Lithium vs AGM again but different.

Submitted: Sunday, Oct 06, 2019 at 17:56
ThreadID: 139159 Views:15218 Replies:12 FollowUps:15
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I have seen a lot on forums like this about the benefits of Lithium batteries, and the capacity to weight ratio is a big benefit.

I read time and time again that another benefit is that they can be discharged to 80, 90 or even 100%. So compared to 50% discharge capacity of an AGM, you get extra capacity for the same size.

E.g. a 100AH in an AGM will give 50AH of usable capacity if you respect the battery life. And you will get 80AH out of a similarly sized Lithium.

But this seems to ignore the fact that lithium batteries have much lower life cycles at deep a discharge too. People quote 2000 to 3000 cycles using lithium, but this figure is generally at........50% discharge.

Specs I looked at (which are hard to find on many manufacturers websites) show life cycles of one tenth or one fifth of the quoted cycle rate when discharged to 80% DOD - that's 200 to 600 cycles. Same as a lead acid.

So the figures that you can get 80% DOD AND 5 times the battery life seem false to me.

So it seems to me that if you need to save weight or get a higher capacity from a restricted size, then Lithiums are great. At a price of 3 times the cost.

But if you think they will pay for themselves over time then thats not right unless you limit them to 50% DOD.

Am I missing something?
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Reply By: Member - Racey - Sunday, Oct 06, 2019 at 18:52

Sunday, Oct 06, 2019 at 18:52
Tony not all Lithium batteries are the same. There are numerious new bradnds on the market, marketed as replacements for AGM and have approximately the same dimensions. Others are more robust and built up with 4 x 2.8 volt cells. In my own van I have 400A/H with 8 x 200A/h cells manufactured by Synopoly in parralel pairs. There life cycle is >2000 cycles @ 80% discharge. Not only that they are capable of being charged at a max of 400amps per cell (normal is 66amps) and discharged @ a max of 600amps (66amps normal). This mean that heavy loads lik microwaves or coffe machines can be used safely without damage to the batteries. Whereas the AGM type replacement have limited max values of less than 100amps. And like everything, you get what you pay for.
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Follow Up By: Alloy c/t - Friday, Oct 11, 2019 at 08:55

Friday, Oct 11, 2019 at 08:55
4 X 2.8 volt cells ???? Unless maths has changed dramatically that equals 11.2 volts ....
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Reply By: RMD - Sunday, Oct 06, 2019 at 18:54

Sunday, Oct 06, 2019 at 18:54
If I were a Lithium battery seller and your comment was on a social media site, I might have your analysis and reporting removed as battery hate speech. I agree it is all questionable.
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Follow Up By: Member - shane r1 - Sunday, Oct 06, 2019 at 21:31

Sunday, Oct 06, 2019 at 21:31
I think a forum is a “social media” site , isn’t it?
Other than that the lithium versus agm subject is very confusing, I hope my agm’s last a few more years. Then I hope it’s all a bit clearer by then , there will be a lot more practical knowledge out there by then hopefully!
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Follow Up By: RMD - Sunday, Oct 06, 2019 at 22:04

Sunday, Oct 06, 2019 at 22:04
It seems Tony and Racey have highlighted the quality and capabilities of the lithium batteries. It is hard for most people to actually find out the real value and life of what is offered, with them all being sold with claims each is the best available.
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Reply By: Ron N - Sunday, Oct 06, 2019 at 22:14

Sunday, Oct 06, 2019 at 22:14
Boobook, I don't think you're missing anything, and I reckon you've figured it right.

Every style of battery is a trade-off, with varying features that appeal to certain types of use. You can't have it all, in the one style of battery.

The L-A battery industry is far from dead, it's fighting back strongly against Lithium, because L-A is proven technology, it's simple technology, and it's all fully recyclable.

L-A simply has a great weight penalty against it. But it's cheap power, as long as you treat it correctly.
Keep L-A batteries cool, don't run them down excessively, keep them regularly charged when you're not using them, and they will provide good value for money.

I for one, do not believe the Lithium mantra that Lithium lasts much longer than L-A.
I've regularly had 9 and 10 years life out of L-A batteries that were looked after.
It'll be a long time before we see cheap Lithium batteries.

