LiFePO4 Batteries Could Invalidate Your Insurance

[twistedtree]

If the fire department can't extinguish the lithium fueled fire and it keeps blazing and reigniting, thereby exposing boats around it to an extended period of heat and flame...it makes a difference.

This is another area where people sometimes get lead astray. Lithium metal will keep burning even if drowned in water. In fact, water accelerates a lithium metal fire. But there is no Lithium metal in a lithium ion battery, so it doesn't exhibit any of those fire characteristics.

 

[Porgy]

Everything I’ve read so far says water puts out lithium fires. Such a fire on a boat would soon become self correcting. Read it from fire protection websites as well as the FAA which has unfortunately had some experience with the issue. Thermal runaway doesn’t mean it can’t be extinguished. It has to be thoroughly extinguished and adjacent cells and batteries must be cooled to prevent the runaway event from spreading or restating.

 

[rslifkin]

Everything I’ve read so far says water puts out lithium fires. Such a fire on a boat would soon become self correcting. Read it from fire protection websites as well as the FAA which has unfortunately had some experience with the issue. Thermal runaway doesn’t mean it can’t be extinguished. It has to be thoroughly extinguished and adjacent cells and batteries must be cooled to prevent the runaway event from spreading or restating.

For most lithium battery runaways, yes, large amounts of water will put it out. Not as much by extinguishing, but by cooling the thing down to the point where the runaway stops.

 

[Riverguy]

LiFeP04 with integral BMS; a "Self-Limiting" current source?

I have been looking at the finalized ABYC E-13 specification in the context of the numerous general and specific exceptions in E-11 (and elsewhere) applying to "self-limiting" current sources such as alternators and generators.

My interpretation is that a 'battery' (of any chemistry) that contains within it a BMS that disconnects the cells internally when discharge current exceeds a safe threshold is by definition a 'self-limiting' current source.

In testing an inverter-charger for a system I am planning to install, I used two such batteries (12v 100AH LiFePO4) in series connected to a 24v inverter. The batteries are UL listed and each battery will self-limit current to 100 amps. Because the batteries are in series, this provides redundancy in the BMS system; if one BMS fails to disconnect at >100A, the other battery would disconnect; shutting off the current from both batteries. I was able to confirm this in pre-installation testing when the inverter/charger tried to draw more than 100A from the LiFeP04's, the BMS systems shut off current within seconds. My tests confirmed this behavior at around 115 amps.

@CharlieJ, I would suggest to ABYC that batteries with internal current limiting protection be identified as examples of 'self-limiting' current sources. This interpretation would also save a huge amount of money in terms of heavy gauge wiring which (in the case of Lead-Acid batteries) is appropriately sized according to the maximum current available. For example the present requirement to size battery cables and inverter case grounding cables according to the maximum CCA/MCA or 'incendiary potential' of a 'dumb' Lead-Acid battery typically results in the need to cable with 4/0. Cables sized according to the 'self-limiting' exception would be much smaller and could easily cut the cost of cabling up an Inverter-Charger by a factor of 5-10x. As an additional benefit, this interpretation would reduce the incentive for installers to skip or scrimp on the critical case-ground conductor, usually the single most expensive electrical conductor on any boat.

 

[twistedtree]

I have been looking at the finalized ABYC E-13 specification in the context of the numerous general and specific exceptions in E-11 (and elsewhere) applying to "self-limiting" current sources such as alternators and generators.



My interpretation is that a 'battery' (of any chemistry) that contains within it a BMS that disconnects the cells internally when discharge current exceeds a safe threshold is by definition a 'self-limiting' current source.



In testing an inverter-charger for a system I am planning to install, I used two such batteries (12v 100AH LiFePO4) in series connected to a 24v inverter. The batteries are UL listed and each battery will self-limit current to 100 amps. Because the batteries are in series, this provides redundancy in the BMS system; if one BMS fails to disconnect at >100A, the other battery would disconnect; shutting off the current from both batteries. I was able to confirm this in pre-installation testing when the inverter/charger tried to draw more than 100A from the LiFeP04's, the BMS systems shut off current within seconds. My tests confirmed this behavior at around 115 amps.



@CharlieJ, I would suggest to ABYC that batteries with internal current limiting protection be identified as examples of 'self-limiting' current sources. This interpretation would also save a huge amount of money in terms of heavy gauge wiring which (in the case of Lead-Acid batteries) is appropriately sized according to the maximum current available. For example the present requirement to size battery cables and inverter case grounding cables according to the maximum CCA/MCA or 'incendiary potential' of a 'dumb' Lead-Acid battery typically results in the need to cable with 4/0. Cables sized according to the 'self-limiting' exception would be much smaller and could easily cut the cost of cabling up an Inverter-Charger by a factor of 5-10x. As an additional benefit, this interpretation would reduce the incentive for installers to skip or scrimp on the critical case-ground conductor, usually the single most expensive electrical conductor on any boat.

