Jump to content
Zolle

Lithium V Agm Batteries - Usable Ahrs

Recommended Posts

Further to my post on replacements for my Fullriver batteries I am seeking information that others may have collected or have experience knowledge of.


Duting my 8 years of use of the batteries on my van I have never montitored the SOC and only checked the batteries voltage making 12v as the low limit.


In seeking prices for replacement AGM batteries I founf an importer/retailer who could supply 2 AGM's for a good price or supply 2 LifePO4 batteries for a much larger price.


I have been advise by the makers of the solar controller and battery charger fitted in the van that both are suitable for use with LifePO4 batteries that have their own battery management system.


The batteries supplier agrees with that proposal.


However my dilema I now have is that I do not know how many A/Hrs are able to be safely drawn from each type of battery so my questions are simply the following -


For a 120 AHrs AGM battery how many AHrs can safely be drawn in regular use without charging.



For a 100 AHrs LifePO4 battery how many AHrs can safely be drawn in regular use without charging.



If I can get comparable information I can make the decision of which battery to buy, ignoring the cost difference of course.



Cheers


John


Share this post


Link to post
Share on other sites

Laugh out loud,

How could you ignore the price difference.... it's huge.......just think about lounging on a sunny tropical island (with a drink in hand) when handing out your hard earned dollars.

Looking forward to hearing which way you go.

Share this post


Link to post
Share on other sites

At the moment, with the price differential being almost 2:1 for LiFePO4 Vs AGM there is little point in getting Lithium over AGM unless you desperately need to save weight. Lithium batteries can deliver 80% of their power without unduly harming themselves, whereas AGMs can deliver 50% of their rated power. So, if you had a 100 AH battery of each type, the Lithium could deliver 30% more power for nearly twice the price.....very hard to justify.



When I purchased Lithium batteries for my Kedron there was only a 30% price differential, which made the comparison equal - and I was after the weight saving, so I was in front. I am buying a new van at the moment and at current prices Lithium is not an option I am considering.



Cheers



Russ


  • Like 1

Share this post


Link to post
Share on other sites

Hi John,


Good topic, I will be watching to see which way you go. Our van is due March 2016 (21' XC3) & we were thinking of going 300Ah LiFePO4. Looking @ prices between 200Ah & 300Ah I was a bit confused as to why per Ah is dearer. I would have thought cheaper :huh: . This could be that I haven't done enough research yet :unsure:.


David I will send you a E-Mail to take you up on your offer, Thanks.



Cheers


Roly


Share this post


Link to post
Share on other sites

Hi David


Thanks for your informative response, however did you mean to say your points 1 - 5 really are myths?


The reason why I am not considering the price differential between the batteries is because my starting point is the cost of a new van upgrade would include a tug upgrade and would be around $70-80,000 to do the same job as the existing ones with a few mods.(Tony I can laugh at the cost saving)


Weight saving is a consideration as we have a plated ATM of 3.1t and only 60-70kg to play with when water tanks are full and fully loaded to travel across the country..


If I lose 30kg with Lithium batteries that could give me enough extra load for a grey water tank and a couple more solar panels.


The straight cost comparison of the offers received from the one supplier is 2 x 120AH Bosch AGM at $600 and 2 x 100 AH lithium with BMS at $2800.


I believe the Lithium batteries would give me a lot more AHrs available without the concern as with AGM's of running the batteries too low and causing damage to them.


Also my fridge stops working around 11 - 11.5V and Lithiums are likely to maintain a working higher voltage longer.


As David said the Lithiums are relatively safe to fully discharge and quick to charge fully.


No decision has been made yet as my old batteries are with the supplier being tested.


I did not know that apparently a proper test of agm deepcycle batteries involves multiple cycles of charges to 100% and discharges to flat over several days.



