Help me assess the value of lithium

[Atlee Hokie]

This is what I'm thinking. If I'm tailgating this fall. I will just run the generator when necessary. We are "dry camping" 2 nights.

This spring-summer if we are touring the northern plains, YNP, Grand Tetons, etc., we will boondock at night, but we will be driving during the day to visit the sites and charging the batteries at the same time.

We should be fine. If it's cold, the furnance will be the biggest draw. Second biggest draw will be my CPAP machine. If it gets too cold, we'll leave for warmer climes.

Originally Posted by jrobe

We quickly found that we don’t need lithium batteries. We don’t stay in the same place very long. We also rarely stay in campgrounds with electricity. With our second alternator we only have to drive 30-60 min daily to fully recharge our AGM batteries which we almost always do anyway traveling. Our AGM battery capacity is plenty for us to use all our devices, coffee maker, TV, refrigerator, satellite dish, etc.. We are probably even fairly high electricity users compared to a lot of RVers.

Living in the north, I am also glad I don’t have to deal with the cold weather requirements of lithium batteries. I just keep a battery maintainer on our batteries all winter and forget about the weather.

I would do a very careful energy use analysis and then decide if you really need lithium batteries. We don’t. We also don’t need solar panels as long as we have our second alternator.

[MsNomer]

"With our second alternator we only have to drive 30-60 min daily to fully recharge our AGM batteries which we almost always do anyway traveling." Just the tail charge on an AGM normally takes a couple of hours. Are you sure you are fully charging?

[@Michael]

Here's a YouTube video of a fairly decent between AGM, flooded and lithium.

https://www.youtube.com/watch?v=iy3hga_P5YY

With details here: https://mortonsonthemove.com/best-rv...-test-results/

Seems like cheap 6V golf cart batteries make sense under certain circumstances, perhaps a case can be made for cheap AGM's in some cases, and certainly for lithium. But based on his tests, expensive, high-end AGM's don't make much sense.

[jrobe]

Originally Posted by booster

I think to anyone who hasn't been around here for a while, it is important to mention that with a big alternator you can recover a day's use in 30-60 minutes without question. But, that is only if you are relatively low on charge when you start the recharge. The upper 20-30% takes much longer to do, so getting to totally full will not happen that fast.
In much of the real world this doesn't matter, as solar will finish off the charge if you have solar, or you will be on shore power in the future to top off and preserve battery life. But, you need to understand you will be starting your next discharge cycle at 80% full instead of 100% full. If you have a big battery bank, no big deal, but it you are on a single battery or two, it might be. Recharge time does not really change much with bank size when you are in the top 20% of SOC.

When I drive 30-60 min or so with my second alternator, my Magnum Energy battery monitor reads 100% SOC. This is exactly the same as it reads after I have the Magnum Energy battery charger / maintainer on it with shore power for several hours or several days. Either my batteries are at full charge after I drive or the thing isn't reading correctly which I doubt

[Atlee Hokie]

I have a question though. I'm way off from being really being knowledgeable about batteries. However I remember reading that a surface charge on a battery, right after charging has finished, may indicate it's fully recharged.
However after a bit of time at rest, the "surface charge" will go away, and the true charge level of the battery will register, which may be 10 to 15% below actual full charge. Could this be happening to your batteries?

I'm sure someone will be along soon to correct me.

Originally Posted by jrobe

When I drive 30-60 min or so with my second alternator, my Magnum Energy battery monitor reads 100% SOC. This is exactly the same as it reads after I have the Magnum Energy battery charger / maintainer on it with shore power for several hours or several days. Either my batteries are at full charge after I drive or the thing isn't reading correctly which I doubt

[booster]

Originally Posted by jrobe

When I drive 30-60 min or so with my second alternator, my Magnum Energy battery monitor reads 100% SOC. This is exactly the same as it reads after I have the Magnum Energy battery charger / maintainer on it with shore power for several hours or several days. Either my batteries are at full charge after I drive or the thing isn't reading correctly which I doubt

I think that is very possible depending on the settings in the monitor. If the monitor is not set to the battery manufacturers specifications for full battery amps and volts while at final charge, you can get a 100% full reading when not at actual full. Another thing that happens with monitors, depending on charge efficiency settings, is that by the time the battery is full while on charge it could read 110-120%. Once it gets to full, the monitor will calibrate and set 100% and the charger will go to float.


