Replacing Wet Cells Battery with AGM

[tamdle]

Hello all,

On my current 2 months trip that I have been gone for 1 week so far and already felt that the house batteries may have the capacity of 100AH (not sure exactly the capacity) are not adequate enough to handle my need for boondocking.

I have only the water heater and refrigerator that ran on LP on my boondocking which use very little battery power (so I thought). Couple nights on the boondocking, the weather turned very cold at 7200 feet on the mountain side of New Mexico, I have to use the furnace which should be able to run on LP without the assistance of the generator.

Ran the furnace for about 3 hours, the house battery went from full to 2/3 which is still good, but I do not want to go below the magical borderline of 50% capacity... ya di ya da...

That said, I am thinking about change both of the house battery out with 4 of the high capacity 6 volts AGM batteries. This could be done easily, BUT...

I would love to learn from some of your inputs, the expert of this RV Life.

1 - I could get 4 of the 6volts VMAX 225AH AGM batteries for $1,000 to replace my two 12volt - 100AH (maybe) current house batteries. Would it worth the swap?

2 - Would the current factory charging system in my 2016 Georgetown XL 352QS charge the AGM batteries or do I have to swap it out with the special charger for the AGM?

3 - Since AGM also the lead acid battery but it is sealed and maintenance free, I assumed that it still have the magic 50% usage capacity as it brother flooded acid, it that right?

Thank in advance for your advice, and have a wonderful weekend.

Tam Le

[Herk7769]

A couple of thoughts to consider.

1) 4 - 6 volt 225AH batteries will be a 550AH battery bank.
2) 4 batteries will weigh twice what your current pair weigh (a factor if you are near your GVWR.)
3) A pair of Group 24 sized "Marine" DP (typical OEM) batteries are about 140Ah (~70AH each). Group 27 sized OEM's are ~90AH each or 180AH.
4) If you currently have 2 - Group 27s; you are about tripling your "hang time" BUT you are also going to triple your charging time as well and there is not much you can do about that.

If you discharge to 50% capacity and recharge, the smart staged charger will detect that a high rate of charge will fry the battery, so it will automatically drop to "absorption" stage and not go into "Bulk" stage.

This is good because forcing your bank into Bulk (some chargers allow this), can boil the electrolyte out of the battery. Basically, the excess electrons have no place to go until the ones on the lead surface get pushed into the lead to make room for them. They just bounce around in the electrolyte creating heat until the surface electrons worm their way deeper into the lead plates. This heat will evaporate the water out of the electrolyte and deposit sulphates (from the Sulphuric Acid solution) as the concentration rises. This sulphate is hard to get off when charging and can permanently ruin batteries. If you think you dodge this bullet by having AGM, remember that the glass mat that separates the positive and negative plates is soaked with electrolyte and (while maintenance free) still has a vent for built up gas and water vapor to escape - you just can't refill one that has had the moisture cooked out.

Absorption mode lasts until the bank reaches 90% of capacity and then the smart charger will switch to "Float" (essentially a trickle charge) until the battery is fully charged.

The bigger the bank and the deeper the discharge, the longer the charge cycle takes. The charge cycle is voltage (not "capacity") driven so each cycle's mode will take longer to complete.

While AGM does not need a specially designed charger (unlike Lion or some of the newer exotics do), your OEM Converter may not have enough amperage capacity to recharge the larger stack and supply all the DC you need in your MH at the same time, so you might want to look at a larger one. Running a smaller converter at near full output is very hard on a converter and it could fail over time. A larger amperage unit will not be stressed as much.

Hope this helps and not confuse the issue.

PS make sure you wire it up correctly as it will look far different from what you have now.

[tamdle]

Originally Posted by Herk7769

... While AGM does not need a specially designed charger (unlike Lion or some of the newer exotics do), your OEM Converter may not have enough amperage capacity to recharge the larger stack and supply all the DC you need in your MH at the same time, so you might want to look at a larger one. Running a smaller converter at near full output is very hard on a converter and it could fail over time. A larger amperage unit will not be stressed as much.

