24 replies to this topic

[TehMarchant]

Okays so I have what was told to be a alternator that puts out 70 amps but it is struggling to keep up with my ICE, I have a 036? pug van battery and I need a high output alternator to keep up with my sub.

 

Any help would be greatly appreciated

[KernowCooper]

Assuming the alternator is running to provide the current to the sub ? otherwise your back to the battery having enough capacity to provide a reasonable running time of the Sub. What output is the amp for the sub.

 

Lets take your 70amp alternator and you can power a device/s that are rated at 840watts so if you have a 1000w Sub you have to rely on the battery to input some amps into the system so you battery will go flat.

 

A 1000w amp power a sub will in theory need 83.3 amps to power it, but in reality the subs amp may well be rated at 1000w Peak, but in real life is only a 500 RMS Watts Amp, if your drive it flat out it will blow!

 

Tell us a bit more about when your having trouble, parked up engine off, driving,?

 

A 036 is a standard battery, the Peugeot Diesel one is usually a 075

 

As a second note if you increase the amps of the alternator you need to rethink and check the cars standard wiring from alternator to starter solenoid as it may not be up to the job.

[TehMarchant]

 

Okay thanks for all of that, I do have the 075 pug battery and I have two amps, one being 700watt and another being 360 and quite ofter have them running at 3/4+ volume and I often drive at night with headlights on and main beam for welsh country side. I also have a cigarette lighter charging up my phone. What would you recommend?

[KernowCooper]

There is a limit to what you can power in a Mini without getting silly and upgrading all the wiring, most of the lads I have put in high powered amps for are in more modern cars with higher amperage alternators and batteries, but the real serious guys run a split charging system like the caravan boys do with a battery powering the amps and the standard running the car.

 

If you upgrade the alternator to a special or adapt something then under those amperage conditions its going to chew through a few v belts. I would be looking at how good the speakers are in the system and sub as having to drive them that hard points towards speakers with a low dB rating.

 

For Example

The dB info in speaker specs relates to the loudness at a set distance usually measured at 1 metre with a known reference input.

Therefore you may see two speakers quoting 100watts, but one states 87dB and another 92dB. It is the later one that will sound louder for the same input.

 

So you could have your 700w amp into 88dB speakers and someone turns up with a amp of 350w but with 92dB speakers and blows yours in the weeds, I have a Yamaha Stereo Amp of 90w RMS per channel and a 400w RMS Subwoofer and while watching Terminator my neighbour came out as she thought a car had crashed into her house.

 

As a rule of thumb the speakers should be equal or better that the amp, good amp and less speakers = volume turned up

 

Look into getting a split charging system and battery for the ICE

[Cooperman]

 

 

Okay thanks for all of that, I do have the 075 pug battery and I have two amps, one being 700watt and another being 360 and quite ofter have them running at 3/4+ volume and I often drive at night with headlights on and main beam for welsh country side. I also have a cigarette lighter charging up my phone. What would you recommend?

 

Put a simple low powered audio system in the Mini and buy a really good system at home. Then drive home in the Mini & listen to some good music in comfort  .

[lrostoke]

 

 

Okay thanks for all of that, I do have the 075 pug battery and I have two amps, one being 700watt and another being 360 and quite ofter have them running at 3/4+ volume and I often drive at night with headlights on and main beam for welsh country side. I also have a cigarette lighter charging up my phone. What would you recommend?

 

 

 

earplugs :)

[Barman]

 

 

 

Okay thanks for all of that, I do have the 075 pug battery and I have two amps, one being 700watt and another being 360 and quite ofter have them running at 3/4+ volume and I often drive at night with headlights on and main beam for welsh country side. I also have a cigarette lighter charging up my phone. What would you recommend?

 

Put a simple low powered audio system in the Mini and buy a really good system at home. Then drive home in the Mini & listen to some good music in comfort  .

 

 

Hahahahahaha!

[bmcecosse]

Use earphones.............and yes - the rest of the world doesn't want to hear your music .....  Just enjoy the natural 'music' of the A series !!

[TehMarchant]

I am going to have a look into the dual battery and maybe use a yellow top deep cycle as a leisure for my audio, any idea if this would leave the normal battery fully charged for the starter even in the leisure battery died?

[KernowCooper]

Why do I need a split charge relay?