If you could list your battery brand, type, model, amp hour capacity, or some of that we should be able to figure out what the settings probably should be in monitor.



It is also possible the monitor is not capable of doing the accurate, from the shunt, charge control. You have to have an ARC50 and a MS2000 model charger or higher to get that control.


Most installers tend to set the monitors very conservatively, and the defaults can be even more conservative, probably because they know most people don't get the batteries to full charge regularly and the settings will mask that problem.


We see this all the time on the forum, where the monitor settings are giving full battery indications early. The problem are not with the monitor, but are with the charging systems that are not capable of accurate charging to full, without overcharging.

[booster]

Originally Posted by Atlee Hokie

I have a question though. I'm way off from being really being knowledgeable about batteries. However I remember reading that a surface charge on a battery, right after charging has finished, may indicate it's fully recharged.
However after a bit of time at rest, the "surface charge" will go away, and the true charge level of the battery will register, which may be 10 to 15% below actual full charge. Could this be happening to your batteries?

I'm sure someone will be along soon to correct me.

Surface charge can be deceptive, particularly if you are trying to keep track of your battery state of charge by checking voltage. Voltage is a difficult way to check state of charge because to be even borderline accurate there can be no load on the batteries, they have to have sat for a hour or more with no load or charge, and any surface charge needs to be removed by running a load for a short time. A good, properly setup, monitor does a much better job although from the previous post you can get wrong readings from them, too, if not setup properly.

[jrobe]

The point of my original post was that for people like us that are driving and moving about most days, a second alternator is more valuable than lithium batteries because we are recharging our batteries every day with minimal driving. If someone is camping in the same place for extended time, lithium batteries and a big battery bank would be very useful. On the other hand, if we were stationary campers, we wouldn't have bought a small Class B RV. Instead, we would have an RV with a much bigger living space. The whole point of a small Class B is mobility. We want to be out exploring the country. For our use (and many Class B owners use) we have no need for a huge lithium battery bank as long as we can easily replace 100-200 amp hrs of battery power every day without shore power. Lithium batteries would have been largely a waste of money for us which is why I suggested to the OP to do a careful energy use calculation for how they will use the van.

I am not exactly sure how this turned into a discussion of the accuracy of the Magnum Energy battery monitor but ours seems very accurate,

[booster]

Originally Posted by jrobe

The point of my original post was that for people like us that are driving and moving about most days, a second alternator is more valuable than lithium batteries because we are recharging our batteries every day with minimal driving. If someone is camping in the same place for extended time, lithium batteries and a big battery bank would be very useful. On the other hand, if we were stationary campers, we wouldn't have bought a small Class B RV. Instead, we would have an RV with a much bigger living space. The whole point of a small Class B is mobility. We want to be out exploring the country. For our use (and many Class B owners use) we have no need for a huge lithium battery bank as long as we can easily replace 100-200 amp hrs of battery power every day without shore power. Lithium batteries would have been largely a waste of money for us which is why I suggested to the OP to do a careful energy use calculation for how they will use the van.

I am not exactly sure how this turned into a discussion of the accuracy of the Magnum Energy battery monitor but ours seems very accurate,

I understand that you were advocating the alternator benefits, and I totally agree based on your pattern of use, no problem.
We got to the monitor and accuracy because you spoke of very short drives filling your AGM batteries to 100% full, which is an important comment for anyone comparing AGM and lithium as in this discussion because that would indicate AGMs will charge to 100% full as fast as lithium batteries will. Unfortunately, AGMs don't charge that fast to full because the charging slows way down for the last 20-25% of the charging. And I mean a lot. It is very typical for the last 25% of charging to take 4-6 hours of charging at absorption voltage and high amp chargers make no difference, so 30-60 minutes is just not going to do it, and potential buyers need to realize that, IMO. The only way to accurately tell if lead acid batteries are fully charged is to look at the amps to the batteries at full absorption voltage and that is what good monitors do very accurately if setup to the manufacturers recommendations.
If you are recharging from 50% SOC for instance, it will charge fast to the 75-80% level, so you can easily and quickly recover a full day or two of use very quickly with fast charging.

If you are happy with how your system performs, you are fine. You are probably not getting past 80-90% full batteries, but neither are most other RV users of lead acid batteries. The net affect is that you have a bit less capacity than you think, and the battery life will be reduced by some amount over time, as it is with most others.

