quesion about using a diode with 2 12v batteries

gennarobasso81

Thank you for taking the time to read my post.

So, what I am trying to do is connect two 12 volt batteries in series to give my motor more power.

The first 12v battery is apart of a circuit that is designed to be ran on 12 volts. I would like to connect this 12v battery to another 12v battery located further down my project to give my motor 24v.

I was thinking of running a diode in the line to prevent any possible back feed to the 12v circuits.

Im having a problem with finding the right diode, the batteries are 12v and 9.5 amps.

Ttailspin

You may not need a Diode, But you do need a Volt meter...:)

Try putting two little AA 1.5V batteries in series, and take some measurements at different locations, the results will surprise you.
It doesn't seem like it would work, but it does...

Go really crazy and put four AA batteries in series and see what happens...:thumb::thumb:



-Tommy

abecedarian

Though it might work, it might be better to just run the batteries in series and use a regulator circuit to source 12v. Then you won't have to worry so much about the unequal discharge rates, or could go to a 24v battery.

Edit- realized you said two batteries, one elsewhere in the chassis... so could do two 24's in parallel for longer run time.

gennarobasso81

Both post are great ideas. However, the project I am working on has already been built around a 12 volt battery. The second battery would be in a different location but tied into the main power line.

I should probably tell a little more about what I'm doing.

I modified my son's power wheels. I added on a real turn key electric ignition switch. High beam headlights, low beam head lights, and a ground effects light kit, with a working radio. I am adding an adjustable speed control dial to keep the motors somewhere between 12 and 24 volts to make sure it isn't too fast.

I am worried that adding a second battery might blow the 12 volt lights

kwinn

As long as the batteries, motors, and 12V parts are connected like the attached diagram they should work without problems. I cannot tell from the pictures how the speed control should be connected (+24V or ground side) so I hope you have instructions or a schematic.

The only problem I can see would be with charging the batteries. Since battery A (the one already in the car) is supplying current for the motors and other systems while battery B supplies only the motor battery A will be more discharged than battery B. The batteries will need to be charged separately so both are fully charged, otherwise battery A may be damaged.

abecedarian

Another option, with two 12v in series to make 24 volts, you could use 24-12v converter, then power draw will be leveled across both batteries.
There are several on that infamous auction site ranging from under an Amp to over 20 Amps.

Ttailspin

Another option, with two 12v in series to make 24 volts, you could use 24-12v converter, then power draw will be leveled across both batteries.
There are several on that infamous auction site ranging from under an Amp to over 20 Amps.

+1
And don't skimp on the wire or terminal connections, use the heavy duty stuff if you can..


-Tommy

abecedarian

Ttailspin wrote: »

+1
And don't skimp on the wire or terminal connections, use the heavy duty stuff if you can..


-Tommy

Screw / ringlet terminals if possible are much better than spade / blade types.
... and dielectric grease and heat shrink on all wiring connections, crimped or soldered, that may get wet. Murphy, of Murphy's Law fame has children too.

Probably want some transient and noise suppression on the system to protect the 12v side from back EMF from the motors when they start braking. If you can harvest that to recharge the batteries, even better... regenerative braking anyone?

gennarobasso81

thank you guys...all ideas are great! I finished the project...ran some extra wires and connected the car in much the same way as Kwinn suggested.