A and b alternator - the same?

[MartG]

Are any of these various alternators more powerful than the standard mk1 A/B?

The rally car seems to suffer from a lack of power (electrical) when we use the spots in the dark. I can understand why, 6 x 80w is a big ask.

Does anyone know of a more powerful alternator that will fit the Mk1?

Also would fitting a bigger battery help?

The one we are using is the smallest and lightest lead acid we could find, therefore it is not hugely powerful.

Just done some quick figuring, using good old Ohm's Law ( V=IR )

Car bulb wattage is specified for 12V, but when running the alternator will be putting out up to 14.4V. At 12V your 6x80W lights will be using 40amps - plus about another 6A for brakelights, tailights, sidelights etc. giving a total of 46A just for lights. At 14.4V this increases to around 56A - and the standard alternator is only rated at 60A, which doesn't leave a lot to run the engine etc., especially as you should only run an alternator at 60% of its maximum load.

A quick Google for other cars fitted with the 4A engine only found one with a bigger capacity alternator, the 92-97 Corolla, and that only increases output to 70A which probably isn't worth the bother.

I think that leaves two options 1) custom bracketry to fit a bigger capacity alternator or 2) fit a bigger battery with enough capacity to run the lights for as long as you need them without going flat

[Fab4MR2]

If you really need a larger capacity alternator for the 4age than just google 'high output alternator, 4age'. You should get some returns as they have been sold for quite some time, at least in the US, as alternatives for those with large stereo systems. I have still seen them listed on the US ebay site on a regular basis. If I recall correctly they have an output of 120w, but if you really wanted, you might be able to get a custom output, as I know that used to be an option for some of the companies that made them.

[MartG]

If you really need a larger capacity alternator for the 4age than just google 'high output alternator, 4age'.

Good plan 130A one here http://cgi.ebay.com/ebaymotors/TOYOTA-C ... 1010r16653

[jimi]

At 14.4V this increases to around 56A

Not quite, current is inversely proportional to voltage, ie if you double the voltage the current is halved, so the current at 14.4v will be less than it is at 12v.
Worth remembering that a bigger alternator (as in higher output) will need more HP to drive it, not much granted but in a race car it may be a consideration

[MartG]

At 14.4V this increases to around 56A

Not quite, current is inversely proportional to voltage, ie if you double the voltage the current is halved, so the current at 14.4v will be less than it is at 12v.

Not for the same resistive load it isn't - V=IR - if R is constant ( which it will be for lights ) then an increase in V will lead to an increase in current too

[MartG]

At 14.4V this increases to around 56A

Not quite, current is inversely proportional to voltage, ie if you double the voltage the current is halved, so the current at 14.4v will be less than it is at 12v.

Not for the same resistive load it isn't - V=IR - if R is constant ( which it will be for lights ) then an increase in V will lead to an increase in current too

[jimi]

Your correct if you use V=IR, but if you use P=VI to work it out you'll get a different answer
6 x 80w = 480w
480w @ 12v = 40A
480w @ 14.4v = 33.33A

[MartG]

Yes, but as I pointed out originally the rated wattage is at 12V - if it was to stay at the same wattage at 14.4V the resistance would have to alter

[aw11rally]

I've only just spotted all these excellent replies, sorry to be a bit slow guys. Anyway thanks for pointing me in the right direction, I've just started a thread asking about the Mk2 alternators which will make me look a bit silly after reading the above info.

And I now remember why I didn't study physics further than GCSE level.

[aw11rally]

At 14.4V this increases to around 56A

Not quite, current is inversely proportional to voltage, ie if you double the voltage the current is halved, so the current at 14.4v will be less than it is at 12v.
Worth remembering that a bigger alternator (as in higher output) will need more HP to drive it, not much granted but in a race car it may be a consideration

But being able to see when flat out on a dark military range with concrete tank stopping devices buried in the verge is worth more than a few HP. As is being able to use the wipers and lights at the same time.

[Cattwooduk]

Quick question, I noticed someone said a Rover 216 Honda engined alternator will fit... this one I've spotted on ebay is a reasonable price but doesn't say what engine it's using, looks the same though. Can anyone confirm this alternator will be alright to go on my N/A? bearing in mine has started making some hellish whining noises and it's driving me insane!

http://cgi.ebay.co.uk/Alternator-Rover- ... 2c51d7ca3e

[Jaspa]

You'll need to change the pulley as they are smaller. and also the plug adaptor is different so would need to be swapped across.

I have both here, I'll dig them out and get a pic up shortly.

[kevin..in]

as above yes it will work with pulley and main plug mod
same seller has MK1 alternator listed but is a whopping £184
http://cgi.ebay.co.uk/Alternator-Toyota ... 3357bc1e88
have you tried a local motor factor for a recon unit?