Charging A Car Battery

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When charging a battery with a charger.......... is it really all that dangerous to hook the negative cable from the charger to the negative post on the battery ? The reason I ask is most of the time I cant tell if the battery is charging or not and think it may have to do with hooking the negative cable to the chassis or other metal part.
 
Personally, I have always, and still do hook my chargers directly to the battery/cables. I guess it is not the "safe" way to do it, but I have been doing it for over 50 years and never a problem.. Not that I am saying that you should, just that is what I do.
 
I think its included in the instructions for liability reasons especially in todays "its somebody elses fault" society.Old school vented batteries maybe, but moder sealed batteries should be fine. When I hook up my charger its disconnected from the wall socket any way, after its hooked up to the car then I plug it in. I would worry about it.
 
I don't think it matters with a charger. Charging batteries can outgas hydrogen, but a charger shouldn't be cranking "lots" of amps, plus when you first hook it up, it hasn't been charging. It'd only be when you're done and unhooking: and if it's fully charged, it shouldn't be charging (no V or I).

For jump starting, that's something different.

My cheapo chargers though don't have power switches, so I hook up the charger to the battery and then plug into the wall.
 
The theory is that in a perfect (bad) environment, a spark could ignite built up hydrogen gas. I've never seen such a perfect environment and always connect to negative battery terminal.

It might almost be an urban myth. Dead battery just sitting there does not produce hydrogen gas, rather it is during severe overcharging, if the airflow is extremely low and somehow trapped which won't happen if the hood is up (hydrogen is lighter than air). It's more of an issue with old crude charging of solar power batteries in a sealed room, long-term buildup.
 
I don't think it matters with a charger. Charging batteries can outgas hydrogen, but a charger shouldn't be cranking "lots" of amps, plus when you first hook it up, it hasn't been charging. It'd only be when you're done and unhooking: and if it's fully charged, it shouldn't be charging (no V or I).

For jump starting, that's something different.

My cheapo chargers though don't have power switches, so I hook up the charger to the battery and then plug into the wall.
This.
When using a charger, you should connect the battery, then plug it in/turn it on. No chance of spark if you do it that way.

As said, with jump starting, there is current in the cables when making that last connection, so the negative on the dead vehicle should not be connected to the battery (which is the last connection made)
 
I know a guy that experienced the dead-battery explosion. It was completely discharged AND frozen. They connected booster cables and during the jump start (not immediately) it went kaboom.
 
When charging a battery with a charger.......... is it really all that dangerous to hook the negative cable from the charger to the negative post on the battery ? The reason I ask is most of the time I cant tell if the battery is charging or not and think it may have to do with hooking the negative cable to the chassis or other metal part.
The danger is when you are jump starting another car, a spark is produced on your last connection.. Negative connection (when jump starting) on the disabled car is made on an engine bracket, away from the dead battery, which should be your last connection.. You can make the direct connections from charger to battery THEN plug in your charger to the wall outlet.
 
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I always do the battery directly to both terminals. For some reason if you try to charge or jump our Ford van from a ground it won’t do it I have no idea why but it wants both cables connected to the battery and not a ground so I do jumping and charging from the battery.
 
This.
When using a charger, you should connect the battery, then plug it in/turn it on. No chance of spark if you do it that way.

As said, with jump starting, there is current in the cables when making that last connection, so the negative on the dead vehicle should not be connected to the battery (which is the last connection made)
My newer charger will check to make sure it's connected properly before it starts charging. So if you reverse it or if it's not connected, it doesn't do anything.
 
The electronic chargers we use at homes for the last 10 years do not produce sparks so they are totally safe. I always clamp them directly on the battery terminals.
That’s not always true. I observed a decent spark from my ctek 25A unit when attaching it to my truck which has healthy new batteries.

I had been adjusting the terminals when it happened. Best practice is to not attach mains power until after connections are made.

I've never had a problem hooking a charger right to a battery. What do you think happens when a battery is charged in the store or shop?
Agree. There can be conditions that are dangerous, but routine charging shouldn’t cause them.

It really would have to be a scenario where a battery was exposed to gassing conditions (high enough voltage), and then a spark pretty rapidly exposed after.
 
Depends on how you do it. I believe the primary concern is that with a dead battery there's a likelihood of hydrogen outgassing that could catch on fire.

I've seen sparks coming up before, so it can be a real concern. I recently jumped from another car's battery - then used a charger because I've been doing that a lot and got tire of having to jump it due to a low state of charge. Even with the connection completed, I saw some sparks while I started. It might not be that important in system where the connection isn't completed at the terminals. Some newer chargers don't connect anything that might spark until it's plugged in or maybe a switch is turned on.

I've charged a new battery before installing, and I didn't complete the circuit with another wire.
 
I've never had a problem hooking a charger right to a battery. What do you think happens when a battery is charged in the store or shop?

I believe the idea is that they're preemptively charged before they get into any state where there's substantial outgassing of hydrogen. Even then it's possible to use equipment that doesn't complete a circuit at the terminals, but at the charger with a switch or by plugging in. My charger has an audible click when it starts charging, and I'm guessing it's a relay. But there are all sorts of variables. Completing the connection at a bad battery away from the terminal is a pretty universal recommendation.

Heck - one I couldn't get a portable jump starter to start a car so just I just did it. I understand it's more likely to go up in a small fireball rather than an explosion.
 
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