charging a large batt bank with little alt

[poorfish88]

It does hurt the alt because it has to work harder until the batt is charged which makes it hotter. Heat an alts is a bad combo, hence the early than normal failures.

An alt charging a dead batt is a huge constant drag on it. To maintain a charge even with a large load of a audio system is

not as bad for the alt because it's dynamic. Lots of alt companies state to make sure the battery is fully charged. You think it's

because there worried about your car not starting, or they don't want the alt to charge the battery.

[Bump4life]

An alternator CAN NOT properly fully charge a battery. kirill007 is a smart dude and knows what he is talking about.

and accessories can easily draw 100A continous. A good, well made alternator can put out its rated power continously without failure for a long time.

now 8 amps is plenty for 1 battery but when you have multiples its best to charge each indiivdually unless you have a charger capable of at least supplying 7 amps minimum per battery. more is better.

alternators give out a constant charge. The newer pcm alternators attempt to simulate a mediocre charger at best. There is a lot involved with properly charging batteries. An alternator can maybe get them to 80% charge if you are lucky.

edit: I would like to note dead battery DOES NOT = battery with bad cell. batteries with a bad cell will over work and kill an alternator. but if your battery is resting at 12 volts, go on a few hours drive and with a solid alternator it can bring it back to life.

[Bump4life]

Yeah sorry for the initial confusion, they will be charged after shows and maintained. Im just trying to get some thoughts on a good and preferably not so expensive option to keep decent voltage at shows

i dont think there is an option to keep decent voltage that doesnt cost money lol.

supercapacitors are your friend when an alt upgrade is not possbile. but to be honest id get that 250 from mike and supercaps and ditch half or more of your batteries.

[MrSkippyJ]

An alternator CAN NOT properly fully charge a battery. kirill007 is a smart dude and knows what he is talking about.

and accessories can easily draw 100A continous. A good, well made alternator can put out its rated power continously without failure for a long time.

now 8 amps is plenty for 1 battery but when you have multiples its best to charge each indiivdually unless you have a charger capable of at least supplying 7 amps minimum per battery. more is better.

alternators give out a constant charge. The newer pcm alternators attempt to simulate a mediocre charger at best. There is a lot involved with properly charging batteries. An alternator can maybe get them to 80% charge if you are lucky.

edit: I would like to note dead battery DOES NOT = battery with bad cell. batteries with a bad cell will over work and kill an alternator. but if your battery is resting at 12 volts, go on a few hours drive and with a solid alternator it can bring it back to life.

He is smart, that's why I was hoping this would be a good learning experience. Glad you jumped in as well!

[Bump4life]

It does hurt the alt because it has to work harder until the batt is charged which makes it hotter. Heat an alts is a bad combo, hence the early than normal failures.

An alt charging a dead batt is a huge constant drag on it. To maintain a charge even with a large load of a audio system is

not as bad for the alt because it's dynamic. Lots of alt companies state to make sure the battery is fully charged. You think it's

because there worried about your car not starting, or they don't want the alt to charge the battery.

a lot of alt companies use aftermarket parts which arent as good as oem and cant take the heat.

most companies recommend charged batts so you see the voltage you want to. a load on the system will drag voltage down.

also a dead cell will kill the alt, so they generally want to make all batteries are in good condiiton. its easier to tell people to have fully charged batteries than to explain every scenario to them

[poorfish88]

Mechman seems to think differently. Alts maintain charge. They are not made to charge rundown batteries.

MECHMAN, on Oct 17 2008, 08:58 PM, said:

Battery isolators and relays are a good way to toast your alternator. By allowing one battery to be run down completely dead, and firing up the vehicle, the relay will swith over to the dead battery and cause the alternator to run wide open untill the dead battery comes up. This causes a lot of heat buildup in the alternator, and reduces the life of the alternator. Depending on the regulator circuitry that is used on the alternator, the under-load switching of the relay can take out regulators also. If the secondary battery bank is big enough, it can melt the alternator in a single charging cycle. The better long-term solution is to just parallel all your batterys together, install a switched voltmeter that you can monitor while the vehicle is parked, and simply start the vehicle up when the batteries start to fall below 12 volts.

Just my $.02

[poorfish88]

Looks like Steve feels the same way by this post.

'meade916', on 26 Jan 2013 - 6:45 PM, said:

don't use an isolator.

