Battery based tank circuit (tested) - Page 15

Curiosity · 07-25-2005, 09:21 AM

A diode works quite well. You can get more efficient ones now though.

Arathranar · 07-25-2005, 11:58 AM

That's exactly what I have. I use a single 20A 0.25V drop Schottky diode. Been working perfectly for months even when I once totally discharged the tank battery.

KyleYankan · 07-25-2005, 12:11 PM

Arathranar: How did you discharge the tank battery? Wouldn't the tank battery be constantly pulling from the main battery also? So they would always be in equilibrium?

Arathranar · 07-25-2005, 12:17 PM

My PC draws 70mA when in hibernation. I have the circuit hooked up to the switched accessory line which is grounded when the car is off. 70mA is enough to drain my tank battery over the weekend.

At some point I will get around to building a shut down controller circuit. In the mean time I disconnect my PC overnight.

KyleYankan · 07-25-2005, 12:31 PM

Sounds interesting. I wonder if it would be better to have a relay on the line with the diode - hooked to ACC? So that way I can run down my second battery and ont worry about the first? Anyone got a schematic for that?

Arathranar · 07-25-2005, 12:47 PM

If you do that, you forego the isolation the diode gives you during crank. You problably want both so your tank battery doesn't have it's voltage pulled down during the crank causing your PC to hang.

KyleYankan · 07-25-2005, 07:23 PM

On my car, during crank the ACC turns off temporaily. So, during crank the batteries would be isolated, after crank, they would be connected. Any time ACC is off, there are disconnected - good for if my PC hangs on shutdown, it will only kill the one battery.

Arathranar · 07-25-2005, 07:39 PM

That's the same as my setup. In which case a relay buys you nothing.

KyleYankan · 07-27-2005, 09:52 PM

It would stop my PC from draining both batteries.

Arathranar · 07-27-2005, 10:01 PM

Sorry - I misread your previous post. You don't have the same setup as me and using the acc line to disconnect your main battery from the PC will stop your PC draining the main battery when the car is not running.

I run directly off the acc line so I get that for free.

jaytyn · 12-01-2005, 12:32 AM

Hi

Im going to make a tank circuit based on the diagram below: (From earlier in the thread)

my question is: with the tank battery constantly connected to the cars 12v battery will this cause drain enough to flatten the car battery? or can it cause overcharge to the tank battery?

zvi · 12-01-2005, 01:07 AM

I had this circuit in my car but I was not happy with it, both batteries were drying up, and making oxyd white crap on electrodes.
eventually I got rid of it, and bought M1-ATX power supply, which is just fine for me, and does not require any kind of additional battery backup

Chris31 · 12-01-2005, 07:11 AM

Check your alternator, it may be pumping out too much voltage, warming up the batteries and making it leaks.

How long have you had the circuit installed before the battery start leaking?

This circuit was designed when those PSU that can survive the crank were not readily available. Yeah ultimately go for a PSU that can do that job just like what you did.

Glad you aint having problems with the M1-ATX, mashina gone nuts cuse of all the problems hes having

zvi · 12-01-2005, 08:43 AM

Chris31
before i installed the second baterry and a carpc at all main baterry was OK, no leak, no oxyding, but my previous main baterry died soon after I installed backup batt and that sircuit

you mean M1-ATX has problems? mine is OK so far. I have redesined all the wiring in my car, when got M1-ATX and VoomPC case (it is soo cool

)

kromec · 06-14-2006, 12:09 AM

hey there guys,

have been here for a while, mostly reading and learning. Have been busy with my carputer project and need some help....due to the fact that i'm not a electronics engineer i might need some help with the following diagram...want to know if this is the correct way to connect everything or am i missing something.