Cheers



John


Share this post


Link to post
Share on other sites

Hi again



I don't wish to start a war about this, but I have to comment on cvtripper's assertion that LiFePO4 batteries can be discharged by 95%. This is only true if you wish to have a VERY short life expectancy for your battery.See the images, below, for an explanation: (Clicking on the images will show a larger version)



DOD.png


This first image shows the voltage of a 4 cell LiFePO4 battery, nominally known as a 12 Volt battery. In reality the battery, when fully charged and at rest, will have a terminal voltage of 13.3V. Once the battery starts to discharge the voltage drops, quite quickly to 13.2V, where it stays until the battery is 80% discharged. After this, the voltage drops away dramatically because chemical changes and damage begin to occur within the cells. Continually discharging LiFePO4 cells more than 80% quickly damages cells.


dod2.png


The second image shows just how the number of charge/discharge cycles is affected by deep discharging. At 80% depth of discharge you could expect a well-made LiFePO4 cell to last 5000 cycles. By discharging to 90% the number of cycles drops dramatically to 3000 and at the 95% DoD that cvtripper advocates, you are looking at closer to 2000 cycles.


So, to wring out the extra 15% of the power from a LiFePO4 battery, you more than halve its life expectancy. This is why most comparisons of lead-acid and LiFePO4 batteries use the 80% figure that I chose in my previous post.


The cost of buying the different types of battery is not the only consideration. Most people want a long service life from their batteries after forking out a lot of dough.


Given these factors, I stick by my assertion that, at the moment, LiFePO4 batteries are not at a competitive price-point.


Cheers


Russ

Share this post


Link to post
Share on other sites

Hi John,

No, what I posted as 1-5 are to address the myths. I have edited the sentence above the list.

200AH of Lithium cells should cost you around $1300.

What BMS are you quoting?

And while deep cycling AGMs to 0% will test their load capacity, it will also severely shorten their life.

Hi David

The supplier told me the batteries have their own built in BMS which is confirmed on the Fusion web site.

http://www.fusionagmbatteries.com.au/tabid/337/cid/8/Products/LithiumIonPhosphateBatteries.aspx

Regarding the testing I have already concluded my batteries have reached their useby date after the cycles I put them through whilst my fridge was playing up and the fact that they would not charge above 97% SOC.

Cheers

John

Share this post


Link to post
Share on other sites

Dave, as I said previously, I'm not interested in a war about this. I am an advocate of LiFePO4 batteries and had good service from those in my caravan, but it doesn't end there. Just to correct you on two things: If you re-read my last post, you will see that I specifically said "This first image shows the voltage of a 4 cell LiFePO4 battery....." so, yes, I am fully aware that you need 4 x 3.2 Volt cells to make a nominal 12 Volt battery. Also, there is no logic to your statement "Cell damage does not occur at 20% SOC - damage occurs when you drive then negative" If a battery has a service life of 5000 cycles at 20% SOC and this service life reduces dramatically to just 2000 cycles by discharging to 5% SOC, then only one thing can account for this loss off lifespan - damage.



I will thank you not to question my competency when you have absolutely no knowledge of my background, as you did in this statement "I don't think you have analysed this properly and it is clear you don't have any practical experience"



For your benefit, my entire career of more than 40 years has been spent working with DC systems of all sorts, including practical experience with LiFePO4 battery installations. I installed my first solar-powered communications site back in the mid 80's, so I know a thing or two about the subject.



In your eagerness to pump up the good points of LiFePO4 you have ignored the simple fact that the Industry itself acknowledges and accepts that an 80% depth of discharge is for all practical purposes the recommended operating limit of practical use. Yes, this still makes LiFePO4 batteries superior to AGM batteries, but to ignore the price differential is wrong. And that was my point.



