Help with automatic battery switching.

[ron roberts]

Can any one help me please with a schematic for the following? I need to switch between 2 12 volt battery’s.
I have 2 12 volt battery’s that run a 12 volt 2 amp motor, but only one battery can be connected at a time to run the motor. Now when battery 1 runs low I need it to automatically switch over to battery 2 at the same time switching battery 1 on to the charger and back again.
Simple with relays but I cannot use relays and don’t want to use mosfets. Some way of adjusting low voltage level would be nice.

 

[ravix]

can we see any schematic you have sofar?

Why don't you want to use relays or mosfets?

 

[mneary]

Without relays or mosfets, this leaves you with a toggle switch.

 

[Pommie]

Without relays or mosfets, this leaves you with a toggle switch.

Or valves.

Why not just wire the batteries in parallel.

Mike.

 

[Bob Scott]

I had a power boat with two batteries. It used a specially built huge two way SPDT rotary battery selector switch that is available at most marinas.

Just use two chargers, one for each battery. Leave them both on so you don't have to switch chargers.

 

[ron roberts]

Thanks to you all for your help on this.
This is a diagram I put together; I don’t want to use a relay, as this will be on 50% of the time. I know it’s not a lot of current drain but it is one, so I would like to remove the relay completely. Now for the mosfets, I just don’t like mosfets. Well let’s say they don’t like me no matter how many precautions I take I just destroy them. Thanks from Ron.

**broken link removed**

 

[ron roberts]

Don’t know if I’m going mad has I’ve been on this for weeks. This is what I done up to date.
I need help with this like values of components. Resisters will be about 630 ohms transistors 2n3055 to drive motor and so on but need help with it my brain is starting to get fried with this now.


**broken link removed**

 

[blueroomelectronics]

How are you going to keep the 12V batteries charged on your solar tracker? Is it a large panel?

 

[ron roberts]

Large panel array well 4 85 watts + wind turbine.

 

[blueroomelectronics]

Have you thought about a latching relay and a simple transistor? You'll only need the relay once a day anyway.

 

[ron roberts]

Thanks Bill but I cannot express how important it is to me not to use any mechanical relays of any type.
-------------------
Ron

 

[ron roberts]

By the way Bill it’s not running a solar tracker, it’s just an experimental unit I’m playing with.

 

[Hero999]

What about using solid state relays then?

 

[Nigel Goodwin]

By the way Bill it’s not running a solar tracker, it’s just an experimental unit I’m playing with.

As it's just an experiment, use a mechanical relay, it's probably the best option anyway - what do you have against relays?.

 

[ron roberts]

Well I think I will give up on this one now but thanks to you all.


Thanks Ron.