Could you suggest a 3 battery wiring diagram please?

[carrswood]

Hi
I currently have a typical switched 2 battery setup. 1 x for cranking and 1 x service battery.

I now want to add a dedicated cranking battery and have the present batteries combined for service. (therefore doubling my amperage for service usage)

Can anyone post a suitable wiring diagram? Any advice on best suited switching / charge splitters etc much appreciated

Have a 115ah alternator on a new Volvo D1-20

 

[pvb]

Can anyone post a suitable wiring diagram? Any advice on best suited switching / charge splitters etc much appreciated

The easiest switching arrangement is to have a simple on/off switch for the cranking battery, and a second simple on/off switch for the house batteries. A VSR (voltage sensitive relay) is a good way to control the charging. BEP, who make VSRs, have this suggested wiring diagram, which also has a third simple on/off switch to link the house batteries to the cranking batteries for emergency starting (this may not be the best way to do this, but that's another subject). The on/off switches can be any make, as long as they can handle the maximum current expected.

 

[mitiempo]

Parallel the two batteries for the service usage and they effectively become one. The cranking is the other. Switching, either separate or 1,2,both is the same as for the 2 batteries you have now.

 

[Tranona]

Suggest you use a BEP Marine switch cluster which includes a VSR, independent switching and paralleling. www.power-store.com for details.

Are you sure you have a 115amp alternator on a 20hp engine? seems massive overkill.

 

[mitiempo]

If you currently have a 1,2,both switch keep it. It is more flexible than the BEP cluster - unless you modify it. A 1,2,both switch would allow you to start the engine from either battery bank while the BEP cluster is designed to only parallel the banks. If one is dead changing to the other makes much more sense than paralleling a good with a bad bank. And buy a VSR by itself. It will cost less as well.

 

[VicS]

There are several alternatives to consider

Manual switching using a 1,2, both, off switch.

Manual switching using two separate isolating switches.

A VSR system including an emergency linking switch. A link to the circuit used in a BEP VSR cluster has been given above.
There is a possible snag with that circuit in as much that the emergency linking switch parallels the two battery banks and does not allow you to isolate a defective bank.
The Bluesea system differs from the BEP system The emergency linking switch links the starter and house circuits rather than the batteries. thereby allowing a defective battery to be isolated. The alternator output is also taken directly to the starter battery eliminating the possibility of disconnecting the battery while the engine is running.

A diode splitter is another alternative. The trouble with a diode splitter is that it creates a 0.7 volts drop. A battery sensed alternator ( or a machine sensed alternator modified to battery sensing) is needed in order to overcome that.

Some more typical circuits, including diode splitting are shown HERE

 

[William_H]

3 batteries

Assuming you have a 2 battery system that you are happy with. The simplest is to add another battery in parallel with the existing service battery. Join the negatives together with heavy cable . The positives can be connected together but there might be value in fitting switches in the +ves to each battery so that the batteries can be isolated if you want or have doubts about the individual batteries. (when they get old)
However mostly just use them in parallel. good luck olewill

 

[jimmcgee]

and if you want to safe a load of cash , then go to a caravan shop for your kit !!

http://www.caravantechnology.com//12V-Voltage-Sensitive-Relay-P125.aspx

 

[PaulJ]

Adverc website

There is a lot of information, including wiring diagrams, on the Adverc website...... Start with this.......

http://www.adverc.co.uk/batterymanagement/ideal-boat-electrics-examples

You don't need to install an adverc for it to make sense and I hasten to add that I am nothing to do with that company, though I did find them very helpful and did wire Damarri according to their advice.

Paul

 

[temptress]

Hi
I currently have a typical switched 2 battery setup. 1 x for cranking and 1 x service battery.

I now want to add a dedicated cranking battery and have the present batteries combined for service. (therefore doubling my amperage for service usage)

Can anyone post a suitable wiring diagram? Any advice on best suited switching / charge splitters etc much appreciated

Have a 115ah alternator on a new Volvo D1-20

It is relatively simple. You are simply increasing the capacity of your existing system. So how do you do this easily?

First find a suitable location for the new battery box you will need. Ideally close to the existing battery box. Fit it and get a battery.

Next remove the wires from the ‘old’ second battery and re-route these to the new battery in. probably a good idea to replace the cables with new ones.

Now you have 3 batteries. Wire up two these in parallel. IE Connect the positives and Negatives together and label as domestic. Label the other one as ‘cranking’ or engine or some such.

Cable lengths and separation is an issue but if your old system was setup to cope with two batteries then you don’t have to do much. There are all sorts of things you can do to improve on this but nothing you HAVE to do.

Your 115amp alternator should cope with the extra demands but again you can improve this by fitting a battery management system and/or VSR or second alternator or just leave as is and see how you get on.

Good luck

 

[nigelmercier]

A VSR (voltage sensitive relay) is a good way to control the charging. BEP, who make VSRs, have this suggested wiring diagram...

A VSR is the best way to go IMO, but you may not need the isolators shown in that diagram; as often these are in the negative rail.

Note also that you can swap the two output terminals on the VSR so it is switching a lower current (to the starter battery). By doing this you can often use a lower capacity unit.

I've wired mine up via a relay in the negative reference lead, so it is only energised when the ignition is on. Otherwise they switch on when the shore-power charger is running.