Isaac-1
Well-known member
I bought that exact same charger in 2016, unfortunately it stopped working a couple of years ago
What replacement house deep cycle batteries would you buy?
- Thread starter jymbee
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Old_Crow
Well-known member
I have plenty of headroom in my battery compartment. In fact, before I started researching different batteries the original plan was to construct a swivel rack and stack a second set of GC2s above the original set(which would also be replaced at that time).
Then I found out about the L16's. The(much easier)plan became to install a pair of L16's this past winter in Quartzsite. The cost difference between 2 L16's and 4 GC2's is negligible , and the available Ah is practically the same. Unfortunately, life, death, and Covid got in the way of this plan and battery replacement got put off another year.
Since then I've been questioning the necessity(thus the question about the different Trojans), but will probably stick with the L16 plan for next year. I have a feeling I'll be doing more boondocking now, since I'm traveling alone.
My goal is modest. I want to be able to run the rear furnace in the coach all night in fall/early winter weather and still be able to start the generator without the jump switch in the morning. The 2 GC2 Interstates I have now come close, but are approaching 6 years of age.
BoiseRules
Well-known member
- Joined
- May 20, 2019
- Posts
- 108
I bought two T-145 batteries last year and they were only $225 each from Battery Systems. They are taller and barely fit in the space...
Old_Crow
Well-known member
That's in line with what I'm finding. 4 of them would be around $900 with around 450 Ah, 2 of the L16's land in the same ball park, with just about the same Ah. The savings in my case would be the cost and effort expended in constructing the housing for the second set of GC2's
Blues Driver
Well-known member
- Joined
- Apr 4, 2018
- Posts
- 151
I bought the Napa because I get 230 ah ( 4 batteries series, series, parallel) and there is a store here. Its hard to beat Costco or Sams if they are near you.
Gary RV_Wizard
Site Team
If you only need a modest increase in AH and have some room for horizontal expansion, consider changing to 12v deep cycles. That would allow you to use 3 batteries and get AH capacity in the range of 270-420, depending on the battery size chosen. Trojan makes 12v AGM deep cycles in Sizes 24, 27, 31 and GC2. So does Lifeline & I think US Battery too.
Lou Schneider
Site Team
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- Mar 14, 2005
- Posts
- 13,245
I'm sold on drop-in replacement LiFePO4 lithium batteries. Yes, they cost more up front but if you shop around you can get a 100 ah battery for $600-650. This isn't as steep as it sounds because you can use 100% of a lithium battery's rated capacity, so a 100 ah lithium battery has the same usable capacity as a 200 ah lead acid that you can only discharge 50%.
If you get something like the more expensive Battle Born battery it will likely be the last battery you'll buy as it comes with an 8 year full replacement, 10 year pro-rated warranty. I bought a pair of 105 ah Lion Safari batteries from Costco earlier this year and they came with a lifetime full replacement warranty. Typical life rating to 80% of the original capacity is 3000-5000 full discharge cycles, or 8-13 years of daily cycling.
A common problem with lead acid is the voltage and current both drop as the battery discharges, often not leaving enough power to spin the furnace blower fast enough to trip the airflow switch at the end of a cold night. Lithium's discharge voltage is higher (13+ volts over almost all of the discharge cycle) and it will put out the same amount current at the end of it's discharge cycle as at the beginning, meaning the furnace will be blowing just as strong in the morning as it was earlier in the night.
Lithium batteries are essentially zero maintenance, you can install them and then forget about them. Unlike lead acid, it's OK to add additional batteries later. You don't have to keep them topped up, they're happy staying partially charged indefinitely. You also don't have to worry about terminal corrosion, venting, etc. as the batteries are completely sealed and can be mounted in any orientation.
On my first trip after installing the pair of Lion Safari batteries, I was in the middle of Nowhere, NV and woke to a dead chassis battery - an internal open to one of the battery posts so it was completely out of the circuit. It was cold and I'd been using the furnace so there was less than 20% charge remaining in the Lion batteries. I thought about jump starting the motorhome from the toad but decided to try the boost switch first. The Lion batteries vigorously started the RV's 7.4 liter gas engine without complaint. This let me finish the trip and return to the land of cheap batteries before I replaced the chassis battery.
