Any experience with Lithiumax start batteries?

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Flow

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Hi folks, has anyone had any experience with these batteries. We don't have access to EarthX downunder.

Specifically any comments on electrolyte decomposition / LiO2 or O2 generation and swelling / case cracking and the quality of the BMS of these items. (Could case swelling also be related to altitude?)

I am running an 'electric' aeroplane so the shut down mode would also be of interest!

They talk about a failure rate of less than 1% which seems rather high to me.


 

aerolithium

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Maybe contact Lmax and ask for details and a picture of their BMS. Ask if you can buy a BMS seperately. I'm sure they would have no problem with that ! I didnt see any specs on their BMS on their website.
 

rv7charlie

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Here's all you need to know (from their website):
"Market leading 68Ah PbEq lead-acid/AGM/GEL equivalent capacity. "

See that rating in bold? That says, 'walk away'. A 'PbEq' number is meaningless, when the battery is a backup for alternator loss. It's a sleazy/deceptive marketing ploy; not a real measurement of anything useful to aviators.
 

Lmax

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Hi folks, it’s reasonable that a reply to a misinformed posting on a product is provided. We understand that in aviation there is little margin for error, so that granted, we wanted to set the record straight and provide some clarity and hopefully useful information for members. Lithium battery producers often struggle to communicate the fundamental differences between the incumbent lead based battery systems and the still relatively new lithium chemistry technology. For example you cannot equally compare a 50Ah AGM battery with a 50Ah lithium nominal unit. They are completely different in the way they sustain output and voltages at varying depths of discharge and that’s without taking into consideration their vastly different charge profiles. So to make it easier for customers and users to equate the lithium experience with their lived lead based battery experience, we like many others provide a PbEq rating that more closely correlates with the unit they are likely replacing. Whether that is in a motor vehicle, boat or aircraft. Lithium nominal numbers are also freely available for those willing to seek them out. We have our batteries installed in a significant no. of aircraft now with great success. So we encourage you to look beyond the sound bites and instead to the facts that may lead to a better overall solution.
 
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rv7charlie

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Before typing my previous post, I spent a few minutes looking around the linked website looking for detailed technical specs on the products, and all I saw was PbEq specs; no reference to actual AH ratings. Looking again today, I do see (in parenthesis) the actual AH rating on at least some of the batteries.

I stand by my statement that 'PbEq' ratings are deceptive marketing, because to the uneducated purchaser, it looks like a 68AH battery contains 68AH worth of energy. That is nothing like accurate, if it's being used like most lithium vendors use the terminology. Most are 'backing into' the number by using maximum cranking amps available, and then translating that number into the AH rating that a lead-acid battery would have if it were capable of that many starting amps. This is Marginally tolerable for ground-bound vehicles, but in aircraft, the battery isn't just for starting; it's also the emergency backup electrical power source with a failed alternator. This is where the deceptive marketing can get someone killed. Examples: The closest ratings the website shows to the 'industry standard' Odyssey PC680 at 16AH would be either the RACE3 at 15AH PbEq or the RACE5 at 26AH PbEq. Note that the RACE3 is 6AH actual, and the RACE5 is 10AH actual. The RACE3 would crank almost any aviation engine without a problem, if the CCA are accurate. But if the alternator failed, and we could extract every last mAH from the battery without the BMS going into protection & shutting it down, it would only run an automotive style injection engine system for about 25 minutes. Less than that if there were *any* other electrical loads, like flight instruments, lights, etc. Pitot heat alone would run it flat in less than 30 minutes, without the engine being in the equation. The 16AH lead acid (acknowledged that it's 1 extra AH) will run that injected engine somewhere between 40 & 50 minutes, and will give warning through voltage degradation as it's getting close to exhaustion. Many lithium BMSs will simply disconnect the battery when they think the battery is too close to exhaustion.

I recognize that you can get a slightly greater percentage of the rated actual AH of energy out of a lithium tech battery than a lead acid battery (assuming the BMS doesn't prevent it to protect the battery). But a 6AH lithium is still 6AH. You aren't going to get 15 AH worth of energy from it.

I'll be happy to be proven wrong. Show us the 20 hour, 10 hour, and 1 hour rates on the two batteries I quoted above so we can compare with published data on lead acids like the Odyssey, and then we can discuss further. (Not married to Odyssey; it's just an easy site to get real world lead acid specs. I've used numerous other brands of SLA with similar performance.)