 

Not only will the split charge relay/system recharge the leisure battery while the engine is running it will also stop current being drawn from the starter battery when the engine is switched off (ensuring you will be able to start your vehicle) should the leisure/auxiliary bank run out of power.

the Smartcom relay doesn't require an alternator connection, you simply wire it from your starter battery to the leisure battery and a separate wire to the amp, or direct to the leisure 

If your vehicle is relatively new and has a complicated engine management system we would recommend using the voltage sensing split charge relay which is easy to fit and requires no connection to the vehicle electrics. Simply wire the relay from your starter battery to your leisure battery. For older vehicles where the split charge relay has a trigger wire (usually the alternator warning light).

Always fit suitably rated fuses close the both the feeds

 

Info here

http://www.split-cha...-relay-faq.html

 

Basic circuit here

http://www.marclelei...litCharge01.htm

 

 

You may need to use a larger amp relay with your system though

Edited by KernowCooper, 08 August 2013 - 12:23 AM.

[tiger99]

The ratio of peak to average power is quite high for any reasonable kind of music, so your amps are most likely running at no more than 20 watts average. Much more than that, with speakers of reasonable efficiency, will do you serious damage within the confines of a Mini.

 

It could be that the amps are badly designed and inefficient (no surprises there, the audio industry is full of incompetents), so they may be consuming far more power than necessary. Otherwise, I suspect that something else is amiss, as 90 amps is just ridiculous.

[TehMarchant]

I am running 100watt RMS per channel at the front and 350watt RMS to the rear sub, and those are most probaly underated as they're alpines figures and not the lies that sheet barnds use.

 

So that is 550Watts when I am not pushing the amps.

[Cooperman]

Silly question, perhaps, but where and how can an audio system in a car, especially a Mini, need that amount of raw power and where/how do you use it without being anti-social?

[zerobelow]

Some people touched on it earlier, but getting better speakers may be a better way to get the right sound off of lower power.

 

In general, speakers will be rated for responsiveness. Something like 89db or 93db. What a sensitivity of 89db means is that it can produce 89db of sound at 1watt of power, measured from 1meter away. Every 3db requires a doubling of power. 120db for even short periods is generally considered permanent hearing loss territory.

 

So, let's say we want to get to 120db, a few scenarios:

 

Start with an 85db speaker. We need to get 35db increase. That's something like 2kw of power needed.

 

An 88db speaker will require just half that power for the same volume.

 

A 100db speaker will only need a 20db gain, or about 7 doublings from 1watt. Only about 128w power to get to the same volume.

 

Anyways, if the alternator and other car mode aren't working out, look at getting even slightly more efficient speakers. Each 3db more efficient the speakers, you cut the draw in half!

[Captain Mainwaring]

There is a limit to what you can power in a Mini without getting silly and upgrading all the wiring, most of the lads I have put in high powered amps for are in more modern cars with higher amperage alternators and batteries, but the real serious guys run a split charging system like the caravan boys do with a battery powering the amps and the standard running the car.

 

If you upgrade the alternator to a special or adapt something then under those amperage conditions its going to chew through a few v belts. I would be looking at how good the speakers are in the system and sub as having to drive them that hard points towards speakers with a low dB rating.

 

For Example

The dB info in speaker specs relates to the loudness at a set distance usually measured at 1 metre with a known reference input.

Therefore you may see two speakers quoting 100watts, but one states 87dB and another 92dB. It is the later one that will sound louder for the same input.

 

So you could have your 700w amp into 88dB speakers and someone turns up with a amp of 350w but with 92dB speakers and blows yours in the weeds, I have a Yamaha Stereo Amp of 90w RMS per channel and a 400w RMS Subwoofer and while watching Terminator my neighbour came out as she thought a car had crashed into her house.

 

As a rule of thumb the speakers should be equal or better that the amp, good amp and less speakers = volume turned up

 

Look into getting a split charging system and battery for the ICE

 

 

Split charge isn't really much good - he only has a limited charging capacity and once the split charge kicks in after the alternator comes on line, the batteries are linked together by the split charge relay so unless he installs an intelligent relay with a great big diode to prevent the cranking battery discharging back through the charge relay then the end result is the same, a flat battery.

Lets say he needs a continuous supply of 83A +VAT when he uses this 1000W monster then he is going to need a 120A alternator to keep up.

Edited by Captain Mainwaring, 10 August 2013 - 04:43 AM.