Assorted questions about options

[Centex]

Originally Posted by Doug2000

1) People will argue, but I consider lithium very dangerous. There have been many RV fires caused by lithium. Not worth the risk in my opinion. Disclosure, I work for a company that mounts their Lithium batteries in a heavy steal box.

You're certainly entitled to your opinion, and that cannot be questioned or argued (or at least won't be questioned or argued by me).

I would sincerely appreciate you sharing source(s) about those "many RV fires caused by lithium" (that because my google-foo when earnestly searching just isn't finding many examples, particularly examples where the chemistry was LiFePO4 and the batteries were not 'DIY built'). I'm coming up totally blank insofar as finding data about frequency of occurrence among the RVing population.

I'm not personally interested in setting myself up for a fire-risk, but I do believe that battery chemistry makes a difference (there's many more than one type of "lithium" battery) along with selecting reputable vendors and exercising responsible operation habits. But I'd sure like to learn if I'm wrong.

One might also wonder if the theft-prone batteries your company works with are specifically LiFePO4 chemistry.

Thanks In Advance

[cpaharley2008]

I have personal knowledge of a potential Escape owner who was charging their li-ion motorcycle battery in the garage and the garage caught on fire.....

[steve dunham]

For us the tank level indicators are a non factor
We have according to Escape - A 28 gallon fresh water tank - A 28 gallon gray tank - A 22 gallon black tank

1) When we are boondocking we only have 28 gallons of fresh water so it would be hard to overfill the black or gray tank unless we ran every last drop of water we use into the black tank ( Not likely)

2) If we camp at a full service campsite , we have sewer so not difficult to keep tank levels in check

3) If we camp at a site with water and electric ( No sewer) I fill the freshwater tank and now were back to Step 1

Right now my tanks are totally empty , drain valves are wide open and my tank gauges read 2/3 full . I could spend $500 or $1000 so I could look at an LED display confirming that my tanks are empty but why ?

[Bobbie54]

Originally Posted by cpaharley2008

I have personal knowledge of a potential Escape owner who was charging their li-ion motorcycle battery in the garage and the garage caught on fire.....

I was using my lithium ion cordless Black and Decker lawn mower for the first (and it turns out, the last) time and the mower caught fire and burned to the ground, luckily not damaging nearby structures (fire department got my car out of the way and helped put out nearby grass fires). The lithium battery may or may not have caused the fire but it sure didn't help when the battery started exploding.

But I still use things with lithium batteries, although not the B&D drill I'd bought and not yet used. (My Ego mower has a fan on the battery charger to keep it from overheating and I've safely used Ryobi batteries for years.).

[Brian B-P]

Originally Posted by cpaharley2008

I have personal knowledge of a potential Escape owner who was charging their li-ion motorcycle battery in the garage and the garage caught on fire.....

LiFePO4, or another lithium-ion battery chemistry? Did the battery have a battery management system?

Originally Posted by Bobbie54

I was using my lithium ion cordless Black and Decker lawn mower for the first (and it turns out, the last) time and the mower caught fire and burned to the ground, luckily not damaging nearby structures (fire department got my car out of the way and helped put out nearby grass fires). The lithium battery may or may not have caused the fire but it sure didn't help when the battery started exploding.

LiFePO4, or another lithium-ion battery chemistry? So the actual cause of the fire was never determined?

[bobwirtz]

Thanks to all who have chimed in on this thread. We appreciate your willingness to share your experience. There is a long time still before we have to finalize our build so we will have ample opportunity to go over all the points of view that have been provided.

As of today the two things I am on the fence about are the detachable power cord and the SeeLevel tank monitor system. Good arguments have been made on both sides of those issues, and it is possible that we will come back to the community for additional thoughts. Glad you folks are here.

[Bobbie54]

Originally Posted by Brian B-P

LiFePO4, or another lithium-ion battery chemistry? Did the battery have a battery management system?


LiFePO4, or another lithium-ion battery chemistry? So the actual cause of the fire was never determined?

B&D had me send them the residual but never informed me as to whether they could determine anything. The handle was intact and apparently the controller was where the "brains" of the mower were so they wanted it. They still sell the same mower and I haven't heard of any others doing the same thing. I don't know what kind of lithium batteries but the big battery consisted of smaller tubes containing the actual batteries- I know because tubes survived and they exploded individually.

[Brian B-P]

Originally Posted by Bobbie54

I don't know what kind of lithium batteries but the big battery consisted of smaller tubes containing the actual batteries- I know because tubes survived and they exploded individually.