If you get something like the more expensive Battle Born battery it will likely be the last battery you'll buy as it comes with an 8 year full replacement, 10 year pro-rated warranty. I bought a pair of 105 ah Lion Safari batteries from Costco earlier this year and they came with a lifetime full replacement warranty. Typical life rating to 80% of the original capacity is 3000-5000 full discharge cycles, or 8-13 years of daily cycling.
A common problem with lead acid is the voltage and current both drop as the battery discharges, often not leaving enough power to spin the furnace blower fast enough to trip the airflow switch at the end of a cold night. Lithium's discharge voltage is higher (13+ volts over almost all of the discharge cycle) and it will put out the same amount current at the end of it's discharge cycle as at the beginning, meaning the furnace will be blowing just as strong in the morning as it was earlier in the night.
Lithium batteries are essentially zero maintenance, you can install them and then forget about them. Unlike lead acid, it's OK to add additional batteries later. You don't have to keep them topped up, they're happy staying partially charged indefinitely. You also don't have to worry about terminal corrosion, venting, etc. as the batteries are completely sealed and can be mounted in any orientation.
On my first trip after installing the pair of Lion Safari batteries, I was in the middle of Nowhere, NV and woke to a dead chassis battery - an internal open to one of the battery posts so it was completely out of the circuit. It was cold and I'd been using the furnace so there was less than 20% charge remaining in the Lion batteries. I thought about jump starting the motorhome from the toad but decided to try the boost switch first. The Lion batteries vigorously started the RV's 7.4 liter gas engine without complaint. This let me finish the trip and return to the land of cheap batteries before I replaced the chassis battery.
Gary RV_Wizard
Site Team
I think a strong case can be made for LiFePO4 batteries at todays prices but only if you keep the RV long enough, at least several years. If you sell or trade before that, it gets a lot more costly. Plus of course you have to figure in the cost of upgrading the charging system, which can add a lot of buck$ if your system is needs a new inverter/charger & its remote panel.
BoiseRules
Well-known member
- Joined
- May 20, 2019
- Posts
- 108
Gary, I agree but our TT has slides on both sides. The front storage compartment has a pull out drawer on the right side and water heater on the left so the only place to install a LiFePo4 battery bank is in the front closet which limits clothes storage. I wish I could mount an insulated battery box for the LiFePO4 batteries on the tongue...
Gary RV_Wizard
Site Team
Why can't you do that? Either way you have to protect the batteries from freezing when the RV isn't being heated.
Did you know that BattleBorn offers a lithium battery with a built in heater controlled by the BMS. At an extra cost, of course...
Did you know that BattleBorn offers a lithium battery with a built in heater controlled by the BMS. At an extra cost, of course...
Lou Schneider
Site Team
- Joined
- Mar 14, 2005
- Posts
- 13,245
The only time you need to heat a LiFePo4 battery is when you're charging it. They'll provide power all the way down to -40 degrees but need to be above about 30 degrees to accept a charge. If below freezing charging is a concern, it's easy to divert part of the available charging power to a fish tank heating pad under the battery to raise it's temperature enough to let it charge.
Ex-Calif
Well-known member
The physics and facts do not support this explanation.
Deeper cycling causes deeper sulphidation. I understand your analogy of "a battery has a limited number of amp hours" but it is not a linear equation. The plates actually do break down and lose material. The deeper you cycle the deeper the damage is to the physical plate.
That why golf cart flooded batteries are constructed differently with thicker plates.
You all can manage your batteries how you want, and there are times you may have to run your batteries dead but it is easy to keep the discharge cycles below 30% and that's how you get the longest life.
The reality is that most RVers are plugged in 90% of the time so a good smart charger takes care of the batteries for you.
I don't make this up. I sailed ocean boats for over 10 years and installed many battery and solar systems for boat folks. Boat folks don't have many places to plug in and most ocean going boats have over 800a/h of batteries. Replacement of a battery bank is well over $1,000 so taking care of them is critical.
In terms of battery life Gary has it right.
Mark_K5LXP
Well-known member
One has to assume that the battery manufacturers understand the physics involved when they publish the data sheets for their products. That all gets factored into the operating parameters they cite. If one doubts the veracity of that data then it would imply one knows more or has more comprehensive test facilities than the manufacturers do. I don't, so I take the data sheets at face value. Just as I take at face value tire PSI charts and engine/chassis lubrication specifications. It seems a bit contradictory to accept some parts of battery performance and characteristics, and not others. I too have decades of practical and application design experience, and as an engineer I let the data drive the design. So until I see some different data, and start seeing operational results contrary to specification I don't anticipate coming to a different conclusion anytime soon.
