Bricking?

There have been many posts from folks that hope to use a huge battset for propulsion or creature comforts.

The new breed of auto batts seem to offer the best chance , tho their charging systems are very complex.

A problem that is claimed with these batterys is "Bricking" , the set must be frequently used , charged and discharged , or it becomes a $10,000 Brick, ready for the recyclers.

Any comments on the life and use of these batts , on recreational boats that may frequently see no use for a month or three?

FF

 

http://www.nytimes.com/2012/03/04/automobiles/Tesla-Battery-Failures-Make-Bricking-a-Buzzword.html

http://www.greencarreports.com/news/1073289_tesla-battery-bricking-the-real-story-behind-the-post

Looks like the problems may be limited to certain designs. Also to prevent it there is no need to discharge and recharge the battery, just keep it from being totally discharged.

So a recreational boat which isn't used for a long period of time might need the equivalent of a trickle charger, possibly a solar powered unit.

It shold be noted that these advanced battery systems need to be treated as systems, not just as collections of batteries.

 

I think many problems can be avoided if the battery-charging system is equipped with a remotely-controlled device like this one: http://www.gsm-auto.com/
It is relatively easy (for those with some knowledge about electronics) to install it on board the car (or the vessel). It could then be programmed to send a warning message to the owner when the charge level drops below a certain value.

 

In a word: Smartcharging

-Tom

 

Dendrite or filament growth is a real problem with the new "solid" cells. It is one of the reasons that most high energy piles still use "wet" cells. FWIW, it happens to all cells, and it really isn't dependent on charge depth but rather ion mobility in the matrix related to charge/discharge rate. This is why high energy wet cells use agitators. In a gel or solid battery, there are ways to mitigate growth (such as controled charging/discharge), but they reduce the discharge rate so that needs to be designed in very carefully for the actual system loads and failures. The laptop battery fires and the Chevy recall that happened are caused by this behaviour...when the dendrites grow and close the plates, the cell shorts and rapidly discharges...usually with a large thermal release and the battery may "rapidly disassemble itself"...

 

And how does this behavior relate to the newer LiFePO4 battery types?

My understanding is they were put into service in electric cars because of their safety. You can shoot them with a gun, crush them, run them, etc... all without danger of fire.

Any thoughts on those?

 

Relative to the Chevy Volt that sounds like speculation, plausible but incorrect. NHTSA concluded that the fire in the crash tested Volt was due to coolant leaking over the battery and electronic devices and resulting "short circuts" external to the battery cells, not an internal problem in the battery cells.

http://www-odi.nhtsa.dot.gov/acms/cs/jaxrs/download/doc/UCM399393/INRP-PE11037-49880.pdf

http://www-odi.nhtsa.dot.gov/defect...r=PE11037&SearchType=QuickSearch&summary=true

 

My understanding is that the Volt batteries are the ones that need the coolant, not the engine, and form part of the safety system to carry away the heat on a failure or impact. It was the loss of battery cooling coupled with the damage that shorted the battery, let the dendrites grow and final lead to a runaway cell. From NHTSA :

"The report indicates that intrusion induced coolant leakage, and subsequent rollover that saturates electronic components, were the only test conditions which resulted in a subject vehicle HV battery fire."


The high energy solid cell systems I'm familiar with have a similiar cooling and control systems that disconnect and moderate a failed cell until it can be removes and disposed of. Failure of either the monitoring system or cooling system can lead to a runaway which can cause othger problems in the cell case.

 

wouldn't it be about $2 to include a shut-down switch that prevents it

from Bricking?

A switch that first sends out an alarm, so you would need to override it if it was life or death(of human) at stake.


And why doesn't my cell phone shut it self off and send out an alarm before going totally dead? It should shut off with 5 minutes of talk or an hour of 'on' before going dead.