Hope this helps and not confuse the issue.

PS make sure you wire it up correctly as it will look far different from what you have now.

Thank for a very educational information.

So the bottom line is while it is doable, I will face 2 issues:
1 - Distribution weight of the batteries itself.
2 - To find another charger that could accommodate the amperage that needed to charge the larger capacity batteries.

That said, does anyone know where I could find the charger location in the RV so I could find out the current capacity and possibly to find a replacement that is comparable with the current charger which has a higher charging capacity?

I am assuming that the house batteries are currently charged by 2 methods
1 - From the engine alternator during transport.
2 - From the 120 volts converter that source power is from the external power hookup.

Is this correct?

If it is, then I have to find out what type of alternator that I have on my coach that would handle the extra charging power too. right?

It is starting out as a simple task, and now it looks like it would be a major overhaul. I am glad that I consult with the expert here.

[Herk7769]

Originally Posted by tamdle

Thank for a very educational information.

So the bottom line is while it is doable, I will face 2 issues:
1 - Distribution weight of the batteries itself.
2 - To find another charger that could accommodate the amperage that needed to charge the larger capacity batteries.

That said, does anyone know where I could find the charger location in the RV so I could find out the current capacity and possibly to find a replacement that is comparable with the current charger which has a higher charging capacity?

I am assuming that the house batteries are currently charged by 2 methods
1 - From the engine alternator during transport.
2 - From the 120 volts converter that source power is from the external power hookup.

Is this correct?

If it is, then I have to find out what type of alternator that I have on my coach that would handle the extra charging power too. right?

It is starting out as a simple task, and now it looks like it would be a major overhaul. I am glad that I consult with the expert here.

Yes, that is correct, but ...

The vehicle alternator is designed to charge the starting battery and "maintain" the "house" battery. Alternators are not designed to charge deep discharge batteries. See attached article on why.

That converter/charger will do OK keeping your bank charged when on campground power. When on Generator, I recommend a high quality dedicated 3 or 4 stage charger that you connect directly to your battery bank.

Here is a nice one.

https://www.walmart.com/ip/Schumache...ery-Charger/25

If you can't find the paperwork that came with the camper (the model number and serial number of the Converter Panel will be listed there in the "as built" sheet) or the power center/converter manual, you should be able to open the circuit breaker door and read it off the sticker. It is most likely a WFCO 50amp power center and the model number should have the amperage of the converter as part of the model name.

WF-9900 SERIES | Product Categories | wfcoelectronics.com

If you have a WFCO 9900 series, the model number should be 9960 for a 50 amp AC service, 60 amp DC panel. That should be fine for the 4 6 volt batteries, for example.

If you decide to replace the OEM converter, use something like this or larger.

https://www.amazon.com/POWERMAX-PM3-.../dp/B008B13NIQ

Don't forget to upgrade the wire set as well. https://www.amazon.com/Cobra-CPI-A40...PPTVTZRR1ANTV1


Lou

[tamdle]

Originally Posted by Herk7769

Yes, that is correct, but ...

Lou

Many thank Lou! Have a wonderful weekend.

[camaraderie]

First...your year Georgetown should have a Progressive 55 amp charger in a compartment where your 50 amp cord ends up. 55 amps is enough to charge your new proposed bank (10% of capacity) but it is not ideal (20-25%) IF you boondock and want to save charging time. You will want to swap out to either a Progressive Dynamics PD9280V with charge wizard 80amp, or Iota's DLS90 with IQ4...and upgrade your wire run to the batteries to thicker stuff to allow delivery of the extra amps safely.

Second... The AGM's are about 2-3x more expensive than wet cells. There is no performance advantage in capacity or life cycle capacity over wet cells. They WILL charge at higher current levels than Wet cells but that is not important in this application since you can't charge either at greater than 90amps. They will self discharge at 1/10th the rate of wet cells in storage which is great espcially if you have cold winters or store in hot climates. They take zero care which is a big deal to some folks. Note that wet cells with a profill system are pretty damned easy to water and will save you the $500 AGM premium. Your choice.