First of all it won't benefit you at all. Second they are actually BAD for the alternator. Think about it. The worst thing you can do to an alternator is hook up a dead battery to it and start your car. Sure, it will start the car on the 2nd battery if you drain the system battery, but once that dead battery is re-introduced into the system, it is bad news. The alternator is not going to blow up but it WILL get hot and it will have a MUCH shorter life. Try to avoid playing your system when the car is NOT running and you should be good. If you insist on playing it with the car OFF then turn the volume down to reasonable levels and cut the bass too so it doesn't tax the battery's very hard.....and don't do it for too long. With or without an isolator, you don't ever want to show your alternator a dead or very low battery. I believe a charged battery can be around a 10a load by itself but a discharged battery can show a 100a load or more while it tries to catch back up again.

IMO, say no to isolators.

[kirill007]

my assumption is that the batteries would be dead, but this was made before he clarified he would be using a charger on the batteries.

and besides, if a battery only uses 8 amps when charging, how do quick chargers work?

Higher voltage charging= more current flowing through the battery.

That's why it's impossible to fully charge a battery at 12.8V, no potential difference=no charge.

Look at the A-meter on these battery chargers, you'll see it won't be very high. (although these batteries aren't "dead")

last 20s of this video, the rest is garbage. :https://www.youtube.com/watch?v=nXqIjjozzsM

last 20s of this video: https://www.youtube.com/watch?v=TdjHPUtUD9I

from 2.30 to 2.40: higher voltage= more current :https://www.youtube.com/watch?v=M8fcYVjCvQE

That's great you watched a bunch of shit videos on how a battery charger charges a battery.

Now go watch videos on how a alt charges dead batteies. You'll notice it's output is a hell of

alot more than 8 amps.

I'm guessing we are disagreeing because of the term "dead" battery.

A truly dead battery won't get a good charge regardless of the charging method.

Dead battery to me is a resting voltage below 12V.

This is a alternator that charges a dead battery, but that battery is more then dead to me.. Im guessing the capacity will have dropped quite a lot.

https://www.youtube.com/watch?v=GA7gDj-4YUg

This video is also good, from Tony Candela. Small battery but you see that the current drops quite quickly while charging.

https://www.youtube.com/watch?v=D8FftSBziUQ

It does hurt the alt because it has to work harder until the batt is charged which makes it hotter. Heat an alts is a bad combo, hence the early than normal failures.

An alt charging a dead batt is a huge constant drag on it. To maintain a charge even with a large load of a audio system is

not as bad for the alt because it's dynamic. Lots of alt companies state to make sure the battery is fully charged. You think it's

because there worried about your car not starting, or they don't want the alt to charge the battery.

I'm guessing because of the term "dead" battery we are not agreeing.

If a alternator can only put out 200A, then it shouldn't get a bigger load then that. If that is while charging a battery bank or to power your amplifiers.

Heat is the biggest failure of any electronic/electricity related product.

[kirill007]

Mechman seems to think differently. Alts maintain charge. They are not made to charge rundown batteries.

MECHMAN, on Oct 17 2008, 08:58 PM, said:

Battery isolators and relays are a good way to toast your alternator. By allowing one battery to be run down completely dead, and firing up the vehicle, the relay will swith over to the dead battery and cause the alternator to run wide open untill the dead battery comes up. This causes a lot of heat buildup in the alternator, and reduces the life of the alternator. Depending on the regulator circuitry that is used on the alternator, the under-load switching of the relay can take out regulators also. If the secondary battery bank is big enough, it can melt the alternator in a single charging cycle. The better long-term solution is to just parallel all your batterys together, install a switched voltmeter that you can monitor while the vehicle is parked, and simply start the vehicle up when the batteries start to fall below 12 volts.

Just my $.02

What's the difference between charging batteries with 300A or using amplifiers that draw 300A? (numbers are randomly chosen)

Electrons are dumb, so is the alternator.

But to answer the original question, no don't use the alternator to charge up that much batteries.

[im45pl]

Yeah sorry for the initial confusion, they will be charged after shows and maintained. Im just trying to get some thoughts on a good and preferably not so expensive option to keep decent voltage at shows

i dont think there is an option to keep decent voltage that doesnt cost money lol.

supercapacitors are your friend when an alt upgrade is not possbile. but to be honest id get that 250 from mike and supercaps and ditch half or more of your batteries.

yeah I know lol, just wishful thinking... ill look into supercaps, never really thought of them. Yeah I will be looking at the alt from Mike soon. If I could get rid of some batts to save weight that would be helpful as well