EV fires and BMSs

Unfortunately, every so ofter, and EV catches fire, and, if unattended, it may burn to the ground.

If the EV uses Li-Ion cells and a BMS, a chorus of “BMS deniers” raises its voice, expressing the view that the fact that the EV had a BMS proves that the BMS was the cause of the fire. I will not bother pointing out the logical fallacy in that point of view, but I would like to address the valid concern that others expressed, that the BMS did not prevent these fires.

What seems to be occurring in the cases, is that a BMS, while physically located in the EV, was not actually installed in such way to allow it to protect the battery pack.

Let’s take 2 recent examples: the Neil Young’s LincVolt and SRJC’s (Santa Rosa Junior College) Ford Focus EV conversion. Both had an Elithion Lithiumate BMS on board.

(Neither BMS was bought from Elithion, nor from Elithion authorized resellers; I say that because when Elithion or one of its authorized resellers sell a BMS, the customer is helped to make sure the BMS is installed correctly.)

Neil Young’s LincVolt

On Nov 9th 2010, the LincVolt (a Lincoln Continental converted to a hybrid) was plugged in and charging, when it caught fire and burned down. While an investigation was promised, it either never happened, or its results were not published.

EV on fire

LincVolt HEV burining up

Based on conversation with people close to the project, two factors caused the fire:
1) While the BMS was physically in the vehicle, it was not connected to the charger, so it had no way of protecting the battery pack from over-charge
2) The charger had never been adjusted for the battery voltage, and therefore it kept on charging the pack past its nominal full voltage.
Granted, the above findings are based on unofficial analysis and reports, and are therefore unproven; but they are the best we have to go on.
What we do know is that the LincVolt staff has very specifically said “LincVolt suffered a disastrous accidental fire stemming from human error” (1), which is a way of saying that the equipment was not a fault.

SRJC Ford Focus

On March 18th 2011, the Santa Rosa Junior College EV conversion caught fire.

Burned up EV

SRJC burned up EV

An investigation may be forthcoming.

In the meanwhile, what we know is that:

  • The EV used (2):
    • Li-Ion cells
    • A Lithiumate BMS
    • A Brusa charger
  • The 12 V battery was not installed at the time of the fire (3)(4)
  • However, a DC-DC converter was installed, and could have conceivably been powering the 12 V bus, if the ignition had been on (5)
  • The charger was in the vehicle, but was not yet functional and was not plugged into the AC at the time(3)
  • The initial location of the fire is unknown (3)
  • Other vehicles nearby were not burned (3)
  • The BMS was not connected to the charger, and could not have turned it off, even if the BMS had been powered at the time (“there was no interface with the charger to turn it off”) (4)
  • The car was not plugged in. (3)(4)

Given that the car was not plugged in, and, in any case, the charger was not operational, the charger would certainly not be the cause. Then the cells may have been the source of energy that started the fire. But not necessarily; it could have been, for example, a soldering iron that had been left on since previous work done on the vehicle.

Preventing EV fires

We know that in the LincVolt, the BMS was not at fault for the fires. In the SRJC Ford, it is very unlikely that the BMS was in any way involved in the fire, but that is yet to be proven. But that does not prove that a BMS is never a contributing factor to EV fires. The only certain thing is that not connecting a BMS properly will not protect the battery pack.

At Elithion we are very insistent that the BMS must be properly connected to the system, or the pack is not protected. The first thing you see in the Lithiumate manual, is a huge warning:

You MUST provide a way for the BMS to shut down the charger, and the motor driver, DIRECTLY!

Still, all too often BMS users assume wrongly that, just by having a BMS physically present, their pack is protected.

Not so.

References:

(1) LincVolt Gazette, press release of Nov 16th,
(2) Class project notes
(3) Chris Jones, a volunteer working on the project, from his message to the NBEAA email list of Nov 20 2011. Chris welcomes you to contact him on this matter: see the NBEAA site for contact info
(4) Peter Oliver, from his message to the EVDL mailing list of Mar 21, 2011
(5)Peter Oliver, private phone call

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