Typically, a Kedron owner will keep his/her van for 6 to 8 years before selling. A well maintained set of AGM batteries used under the typical conditions that you, yourself describe, should last no less than four years. That means, discounting the original set of batteries, a typical owner will only need to replace their batteries once. After that, whatever happens, the next owner is going to get the legacy of any battery life that may be left. So, at the current price of LiFePO4, would I be donating the extra money I spend to the next owner, or would I be getting AGMs and spending the difference on something else? I'm going through that decision making process right now and I'm thinking that the money is better in my pocket.



Just for the record,I have a real-world example of LiFePO4 NOT giving good service and it turned out to be an expensive experiment. I purchased a DC motor for my kayak. At top speed it drew 15A. As weight is only good in steamrollers, I decided to buy a 60AH Winston 12V LiFePO4 battery to run the motor. My sounder/plotter gives a readout of the battery voltage and I used this to monitor the battery volts at all times.At no stage did I ever allow the terminal voltage of that battery to drop below 13V. It was charged religiously after every trip, using a Sterling battery charger that was purchased specifically because the charging regime could be customised for perfect LiFePO4 charging and when 240VAC was not available, charging was via a Plasmatronics PL-60 that had been customised for perfect LiFePO4 charging. Yet, even after doing everything correctly, I noticed that the time that elapsed before the 13V was displayed on my sounder was getting shorter and shorter - in other words, the battery was losing capacity. I never did count the number of cycles that the battery underwent, but in two years of using the battery for maybe three months per year at most, that battery died. Possibly 100 cycles at most. OK, it might have been a dud. It might not have too. One thing is for sure, that battery could not have been treated any more kindly and it failed. Warranty expired, money gone.



So the science is still not perfect. I still advocate LiFePO4 batteries - those in the Kedron (which were also Winston batteries) were still at peak condition when we sold the van - but I do not advocate LiFePO4 to the exclusion of all other options and I don't believe that encouraging people to spend twice as much money (at least) as they may need to, is a good thing, particularly if people are retro-fitting LiFePO4 batteries and will have to fork out for a new 240VAC charger and perhaps even a new solar regulator as well.



Cheers



Russ


  • Like 1

Share this post


Link to post
Share on other sites

Russ obviously has all the knowledge that Kedron owners need, so good luck with your AGM setups, knowing we are camped near you boiling the kettle, using the electric oven and A/C on LiFePO4..... but obviously using an inferior technology... Pleased don't start that noisy generator up to use the microwave to cook dinner like have have seen many do...



My offer is still there is anyone is serious about wanting help. david@trip-tracks.com.au

  • Like 1

Share this post


Link to post
Share on other sites

One of the things I have always enjoyed about the Kedron Owner's Group forum was the general politeness of the members, the willingness to pass on knowledge and share experiences and the tolerance for differing points of view. Having sold our Kedron, I decided to stay on at the forum, as a guest, to continue that experience. But, just as one changes channel or turns off the telly if the programs are rubbish, I am too old to endure smart-arses for the sake of it, so rather than have my credibility attacked and put up with less than subtle smart-arsery, I'll just bid you all adieu. It has been great, being a Kedron owner and being on this forum, but all good things come to and end.



Bye all.



Russ.


Share this post


Link to post
Share on other sites

I am posting this as a Kedron owner and as someone who knows both CV Tripper and Russ. I have personally benefitted from advice and assistance from both of them over the years, and have valued their respective inputs to this forum.



I can see that there has been a degree of miscommunication in this discussion and appeal for some calm reflection on the topic.



Russ, please reconsider and continue your presence here as we value your input.

  • Like 3

Share this post


Link to post
Share on other sites

I am posting this as a Kedron owner and as someone who knows both CV Tripper and Russ. I have personally benefitted from advice and assistance from both of them over the years, and have valued their respective inputs to this forum.

I can see that there has been a degree of miscommunication in this discussion and appeal for some calm reflection on the topic.

Russ, please reconsider and continue your presence here as we value your input.

I also know both these guys and value their input on the forum.

I agree with you Chris.