In your coach running down the road for a lot of hours WILL fully charge your batteries...as it does mine...but it should not be relied on as the only way they are charged...plugging into shore power or running the Onan Generator are your other options without a solar set up.

When you go to 50% on your new batts...with the EXISTING charger....your going to be putting back 220 amp hours or so. At 55 amps output that will take you 3-4 hours just to get to 80%...and another 2-3 to top it off.
With a 90 amp charger (and wiring upgrade) you'll get to 80% in 2 hours and need another 2 to top it off.
It's also just fine to just charge to 80% for a few days and then plug in overnight somewhere and let the electric company do its' thing. But never put the coach away without bringing it back to 100%. Will cost you capacity and life cycles.
If you plan to do several nights at a time in dry camping mode...you should really invest in a true battery monitor like the trimetric or victron models and you will save your batts and save money and time on gas and generator/engine run time.

Hope this is helpful. Good luck

[D. J. Schuler]

Well written advice. Be sure to at least use the same gauge wire as output to strap batteries in series or parallel.

[Herk7769]

Cam has given you excellent advice.
Herk

[Tom48]

Originally Posted by tamdle

Thank for a very educational information.

So the bottom line is while it is doable, I will face 2 issues:
1 - Distribution weight of the batteries itself.
2 - To find another charger that could accommodate the amperage that needed to charge the larger capacity batteries.

That said, does anyone know where I could find the charger location in the RV so I could find out the current capacity and possibly to find a replacement that is comparable with the current charger which has a higher charging capacity?

I am assuming that the house batteries are currently charged by 2 methods
1 - From the engine alternator during transport.
2 - From the 120 volts converter that source power is from the external power hookup.

Is this correct?

If it is, then I have to find out what type of alternator that I have on my coach that would handle the extra charging power too. right?

It is starting out as a simple task, and now it looks like it would be a major overhaul. I am glad that I consult with the expert here.

While Herkimer is correct, more battery and therefor more discharge is possible, and certainly twice the battery will charge FASTER if you added a large charger, the stock charger will do, just not as fast as an upgraded charger might. STILL, IF YOU NEED MORE BATTERY, GO FOR IT. MORE CHARGER CAN COME LATER IF YOU DECIDE YOU WANT IT.

Battery capacity can be Necessary. Faster recharging will not be a necessity. Also I have read varying opinions, but it sounds like not only do AGM have more recharging cycles than wet cells, but evidently they tolerate deep discharge better than wet LA batteries so you may not optomize completely if you do as you originally stayed, it will still be one heck of an upgrade.

Later when you add solar, you will have the additional charge Herk was wanting you to have.

[Wilco]

Is it really worth spending over $1000 in batteries to keep from running the generator a couple of times a week? It only costs ~$6/day to run a generator for 4hrs to top off the battery. Do you really plan to boon dock often enough to justify the cost? I would live with what I have until it is time to replace the original house batteries. If I were to spend that amount of money, I would look at a small solar array/charger to top off my existing batteries.

[tamdle]

Thank Cam, Lou, Tom and Wilco for the advice. I will think through all this and see if really what I should do first. Maybe I do need to invest in a good battery monitor first, then monitoring my usage then upgrade the batteries at the later time when my house battery begin do slow down. These batteries are not a year old yet and. If after the monitoring and I still feel like the usage of the batteries are not adequate, then I begin to work on which route would be more cost effective and still provides the best service for my need.

Thank again gentlemen.

[SidecarFlip]

Originally Posted by tamdle

Hello all,

On my current 2 months trip that I have been gone for 1 week so far and already felt that the house batteries may have the capacity of 100AH (not sure exactly the capacity) are not adequate enough to handle my need for boondocking.

I have only the water heater and refrigerator that ran on LP on my boondocking which use very little battery power (so I thought). Couple nights on the boondocking, the weather turned very cold at 7200 feet on the mountain side of New Mexico, I have to use the furnace which should be able to run on LP without the assistance of the generator.

Ran the furnace for about 3 hours, the house battery went from full to 2/3 which is still good, but I do not want to go below the magical borderline of 50% capacity... ya di ya da...

