Dual Alternators & Batteries

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
R

RobDenton

Member
Posts
24
Hi, I am thinking about dual alternators each charging it's own battery in completely isolated circuits. One for winch etc, and one for the general car electrics.

I was going to add a solenoid so you could switch the batteries to parallel mode when either was getting flat and needed a boost. (I.e. Connect them both together)

Do you think I also need to add another to break the second alternator charge feed to the battery so I don't end up with 2 alternators output connected together (they are not the same output Amps)? I could put this on the same switch.

I was concerned at they may fight against each other if connected together

Thanks again in advance for your help!

Rob
 
RobDenton said:
Hi, I am thinking about dual alternators each charging it's own battery in completely isolated circuits. One for winch etc, and one for the general car electrics.

I was going to add a solenoid so you could switch the batteries to parallel mode when either was getting flat and needed a boost. (I.e. Connect them both together)

Do you think I also need to add another to break the second alternator charge feed to the battery so I don't end up with 2 alternators output connected together (they are not the same output Amps)? I could put this on the same switch.

I was concerned at they may fight against each other if connected together

Thanks again in advance for your help!

Rob
Click to expand...

I think you would best fit a split charge system with two batteries and one good alternator. If you fit a second alternator, where on earth can you find room for it ? And
can you run it off an existing drive belt ? Would you have to fit an extra pulley somewhere ? I also think it would be extra load on the engine which would have some effect on the power output and the fuel consumption. Food for thought.
 
Hi, thanks for your reply... Interesting thoughts, the alternator fits right where the Aircon pump goes and links to he same pulley. The thought of 2 alternators is both as a backup and if you have heavy load on the battery system it can charge both batteries simultaneously. To get this with one alternator you would need to have a high amp alternator which would be equally expensive.

I know there is a lot of debate as to which of the 2 systems is better.

I think I will put an isolator relay (100a +) between the secondary isolator and second battery to be on the safe side

Rob
 
LifetimeLandy said:
I think you would best fit a split charge system with two batteries and one good alternator. If you fit a second alternator, where on earth can you find room for it ? And
can you run it off an existing drive belt ? Would you have to fit an extra pulley somewhere ? I also think it would be extra load on the engine which would have some effect on the power output and the fuel consumption. Food for thought.
Click to expand...

You have answered a thread about advice on dual alternators ,and your answer has proved you should not have answered the ops question as you dont know about dual alternators!!:p
 
pressbrake said:
You have answered a thread about advice on dual alternators ,and your answer has proved you should not have answered the ops question as you dont know about dual alternators!!:p
Click to expand...

You are quite right, I had not heard of dual alternators before. The main point I was making was whether there was room to fit two alternators, and that I thought it simpler to have a split charge system. After all that set up has been available as an optional extra on Land Rovers going back to the Series vehicles. Please explain the pro's and cons of a dual alternator set up for the benefit of those (me included) that don't have your knowledge.
 
I came up with an elaborate solenoid switching system which allowed me to switch between parallel and series connections between two batteries. This was to allow me to run a 24v starter and winches.

I never got round to simulating the circuit as I soon realised it was more hassle than it was worth.
 
Hi, Thanks for all the responses... I guess I should have been a little more specific.

I have searched the forum and Google, I have looked at various wiring diagrams, none of which answer my specific question.

I am going to have dual alternators, if I connect the batteries in parallel with both alternators sill connected (albeit for a relatively short period of time, when I am suffering excessive load or low charge on either battery), thus connecting the outputs of the 2 alternators together will this cause them to fight against each other as they are not the same amp output?

In this case would I be better to connect a relay in the output of the second alternator so I can disconnect it in this scenario.

Thanks
Rob
 
RobDenton said:
Hi, Thanks for all the responses... I guess I should have been a little more specific.

I have searched the forum and Google, I have looked at various wiring diagrams, none of which answer my specific question.

I am going to have dual alternators, if I connect the batteries in parallel with both alternators sill connected (albeit for a relatively short period of time, when I am suffering excessive load or low charge on either battery), thus connecting the outputs of the 2 alternators together will this cause them to fight against each other as they are not the same amp output?

In this case would I be better to connect a relay in the output of the second alternator so I can disconnect it in this scenario.

Thanks
Rob
Click to expand...
I think your trying to complicate things too much
 
Dual alternators are a simple way of achieving high output with cheap and easily available alternators, and is true split charging if you run a winch your not going to drain the main battery as you have independant circuits.

As for the gentleman mentioning 24v the easy way is to use a bosch parallel start relay which is for diesel cars running 12v alternators and main electrics with a 24v starter motor .

On my discovery im fitting a second 24v alternator and battery system to give me full power 24v to bump start comercials etc
 
Not sure anyone has actually answered the original question...

If you have dual alternators and choose to connect the batteries together you WILL need to isolate one of your two alternators, you can not have two alternators charging one battery (without further modification)

I'd look for a specific switch or relay which does both actions in one go, if you use two relays / solonoids and one fails you could still end up frying both alternators.

Having two alternators and two batteries is superb redundancy and is a good option if you think you'll need it or just fancy it!
 
Bump said:
Not sure anyone has actually answered the original question...

If you have dual alternators and choose to connect the batteries together you WILL need to isolate one of your two alternators, you can not have two alternators charging one battery (without further modification)

I'd look for a specific switch or relay which does both actions in one go, if you use two relays / solonoids and one fails you could still end up frying both alternators.

Having two alternators and two batteries is superb redundancy and is a good option if you think you'll need it or just fancy it!
Click to expand...
since dedicating the 2nd 100amp alternator to my 8274 winch only,the winch is simply brilliant theres no drop off in power anymore
 
GINGE said:
The amps needed to get you really really unstuck will be enough to make any split charge system cough a little.
Click to expand...

I understand that but how many amps does the car use while running? the question being how many extra amps does a dedicated alt and batt provide to the winch? or is the increase the effect of uprating and improving the wiring?
 
SteNova said:
I understand that but how many amps does the car use while running? the question being how many extra amps does a dedicated alt and batt provide to the winch? or is the increase the effect of uprating and improving the wiring?
Click to expand...

depends...

heater on or off?
lights on or off?
LED lights?
any spots?
radio on or off?
amp?
wipers on or off?
what vehicle? Ecu?
CB on or off?
any other accessories?
 
SteNova said:
I understand that but how many amps does the car use while running? the question being how many extra amps does a dedicated alt and batt provide to the winch? or is the increase the effect of uprating and improving the wiring?
Click to expand...

Apologies.

Depends what alternator you use (80-140 are the norm fitted) but having a constant supply that unwavering and not drainable is a great start for something like a 8274.

Obviously its a bigger expense to fork out for another alternator and a mounting bracket etc etc vs the cost of a simple £2.50 relay to make a split charge.

I have a split charge system as when i installed it i didn't have an 8274 or a lot of accessories to draw big amounts. Now i do have an 8274 :banana: :D i would switch to a 2nd alt if i was keeping the car.
 
You must log in or register to reply here.

Similar threads

G
48V Alternator run off the PTO to supply a big battery bank and inverter?
Replies
5
Views
136
SteveMarquis
SteveMarquis
S
replacement battery size
Replies
4
Views
325
WoodyO
WoodyO
Rubberknees
P38 key fob
Replies
14
Views
1K
Rubberknees
Rubberknees
Blob
L322 Lower glovebox won't open
Replies
3
Views
242
marjon
marjon
C
Freelander 1 My car doesn't work.
2
Replies
33
Views
2K
Freddie17
Freddie17
Back
Top