I get it, the "50% Rule" is deeply entrenched in the RV community and most RV'ers aren't interested in becoming an EE to go camping. It's an easy rule of thumb to follow and at face value doesn't hurt a thing. Where I part ways is the folly of half of the battery isn't usable, or using it damages the battery. That is plain not true, period. If it were true, it would be reflected in battery data sheets and in actual use.
Mark B.
Albuquerque, NM
Ex-Calif
Well-known member
But it is true. Field experience proves it. A full discharge of a battery, especially at high amp loads can destroy a battery in one cycle.
Ergo depth of Discharge is a factor on battery life - I have posted the manufacturers tables on this before so I won't do so again.
DoD is where you and I part company. You contend the damage is linear regardless of DoD whereas I do not. Peace...
Mark_K5LXP
Well-known member
I never once stated that "full discharge at high amp loads" was an acceptable use. DOD and discharge rate have defined limits and are separate operating parameters.
Wear through cycling and "damage" are different. 80% DOD is within the specified DOD of nearly all deep cycle batteries. The solar line of Trojan batteries are specified to 100% DOD.
From the Trojan Battery User Guide (p.23):
Maximizing the Performance of Your Trojan Battery
Do not discharge your battery to more than 80% depth of discharge. This safety factor will eliminate the chance of over-discharging and damaging your battery
The way I read that is 80% DOD is not over discharging, and is non damaging. Data sheets nearly universally include 80% DOD in their performance charts. It's "within spec".
Attached is a graph I made that shows the lifetime delivered Ah ("service life") of a flooded T105 based on the Ah at different rates, and the "manufacturer table" (cycle chart) that is often cited. The gap between the rate lines is Peukert effect. Of particular note is that the peak delivery point is 30% DOD and the "50% Rule" bump is actually 60% DOD. But that's for this particular battery, other battery models and topologies will exhibit their peaks at different points. The max delta across the Ah range is 10%, and the delta between 50% and 80% DOD is 3.3%. Between the range of 40% to 80% the line looks pretty linear to me and an overall magnitude difference of 10% over the entire range is not a number one can readily justify trying to optimize, when that point represents a quantity of cycles that is not practically realizable in RV service (>2000). The folks that get wrapped up in hitting these sweet spots are the solar guys, where batteries do get cycled every day, they're in a controlled thermal environment, and both charge and discharge profiles are tightly controlled. They are likely running large battery banks representing a significant expense and a year or more of additional calendar life translates to dollars saved. None of this describes RV service. There are easily half a dozen likely failure modes that will take an RV house battery out before any amount of cycling at any rated DOD will. So all that being said, per my earlier post there is no harm in using the 50% Rule, it's just that if you make it a hard line in the sand (deny using your batteries or buy more/bigger batteries) all you're assuring is you will age your batteries out before you wear them out. The notion that DOD >50% "damages" batteries is patently false and there is plenty of manufacturer data to support that. If one experiences a different result it's going to be due to other issues like charge profile, neglect, abuse, storage, etc. Because the effects of these are cumulative, it can seem like everything is OK until it isn't, and that's when the 50% Rule rears it's ugly head when in fact it was one or more other damaging conditions at fault.
Mark B.
Albuquerque, NM
Wear through cycling and "damage" are different. 80% DOD is within the specified DOD of nearly all deep cycle batteries. The solar line of Trojan batteries are specified to 100% DOD.
From the Trojan Battery User Guide (p.23):
Maximizing the Performance of Your Trojan Battery
Do not discharge your battery to more than 80% depth of discharge. This safety factor will eliminate the chance of over-discharging and damaging your battery
The way I read that is 80% DOD is not over discharging, and is non damaging. Data sheets nearly universally include 80% DOD in their performance charts. It's "within spec".