Cheers, Ron.
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Follow Up By: Dave B18 - Saturday, Oct 12, 2019 at 19:02

Saturday, Oct 12, 2019 at 19:02
LA battery technology in RV's is dead for regular travellers.
LA batteries are no longer cheap against LiFePo4 drop in replacements if you look at the facts and figures.
Well you may not believe the mantra that LiFePo4 batteries well outlast LA batteries, so I would hate to confuse you with facts.
We are seeing cheap Lithium batteries now.
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Reply By: Member - nickb "boab" - Monday, Oct 07, 2019 at 06:41

Monday, Oct 07, 2019 at 06:41
where would a lead crystal battery rank in this battery war ? . I watched a well-known YouTuber sprouting on about lead crystal batteries .

Video lead crystal
Cheers Nick b

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Follow Up By: Allan B (Sunshine Coast) - Monday, Oct 07, 2019 at 12:27

Monday, Oct 07, 2019 at 12:27
Hi Nick,

The lead-crystal battery is another variant of the traditional AGM lead-acid battery with claimed advantages. Whether those "advantages" are of benefit in your application is moot. Certainly the price is not comparable and the weight is identical to AGM.

The claims of extreme discharge capability is perhaps a red herring as battery voltages below 12v are of little use to your refrigerator and its precious contents.

They seem to be promoted in Australia much more so than overseas and I can find little sensible technical information from overseas websites.

Betta Batteries appear to be the main proponents in Australia and of course all their information is sales-oriented rather than technical. As is of course the grandiose monologue from your referenced Andrew St Pierre White who could be more convincing delivering Shakespeare from a stage. What he knows about battery technology is below my comprehension and his presentation uses extensive graphics from the Betta website....... draw your own conclusions!!!!

I think that if I were considering a move up from conventional AGM batteries it would be to Lithium, not to some intermediate "Golly-Gee" technology.

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Follow Up By: Member - nickb "boab" - Monday, Oct 07, 2019 at 20:48

Monday, Oct 07, 2019 at 20:48
thanks Allan : enjoyed your spin on it.. LOL :)))
Like a lot of stuff out there ... cheers
Cheers Nick b

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Follow Up By: Dave B18 - Saturday, Oct 12, 2019 at 19:10

Saturday, Oct 12, 2019 at 19:10
Lead crystal batteries will only shatter your dreams and make your wallet substantially lighter than it should be.
The prices seen on some lead crystal batteries were dearer than LiFePo4.
200Ah LiFePo4 $1,275.00
150Ah LC $1,079.00
Yet to see a NATA certified lab test or anything of any consequence to support their amazing and stunning claims of lead crystal batteries. IMHO all sales spin and zero substance.
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Reply By: HKB Electronics - Monday, Oct 07, 2019 at 11:02

Monday, Oct 07, 2019 at 11:02
I can only go by what I have found with my setup.

Camper was originally equipped with two very expensive (and heavy) gel type batteries. Even though I tried to look after them as best I could, on a few couple occasions had no choice to discharge them to around the 30% SOC level. After approximately three years I found one battery had died. As we were installing more power consuming devices into the van and I was sick and tired of managing battery levels I decided to bite the bullet and replace the gel batteries with two 100 hundred Ah CALB battery packs from EV power. These have been in the camper now for three years. We are much more power hungry now from the vans view as we now leave the van plugged into the car to supply the freezer in the car so we don't have to worry about maintaining the SOC level of the cars lead acid aux. We have also used the van a lot more in the past three years than the previous three and on many occasions the SOC of the batteries has dropped to around the 30%. I now only occasionally look at battery levels to see where they and as I no longer worry about dropping them below the 50% SOC level.

I did a discharge test on the pair a few weeks back after returning home and preparing them for storage. I found the voltage readings of both batteries at 5% increments from 100% down to 20% were the same as they were when I received the batteries. I'm not saying they have not suffered any degradation, I'm sure they would have probably lost some capacity but as I never discharged them empty levels when I purchased them I don't know what the actually total Ah capacity was new. At this point in time they would still be at least 100Ah.

For me it was a win win scenario and I would never go back to a lead acid setup. If only I could find an under bonnet Lithium unit that I was sure could handle the heat the aux in the car would also be Lithium.

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Follow Up By: Allan B (Sunshine Coast) - Monday, Oct 07, 2019 at 11:36

Monday, Oct 07, 2019 at 11:36
Leigh, I like your attitude to monitoring your batteries. They do the job and you allow them to do so without constantly peering at them.
I reflect on those who constantly review their in-and-out Ah's and SOC and send it to a smart phone via Bluetooth only to agonise over the data.