Pete

Share this post


Link to post
Share on other sites

I think after reading the various posts in relation to the topic the basic question comes down to:- At this stage is it cost effective to instal during build time or even to retrofit a lithium set up in a van? Simple question.




Cheers



Merv


Share this post


Link to post
Share on other sites

Hi All


I have decided to buy 1 x 200AH LifePo4 battery as it is the best value $/AH in the range of 100, 200 & 240 AH batteries from my chosen supplier.


Weight saving over 2 x 100 AH AGMs is about 37Kg.


Cost factor over 2 x my original Fullriver batteries is just over 3/1 and compared to the Enerdrive systems Kedron are fitting my conversion costs are reversed at about 1/3.


Value for money is a combination of factors relavent to individuals.


Time will tell if the choice is right.



Cheers



John


  • Like 1

Share this post


Link to post
Share on other sites

This topic must eventually be of interest to all Kedron owners as batteries are critical to those of us that love the outback. It's a real pity if the forum loses someone with Russ' experience so if it is the last we have heard I wish he and Sue all the best.

I sometimes have problems with the technical details but I have no problem with understanding financial comparisons. One key point to remember with any financial comparison is that they should be looked at over comparative lifetimes. If one option has a lifecycle of 4yrs and the other a lifecycle of at least 15yrs then this must be a consideration in the comparison. If as claimed by Russ the owners dispose of their van prior to the expiration of the lifecycle of the item being considered then that also can be a consideration bearing in mind that it is also an improvement of that van over others fitted with AGM that might attract a price premium when selling the van..

It is stated in the thread that the replacement cost of 120ah AGM is $600. The life will average somewhere 4yrs. Over an equivalent life of 15yrs they will be replaced 4 times. If the van has two batteries that will be a total cost of $4,800. Our van has 3 batteries so the cost will be $7,200.

There is conflicting claims in the thread about a lithium system. The Enerdrive system needs replacement charger and controller whereas Fusion claim they have a management system built into the battery that nullifies the requirement to replace these items. If Fusion is correct and 200ah can be purchased for $2,800 then the outcome is a no brainer as the lithium comes with other benefits over the AGM.

Lithium DoD on 200ah will be 180ah whereas AGM on 200ah will be only 100ah, an extra 80ah, In addition lithium has a very favourable weight differential as well as size differential.

Our batteries are now in their 5th year but they are well on their way out so I will be faced with the task of chasing up information and doing my research when we get home.

Good luck to everyone else who is in a similar position.

Share this post


Link to post
Share on other sites

Good Morning Brian


In the forum they said they got 2 AGM batteries for $600, not each so this will half your figures. Also I wonder what the cost difference is if you buy a New Kedron with Lithium or AGM Batteries.



Interesting Neville.


Share this post


Link to post
Share on other sites

Hi Neville, Thanks for that. It brings both options back onto an even keel. When I discussed lithium with Kedron they were still working out their numbers but said the incremental cost of lithium above AGM would be in the vicinity of $2,000. This was for the enerdrive system which includes a new charger, battery monitor and I think a controller but you should contact David and get the correct information.

If AGM v’s Lithium are level pegging when I do my research then I will probably still favour Lithium. I spoke to a guy I met on this trip who has had 600ah lithium installed for 6 years. He got his battery from China, apparently it is a model used by the Chinese military. He hadn't experienced any problems and couldn't speak highly enough about lithium batteries. Another example is Russ who has reported their performance after 2 years and all’s good.

The problem that I will face is understanding all the technical jargon as in the articles I have read it seems that a lot of people have different information which sometimes is in conflict. This is where there is benefit for non-technical people in going with a complete system such as that being marketed by enerdrive but it certainly comes at a cost. This is just another variable in the analysis.

If you are interested in chasing up more information on Lithium then check out the following link on caravaners forum :

http://caravanersforum.com/viewtopic.php?f=2&t=55972&start=60

These challenges are all a part of this great off-road caravan world we enjoy.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...