AGM or not?

ovsa · 05-08-2021, 03:34 AM

I was ready to spring for an AGM 12v 105 Ah for my 2003 Chev Roadtrek 170P but then I read that the charger does not recognize AGMs and would probably shorten its life span.
Can anyone confirm this.? I have the Parallex 7345a that the owners manual calls a multistage charger. I'm wondering if it's suitable for AGMs.
If not ..is it worth changing out the charger only? Is that possible or is it all integrated? Or should I just stick with the old flooded type.?
Thanks for your input.

mikeehlert · 05-08-2021, 03:42 AM

The charger will be fine for your AGM battery. Life will depend on ho you treat it. Drain it to 11 volts and you can kill it in a month. Keep it 12.0 and above with full charges after use and it should last 5 years or more.

ovsa · 05-08-2021, 04:10 AM

O.k. thanks.

booster · 05-08-2021, 01:09 PM

That charger appears to be a 13.8v fixed voltage model and will not take good care of any lead acid battery. It will not get the battery to complete full because of the lower voltage compared to the 14.4v typically required and if left on the battery for long periods will dry out the battery from being to high a voltage compared to the 13.2-13.5v recommended for lead acid.

Wet cells, at least true deep cycle ones, probably handle it a bit better than AGM, but in a GP27 you may have trouble finding a true deep cycle any more.

You would be able to get fair life out of the battery on that charger, but would need to use it carefully, making sure you shut it off from charging after getting as full as it will get on that voltage. Probably in the range of 12 hours per this old charge curve they show. It was for a 50% discharge cycle, so more discharge would add more time by a couple of hours.

Wayback Machine

No long term "float" with this kind of charger, just do a charge every few weeks.

Predicting life is really hard to do accurately as everybody's use patterns and driving amounts are different.

Many users have upgraded that model with a Progressive Dynamic units which I think goes into the same case and uses the output panel you have. Might be worth considering.

SteveJ · 05-08-2021, 02:43 PM

I replaced my factory converter/charger guts with a Progressive Dynamics PD4645 and it took very good care of my lead acid battery.

https://www.bestconverter.com/4600-s...its_c_133.html

ovsa · 05-08-2021, 09:11 PM

Will it do AGM as well? Thx.

ovsa · 05-08-2021, 09:36 PM

I was reading through the Parallex 7345A document included with the Roadtrek manual and found this.:
" Your Parallax 7300 series power converter is capable of delivering its full rated output to the battery(s) if needed, but will taper off to a few hundred milliamps when the battery(s) are at full charge."
Does that make it a multistage charger then?
Is there an advantage if swapping out to the PD 4645?

booster · 05-08-2021, 09:46 PM

Quote:

Originally Posted by ovsa

I was reading through the Parallex 7345A document included with the Roadtrek manual and found this.:
" Your Parallax 7300 series power converter is capable of delivering its full rated output to the battery(s) if needed, but will taper off to a few hundred milliamps when the battery(s) are at full charge."
Does that make it a multistage charger then?
Is there an advantage if swapping out to the PD 4645?

The link I provided about shows the charging profile and it is one voltage at 13.8v so is not multistage. Tapering amperage will happen with it but multistage refers to voltage which is needed to get batteries fuller and quicker plus preserve their capacity. The PD is a multistage charger and if purchased with the pendant can also be manually controlled by pushing a button. The problem is that the 13.8/v is too high if the unit is left on for longer periods and is too low for decent and reasonably fast charging.

Road Toad · 05-13-2021, 06:02 PM

Quote:

Originally Posted by booster

The link I provided about shows the charging profile and it is one voltage at 13.8v so is not multistage. Tapering amperage will happen with it but multistage refers to voltage which is needed to get batteries fuller and quicker plus preserve their capacity. The PD is a multistage charger and if purchased with the pendant can also be manually controlled by pushing a button. The problem is that the 13.8/v is too high if the unit is left on for longer periods and is too low for decent and reasonably fast charging.

Booster is correct.
I own this same unit.
Constant charge voltage of 13.6 on mine.
If keeping, do not keep it plugged in continuosly.
Chage every few weeks.
Best to upgrade via BestConverter
Very simple to R&R the charger part.

rvsprinterguy · 05-13-2021, 07:21 PM

I'm no expert in this field, but I replaced my house wet cell battery with an AGM battery of same dimensions and similar capacity about four years ago and it's still going strong. I did nothing to the charging system.