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Follow Up By: HKB Electronics - Monday, Oct 07, 2019 at 11:56

Monday, Oct 07, 2019 at 11:56

Some seem to enjoy that, being a techo type initially I was the same but then found it was ruining our trips hanging around camp and chasing the sun. Much nicer now travelling and camping knowing the system can take care of its self and not having to worry about it :)

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Reply By: Iza B - Monday, Oct 07, 2019 at 16:05

Monday, Oct 07, 2019 at 16:05
The 50% myth for LA is just that, a myth. I have a 110AH Deep Cycle AGM that weighs 38Kg. After 9 years DOM, the battery still holds 12.7 and my Low Voltage cutoff is set at 11.6. Four of us bought these batteries ex-UPS 7 years ago. We all flog the batteries regularly down to LV cutoff. Care is to recharge as soon as possible and float for at least 8 hours. The weight and physical dimensions are a pain. Hoping the thing dies soon while recycling prices are high.

AGMs in the caravan are over 6 years old now and I just use them. They hold 12.82 rested so I am not concerned in any way about trying to track cycles or DOD post using a low voltage cutoff.

LiFePo4 I have is constructed from discrete cells with a DIY BMS. Top is kept to 14.2 and low is set at 11.8. The Lithium is in a campervan specifically for the smaller size and low weight. 4 years so far and they capacity test above nominal rating.

I ignore the cycles discussion because no one ever defines what a cycle is and under what conditions.

Li-ion is latest interest. I use the Li-ion for the electric outboard and to run the quad I am converting.

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Follow Up By: Malcom M - Tuesday, Oct 08, 2019 at 08:06

Tuesday, Oct 08, 2019 at 08:06
A cycle is defined as a charge and discharge event.

Doesn't matter what volts are involved. Even if not fully discharged, the charge action is another cycle.
Theoretically you use them up quick when camping with constant topups from solar but you get thousands of cycles. Anyway who's counting. I just use it and enjoy teh benefits.
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Follow Up By: Iza B - Tuesday, Oct 08, 2019 at 11:51

Tuesday, Oct 08, 2019 at 11:51
Yes, a good example of a totally useless definition of a cycle and why I never get into any discussion of Life as a count of cycles. Avoiding the discussion is a great way to avoid any of the anxiety that comes with trying to get maximum life out of a battery. Naughty of me but I often get people upset when I ask them how they work out what is that magic 50% SOC level when damage starts to occur. Having a battery is the cost of doing business. I'm doing well the way I do it so no need to be concerned.

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Reply By: Malcom M - Tuesday, Oct 08, 2019 at 08:15

Tuesday, Oct 08, 2019 at 08:15

You do not discharge lithium down by 100% as this will shorten the cell life considerably. Similarly you dot charge to 100% for the same reason.
There is only a small amount of extra usable capacity and its not worth the resultant loss of life.

If you use a battery pack with a built in BMS then you likely have no control over anything but if you DIY then for LiFePo4 your BMS will typically charge each cell to 3.65v and disconnect when discharged to 2.5v. Thats generally considered the optimum range for max life.
How this equates to the state of charge, I don't know. I just let my BMS take care of things and enjoy life.

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Reply By: SCUBADOO - Wednesday, Oct 09, 2019 at 09:47

Wednesday, Oct 09, 2019 at 09:47
I have no interest in "cycles" and look forward to someone attempting the impossible task of counting them for me. Outside of the lab do they even exist especially in the typical RV environment?

Our 4 cell 300Ah Sinopoly LiFePO4 battery pack has now survived 5 years of fulltime travel here in NZ. It is the only battery we have on board and also starts the 3.9l turbo diesel engine, often multiple times daily.
Cyle count? No idea but I can report the last capacity test @ 30A last November ( year 4) was 311Ah when the first cell dropped to 2.80V and the counting stopped.

I will report back in another 5 years.

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Reply By: Peter_n_Margaret - Friday, Oct 11, 2019 at 15:21

Friday, Oct 11, 2019 at 15:21
Forget cycles or years.
The way to measure battery life is total power delivered.
Same for LA or Li.
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Follow Up By: Member - Boobook - Friday, Oct 11, 2019 at 18:49

Friday, Oct 11, 2019 at 18:49
How does that help Peter?

A 12v lithium delivering 20Amps is the same power as a 12v Lead Acid delivering 20A. Ie 240 watts. (Give or take a few percent due to slightly different voltages)

Power is an instantaneous measure of work, It has nothing to do with capacity as far as I am aware.

