Battery Type Choice

[jkhenderson]

Currently, I have two standard 12V “80 ah @ 20 hr” batteries, and my fifth-wheel includes a 1000W inverter for the “household fridge/freezer”. The batteries are 5 years old and showing signs of needing to be replaced. I am considering GEL or AGM replacement batteries, but don’t know if either would be an issue with the WFCO true sine wave inverter? Any thoughts from someone with battery knowledge experience?

 

[Gary RV_Wizard]

Use of Gel or AGM batteries has no effect on the inverter - it's all just 12v as far as the inverter knows. I don't hink any of the WFCO inverters is also a battery charger, but if it is, make sure the charging profile is suitable for whatever battery is being charged.

Gel is pretty much obsolete as a lead-acid battery type. AGM has the same advantages and has supplanted Gel in most all uses. You might consider Lithium as an alternative, though.

 

[jkhenderson]

Use of Gel or AGM batteries has no effect on the inverter - it's all just 12v as far as the inverter knows. I don't hink any of the WFCO inverters is also a battery charger, but if it is, make sure the charging profile is suitable for whatever battery is being charged.

Gel is pretty much obsolete as a lead-acid battery type. AGM has the same advantages and has supplanted Gel in most all uses. You might consider Lithium as an alternative, though.

My inverter does not provide charging capabilities. You answered my concern and I thank you. Can you speak to any advantages of the AGM batteries over standard wet-cell to justify the higher cost…e.g. do they last longer, etc. I don’t camp off the grid, so my batteries provide electricity for the two refrigerators while physically traveling…typically between 3 and 6 hours. And while I would have originally thought that my tow vehicle’s electrical output would provide sufficient power for the fridge, I guess that’s not the case for normal set-ups.

 

[PancakeBill]

Can we use lead acid along with AGM in a system? Adding batt to my truck which will help power the truck camper which already has a recent lead acid.

 

[Isaac-1]

AGM work best with a slightly different charging profile than flooded lead acid, also AGM are more sensitive to higher charging voltages, if your charger / converter does periodic equalization charging, don't use it with AGM if it equalizes at over 14.4VDC.

As to the topic of AGM in general, they cost a fair amount more than standard flooded Lead acid, in fact with the raising cost of lead acid batteries of all types, and dropping prices on LiFePo4 lithium we have reached a point in time where LiFePo4 can actually be cheaper than AGM.

This Group 27 AGM rated at 95AH from NAPA with 12 month full replacement warranty is listed at $322 at the moment https://www.napaonline.com/en/p/BAT9827M

For less money you can get a semi-name brand 100AH LiFePo4 with low temperature charging protection from Amazon starting around $300 https://www.amazon.com/gp/aw/d/B0C8T1FD7M/ This comes with a 5 year warranty and an estimated 4,000 to 15,000 charge cycle life (4,000 charge cycles is cycling the battery once per day for almost 11 years). Some no name 100AH LiFePo4 batteries are under $150 online now, but you get what you pay for, and some of these are poorly built to the point of being unsafe, and are often built with used or grade B cells.

Of course if you switch to LiFePo4 you might need to upgrade your charging system / converter to one that is LiFePo4 friendly (note some lead acid converts will work with LiFePo4, some will not even if they are not marked as LiFePo4 compatible), for example my Progressive Dymanics 9200 converter which does not have a "Lithium" mode works fine with my LiFepo4 batteries, though is not a perfect match, going on 2 years now with no issues.

 

[Mark_K5LXP]

any advantages of the AGM batteries over standard wet-cell to justify the higher cost…e.g. do they last longer, etc.

Slightly lower internal impedance which translates to less terminal voltage drop at a given current delivery, and slightly faster bulk charging. Requires a more carefully controlled charge profile specific to AGM.

No electrolyte level checking or maintenance. Less opportunity for terminal corrosion.

Can usually be operated in any orientation, and in habitable space.

No real advantage in Ah or longevity.

Mark B.
Albuquerque, NM

 

[John From Detroit]

There is no advantager to AGM or GEL over standard Lead Acid and a major disadvantage to GEL.
Now replacing those with GC-2 Deep cycle Golf Car batteries (Two of them in series to make 120volts) Will gain you some watt hours
Or LiFePO4 (Major gain)

Gel batteries are "Very finikey" eaters (AGM's are not at all finikey it is one minor advantage of AGM the other being no "This Side Up which gel shares)

LiFePO4 is also a bit finikey but they have a Battery Manager built in to handle that.

Finikey = Do not charge too fast.

 

[Isaac-1]

John I have to disagree, in my mind the MAJOR benefits of AGM is that it does not require you to check water levels, which can be an issue if the batteries are located in a hard to access position, also the fact they don't outgas under normal operation means don't cause nearby metal to corrode.

As to LiFePo4 being finikey, LiFePo4 is different from Lead Acid, as a result people need to unlearn those things they thought applied to all batteries, but in reality were lead acid traits. For example LiFePo4 don't need to be routinely fully charged, so there is no need to float them, they in fact last longer when stored at a partial state of charge, something that will greatly shorten the life of lead acid. LiFePo4 also tends to accept charge rates much faster than lead acid, charging up to 4 times faster to get to a full state of charge, with much lower (almost trivial) charging losses.

Overall switching to LiFePo4 is a bit like switching from driving a manual transmission car to one with an automatic transmission, people that have never tried it will tend to question the idea, some that have seen it and maybe just tried it will complain about slamming their left foot only the over sized brake pedal, and about how it tries to run into the car in front of you when stopped at red lights. However most after a brief adjustment period would never go back, particularly in stop and go traffic. Note this comes from someone with multiple manual transmission vehicles, the difference here is manual transmission cars can be more fun to drive, in some cases, the same can not be said for lead acid batteries.

 

[Gary RV_Wizard]

Can we use lead acid along with AGM in a system?

An AGM battery IS lead-acid, so the answer is a qualified yes. The qualification is the optimal charging parameters are slightly different, so a combined use won't be textbook optimal. But for practical purposes, it will work fine.

I think you mean to ask whether an AGM lead-acid can be used with a flooded-cell lead acid. AGMs have a different internal construction that allows it to be sealed and is essentially zero-maintenance. Thus its two major advantages vs flooded-cell lead acid.

 

[John From Detroit]

John I have to disagree, in my mind the MAJOR benefits of AGM is that it does not require you to check water levels,

But reguklar Maintence free have that benefit at lower cost. So it's not a benefit of AGM

And the fact you can ADD DISTILLED water to a standard "Flooded wet" means it, if properly maintained, may well last longer and that IS a benefit.

The benefits of AGM are mostly overrated. Long life- no
Maintence free yes but not exclusive
Mount other than THIS SIDE UP yes
One make does take faster recharge.. ONE MAKE.
Higher cost= YES

 

[Gary RV_Wizard]

The benefits of AGM are mostly overrated. Long life- no

Depends on what you are comparing to. Versus the typical marine/rv flooded cell sold with many new RVs or a replacement by RV dealers, any AGM is likely to be last 50% longer. But compared to a true deep cycle with adequate maintenance, the AGM is probably similar or slightly less in life.

Maintence free yes but not exclusive

It's true that "maintenance-free" (sealed) flooded cells don't require regular watering, but they still have the other maintenance woes of flooded cells, i.e. corrosion of terminals and surrounding metals from outgassing. I'd rate maintenance-free flooded cells as "good" but AGM as "superior".