That said, I am thinking about change both of the house battery out with 4 of the high capacity 6 volts AGM batteries. This could be done easily, BUT...

I would love to learn from some of your inputs, the expert of this RV Life.

1 - I could get 4 of the 6volts VMAX 225AH AGM batteries for $1,000 to replace my two 12volt - 100AH (maybe) current house batteries. Would it worth the swap?

2 - Would the current factory charging system in my 2016 Georgetown XL 352QS charge the AGM batteries or do I have to swap it out with the special charger for the AGM?

3 - Since AGM also the lead acid battery but it is sealed and maintenance free, I assumed that it still have the magic 50% usage capacity as it brother flooded acid, it that right?

Thank in advance for your advice, and have a wonderful weekend.

Tam Le

If I were you and I was going to lay out a grand for a bank of 6 volt (I presume Trojan Golf Cart style batteries), I'd consider one or two Li-Iron (not Ion) batteries. They are expensive (about 800 bucks for a group 24 size) but, One, they can be almost totally discharged with no issue and they output 12 volts until almost totally dicscharged, Two, they weigh about a third of what a comparable flooded cell weighs, Three, unlike Lithium Ion batteries, the retain no memory and Four, they will take a fast charge with no issue. Cycle life about 1000 or better discharges and charges.

They will be my next battery (s).

Mounting is no issue, anywhere, even upside down and they require no venting either.

[tamdle]

Originally Posted by SidecarFlip

If I were you and I was going to lay out a grand for a bank of 6 volt (I presume Trojan Golf Cart style batteries), I'd consider one or two Li-Iron (not Ion) batteries. They are expensive (about 800 bucks for a group 24 size) but, One, they can be almost totally discharged with no issue and they output 12 volts until almost totally dicscharged, Two, they weigh about a third of what a comparable flooded cell weighs, Three, unlike Lithium Ion batteries, the retain no memory and Four, they will take a fast charge with no issue. Cycle life about 1000 or better discharges and charges.

They will be my next battery (s).

Mounting is no issue, anywhere, even upside down and they require no venting either.

Thanks for your advice, I am not sure if I have the budget for that, but that is something that good to know and very educational. I looked for this type of batteries after see your post, and I could not find any deep cycle battery at high amperage and not sure the type of charger that would be used for this type of battery. Also, if you use this type of battery, how would your engine generator be able to charge these batteries while in transit?

I assumed that you have the answers since you may already do a lot of research of this type of batteries for the RV application. Would you mind to share some links?

Thanks,
Tam Le

[Tom48]

Sorry Herk, the auto spell made it Herkimer. That must be the new "The Dog Ate My Homework"

[garbonz]

One good idea is to have both generator and solar for boon docking. AND a good charger that will maintain the bulk charge at max amps as long as possible. So what you can do is run the generator in the morning until the bulk set point is reached (usually 14.4 ish volts) and then shut it off and let the solar panels push up from there. The most efficient charging for the generator and 3 stage charger is from 50% to about 80% where the charging rate starts to taper off. If you really monitor a charger in operation, they do not put out a rated amp output steadily, but taper off, so a 55 amp charger does not put that out for very long and so that is a factor in trying to replenish your battery bank. The solar panel helps out by slowly adding to the battery bank over the 8 or so hours of sun.

[SidecarFlip]

Originally Posted by tamdle

Thanks for your advice, I am not sure if I have the budget for that, but that is something that good to know and very educational. I looked for this type of batteries after see your post, and I could not find any deep cycle battery at high amperage and not sure the type of charger that would be used for this type of battery. Also, if you use this type of battery, how would your engine generator be able to charge these batteries while in transit?

I assumed that you have the answers since you may already do a lot of research of this type of batteries for the RV application. Would you mind to share some links?

Thanks,
Tam Le

This should explain everything you need to know..

Manufacturers website: https://battlebornbatteries.com

They will be my next coach batteries. Made here in the USA btw.