Charlie
 

dave wolfe

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Dont forget to carefully assess the battery protection circuitry for electrically dependent aircraft. Battery over voltage protection circuts have contributed to at least one engine failure and subsequent fatal air craft accident that I am aware of.
 

aerolithium

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I always state the Ah rating of the battery from the Ah rating of the cells I assemble batteries with. Aerolithium.com
Ah IS Ah like R7 said... sort of
NOW, i say "sort of " because the Ah I usually see in PbA batteries are based on a C/10 or 20 rate ...see A
In the case of a PC680, u get 16Ah for C/10... BUT, if you do a C/1 ( like I do ) then, the PC680 will NOT get 16Ah... maybe 12Ah or something.
Its easy to inflate the Ah by discharging at less than 1C
Plus u have to figure in the fact that Pb batteries only discharge 50% of their " capacity vs Li batts that can go down to 80%.
Plus you have to also consider the discharge curve.
So, there is no good way to compare the two.. so, dont even try.
If anybody here would like to 'test" a lithium battery and report back to the forum, I would be willing to supply such ( as long as it is returned)
I'd like to hear more about the engine failure because of an overvoltage protection circuit.. you have a link ?

A. The ampere-hour (Ah) rating defines the capacity of a battery. A typical battery that is rated as a 100Ah battery at the 10 hour rate of discharge is capable of delivering 10A for 10 hours before the terminal voltage drops to a standard value such as 1.67 volts per cell, or 10.02 volts for a 12V battery.
 

rv7charlie

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Plus u have to figure in the fact that Pb batteries only discharge 50% of their " capacity vs Li batts that can go down to 80%
The part in italics isn't factually accurate. It's true that Pb batteries have much longer lives if they're never discharged below 50%, differing from lithium. But, and it's a big 'but', that is *not* a hard limit on how deeply they can be discharged. The Pb can be discharged all the way down to nothing, if the need arises.

In normal operation, neither battery will ever get discharged below about 95% of capacity; reflecting the energy needed to crank the engine. The critical thing for a battery in an a/c is how it performs after a failure of the generating system (alternator), and that's the reason for my 1st post in this thread. It's correct that the AH available from a Pb battery decreases at high discharge rates, and you can find that well documented information on the better mfgrs' web sites (the reason I used the Odyssey brand as an example). Also true that there's less AH variation due to high loads with lithium. As long as all the data on the batteries is available, and we know the real world current demand from our a/c when operating without the alternator, it's relatively easy to determine how many AH you need in either Pb or lithium chemistry. If your 16AH Pb battery can deliver, say, 12AH at high load, it will deliver 12 AH it's straightforward to determine duration on a healthy battery. If you purchase a '15AH PbEq' lithium battery that's actually a 6AH battery, it will never deliver more than 6AH of energy. If, as has been indicated, the lithium is limited to 80% discharge of its rated capacity (as is frequently the case when BMS is included in the battery), then the real world capacity of that battery in a no-alternator situation will be 6 * 0.8 = 4.8AH; roughly 40% of the Pb battery's capacity.

I say again: The vast majority of 'PbEq' numbers you'll see in lithium starting battery marketing are derived from maximum cranking amps, and that number has nothing whatsoever to do with how long the battery can supply the energy needed to keep the a/c safely in the air.

edit: For a 'gas engine' analogy, consider a 500 HP Corvette with 1 gallon of gas in the tank, vs a 60 HP Chevette, with 10 gallons of gas in the tank. In a 1/4 mile race, no contest. In a 100 mile race, also no contest, but the results will be very different.
 

Lmax

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There are some valid points made here, thank you, however it’s important to clarify that the PbEq no. is not a derivative of CA or CCA and instead takes into account that not only do Pb based chemistries such as Odyssey degrade in performance over time below 50% discharge but also experience significant voltage drops so are effectively useless in a 12V dependent system below this level. A Pb based battery therefore is only useful in critical systems for ‘approx’ half its rated Ah capacity. Our Race+ series units will achieve 90% DoD until the 8V cut intervenes and will maintain voltages at useful levels until that point where it then drops to the 8V cut relatively quickly. Completely understand your points regarding alternator failure and battery run-time so we would always recommend the largest lithium unit you can afford to carry in weight and that will always be significantly superior to any Pb based solution. You could comfortably double your run-time for the same weight carried by following this common sense approach.
 