[GeorgeRa]

Originally Posted by jrobe

………………….. If someone is camping in the same place for extended time, lithium batteries and a big battery bank would be very useful………………..

…or small battery bank and solar cells in areas of reasonable harvesting. My 230Ah AGM with 300W solar are enough on no LPG camper van. By noon on next day of camping my batteries are full. Is it a perfect solution, no really because I need to pay attention choosing exposed campsites, google maps during reservation are very helpful.

My ideal choice would be a 300-500W 24/7 capable generator powered by gas, LPG, or diesel, unfortunately none are quiet enough to be 24/7 capable.

[coss370]

A standard van battery is about 100ah. Assuming you draw about 50w on average for 2 days straight, you are probably going to drain the battery. You have to decide how far you want to draw your battery down.

I know a lot of people don't care, but generators are loud, smelly and they vibrate like a toy. I understand they are a necessary evil, but nothing on the market is quiet. They are super annoying in my opinion.

Originally Posted by Atlee Hokie

This is what I'm thinking. If I'm tailgating this fall. I will just run the generator when necessary. We are "dry camping" 2 nights.

This spring-summer if we are touring the northern plains, YNP, Grand Tetons, etc., we will boondock at night, but we will be driving during the day to visit the sites and charging the batteries at the same time.

We should be fine. If it's cold, the furnance will be the biggest draw. Second biggest draw will be my CPAP machine. If it gets too cold, we'll leave for warmer climes.

All I am saying is that don't buy an AGM battery thinking you can get anywhere near the rated ah, at least not for the rated life of 6 years anyway. For one, you have to assume you wont ever get to that 100% charging. If you try to be conservative and not draw down past 50%, you are left with a lot less than you think. Now can you take it way down to 10v every time? Of course, but how long is that battery going to last?

Originally Posted by booster

The ratings for the AGMs is normally the point they get to 80% capacity so nowhere near only having 30-40% capacity.


I think you can come close to the rated life in AGM batteries if you have very good charging equipment, maybe not all the way, but close. Our Lifelines are about 5 years old and still test as new for capacity and voltage.


From the data given on the life charts, when going by energy in/out, the lifespan deteriorates fairly quickly when you get below 20% state of charge, so using the 20% normally stated by the manufacturers for deep discharge looks to be a good point to go to. At least with AGM, and probably lithium also, the cycles of various discharge depths average out in terms of battery degradation, so an 80% discharge and a 20% discharge cycle are basically equivalent to two 50% discharges.


The energy stored in a 100ah AGM at 20% SOC is nearly the same as in a 100ah lithium with a bit of difference due to voltage.


The big deal right now is that nobody really knows how long the lithium will last in RV use yet and based on the wide range of life ratings we see in them, it is anyone's guess which is even close to actual.


Glad you are happy with what you have, but your original statements did not reflect the actual characteristics or capabilities of the AGM batteries, IMO.

[coss370]

I have one of those battery isolator on my car. It takes 6 hours to charge about 100-150ah. As I said, a good shunt is an eye opener on what goes in and out of the battery.

[booster]

Originally Posted by coss370

A standard van battery is about 100ah. Assuming you draw about 50w on average for 2 days straight, you are probably going to drain the battery. You have to decide how far you want to draw your battery down.

I know a lot of people don't care, but generators are loud, smelly and they vibrate like a toy. I understand they are a necessary evil, but nothing on the market is quiet. They are super annoying in my opinion.



All I am saying is that don't buy an AGM battery thinking you can get anywhere near the rated ah, at least not for the rated life of 6 years anyway. For one, you have to assume you wont ever get to that 100% charging. If you try to be conservative and not draw down past 50%, you are left with a lot less than you think. Now can you take it way down to 10v every time? Of course, but how long is that battery going to last?

I would have to disagree with the premise of this is several ways.


You can get full charging on a regular basis with the right equipment. We have been doing it for quite a number or years. And yes, I mean full per the battery manufacturers parameters of amps to the battery at absorption voltage measured through a very accurate shunt based monitor. You shorten the life if you don't get full, but it isn't the batteries fault, it is the charging.



6 years? and not making specification is not good and would certainly indicate an issue unless it is a daily deep discharge recovery that would be way over the rated cycles. Ours are 5 years+ old, we don't hesitate to go under 50% if needed, but is not all that common, and they still test at a bit higher than rated amp hours in a draw down test. We have good chargers that control by the actual amps to the battery, and even on alternator I can watch the amps from the cockpit and switch the alternator(s) to float or disconnect charging and let the amp controlled solar finish it off to full.


