My Batteries Came Today, Couple Questions

[scottiej]

I could see you point about a battery that had shorted cells or some other major defect, but simply low charged batteries out of the box should not draw more power than the alt would be required to make when the audio is pumping. Let's take this guys specific example. He had a D3100 @ 12.74v and a D3400 @ 12.51v out of the box. How many amps of current would you expect to see these two batteries draw in order to charge? I would bet my left nut (right one is no good) that it would be less than 50A of draw to charge them. So what you are saying is that this guy would burn up his alt by pulling 50A to charge these? If that is true, then he has one POS alt and should NEVER install an audio system in that vehicle.

Agree?

A new, but low battery (below 12.5V) can require a large amount of current to pull the voltage up to 14+V. The size of the battery(s) will determine exactly how much. For example, with the batteries you have mentioned above, at a 25A charge rate I would estimate the charge time to be around 30min to 14.4V. However, this is not how an alternator works. When you install a new battery in a car and crank the engine, the alternator regulator wants to bring the battery up to the alternator's set point (usually 14.4V). The output of the alternator will depend on the temperature and rpm's of the engine. For a stock honda, I would estimate the output at idle to be around 60A. In this same scenario, with 60A it should take less than 10 min to bring the batteries up to 14.4. This should not kill the alternator, but that does not mean it will not happen. I've seen alternator failure in a matter of minutes depending on the load, temp, and rpm (cooling available to the alternator). If the alternator's capacity is 60A at idle, and your draw is above 60A, heat will build very quickly, and at idle it is difficult for the alternator to spin quickly enough to cool. To add to this, if you install these two batteries, and immediately begin jamming on the system, you are very likely to exceed the alternator's capacity to the point where it may never catch up and will certainly die. And yet, it is completely possible, that the alternator could be much smaller, but still completely charge the batteries mentioned with no problems. Every scenario is different, and no single experience is going to be true for everyone. For this reason, I suggest fully charging new batteries before installation, and I think you will find that all other alternator manufacturers recommend the same. If a charger is not available, and the voltage is above 12.6V, typically it will be no problem to plug and play

[scottiej]

Hmm... Scottie, I did some more research and have found that you have given other advice on a similar issue on another board. Here is a quote:

http://audioforum.termpro.com/topic/22/4999.html#000012

So after reading your posts, I am confused if you really think that an alt is a safe charging method or not? I think most of us here want a real sound answer on this subject. I know this probably looks like I am trying to back you in a corner, I truly am not. I just want to get to the bottom of this issue once and for all. I know that you have been in this industry for years. I remember back before you joined PM, when you ran Optima batteries. I trust your advice.

Hopefully my comments from the above post will clear it for the majority. For the situation you quoted above, the user had already installed and began charging/using the battery. At this point, there would be no need to remove the battery to re-charge.

I don't feel backed into a corner... that's what happens when you speak about what you know and nothing more. You wont find me in the computer section talking about processors, and floppy drives because I know nothing about them. Car audio on the other hand... I would like to think that my many years of dedication to it have taught me a thing or two

Don't hesitate to ask if there are still questions...

[scottiej]

That is exactly my point. If your 200A alt cannot handle charging 2 batteries, then someone needs to start making better alts, and/or we need to quit running more than 50A of audio current on them.

Agreed

I'm still not going to recommend it though

[scottiej]

Can / how do people do the MLA modules with them?

Many people do... although I do not agree with sustained exposure to 15+V to any sealed 12V battery.

[loopkiller]

Hopefully my comments from the above post will clear it for the majority. For the situation you quoted above, the user had already installed and began charging/using the battery. At this point, there would be no need to remove the battery to re-charge.

I don't feel backed into a corner... that's what happens when you speak about what you know and nothing more. You wont find me in the computer section talking about processors, and floppy drives because I know nothing about them. Car audio on the other hand... I would like to think that my many years of dedication to it have taught me a thing or two

Don't hesitate to ask if there are still questions...

I wasn't trying to back you into a corner, but just wanted some clarity on the subject. It was just hard for me to understand why we rely on alts to charge batteries all the time, but then to have an expert say that we should not rely on alts to charge them was a little hard to understand. I apologize if my questions seemed like they were intended to question your authority in the industry, that was never my intention. I just don't feel the need to show as much respect as other fanboys seem to do. I would rather call it like it is and say BS when my detector goes off. Just so happened my BS detector was set off by the "don't charge your batteries with an alt" conversation. And then when Steve and Scotty jump in to back it up, at that point I have to assume that there are real reasons behind the statement. At that point I was intrigued by the reason behind the statement. I am never the type to take things on face value. I need the why as well.

And I also respect the fact that you have to give advice for all here and not for some. One guy will have a certain setup that will require a certain set of advice that may or may not apply to another guy. I get that. But when you are given an exact scenario like this thread offered, I think it deserves a specific answer, followed by a general statement to others. That way, we can see how you came to the suggestion that you gave.

I just don't want people in general thinking that alts are a poor charging option. True, they may not be the best, but they get the job done. And for the guy out there that does not have $400 to spend on a charger, his alt will most likely get the job done. Especially if it is less than half a volt low out of the box new product.

[scottiej]

I wasn't trying to back you into a corner, but just wanted some clarity on the subject. It was just hard for me to understand why we rely on alts to charge batteries all the time, but then to have an expert say that we should not rely on alts to charge them was a little hard to understand. I apologize if my questions seemed like they were intended to question your authority in the industry, that was never my intention. I just don't feel the need to show as much respect as other fanboys seem to do. I would rather call it like it is and say BS when my detector goes off. Just so happened my BS detector was set off by the "don't charge your batteries with an alt" conversation. And then when Steve and Scotty jump in to back it up, at that point I have to assume that there are real reasons behind the statement. At that point I was intrigued by the reason behind the statement. I am never the type to take things on face value. I need the why as well.

And I also respect the fact that you have to give advice for all here and not for some. One guy will have a certain setup that will require a certain set of advice that may or may not apply to another guy. I get that. But when you are given an exact scenario like this thread offered, I think it deserves a specific answer, followed by a general statement to others. That way, we can see how you came to the suggestion that you gave.

I just don't want people in general thinking that alts are a poor charging option. True, they may not be the best, but they get the job done. And for the guy out there that does not have $400 to spend on a charger, his alt will most likely get the job done. Especially if it is less than half a volt low out of the box new product.

It's cool... I'm the same way. If something's not clear, I wan't to get it clear in my head. It's the only way to learn

[dr hypothesis]

Gotta say I love these batts. I was wondering if this was going to be enough to keep the Memphis 4kw happy. So far, so good. http://www.stevemeadedesigns.com/board/public/style_emoticons/default/hairtrick.gif