Thanks

Those tubes are the cylindrical cells, commonly in the "18650" format (which just means 18 mm in diameter and 65.0 mm long) which were first made for laptop computers and still go in the older models of Tesla electric cars... and Battle Born RV batteries. Many different variations of lithium-ion cell chemistry are available in this format, so we'll never know whether these were one of the less-stable types, or the more stable LiFePO4 typically used in RVs, but I'm guessing from the description that they were not LiFePO4.

[Brian B-P]

Originally Posted by steve dunham

For us the tank level indicators are a non factor
We have according to Escape - A 28 gallon fresh water tank - A 28 gallon gray tank - A 22 gallon black tank

1) When we are boondocking we only have 28 gallons of fresh water so it would be hard to overfill the black or gray tank unless we ran every last drop of water we use into the black tank ( Not likely)...

That makes sense, and that is how the tank sizes are planned, but water and sewer services don't always come together. In an ideal world the waste tanks would be dumped every time the water tank was filled, so the waste tank levels wouldn't matter. In the real world for many people water is topped up when it is available and waste is dumped when a dump site is available; waste dumps are less common than water sources, so the two can get out of synch.

[sameo416]

Originally Posted by Brian B-P

LiFePO4, or another lithium-ion battery chemistry? Did the battery have a battery management system?


LiFePO4, or another lithium-ion battery chemistry? So the actual cause of the fire was never determined?

My understanding is that the Lithium Iron Phosphate batteries are more robust than the ones which spectacularly fail, which are mostly the flex-pack type Lithium particularly when there has been some mechanical damage (even very slight is enough to start a failure). The usual failure mode begins with a short-circuit internal to a cell, which leads to heating, which results in thermal runaway and potential cascading failures of adjacent cells.

Thermal runaway is a problem with some high energy density batteries. NiCad had the same issue. With aircraft using NiCad batteries there were special response kits in place to deal with thermal runaway. As Lithium makes its way into the aviation marketplace there will need to be the same provisions as we had for NiCad.

All that said, Lithium batteries regardless of chemistry do have spectacular failure modes. Some of the risk is tied to manufacturing process and quality (the inclusion of contaminants in batteries is one cause of failure) but some is intrinsic to the technology. Even LiFePO. While the battery management system is critical to monitor individual cell health and to control charging, a failure in the BMS can also lead to battery troubles.

Like most decisions, there's a cost-risk-benefit tradeoff decision. Lead Acid have been around for a long time and don't have as spectacular failure modes (while creating other risks, electrolyte and Hydrogen gas).

We won't be installing Lithium any time soon, but our use profile makes the extra cost and risk unnecessary.

Lithium battery fires are hard to extinguish and have a tendency to re-ignite as long as there is a source of energy remaining in the battery.

This is based on my investigation of a number of home fires which were initiated by hobby type batteries, which are certainly higher risk than hard-sided LiFePO technology. Like most design decisions, you don't get that high energy density without some other issues to consider.

[Brian B-P]

Originally Posted by sameo416

My understanding is that the Lithium Iron Phosphate batteries are more robust than the ones which spectacularly fail, which are mostly the flex-pack type Lithium...

Electrode chemistry, electrolyte type, and packaging are all separate characteristics of lithium-ion battery cells. "Lithium Iron Phosphate" (or LFP, or LiFePO4) is an electrode chemistry - one now rarely used for electric cars but suitable for RVs due the associated operating voltage range and their stability - which has nothing to do with the packaging.
"Flex-pack" is known in the industry as the "pouch" style of packaging; it is the most common choice for both electric cars and small mobile devices.

Originally Posted by sameo416

... the ones which spectacularly fail, which are mostly the flex-pack type Lithium particularly when there has been some mechanical damage (even very slight is enough to start a failure). The usual failure mode begins with a short-circuit internal to a cell, which leads to heating, which results in thermal runaway and potential cascading failures of adjacent cells.

Yes, this is how the mobile device batteries typically fail, but the pouches in electric vehicles are held in strong module structures, which are mounted in substantial battery pack cases; an RV battery unit should be packaged comparably to an electric vehicle battery... they're not, but they're still in reasonable boxes.

Originally Posted by sameo416

Thermal runaway is a problem with some high energy density batteries.

This is where the electrode chemistry comes in, and where LiFePO4 is a good choice.

Originally Posted by sameo416

While the battery management system is critical to monitor individual cell health and to control charging, a failure in the BMS can also lead to battery troubles.

