Dual Alternators, 75 series Cruiser

Submitted: Wednesday, May 28, 2003 at 14:00
ThreadID: 5154 Views:4463 Replies:4 FollowUps:7
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Has anyone had any experience fitting a second alternator in a 75 series crusier (1HZ) or any other vehicle?

I wish to run the second alt. at a higher voltage output dedicated to charging a pair of deep cycle batteries. The idea of the higher voltage being that deep cycle batts prefer a higher charge voltage than a starting batt (and higher than is provided by a typical factory alt.).

Cheers
Craig
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Reply By: Rod - Wednesday, May 28, 2003 at 18:16

Wednesday, May 28, 2003 at 18:16
Out of curiosity, how are you going to alter the output voltage ? Does the second alternator have an external voltage sensor or is it a marine type alternator ?
AnswerID: 21301

Follow Up By: CT - Thursday, May 29, 2003 at 08:15

Thursday, May 29, 2003 at 08:15
Rod,
The alternator has an external voltage regulator. Its an older unit, approx . 35amp and I believe its a Land Rover item. Are marine alternators different again?
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FollowupID: 13902

Follow Up By: Rod - Thursday, May 29, 2003 at 08:33

Thursday, May 29, 2003 at 08:33
My limited knowledge of marine alternators is that they are typically of the external voltage regulator type and are easy to modify to have 3-stage charge controllers
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FollowupID: 13905

Reply By: desert - Wednesday, May 28, 2003 at 20:23

Wednesday, May 28, 2003 at 20:23
Yes Craig, One of my team of off-roaders has a very successful dual alternator set up that is a cinch to fit up on a 1HZ engine. We use a small 40amp alt from a Daihatsu Charade (about mid 80's vintage), it sits on top of the air con compressor and a Magna PS belt fits perfect on the spare groove of the compressor. The alt is internally regulated and recharges the aux. battery bank. Alignment is perfect, system is completely seperate to the original and can be removed in 15 minutes if you wish. Dash light/and or voltage meter optional.
AnswerID: 21318

Follow Up By: CT - Thursday, May 29, 2003 at 08:19

Thursday, May 29, 2003 at 08:19
Perfect answer. Exactly what I wanted to hear. I'll probably go down this road as there is very little useable space anywhere else in the engine bay to fit belt driven equipment.
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FollowupID: 13903

Reply By: eTech - Wednesday, May 28, 2003 at 21:05

Wednesday, May 28, 2003 at 21:05
Craig you can usually setup your present alternator to charge at a higher voltage and drop back your starter battery to the correct voltage with a 100 amp diode. After all you are only looking at between .4 and .6 volt increase.

We do this fairly often to boost the charge voltage when they are fitting auxilliary batteries in caravans or camper trailers.

Depends on the type of battery you are using. The only viable value for money deep cycle batteries are lead acid deep cycle batteries. The sealed type batteries are poor value for money and low capacity for the size. Do not bother to try and get a warranty claim on sealed batteries. It is never the batteries fault it dies, it will always be yours. They have 101 excuses why you should pay and the battery is not covered by warranty.
AnswerID: 21327

Follow Up By: Andy - Wednesday, May 28, 2003 at 21:22

Wednesday, May 28, 2003 at 21:22
etech,

can any auto elec make the changes to the alternator as you have suggested. Would it make a huge difference and any ideas on cost?

thanks

andy
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FollowupID: 13892

Follow Up By: CT - Thursday, May 29, 2003 at 08:28

Thursday, May 29, 2003 at 08:28
I assume that the increased voltage goes straight to the auxillary bank with the diode between the auxillary bank and the start batt, or otherwise you wire up via a three position battery switch with the diode between the switch and the start batt ?

I fully agree on the lead acid deep cycle batts. Unfortunately, deep cycle batts. are an expensive learning curve when you find out after that you did all the wrong things in maintaining your batt.

Cheers, Craig
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FollowupID: 13904

Follow Up By: eTech - Thursday, May 29, 2003 at 19:14

Thursday, May 29, 2003 at 19:14
any auto electrician should be able to do it for you

use a standard battery isolater Redarc type

Diode to main cranking battery would drop the supply back by .6 volt to make up for the increased voltage

What type of secondary battery do you have fitted?
How far is the secondary battery from the main battery?
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FollowupID: 13951

Follow Up By: Andy - Thursday, May 29, 2003 at 19:29

Thursday, May 29, 2003 at 19:29
etech,

My auxilary battery is a 130 ah Trojan Deep cycle and it is in my camper trailer along with the fridge. I actually already have an Arrid Twin/Charge
dual battery controller along side the battery in the camper. This was how it was when i bought the camper. I also have a basic solenoid in the fourby, with about 8mm cable running to Anderson plug at the rear.
I thought battery controllers should be as close to the main battery as possible. But not according to Arrid! They reckon it increases the power some how.

thanks

andy
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FollowupID: 13952

Reply By: Dozer - Thursday, May 29, 2003 at 11:00

Thursday, May 29, 2003 at 11:00
Hi
I have a second alternator for the second battery. If you can work out how to drive it, and where to put it, it is an excellent alterrnate method that keeps everything seperate. Most efi alternaters are internally controlled to a higher voltage than usual,(my Toyota is 14.6v) so getting one off an efi car might be advantageous in your endevours:-)
Andrew
AnswerID: 21368

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