Bud · 05-13-2021, 07:33 PM

Quote:

Originally Posted by rvsprinterguy

I'm no expert in this field, but I replaced my house wet cell battery with an AGM battery of same dimensions and similar capacity about four years ago and it's still going strong. I did nothing to the charging system.

What charging system do you have?

rvsprinterguy · 05-13-2021, 07:46 PM

I have a Parallax 7300 converter charger, which was furnished by the upfitter when the van was built.

Polo · 05-14-2021, 05:12 PM

An AGM battery is no different from a flooded battery or any other sealed lead acid (SLA) battery when it comes to your alternator or charger/converter. Their main advantage is that they do not need venting and can be installed in awkward locations. This is like all the hype about KETO free and Gluten free diets... people need to do the research to understand what the hype is all about before they get all worked up.

That said, we did upgrade our charger/converter from the legacy Parallax to a modern, 4-phase, microprocessor controlled charger converter (Progressive Dynamics PD-4645). It cares for our house batteries much better than the old one which boiled one of our two batteries over when the other developed a weak cell.

Our approach and your mileage will surely vary. Happy Trails!

Paul and Christ
06 Winnebago View 23H in NW FL

booster · 05-14-2021, 05:42 PM

Quote:

Originally Posted by Polo

An AGM battery is no different from a flooded battery or any other sealed lead acid (SLA) battery when it comes to your alternator or charger/converter. Their main advantage is that they do not need venting and can be installed in awkward locations. This is like all the hype about KETO free and Gluten free diets... people need to do the research to understand what the hype is all about before they get all worked up.

That said, we did upgrade our charger/converter from the legacy Parallax to a modern, 4-phase, microprocessor controlled charger converter (Progressive Dynamics PD-4645). It cares for our house batteries much better than the old one which boiled one of our two batteries over when the other developed a weak cell.

Our approach and your mileage will surely vary. Happy Trails!

Paul and Christ
06 Winnebago View 23H in NW FL

You also need to understand how the PD converter works, as it is a straight timer style converter for the most part. It will put the same amount of charge into a battery that is down 20% as one that is down 80%, for instance, when looking at the absorption stage as the "charging" section of the charge profile. PD calls it "boost" however for some reason. On low batteries they count on the batteries getting full on a semi-float stage that takes a full day or more.

The PD can be run manually, also, which is it's biggest feature IMO. If you have a battery monitor that reads battery charging amps and volts, plus has an amps based 100% charge indicator, you can easily have the PD charge just as well as over $2K+ worth of Magnum charger. You just have do it manually instead of having it do it itself. You do the control from the add on pendant for the PD.

booster · 05-14-2021, 05:48 PM

Quote:

Originally Posted by rvsprinterguy

I have a Parallax 7300 converter charger, which was furnished by the upfitter when the van was built.

I am pretty sure that is a fixed voltage at about 13.8v charger, so it will not get the batteries totally full or charge very fast. You also need to shut them off if it is going to be more than a day when you are through charging as they will dry out the battery. If you do that they are OK, but won't get full completely full batteries.

Polo · 05-14-2021, 05:49 PM

Booster,

Thanks. I'm an engineer but not an EE. I was pretty sure someone would set me straight!

Paul and Christine G.
06 View 23H in NW FL

Road Toad · 05-14-2021, 07:12 PM

Quote:

Originally Posted by booster

I am pretty sure that is a fixed voltage at about 13.8v charger, so it will not get the batteries totally full or charge very fast. You also need to shut them off if it is going to be more than a day when you are through charging as they will dry out the battery. If you do that they are OK, but won't get full completely full batteries.

Booster.... If we attach a 4 amp battery-tender to the batteries, should we disconnect with the coach panel switch, or does it matter?
Opinion of that idea??

booster · 05-14-2021, 08:35 PM

Quote:

Originally Posted by Road Toad

Booster.... If we attach a 4 amp battery-tender to the batteries, should we disconnect with the coach panel switch, or does it matter?
Opinion of that idea??

A four amp tender is a pretty big one so it probably wouldn't matter much as the coach probably takes under 1/2 amp. It is still a good idea just so the tender sees actual battery maintaining current though as there is no reason to run the van stuff.

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