On Tuesday, June 5, 2018 at 1:32:31 PM UTC-7, jfitch wrote:
On Tuesday, June 5, 2018 at 11:21:08 AM UTC-7, K m wrote:
On Tuesday, June 5, 2018 at 9:55:30 AM UTC-6, jfitch wrote:
On Tuesday, June 5, 2018 at 7:08:03 AM UTC-7, kinsell wrote:
On 06/04/2018 09:59 AM, jfitch wrote:
On Monday, June 4, 2018 at 6:55:55 AM UTC-7, krasw wrote:
On Monday, 4 June 2018 02:01:18 UTC+3, jfitch wrote:
On Sunday, June 3, 2018 at 8:29:08 AM UTC-7, Richard Pfiffner wrote:
On Sunday, June 3, 2018 at 8:18:49 AM UTC-7, Nick Kennedy wrote:
So is the problem of a fire caused by a dead short across the battery terminals?
Shouldn't a inline fuse coming off the positive terminal take care of any fire problem? I realize a wrench or something like it placed across the terminals would cause a massive short and possible fire, but lacking that, whats the problem?
Do these things spontaneously combust? I have two in my ship and want to know.

I shorted two different batteries, by placing upside down on a metal plate.

The LiFEPO4 was a non event. The battery management shut down immediately.

On the other hand the Lead Acid got quite hot melted the case.

Richard

There you go bringing real data into the discussion again.

I would like krasw to elaborate on the event, if he knows more. Anything that stores energy is potentially dangerous. The devil is in the details.

So far I have no other info, battery was smoking after removed from the glider. Was it LFP cells or BMS electronics, I don't know.

Keeping sco so far we have one FAA documented fire due to an SLA battery leading to the loss of the aircraft, against a rumor of a smoking battery that may or may not have been LFP which was removed from the glider on landing without damage to it. Other lithium chemistries are irrelevant, unless you are using those in your glider (such as the FES).


Wow! Did you read a different report than I did? What I saw was from
the NTSB (the folks who do the investigations), it used the term "gell
cell" instead of SLA, and most importantly it assigned no blame to the
battery. It said there was enough fire damage that they couldn't
determine if there was arcing on the terminals. They did find signs of
arcing on the wiring. That's quite a jump to calling it a "fire due to
an SLA battery", isn't it?

Apparently a "rumor" is something you don't want to believe, and a
"fact" is something you do.

A couple of facts: A gel battery IS an SLA battery. Its I/V characteristics and chemistry are substantially identical to an AGM, which is also an SLA battery. The only difference is in how the acid is immobilized. Second fact, a battery - any battery - does not spontaneously combust. If they do so, it is while being charged or discharged, usually under out-of-spec circumstances. Another fact: most electrical fires are caused by faults in wiring. Some further facts: the incident in question was caused without question by the SLA battery. It was an electrical fire which would not have occurred had the battery not been present, and therefore a proximate cause. A fact that you will find very inconvenient: had that battery been a properly constructed LFP, the incident would not have occurred. As Richard has pointed out above, the BMS would simply have disconnected the output and the glider would have landed without incident. For mitigation of wiring faults (by far the highest cause of electrical fires) an LFP is much safer than an SLA battery, which has no such protections.

Once again, you can use whatever battery you like, but you don't get to use "alternative facts".

And finally, I do believe in facts, and I don't (necessarily) believe in rumors.

Fitchy, Here is a "Fact" you may find inconvenient, You could stand to lighten up. An electrical fire in ANY glider with a battery installed would not occur if it were not present (Laughing), now would it? Whats your point? Granted they guy got the name a little mixed up (AGM, SLA, Gel Cel, whatever) but a proper SLA or AMG installation is as safe as anything out there. Why do you think auto manufacturers have been putting terminal covers on batteries for the past 30 years or so? Post crash fire protection.

Kirk

And finally, I believe in facts, but I also like rumors, innuendo, wives tales urban legends, hoaxes, and a lot of the stuff on RAS.

K m, I'm pretty light already . And my point is exactly as you took it: ANY battery stores energy and is a potential hazard unless installed correctly. (The fire in this case was pre-crash, but your point is valid). The difference in risk between SLA or LFP chemistry storing the energy is quite small, if both are correctly installed. There is a valid argument that LFP (with proper BMS) is safer since the protection is inside the case - even if you directly short the terminals, it will fault and disconnect. This is not true of available SLA batteries.

For about the 10th time, I'm not evangelizing the use of a particular battery. I AM correcting errors of fact where they are publicly stated. I didn't say I didn't like rumors. I said I don't (necessarily) believe them.

While we are at it, while the electric plane crash is a tragedy and related to FES sailplanes which use similar batteries, it is unrelated to the LFP batteries used to power instruments in sailplanes. Take a look at the link provided by Tom above (you'll have to hack into his computer to get it.....) or any of the many studies on this topic.

Sorry about that - try this link:

http://www.mdpi.com/2313-0105/3/2/14/htm

Tom