to periodically release small amounts of their water in vapor form out of their one-way relief valve).

Probably Mex would disagree with me, but when an AGM battery is specified for a float range of 13.5-13.8 volts instead of the usual lead-acid value of 13.2 volts I take it to mean that the AGM battery is designed slightly different mechanically or electro-chemically such that the higher float voltage will not dry it out. However, maybe all AGM batteries can be floated anywhere from 13.2 volts to 13.8 volts due to their intrinsic lower internal resistance giving rise to lower internal heating at any applied voltage. :h

(A Concord rep told me that Lifeline AGM batteries should not be floated at normal fixed voltage converter output voltages, so I passed on using Lifeline AGM's at our last battery change. I chose a set of AGM batteries with a higher specified float voltage.)

By the way ... the Parallax converter I would REALLY LIKE to use to take care of my particular AGM batteries is one of their discontinued 73XX "T" models. These models had an internal timer circuit such that every time you powered them up they supplied 14.4 volts for four hours then dropped back to 13.6 volts for the rest of the time you had the converter powered up.

That (four hours at 14.4 volts then the rest of the time at 13.6 volts) would be perfect for AGM batteries with the specified higher float voltage: Whenever one's AGM battery bank was low, just fire up the generator for a fast charge due to four hours at 14.4 volts and whatever hours needed after that at ~13.6 volts ... all automatically. In essence, the perfect set-it-and-forget-it two-stage converter/charger for use on AGM batteries with a higher specified float voltage.

"I'm curious ... is your particular AGM battery type specified to be floated at around 13.5-13.8 volts (at 77 degrees F)?"

Phil, here are the specs for the AGM I got. I use a different charger that will do 14.6v or so if it needs recharging. I float it on the 7445 at 13.7ish.

http://www.hespv.ca/hesproductspecs/HES/Stark_Battery_TD_ENG.pdf

The battery is made in China. It seems to be the same as the one sold by UPG in Texas. (121 is the AH at the 100hr rate which seems to be where its name came from)

https://www.amazon.com/Universal-UB121000-45978-100AH-Cycle-Battery/dp/B00S1RT58C/ref=pd_lpo_263_bs_img_2?ie=UTF8&psc=1&refRID=789CYR3NBFDNM49NW7AG

BFL13,

Excellent ... both of those AGM batteries appear to be designed to be safely floatable on the fixed voltage output of a 73XX converter.

Being AGM, you might find that they also charge fully reasonably soon on only your converter.

pnichols wrote:
BFL13,

Excellent ... both of those AGM batteries appear to be designed to be safely floatable on the fixed voltage output of a 73XX converter.

Being AGM, you might find that they also charge fully reasonably soon on only your converter.

Phil, I understand your point that they might accept more amps at the 13.7ish voltage from being AGMs vs Wets. But--- their spec is clear that they should be recharged at 14.5-14.9, so that means using a different charger.

I suspect it is the same as with Wets for this, that you need those higher voltages to get as much sulpher as possible out of the lead-sulfate and back into the acid.

I know you get yours down to where they won't accept any amps at all, signalling that they are "full." What would happen if you could then raise the voltage to 14.8? I am thinking they would accept amps again, and taper those to a "true full." Unless your particular AGM specs say otherwise?