What happens when you make your alternator charge a dead battery?

This is a brief demonstration of how to assess alternator output when charging a dead battery. Various methods to charge a dead battery are discussed.

[DJDevon]

That's the quickest and easiest to understand explanation for charging dead batteries I've seen. Excellent video. More like this.

[prodigal]

You made more sense and gave better information than the many others sites I looked at while researching this topic. Thank you.

[spelunkerd]

Last week I went through an outstanding Wikipedia article on lead acid batteries, and it brought clarity to a lot of issues for me. It pointed out the mechanism of sulfation that happens to these batteries when deeply discharged. Deep discharge batteries have thicker plates that are more resistant but they have a lower peak output. Thank you for watching!

[bgregg]

You are the guy that convinced me to stick with a 6 amp charger & 1 1/2 amp trickle charger rather than getting a 50+ amp fast charger. I get 8+ years out of my car batteries.

[SchrodingersBox]

Great video as always. I see some people say the video should be longer, others say it's better shorter, but if you ask me I could listen to you pronounce "battery" all day and never be bored!

[spelunkerd]

Thanks for your kind remarks, Matt. As you know I like watching your thoughtful videos.

[THEMOWERMEDIC]

never thought of it like now on i will charge my batteries before i put them back in service!

great vid! and advice! thank you!

[desertfox]

I for one love long videos, in the area of 10-20 minutes, especially for a topic as complicated as this.

[stuzman]

Nice video Dave and straight to the point! You know, I've been debating the same thing over and over about how much detail to put in videos. Like you said, on one hand people prefer short videos, but then the content is not there and not much to learn. Then on the other hand, people prefer longer videos with more detail. Oh, what to do!

[spelunkerd]

It's always good to simplify things when problems happen, it is easier to sort out what is happening. Good luck!

[trainer]

Nice video, if you haven't noticed I'm an electrical nerd lol. Keep doing electrical videos, I like those.

[spelunkerd]

I'm not sure. Maybe if the alternator current was too high, it blew? In any case, I'm glad you found the problem. Thanks for updating the thread here.

[spelunkerd]

It's great to have you on board, thanks for watching and commenting.

[spelunkerd]

Thank you, Jeremy. As you may know, I always give your small engine videos a look.

[spelunkerd]

Thank you, Devon. I'm working on trying to make these shorter without losing substance. Most of us, including me, have a very short attention span (grin).

[spelunkerd]

I've thought about your response and I do understand what you are getting at when you prefer longer videos. However my biggest problem is to hold people's attention, which on Youtube is easily diverted. It seems the most successful channels, like minutephysics and vlogbrothers, use a rapid-fire compressed format, one that pushes the boundaries of normal communication speed. Ultimately it's content that viewers want, and I'm trying to compress that but still make it entertaining. Thank you!

[spelunkerd]

As you know, your point has general implications that a bad battery puts extra continuous strain on the alternator, maybe even killing it. That's an important, classical lesson. Perhaps I've been lucky because I've quickly diagnosed bad batteries before that happened. In this case the battery is fine, and it passed testing with my 500A carbon pile load tester. Thanks for emphasizing the point! To get to that 10A figure you subtract the baseline load used by the engine -- I measured the sum.

[dusty]

Oh my lol. Okay, well that 50amp might have said it was bad, but it's really not bad.. a smaller fuse was literally popped out and sitting on top of where it plugs in.. plugged it in, trucks running perfectly fine now. No battery light, and alternator IS charging! Thanks for the tips and stuff. Hope you have a good evening, and rest in peace the victims of 12 years ago on that tragic day!

[dwoodog]

One of your best quick tips. I had a similar issue, from what I understand these batteries don't like being ran down to nothing. Mine never did regain life, although it was a 5yr old battery. Never seem to make it back above 10 volts. It sat on the charger for hours.

[desertfox]

I do understand completely. I guess I'm in the minority here, but as much as I like minutephysics, I'd rather sit back and watch a TV-show length video about something explained in detail, and shown, demonstrated, etc. Scannerdanner is a good example. I think you make a nice mix of the short to the point videos and the 10+ minute in depth ones.