AGM Batteries replacement ?

[MelGoddard]

Originally Posted by lewster

Actually.......not so much!!!

There are major discrepancies between the bulk/absorb requirements of liquid cells vs. AGM batteries.

For example: Many of the 'better' liquid lead acid cells like Trojan require up to 14.8VDC for a bulk/absorb charge while many AGMs like Lifeline require 14.2-14.4VDC. It may not seem so.....but a differential of 0.4-0.6VDC is HUGE!!!!

Also, 3-stage converters used as battery chargers are a severe compromise for a few reasons:
• no temperatrue compensation to vary the charge voltage as the ambient temperatures change
•*a 'one size fits all' approach to the size of the battery bank. Battery banks of larger capacity require longer absorb charge times than smaller banks
• you have to use the pre-set charge voltage levels that come programmed into the converter, which don't specifically apply to ANY battery bank

......AND......the quickest, BEST (since you mentioned the word) way to charge any type of battery bank (including lithiums) is to use a FULLY PROGRAMMABLE charger like those found on quality inverter/chargers like Magnum and Victron or Victron's dedicated battery charger systems like the Phoenix and Centaur units.

All are fully programmable for voltage settings, input amperage to the batteries, length of the absorb charge and have full temperature compensation.

So, on my 2016 30' FC, did I not do right by replacing my Parallax 7300 with a Progressive Designs PD 4655?
It seems to be keeping my Interstates charged up, with the voltage at 12.6 at 0 Deg. C.
My only 'eyebrow raiser' is that the SG. MEASURES AT 1.300 (0Deg.C) way up at the top of the white band on my trusty Hydrometer.
It doesn't seem to be using water; the levels are right at the indicator slots. BYW. the trailer is in storage, out the back on a dedicated concrete pad.

Look after your equipment, it will look after you.
Trailer Trash.........."

[MelGoddard]

Originally Posted by Troutboy

The Parallax will kill your AGMs. Get a new one that is programmable, Lewster knows his stuff. He guided me to the new system I am installing as well as many others on these forums.

Getting new AGMs and not a new charger is like changing oil and not replacing filter, or taking a shower and putting on dirty underwear! [emoji12]

Nice analogies!

trailer trash....................

[DaveP]

Woodfox45,

I have two battery doors also (on a 2004 Classic 28). The Lifeline GPL-27T battery will fit in these boxes. Two of these batteries would give you a 100Ahr capacity before requiring a recharge (at 50% discharge). They would need a capable charger and monitor, however, as already mentioned in other posts. Otherwise, as I have done, you can cut out the boxes, seal the doors and install batteries under the front couch. I put in four GPL-4CTs in series/parallel to get 12v and 220 Ahr effective capacity (coupled with a Magnum 3012M for charging and inverting).

DaveP

[franklyfrank]

Originally Posted by Tn Traveler

Deka AGM batteries are manufactured by East Penn. Deka dealers will sometimes negotiate price. At any rate the price will be better. I got tired of paying the Lifeline price on my boat. I negotiated two 8d Dekas down to $485.00 ea. That's much better than he nearly $800.00 for Lifelines. Sure the Dekas will not last as long, but at about a 40% savings they are a good deal.

For optimal charging on AGMs a 3 stage chargers is best. However, the flooded battery charge voltage is close to the rate of charge of AGMS. For best charging results in the shortest charge time a 3 stage is best.

I get 4 plus years out of my Interstate batteries and can replace them for $ 129.00 per. for the two back ups and $ 178.00 per for the two house batteries on my boat. I got six years out of two of these. So why would I go to AGMs for almost triple the price ? What am I missing ?

[DaveP]

Originally Posted by franklyfrank

I get 4 plus years out of my Interstate batteries and can replace them for $ 129.00 per. for the two back ups and $ 178.00 per for the two house batteries on my boat. I got six years out of two of these. So why would I go to AGMs for almost triple the price ? What am I missing ?

Frank,

Mostly for greater Amp Hour capacity (and a sealed, no maintenance battery).