Like most decisions, there's a cost-risk-benefit tradeoff decision. Lead Acid have been around for a long time and don't have as spectacular failure modes (while creating other risks, electrolyte and Hydrogen gas).

I agree - using any lithium-ion battery without a BMS would be a bad idea, and both safety and reliability depend on the BMS... which is probably an under-$100 item from a nearly random supplier, as discussed in an earlier thread.

Lead-acid batteries would benefit from most of the same battery management features as lithium-ion batteries get (cell-level voltage monitoring, protective disconnection based on voltage, cell balancing), but they are safe enough that a BMS is not seen as needed, and inexpensive enough that no one bothers with a BMS.

Originally Posted by sameo416

Lithium battery fires are hard to extinguish and have a tendency to re-ignite as long as there is a source of energy remaining in the battery.

Yes, battery fires confuse most people, because smothering them doesn't stop them and - despite being electrical - they need lots of water to cool them down and thus put them out.

Originally Posted by sameo416

This is based on my investigation of a number of home fires which were initiated by hobby type batteries, which are certainly higher risk than hard-sided LiFePO technology. Like most design decisions, you don't get that high energy density without some other issues to consider.

There's nothing inherently "hard sided" about LiFePO4 batteries, but a substantial case (whatever is inside it) is a good thing. "Hobby type batteries" brings up the possibility of polymer-electrolyte batteries, which have a horrendous reputation for failures. Remember the riding toys that were called something like "hoverboards"? An RV should definitely have a better-designed and better-constructed battery system than that.

[sameo416]

Originally Posted by Brian B-P

Electrode chemistry, electrolyte type, and packaging are all separate characteristics of lithium-ion battery cells. "Lithium Iron Phosphate" (or LFP, or LiFePO4) is an electrode chemistry - one now rarely used for electric cars but suitable for RVs due the associated operating voltage range and their stability - which has nothing to do with the packaging.
"Flex-pack" is known in the industry as the "pouch" style of packaging; it is the most common choice for both electric cars and small mobile devices.


Yes, this is how the mobile device batteries typically fail, but the pouches in electric vehicles are held in strong module structures, which are mounted in substantial battery pack cases; an RV battery unit should be packaged comparably to an electric vehicle battery... they're not, but they're still in reasonable boxes.


This is where the electrode chemistry comes in, and where LiFePO4 is a good choice.


I agree - using any lithium-ion battery without a BMS would be a bad idea, and both safety and reliability depend on the BMS... which is probably an under-$100 item from a nearly random supplier, as discussed in an earlier thread.

Lead-acid batteries would benefit from most of the same battery management features as lithium-ion batteries get (cell-level voltage monitoring, protective disconnection based on voltage, cell balancing), but they are safe enough that a BMS is not seen as needed, and inexpensive enough that no one bothers with a BMS.


Yes, battery fires confuse most people, because smothering them doesn't stop them and - despite being electrical - they need lots of water to cool them down and thus put them out.


There's nothing inherently "hard sided" about LiFePO4 batteries, but a substantial case (whatever is inside it) is a good thing. "Hobby type batteries" brings up the possibility of polymer-electrolyte batteries, which have a horrendous reputation for failures. Remember the riding toys that were called something like "hoverboards"? An RV should definitely have a better-designed and better-constructed battery system than that.

Thanks - 'hard sided' in the sense that they're not in flex packs so less susceptible to impact damage which is a big failure mode for soft-pack Lithium batteries regardless of electrode chemistry (because the problem is the impact, not the chemistry).

My main point in responding: different technologies have different risks, and saying that one particular chemistry is "safe" isn't entirely correct, "safer" than an alternative maybe if you have some data to back it up. High-energy density batteries have different failure modes than lead acid, and that needs to be considered in an overall trade-off risk assessment when you're picking a type of battery for use. ie the fact you can't point to a LiFePO RV battery failure doesn't mean the risk doesn't exist.

BMS is a good example of that. One of the things which makes Lithium batteries function is lots of condition monitoring built into the BMS, and often right into the battery. That includes temperature, voltage and current monitoring of individual cells within the battery. If the BMS fails with a Lithium tech battery you can have spectacular failures. The need to rely on another set of condition monitoring and control systems is an added set of failure modes not present in traditional lead acid batteries.

This is what caught both Boeing and the FAA with the 787 battery fires in 2013. That's a different type of Lithium battery of course, but one that was supposed to be flight-qualified. Both agencies were faulted for not performing adequate failure modes analysis and with not understanding the new technology they were dealing with.

So if you decide that Lithium is needed to fit your RV style, and you're willing to accept the risks associated with that tech, go for it.