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Follow Up By: Peter_n_Margaret - Friday, Oct 11, 2019 at 18:55

Friday, Oct 11, 2019 at 18:55
Forget cycles or years.
The way to measure battery life is total ENERGY delivered OVER ITS LIFETIME..
Same MEASURE for LA or Li.
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Follow Up By: HKB Electronics - Saturday, Oct 12, 2019 at 10:34

Saturday, Oct 12, 2019 at 10:34
Or another way to put it is throughput or Ah in and Ah out over the life battery.

I read somewhere that Victron specified for their Lithiums 2500 cycles @ 80% DOD, and 5000 cycles @ 50%DOD. Therefore 80X2500=200000Ah throughput, and at 80%DOD we have 50X5000 =250000A.

So we loose 20% at 80%DOD compared to 50%DOD.

Another aspect to keep in mind is most manufactures when they say end of life for a Lithium mean the battery has dropped to 80% of its original capacity so a 100Ah Lithium will still be around 80Ah, what is your AGM capacity going to be under the same conditions?

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Follow Up By: Peter_n_Margaret - Saturday, Oct 12, 2019 at 13:36

Saturday, Oct 12, 2019 at 13:36
Whether it is 20% loss of capacity or something less, the point is that they are not being "murdered" by taking them below 50% on a regular basis as some would have you believe.

There are some lithium makers who over state the original capacity in order to have a longer life before reaching the magical 80% too, so as with everything, we need to start at a known place before drawing too many conclusions.

I suspect that more batteries of all types are killed by poor treatment of various types than die from natural causes.
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Reply By: Member - peter_mcc - Friday, Oct 11, 2019 at 20:27

Friday, Oct 11, 2019 at 20:27
Most of the datasheets I've seen for individual LiFePo4 cells indicates 2000 cycles at 80% discharge - not 50%. They usually give a discharge current as well - a CALB 180A cell was 2000 cycles at 0.3C/80% (ie drawing 54A from it). A 160A Thunder Sky Winston cell was > 5000 cycles at 0.5C & 80% discharge (ie 80A discharge current).

I can't comment on assembled "batteries" as I haven't done any real research on them. But looking at just the cells it seems 2000 cycles at 80% DOD is pretty common. 5000 is possible.

I've just installed a 216Ah pack made up of 12 x 72A CALB cells in our Tvan. That gives me around 173Ah of usable capacity (80% DOD). It fits into one battery box (poking out the top a bit but I'm ok with that), leaving the other box free for storage. It weighs 22kgs.

To replicate that with AGM batteries would need 3 1/2 105Ah ones at 30kgs each - 90kgs if you had 3. The CALB cells cost $1450 delivered to Sydney - 3 x Full River 12V 105Ah batteries would have cost about $1000 delivered.

I realise my solution isn't for everyone - it doesn't include a battery management system and I use a Manager30 to charge it instead of the usual Tvan Projecta charger. But LiFePo4 batteries can be done reasonably cheaply.

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Reply By: 9900Eagle - Friday, Oct 11, 2019 at 21:01

Friday, Oct 11, 2019 at 21:01
Have a talk to Trevor Richards from Kuttabul just north of Mackay and he can give you a great rundown on lipo4 batteries. He will give you the degradation of the batteries over many years of use.

He uses winston cells and from what he told me, he has had only one fail and it just smoked a bit ant that was it. He is the fella that has a 2000 Hilux that he converted to battery bin 2007 and he drives it to Brisbane often. He is a hell of a nice genuine person, so you will get very honest answers from him.

I am away for awhile but try this number 4954 0285.

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Reply By: Member - Stefan F2 - Tuesday, Nov 05, 2019 at 20:58

Tuesday, Nov 05, 2019 at 20:58
hm I moved to LiFePo4 about a year ago

Most quality 100AH LiFePo4 will really be 125AH and 25% is reserved for battery safety and can't be accessed so my Revolution LiFePo4 100AH battery I have 100 usable AH.

If you look at the DCS LiFePo4 battery you will see that they have a cycle of 2500 at 100% DOD
which is 5 times of an AGM and around 5000 cycles of 40% DOD

An AGM will just die a LiFePo4 will reduce the capacity it can hold so may work much longer at a reduced capacity.

A good quality LifePo4 is safer inside the vehicle (The DCS LiFePo4, for example, uses a fire retardant electrode so they can't combust vs an AGM which has lead-acid so would leak hydrogen which is explosive when mixed with oxygen)

Depending on the LiFePO4 you can also recharge much faster (my dual DCS 100ah under the bonnet of Cruiser will be charging at 270amp from my M2k high output alternator.

It provides a constant current much better for winching and charging my camera and drone equipment.

So in my book, there is quite a few more reason for LiFePo4 beside weight savings.

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