I suspect the cost per unit will decrease as they become more mainstream. New technology is always pricey. I like the weight per unit (27 pounds) and the fact that they can be recharged with a conventional solar or converter unit in the coach, nothing out of the ordinary needed.

Unlike Lithium Ion batteries, there is no danger of overheating, fire or combustion (Samsung Galaxy Phones catching on fire....)

[SidecarFlip]

At 800 bucks a pop, I've done a lot of research on them.

Couple interesting points I like.

One, you can discharge them to almost nothing left and the output voltage will remain at 12 volts +.

Ordinary batteries (deep cycle or AGM or Flooded Cell can only be discharged to 50% and then they start off gassing. Not so with a Lithium Iron Phosphate battery, They don't off gas at all. In fact they are sealed and can operate in any position, even inverted.

I like the weight too. 27 pounds versus 50 plus for a Group 24 is substantial weight savings and like I said previously, they are not charge critical. Ordinary staged converter charging or solar work just fine.

[SidecarFlip]

I realize the Lithium Iron Phosphate battery is a bit over the ordinary Forest River RV stuff but you asked. They aren't for everyone but I sure will have two in the near future.

BTW, I run 2 Trojan 6 volt GC wet cells in series now. Good batteries but heavy and must be vented because they do off gas like every flooded cell battery does.

Off gassing is corrosive. It's acid fumes after all.

[tamdle]

Originally Posted by garbonz

One good idea is to have both generator and solar for boon docking. AND a good charger that will maintain the bulk charge at max amps as long as possible. So what you can do is run the generator in the morning until the bulk set point is reached (usually 14.4 ish volts) and then shut it off and let the solar panels push up from there. The most efficient charging for the generator and 3 stage charger is from 50% to about 80% where the charging rate starts to taper off. If you really monitor a charger in operation, they do not put out a rated amp output steadily, but taper off, so a 55 amp charger does not put that out for very long and so that is a factor in trying to replenish your battery bank. The solar panel helps out by slowly adding to the battery bank over the 8 or so hours of sun.

Adding solar is what I always want to do for the reason that you mentioned above, however, that might be the project after this is done or sometime in the near future. Thanks for sharing the thought.

[tamdle]

Originally Posted by SidecarFlip

At 800 bucks a pop, I've done a lot of research on them.

Couple interesting points I like.

One, you can discharge them to almost nothing left and the output voltage will remain at 12 volts +.

Ordinary batteries (deep cycle or AGM or Flooded Cell can only be discharged to 50% and then they start off gassing. Not so with a Lithium Iron Phosphate battery, They don't off gas at all. In fact they are sealed and can operate in any position, even inverted.

I like the weight too. 27 pounds versus 50 plus for a Group 24 is substantial weight savings and like I said previously, they are not charge critical. Ordinary staged converter charging or solar work just fine.

I just look at the website that you gave me, and it is looking good. If i spend the money to buy 4 of the 6 volts batteries my total AH would be 450, but I could only use 50% of it and I have to make sure that I do not accidentally use up more than 50% of its capacity or the battery life would go downhill, therefore the usable capacity would be only 225AH and the weight of 4 batteries would be no less than 250 lbs.

If I use 2 of this type of battery, it would cost me about 60% more money, but I could use up to the capacity which is 200AH for 2 batteries and not worry about the degradation of the battery life, on top of that, the weight would only be around 60 lbs which are 1/4 of the AGM batteries.

The bottom line is: I like the idea which is I still have the same batteries capacity, but can use the full battery power instead of 50% of the capacity of the current batteries, therefore, I do not need to change or upgrade any of my charging systems for both of RV alternator and the RV original manufacturer charge. I need to research a little more about this type of batteries and its reliability.

Here are the questions:

1 - Per the web site information, I should not pack the batteries by charging them 100%. Would the smart charger will handle this type of charge? another word would the smart charger will charge up the batteries so far, then it will trickle charge until it full then shutdown by itself?

2 - During driving, since the RV does not plug into shore power, the smart charger would not be the primary charger, the RV alternator will charge the batteries. How would this working out?

Thanks again for your advice.