Outer Limits 4x4 Board

i think the alt on my '90 gq is a 70amp. i'm getting flat battery whenever i go out for a night run. only got 1 batt. running two LF 240 spots.
the question is, can you have an alternator too big?
Hitachi do a 110,90,85 and the 70amp.

i have plans to have a 2nd battery, than get a fridge, more lights, winch all the other power hungry things to make life easy.

should i just go and get a 110amp and be done with it?, or will it have a negitive effect on the life span of the single battery that i have now?

I would be checking other avenues before upgrading the alternator (i.e. faulty alternator / regulator) - 2 x LF240's draw only around 20 amps ... which the (70a) alternator should have more than enough capacity to run these for whatever period.

There are many of us that run a heap more lights than this and have no trouble on the standard alternator.

i wouldn't think that you could have an alternator to big, as if it was to big, it would just go unutilized, same as when you drive during the day and using stuff all power. Amps are generally drawn, meaning that your car will only pull what it needs, up to the capacity of the alternator (and batteries)

marin

yeah a larger alt isnt a drama. I went from a 35 amp to 120 bosch falcon one in my 4runner and its all sweet.



Choice

the TB42 standard Alt is a 50 amp model, the EFI is a 70 amp model and the GU is a 90 amp model

If you are getting a flat battery its either the alt not charging properlly or its overcharging, causing the battery to drain due to damage.

I just replaced my 50 amp one from my TB42 with a 100Amp after market one because my diodes died and it was leaking back through the alternator, so while not charging while going it was leaking when the engine was off.

All alternators regulate the amount of voltage that they send out at around 14-15v. its just how many amps you can use before the alt stops supplying power and it starts to draw off the battery, bigger the better thats for sure.

i have 4x 100watt IPF spotties on mine, so 100Amp is a good number.

it could also be a old or crap battery just not holding its charge correctly

cheers for the help.

i run 2 narva spots up front have the head lights through relay and also 4 hellas up on roof my alternator is a leese neville (out of dump truck from mine) 140 amp. when at idol it is still able to charge with all lights whereas with standard alternator i was draining the battery unless i was at speed so larger is always better! why run extra battery if you cant charge check wot current is drawn with lights on etc at idol should be around 13 or 14 volts the volts should be 14ish with out anything on hope this may help others as it did me