DaveP

[Troutboy]

Frank, if you boondock for any length of time you will need more amp hours. If most of your camping is on hookups, I think the stocks work great and you seem to have the touch to ge the, to last. The only reason I am upgrading is because we tend to boondocks more and for longer periods of time.

[gecko]

A lot raised here!

First of all, if you're boondocking, do you have solar for recharging?

We have four six volt Lifeline AGM's that should have died since we have the original one stage Parallax charger, but the theory as to why they are still going strong after 8 years is that we use a BlueSky programmable 3-stage solar "charger" which they seem to like.

For boondocking, the 440 amp (220 usable) has worked fine for weeks with only 270 watts of roof mounted panels. Anything less would require more solar generating capacity, I would guess, for long stays in sometimes cloudy weather.

If you do want a large capacity bank with light weight and more adjustable shapes/volume and can afford them, talk to Lewster about a lithium battery bank. Pricey, but you can safely us 85% instead of 50% with AGM's, so you can buy a smaller battery bank.

If you near Naples Fl in the winter or Hood River, OR (100 mikes east of Portland,) you should strongly consider hiring Lew to do yiur setuo. He is knowledgeable, quick and does very clean work.

[16595]

I installed two group 31 AGMs in spring of 2008. Tight fit. (2005 Classic)

They are still doing quite well. I will replace with AGMs when the time comes.

Bought these at Interstate Batteries I think.

Dwight

[franklyfrank]

Originally Posted by Troutboy

Frank, if you boondock for any length of time you will need more amp hours. If most of your camping is on hookups, I think the stocks work great and you seem to have the touch to ge the, to last. The only reason I am upgrading is because we tend to boondocks more and for longer periods of time.

I buy that.
Our boondocking is no more than three days and if longer I fire up the generator.
One thing I like to add is that our AS is plugged in 24/7 365 with the exception of the dozen days or so we boondock. The batteries and all the electrical on the AS is all original haven't altered a thing.

[woodfox45]

I'm the original post and a lot of questions have been answered . But what is the advantage of having 2 or more batteries ? Do you get more amp hrs. such as reserve capacity minutes 25A:190 as listed on one 12volt AGM I looked at and what does Capacity 20hr:90AH mean that is listed on same battery ?
Les Grace

[DaveP]

Les,

The advantage is capacity in amp hours. The more you have, the longer you can run the 12v systems without recharging the batteries. You should not take your batteries below 50% charged. If you do, you shorten the battery life or can potentially kill the battery. If you have two GPL-27Ts with 100 Ahr @ 20 hrs each, you have an effective Ahr capacity of 100 amps. Then you have to look at consumption over time. If you are consuming 15 amps per hour, you would have a run time of 5.4 hours before you reached the 50% discharge limit. So, it depends on how many systems you are running (like furnace, refrigerator, lights, etc). You have to add up the power you would consume. We did four 6v batteries because we wanted to be able to consume more energy during the hours generators are not allowed in the national and state parks. We have 12v systems we want to run and 120v devices we want to run through our inverter (like the television).

Look at the Lifeline or AMSolar web sites. They have a good explanation of how the batteries work and how many you might need.

[thomasjstone]

We are the 2nd owners of a 2014 FC 25 foot FB Twin that came with the Factory 300 watt solar option (and the original Interstate wet cell size 24 batteries are still installed). Thinking of switching to AGMs but do not know if the factory solar recharging system will be compatible. Please advise.

[n2916s]

AGM's are, in basic terms, a more rugged (no maintenance, mount as you like) lead acid battery. They work exactly like your OEM batteries with a very similar charging regimen. For their size, they tend to have greater capacity.

Unless your current batteries are dying, there really isn't much of an advantage to replacing them.

[blkmagikca]

thomasjstone => Before changing your batteries, ensure that your charging system is multi-stage (bulk, absorb & float). The fullly charge resting voltage for AGM's is 12.89 volts, as compared to a typical wet cell of 13.2 volts. You will need to use these parameters for your charging system & solar controller. Do NOT use the equalizer setting (which blasts at 15.2 volts) or you will shorten the life of your AGM's.