IMO, this all can be done, but many choose not to do to cost and are willing to accept the lower available capacity and battery life, and I can't argue with that as it is their choice. The problems come because the charging companies say their chargers charge to 100% but the don't actually do it. The monitor companies set their defaults so an 80% full battery indicates full when it is not. Folks need to understand this, I think, before making decisions.


We hear all the time on the forum from users that think they are getting full charges "all the time", when in reality they are probably not, have no way to tell if they are, and have no way to make it better anyway.


Bottom line, IMO, is that you can certainly charge full to 100% almost all the time and certainly often enough to not shorten battery life. It takes good equipment though which is expensive, and an understanding of what a full battery really is. Very few techs even understand this stuff, I have found.

[coss370]

I don't disagree with you that good charging equipment is expensive, and you are right most cars don't have the proper equipment to make the batteries last as long as they could. I am just saying for a regular person driving an off the shelf RV should not expect a perfect number in their power calculation. You need plenty of reserves and be conservative. This is not much different than someone buying an EV car and expect the EPA range.

[booster]

Originally Posted by coss370

I don't disagree with you that good charging equipment is expensive, and you are right most cars don't have the proper equipment to make the batteries last as long as they could. I am just saying for a regular person driving an off the shelf RV should not expect a perfect number in their power calculation. You need plenty of reserves and be conservative. This is not much different than someone buying an EV car and expect the EPA range.

Yes, exactly, factory setups are commonly not good, capable, equipment. The big thing is to let folks know that it isn't the batteries and getting "better" batteries may not change anything. I just wish the charger and monitor folks would be more upfront on their real capabilities and give settings that actually tell you something, be it good or bad.

[GeorgeRa]

Originally Posted by coss370

A standard van battery is about 100ah. Assuming you draw about 50w on average for 2 days straight, you are probably going to drain the battery.......

If you draw 50W on average in 2 days you would draw 200Ah from a 12V battery. Rather impossible with a 100Ah 12V battery. 50W x 48hrs/12V = 200Ah. Please correct me if I am wrong.

[coss370]

Originally Posted by GeorgeRa

If you draw 50W on average in 2 days you would draw 200Ah from a 12V battery. Rather impossible with a 100Ah 12V battery. 50W x 48hrs/12V = 200Ah. Please correct me if I am wrong.

You are right, I was thinking 200ah total size with 100ah what they like you to use for longevity.

[steverosen]

First thing: there are two entirely different lithium systems being conflated in some of the discussions of lithium. The $20k system replaces the generator, allowing days of full electrical use (including AC/heat). The other lithium choice (~$2k) is to replace the chassis batteries with similar capacity (200aH or more), permitting deeper discharge, lower weight, longer life, This option may require some additional upgrades to charger, depending upon your original equipment.

[avanti]

Originally Posted by steverosen

First thing: there are two entirely different lithium systems being conflated in some of the discussions of lithium. The $20k system replaces the generator, allowing days of full electrical use (including AC/heat).

Huh? In what possible way does any battery "replace the generator"? Generators turn fuel into electricity. Batteries store electricity.

The other lithium choice (~$2k) is to replace the chassis batteries with similar capacity (200aH or more), permitting deeper discharge, lower weight, longer life, This option may require some additional upgrades to charger, depending upon your original equipment.

Has ANYBODY ever replaced their chassis battery with lithium? (Well, I'm sure SOMEBODY has, but...). Very difficult and expensive (as you say). Almost impossible to do properly in a modern vehicle. And, if you succeed, you have succeeded in adding all the lithium temperature restrictions to a previously temperature-robust vehicle. Sounds like a solution in search of a problem.

I don't mean to be snide, but let's not confuse future readers.

[booster]

Originally Posted by avanti

I don't mean to be snide, but let's not confuse future readers.

I agree, there is so much misinformation being slung around by the manufacturers and sellers of all of this stuff, be it lithium, AGM, chargers, solar, big alternators, whatever, that it is very common for people to take it as gospel, when it is far from it, when you look at the technical details of the claims.


There are piles and piles of discussions on this forum that contain good information, and opinions, but are also backed up by technical information and references. It certainly is a lot to read and decide if you agree or not, but IMO that is a much better way to go than to believe whatever the sellers are telling you.


This thread is full of things that have been discussed a lot on here, so no shortage of information.