Best practices for connecting battery, to min explosion risk?
 

Just got back from vacation. Batt safety question for you guys.

I've always disconnected the batteries of all three cars before leaving so that the batts don't drain down to plate damaging levels (with alarms, that degradation starts in only four days). I disconnect the positive, then place some kind of thick insulating material in between the terminal and the cable (chunk of rubber usually). When I get back, I reconnect. Out of guessing.. superstition .. etc, I've always connected battery terminals 'quickly' because I've noticed it is less likely to spark.

It occurred to me yesterday.. hmm.. I wonder how likely it is that a battery could explode? Did some research; While not very common, it does happen all the time. Triggered by the micro spark of connecting the cable or a jump cable, any lingering hydrogen gas outside the battery (usually only likely with older slightly leaky batteries) instantly ignites, and then finds a way into the interior of the battery. One thing the articles are clear on, is that the resulting plastic shrapnel and acid flying out from the battery causes severe injury, and possibly kills the individual.

So there I am reconnecting the X.. and because our rear clam shells won't work unless the battery is already connected, I'm performing this work from inside the car with the cargo lid off and me hunched straight over the battery compartment. Hmm.. could this be any worse of a position to perform this! I do it quickly, but yeah.. there is a small spark.

So, any recommendations?; Disconnect the negative instead (a more obscured cable lead on the X5 btw)? Put on protective gear and lay your body down off to the side as low as possible? Figure out a way to open the rear clam shell without the battery connected? Find a neighbor you're not all that fond of to connect it for you?

One thing's for sure. I've decided not to offer other motorists a jump off my batt for their dead battery. No reason to increase the number of opportunities for an explosive incident. Even if the other guy did it, there's the (tremendous) damage to your own car.

Thx

TA,
Maybe my paranoia level is much lower than yours: I leave a car, attached to a Batt Tender w/appliance timer in line, and three motorcycles,
(not attached), for 5 months on end. Have been doing this for 5 seasons: the car batt is always fresh and the m'cycle batts come "back" with
a couple days of slow charging. Never a problem.

Yes, a mouse could bump the Batt Tender cables attached to the car battery; yes, a St Elmo's Fire could roll throw the garage while we are gone;
yes, crap happens, but I don't give it/my battery(s) situ a 2nd thought.

I had a little trouble understanding your process, but I hope you disconnect the neg terminal first, before fiddling with the pos cable.

Everyone has a different bag, but why disconnect your batt(s), for a couple of weeks?
GL, mD

I agree. If your battery is healthy and being charged properly a couple weeks without use should not be a big deal at all.

If you are still concerned, I would recommend a trickle charger. Something like this -

OG Racing - CTEK MULTI US 3300 BATTERY CHARGER - The CTEK MULTI US 3300 Battery Charger is versa...

Cheers,

FLi

Luckily for you BMW's batteries vent the hydrogen gasses outside the vehicle, so no worrys there. That plastic elbow with the vent tube that plugs in the side of the battery puts the gasses outside the vehicle.

And on other vehicles, abtteries sitting idle don't really produce gasses, but when used they do. I've personally seen one blow up in someones face. A master tech at a shop I used to work for was doing a diagnosis on a non starting car so was cranking it checking for spark, fuel pressure, injector pulse etc. so the battery was putting out plenty of fumes... He goes under the the hood and rests his hands on the engine and battery and his left hand went on a battery terminal that was a hair loose and it sparked, blowing the battery in half and covering his whole face in battery acid! The safety glasses did not help much and his eyes were solid bloodshot red for hours.

But as I said, the risk of that when the battery has been just sitting idle, not connected is probably 1% at best and just as low or lower in a BMW that externally vents so the fumes aren't even by the battery.

Yeah the nominal draw on a X5 battery is 14 mA which is next to nothing. I wouldn't worry about it if for a couple of weeks or even a few months. If you want, connect up a battery trickle charger like motordavid said, maybe even on a weekly timer.
http://www.xoutpost.com/bmw-sav-foru...w-one-fyi.html

Thanks mD.

The prob is we have a one car garage. The Coupe gets locked in, but the X5 and the Roadster sit outside.. in the weather.. so a tender isn't doable there.

I've been disconnecting the positive cable, because its easy to get to. On all three cars the negative terminal is harder to get to. So, that's exactly the kind of advice I was looking for... errr.. so disconnecting the negative lowers the risk of spark?

Ahh! That's right, I forgot about that little feature. Ok, thanks!

CTEK's are waterproof. If you have a driveway then just run a waterproof extension cord (thick gauge) to the car connected to the jump start terminals under the hood.

I've left my truck parked for a couple weeks before with no problems... even recently. If it is just a couple weeks it should be just fine, but a couple months and I'd pull the cable or something.

If you are really that worried, charge each of your vehicles up full just before you leave. That way they'll drain from max capacity and for the short time you are away you should be fine.