I’ll be interested to see what Charlie thinks. I don’t think there is any way that such a battery would qualify as self-limiting. Devices that are considered self limiting have output limits even in the event of something going wrong. An alternator is a good example. With a battery you are counting on correct operation of the FET switches for power limiting. Inherently the batter is a nearly unlimited power source, not a limited one. Also, I understand that when FETs fail, they tend to fail closed which would allow full power from the battery, at least until they all go up in smoke.

If you want to get an official answer from ABYC you can write to them asking for an interpretation, and that will go to the committee for a formal answer.

 

[Comodave]

They would be self limiting when the battery cables melt…

 

[Simi 60]

. With a battery you are counting on correct operation of the FET switches for power limiting. Inherently the batter is a nearly unlimited power source, not a limited one. Also, I understand that when FETs fail, they tend to fail closed which would allow full power from the battery, at least until they all go up in smoke.

We went BMS with contactor switch for this reason.

 

[SteveK]

So I read my policy twice and could not find either ABYC or Lifepo4 mentioned.
This concern must be a made in the USA issue

 

[Delta Riverat]

I don't care abut the insurance, don't have any (liability only), but do care about doing it right. Keep the LiFePO4 side completely isolated from the lead acid side.

One alternator with lithium regulator to charge the Li side and one alternator with standard for the lead. Two isolators, one for each side like the alternators. Two chargers for each side.

 

[SteveK]

I don't care abut the insurance, don't have any (liability only), but do care about doing it right. Keep the LiFePO4 side completely isolated from the lead acid side.

One alternator with lithium regulator to charge the Li side and one alternator with standard for the lead. Two isolators, one for each side like the alternators. Two chargers for each side.

why the isolation of two battery types?

 

[Delta Riverat]

A lithium charger will fry a lead acid battery and a lead acid charger will not charge a lithium to full capacity.

 

[SteveK]

A lithium charger will fry a lead acid battery and a lead acid charger will not charge a lithium to full capacity.

OK, but it sounded like there was a physical reason to isolate, separate them.
Of course there is a different charging profile.

 

[Delta Riverat]

No, that's it.

The boat is now equipped with one alternator with an external regulator to charge house bank and a stock alternator on the other engine to charge port, starboard and generator start batteries. Five batteries,all now lead acid. Plan to change house bank to LiFePO4.

So, change external regulator to Balmer, add 2 isolators with charge input from alternators and a separate charger for each side for dock.

 

[tiltrider1]

So I read my policy twice and could not find either ABYC or Lifepo4 mentioned.
This concern must be a made in the USA issue

I have never seen ABYC nor LiFePO4 mentioned in an insurance policy here in the US.

While I think ABYC standards are good practices, It doesn’t mean that there are not others equally as safe ways to do things.

 

[SteveK]

I have never seen ABYC nor LiFePO4 mentioned in an insurance policy here in the US.

While I think ABYC standards are good practices, It doesn’t mean that there are not others equally as safe ways to do things.

Interesting. Makes me wonder why surveyors quote ABYC when they write you up. Insurance agent not knowing any better says fix it or else.
I actually expected to see it in the policy.

 

[tiltrider1]

In my experience, good surveyors don't quote ABYC. They point out a deficiency and explain the safety implications of not correcting it.

The positive lugs on my starters have been exposed for 30 years. My surveyor wanted some protection on them. I took some vinyl hose and cut it to slide over the lugs. He was happy with that and I had to agree it was a safer arrangement, ABYC was never mentioned.

Similarly, my Raycor fuel filters have been on the boat for 30 years with no problems. Now the surveyor wants me to have heat shields. I found doggy pails. They are miniature buckets that make great heat shields with the added bonus of catching the diesel when I drain the bowls. I can't argue, its now safer, ABYC was never mentioned.

 

[rslifkin]

Interesting. Makes me wonder why surveyors quote ABYC when they write you up. Insurance agent not knowing any better says fix it or else.
I actually expected to see it in the policy.

I think many quote ABYC because it's better from their perspective to point to a standard as the proper way to do something (even if compliance with that standard isn't explicitly required) than to have a bunch of surveyors out there each recommending what they think is the best way to do something.