Thread: Do I need a new alternator?

A 60 amp alternator is too small for duel batteries. Pat

Check and replace your earth straps. Particularly the one from the chassis to the engine.
I had a similar problem on my Disco. Everything checked perfectly (including the earth straps and their attachment points cleaned) so I put a new alternator on and it made no difference. In desperation, I replaced the earth between chassis and engine (only because I had the parts to make one and couldn't think of anything else) and it solved the problem. Voltage on both batteries now sits just below 14V.

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A 60 amp alternator is too small for duel batteries.

why

Because for batteries to duel properly they need more power .

It should be sufficient for dual batteries, depending on how much power is being used out of them.

Originally Posted by PAT303

A 60 amp alternator is too small for duel batteries. Pat

I fail to see why, assuming you don't have 1001 different things plugged into it. A dual battery system, by its very nature, charges the cranking battery first, then the auxiliary battery. Its more of a case that the 60amp alternator will take longer to get both batteries up to full capacity.

Now if you have a million and one things powered off said batteries, then things change. Picture your batteries as a water tank, the alternator as a water pump, and all of your electronics as a hole in the bottom of the tank. If the hole is losing 80 litres (amps) a minute, and the pump is only supplying 60 litres a minute, then there's a problem. Before long the tank will be empty. Only then a bigger pump will help. Swap the pump out for a 100 litre/minute pump, and the tank stays topped up....

Originally Posted by naradataranto

Ok so im no mechanic but I am finding that my dual battery system is not recharging properly and the battery meter installed is reading a charge rate of only 12 Volts or so,even less when I am running the AC. If I turn off all the electrics I can get the volt meter to charge to around 13 volts but no higher. The dual battery System I am running is new so I have not taken any previous notice of the voltage of the altinator untill now.
I appears that the defender 110 300tdi model only uses a 60amp alternator. Is my Alternator on the way out or is it just too small to run a large battery and air ect at the sametime.

Thanks in advance for the help.

Check that the tensioner is doing a good job on your belt, dropping Volts with the A/C on made me think that your belt maybe slipping. I am not familiar with the setup but if the fan motor on the A/C blower is pulling that much current to drop the voltage then you may need to examine the wiring as others have said.

funny I managed the cape with just a 35 amp alternator and dual batteries.

so long as the alternator makes more amps than you're drawing it will charge the batteries.

check the connections in particular the excitation connection and the earth connections then do an AC ripple check on the alternator output.

Thanks for the help but riddle me this. When the battery is drained and I set off on a trip to charge it again the volt meter does not read a charge at all untill a half hour or so of motoring. After that the charge increases gradually and as the battery gains more charge the charge light on the volt meter rise untill the battery will charge at around 14 volts once almost full.
Despite this it will only charge at full volts when the revs are at around 2700rpm. Also the battery never seems to get to full charge stops at around 80-90% full never 100%.
This is my second battery in the system and is a vada 95amp hour. I want to get it right as the battery alone is around $800.00 and I want to make sure its working likea dream.