Attached is a graph I made that shows the lifetime delivered Ah ("service life") of a flooded T105 based on the Ah at different rates, and the "manufacturer table" (cycle chart) that is often cited. The gap between the rate lines is Peukert effect. Of particular note is that the peak delivery point is 30% DOD and the "50% Rule" bump is actually 60% DOD. But that's for this particular battery, other battery models and topologies will exhibit their peaks at different points. The max delta across the Ah range is 10%, and the delta between 50% and 80% DOD is 3.3%. Between the range of 40% to 80% the line looks pretty linear to me and an overall magnitude difference of 10% over the entire range is not a number one can readily justify trying to optimize, when that point represents a quantity of cycles that is not practically realizable in RV service (>2000). The folks that get wrapped up in hitting these sweet spots are the solar guys, where batteries do get cycled every day, they're in a controlled thermal environment, and both charge and discharge profiles are tightly controlled. They are likely running large battery banks representing a significant expense and a year or more of additional calendar life translates to dollars saved. None of this describes RV service. There are easily half a dozen likely failure modes that will take an RV house battery out before any amount of cycling at any rated DOD will. So all that being said, per my earlier post there is no harm in using the 50% Rule, it's just that if you make it a hard line in the sand (deny using your batteries or buy more/bigger batteries) all you're assuring is you will age your batteries out before you wear them out. The notion that DOD >50% "damages" batteries is patently false and there is plenty of manufacturer data to support that. If one experiences a different result it's going to be due to other issues like charge profile, neglect, abuse, storage, etc. Because the effects of these are cumulative, it can seem like everything is OK until it isn't, and that's when the 50% Rule rears it's ugly head when in fact it was one or more other damaging conditions at fault.
Mark B.
Albuquerque, NM
Attachments
Ex-Calif
Well-known member
Even your data shows maximum life at 30% DoD. I did not contend that 80% DoD was over discharged. I have been stating over and over that minimum battery cost per a/h occurs around 20-30% DoD. You chart supports that.
Batteries don't time out - I am not sure where that is coming from. They "chemistry" out (unless they are damaged due to abuse) - You don't explain the lower number of cycles at higher DoD - It is simple, higher DoD wears batteries out faster as does higher rates.
You can talk about in-service vs. lab testing but the lab is the place where apples to apples gets done.
Low rate of discharge to 20-30% is the sweet spot for battery cost of ownership.
Batteries don't time out - I am not sure where that is coming from. They "chemistry" out (unless they are damaged due to abuse) - You don't explain the lower number of cycles at higher DoD - It is simple, higher DoD wears batteries out faster as does higher rates.
You can talk about in-service vs. lab testing but the lab is the place where apples to apples gets done.
Low rate of discharge to 20-30% is the sweet spot for battery cost of ownership.
Mark_K5LXP
Well-known member
Yes, there is the "max" at 30%. Several points- the difference between the maximum and minimum Ah output is 10%. So do you go through the throes of never discharging your battery more than 30% DOD, -ever-, to glean at most 10% additional service life? That's the point where I ask the question are your batteries serving you, or are you serving your batteries?
To use just 30% means to restore back to 100% requires a full absorb phase. That translates to at least several hours of recovery, either by generator or solar at a slow rate. Possible, but not convenient contrasted to restoring bulk phase amps which is comparatively quicker and more efficient. At 30% DOD you can expect around 2000 cycles. That's 5.5 years of daily cycling. How many RV'ers do that? If you aren't in that very small group of full timers glued to their battery monitor so that fateful line is never crossed, you're buying and hauling around battery capacity you aren't using, and is likely going to end up getting recycled. A more cost effective and practical strategy is to size the battery bank vs your usage to ensure they're worn out before they age out. Including operating margin and allowance for degradation, that capacity would take a concerted effort to wear out intentionally and it likely wouldn't happen, but taking a little bit of life left to the recycler is better than a lot.
Lead batteries age out, no matter what environment they're in or how they're used. Lightly used batteries have certain failure modes, heavily used batteries have others, but they all fail. 5 years is when they first start showing signs, 6 years they're getting tired, and it's unusual to see them make 7. When you hear of someone saying they got 7 or more years out of a battery it's not because the battery is "good", it's because they're not expecting any more from it than the diminished capacity it has. AGM's tend to be a bit longer lived but they suffer the same anodic corrosion, paste shedding and sulfation all lead acid batteries succumb to. Lots of information on the intertubes about lead acid battery aging mechanisms. One article here shows a degradation study under a pre-defined renewable energy profile and on page 22 shows a graph very similar to mine based on lifetime Ah throughput.
My explanation of fewer cycles at higher DOD's is to graphically display the lifetime delivered Ah. I think I pretty adequately illustrated that between 40% DOD and 80% DOD the difference in delivered Ah and thus service life is 3%. If one wants to "preserve" their batteries to the point they age out for the sake of 3%, ultimately giving up much more than that in unused capacity then full steam ahead. Per above, there are any number of more likely failure modes they'll suffer and certainly other operating conditions that will wash out the even 10% peak delivery at 30% DOD much less 3% at >40% DOD, so I guess it's all about what hill you choose to die on. Lose 50% or more at the back end to gain at most 10% at the front end? Not sure how that math works.
