MK alternator upgrade

[Crankshaft]

Hello all

I wasn't sure weather to put this under electrical or here.

My MK , has a 50amp alternator. I have just installed a second battery and have yet to hook it up and am thinking that I will need a bit more than 50 amps.

I see two alternatives

One to to get a X-trail or similar alternator, if I can find one with a V pully and looking for about 100 amps.

I expect to upgrade the wiring a bit and remove the external regulator but essentially run it all from that .

Two is to install a second 50A alternator on the other side of the engine to feed the second battery. Good voltage regulation, great redundency, and I have enough room.

Has anyone had any experience with either of these ideas and if so do you know of any hidden traps?

Cranky

[aussiemale]

So are you going to have the 2nd battery set up as parallel or as a stand alone?
With batteries nowadays you do need to get the correct battery for the correct job.
If you're getting it to run extras it will pay to get it as a stand alone rather than setting it up in parallel.
Your starter battery is different to a Deep Cycle (DC) in the same way a sprinter is different to a marathon runner.
Starter batteries supply quick bursts of CCA to crank over an engine and requires HIGH amps to recharge it where as a DC is designed to release long slow ebb of Amps and low amps to recharge.
Starter batteries also don't like being cycled (charged, discharged, charged, discharged) unlike the DC, the main job the starter battery does is supply power to the starter, that draws the CCA from the battery to crank over the engine, as the engine starts the alternator kicks in and tops up the battery and then supplies the power requirements to the vehicle. If the draw is more than the alternator can supply, the power is pulled from the battery and that will kill it in the long haul.
Charging the battery has it's pitfalls itself
Put low Amps into a Starter and it'll gas and vice versa put high amps into a DC will cause that to gas.
Obviously with every RULE, there's the exception, I use Yellow top Optimas which are a semi DC/Starter that has coils rather than plates (harder to shatter) and don't mind high or low amps. Those are perfect for setting up as parallel. Apart from that they're not wet filled and you can lay them down on their sides (side mount terminals). I'm tossing up on having one in the engine bay and the other under the passenger seat.
DON'T go Red Top Optima as they're only designed for starting.
Not often I can offer much advice in this forum but do know the odd thing about batteries

Bryan

[Finly Owner]

I would also suggest a smart charger regulator that auto switches when the second battery needs the charge. This would allow just one alternator. And I suggest you replace your current alternator with a 80 amp alternator. They are available at all good auto elecs.


Tim

[GQ TANK]

I was running a ef alternator - around 100 amps

i swapped the pully from the l28 alt - currently running a VL alt on the rb30 (but changed the pully to a V belt)

[Crankshaft]

I have an alternator from a RB30 skyline executive but it is only 70 amps and it seems a lot of work for just another 20 amps. I like the idea of the EL alternator at 105 amps. should do the job nicely.

I have had a look at all the dual battery systems and like the look of the "Red arc" system. I have ordered one off Ebay and will fit it when I find an EL or similar alternator. I have been offered one from a wreck with low km. Just need to make time to pick it up.

[meakinelli]

thanks for the reply, jolly good info. Lots to thik about.jm

[anvil77]

Thanks a lot. I must to do that