rv7charlie

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A Pb based battery therefore is only useful in critical systems for ‘approx’ half its rated Ah capacity.
Again, that's at best, misleading. The point at which a 12V Pb battery is considered discharged is around 10V, though it will continue to supply current at much lower voltages. Most (not all) avionics in a/c will continue to operate properly until voltage drops into the 8.5-9.5V range. *All* batteries, lithium included, degrade in capacity over time. Lithium chemistry can typically withstand more charge/discharge cycles than Pb, but real world anecdotal evidence suggests the the time difference when used in an a/c isn't nearly as great as the theory suggests. If you aren't doing a capacity check on your battery when you do the annual, you are not following the 'letter of the law' in FAA rules. I repeat: that 50% discharge limit number is *purely* to extract maximum *useful life* (basically years in service) from Pb batteries used in 'deep cycle' environments (trolling motors, electric wheel chairs, emergency lighting, etc) and is meaningless for batteries used in motor vehicles that have integral charging systems. I say again: In normal use, a Pb a/c (or car, or boat, or motorcycle) battery will never be discharged by more than 5% of capacity (meaning it never gets below 95%) because it takes less than 5% of a typical Pb battery's total energy to crank the engine. (Don't make this assumption with a 'PbEq' lithium that really has only 1/3 the capacity of the Pb; in that case, it would take closer to 15% of total capacity.)

While Pb batteries do fail, they almost always give some warning that their capacity is degrading before any outright loss of power; they fail 'gracefully' if they have proper care. On the other hand, there have been numerous reports of LFP batteries which contain built-in Battery Management Systems (BMS) going into hard shutdown (system disconnect) due to real *and* imagined (by the BMS) external issues that a Pb battery would have handled for many minutes (or totally ignored, in the case of a 'false positive'). This has the potential of total loss of avionics or even engine power, and also of destroying expensive avionics, if the alternator is on line at the time and doesn't have a very effective 'load dump' prevention circuit in its voltage regulator.

There are more potential 'gotchas' with lithium; we can discuss further if anyone's interested. I'm not saying that they shouldn't ever be used; I'm just saying that they are not true 'drop-in' replacements for Pb and if you don't know what you don't know, you can get bit.

Back to the capacity issue. Odyssey shows us their detailed info for their 16AH Pb starting battery; roughly the same performance can be had from many of the other Pb brands:
1636669190583.png
EarthX, after persistent prodding from some of us in the RV-x world, has shown us their lithium discharge curves (for their PC680 'drop-in' replacement). Note that EX has, after persistent prodding, published the 1C capacity so it can be compared directly with the Pb battery they want to replace. Here it is:
1636669647157.png
Remember what I said about 'prodding'? Here's what the ETX680 replaced:
1636670137961.png
See the 2nd line in the chart? (36AH PbEq) See the 3rd line in the chart? Does the 3rd line look a bit like the 1C rating on the new ETX680? Until a lot of us beat them up *publicly* for months, their battery that had the same usable capacity as a 16AH Odyssey (and a bunch of lesser known brands for 1/3 the money of the Odyssey) was being sold as a '36AH PbEq' battery *to aviators for use in their electrically dependent aircraft*.

All the above was snipped from the mfgrs' data sheets. I can attach them if anyone wants to see the source material.

Can you show us the model number, weight (and $money) to supply, say, 12A for one hour (the 1C rate) using your lithium? What's the PbEq rating you assign to that battery in your marketing material?

Many thanks,
Charlie
 
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Lmax

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It’s not misleading at all, we made it clear that below 50%, Pb based batteries are no longer effective in “a 12V dependent system”. You are correct however in suggesting that what is effectively a lump of lead is not as complex as a lithium battery with a sophisticated BMS. Aircraft should have its charging system operating in accord with the battery technology chosen and maintained to a level that you would expect a critical system to be maintained. This includes being able to fly independent of the battery in extreme cases and vice versa should the charging system fail. It’s about redundancy planning, which you would expect in good aeronautic design. That discharge curve is fairly typical for LiFePO4 cells. If you want to plan around the benefits of lithium, take into account the lithium nominal figures. They will again give you significantly superior capacity to Pb Ah ratings and the equation tips strongly in favour of Li when you then take per kg carried into consideration. The PbEq no. should not be relied upon in a/c just as Pb Ah no.s should not. As we know a 16Ah Pb battery will not yield anything like 16Ah to reliably serve a 12V system. The lithium nominal no. is the closest indicator of true usable Ah available at present.
 
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