Lastly, I get this is "ideal" conditions and it doesn't take into account the ultimate reduction in capacity batteries exhibit towards end of life irrespective of DOD. It's difficult to take in all subtleties of operating environment like temperature, time between charges, charging profile, storage, on and on. Because everyone's installation and usage is going to be a little different and likely not ideal, "your mileage may vary". It can be postulated that with all of these system variables DOD becomes even less of a lifetime determining factor, compared to ideal. There is software the NREL did that can model these conditions literally by the hour for the entire lifespan of a system but one would be hard pressed to predict just what those future operating conditions would be in an RV. I'm going with the notion that most users will only exercise several hundred cycles on their batteries at most, and most of those cycles will not be 80% DOD. The long pole in the tent isn't DOD, they're going to age out unless they're injured or killed. And as I've said all along if you're one of the very few that manage to wear a battery out before it ages out or gets killed, that's the most cost effective battery you can have.
Mark B.
Albuquerque, NM
To use just 30% means to restore back to 100% requires a full absorb phase. That translates to at least several hours of recovery, either by generator or solar at a slow rate. Possible, but not convenient contrasted to restoring bulk phase amps which is comparatively quicker and more efficient. At 30% DOD you can expect around 2000 cycles. That's 5.5 years of daily cycling. How many RV'ers do that? If you aren't in that very small group of full timers glued to their battery monitor so that fateful line is never crossed, you're buying and hauling around battery capacity you aren't using, and is likely going to end up getting recycled. A more cost effective and practical strategy is to size the battery bank vs your usage to ensure they're worn out before they age out. Including operating margin and allowance for degradation, that capacity would take a concerted effort to wear out intentionally and it likely wouldn't happen, but taking a little bit of life left to the recycler is better than a lot.
Lead batteries age out, no matter what environment they're in or how they're used. Lightly used batteries have certain failure modes, heavily used batteries have others, but they all fail. 5 years is when they first start showing signs, 6 years they're getting tired, and it's unusual to see them make 7. When you hear of someone saying they got 7 or more years out of a battery it's not because the battery is "good", it's because they're not expecting any more from it than the diminished capacity it has. AGM's tend to be a bit longer lived but they suffer the same anodic corrosion, paste shedding and sulfation all lead acid batteries succumb to. Lots of information on the intertubes about lead acid battery aging mechanisms. One article here shows a degradation study under a pre-defined renewable energy profile and on page 22 shows a graph very similar to mine based on lifetime Ah throughput.
My explanation of fewer cycles at higher DOD's is to graphically display the lifetime delivered Ah. I think I pretty adequately illustrated that between 40% DOD and 80% DOD the difference in delivered Ah and thus service life is 3%. If one wants to "preserve" their batteries to the point they age out for the sake of 3%, ultimately giving up much more than that in unused capacity then full steam ahead. Per above, there are any number of more likely failure modes they'll suffer and certainly other operating conditions that will wash out the even 10% peak delivery at 30% DOD much less 3% at >40% DOD, so I guess it's all about what hill you choose to die on. Lose 50% or more at the back end to gain at most 10% at the front end? Not sure how that math works.
Lastly, I get this is "ideal" conditions and it doesn't take into account the ultimate reduction in capacity batteries exhibit towards end of life irrespective of DOD. It's difficult to take in all subtleties of operating environment like temperature, time between charges, charging profile, storage, on and on. Because everyone's installation and usage is going to be a little different and likely not ideal, "your mileage may vary". It can be postulated that with all of these system variables DOD becomes even less of a lifetime determining factor, compared to ideal. There is software the NREL did that can model these conditions literally by the hour for the entire lifespan of a system but one would be hard pressed to predict just what those future operating conditions would be in an RV. I'm going with the notion that most users will only exercise several hundred cycles on their batteries at most, and most of those cycles will not be 80% DOD. The long pole in the tent isn't DOD, they're going to age out unless they're injured or killed. And as I've said all along if you're one of the very few that manage to wear a battery out before it ages out or gets killed, that's the most cost effective battery you can have.
Mark B.
Albuquerque, NM
