Lola Wiring

[Mike Jones]

How do I wire the back set-up for an additional battery for starting and charging the on-car battery? Do I run form the starter for the positive side? If so, do I just have to have the shut off switch turned on to charge?

Mike

[Allan T. Chou]

I'm sure everyone has there own method, but I found taking the positive from the starter and then just grounding the negative to the frame requires you to have the master switch on for charging, which is ok if the ignition is not energized directly by the master (should be the kill switch on the dash which is down stream of the master). But you have to remember to switch the master on each time you charge the battery when sitting in the pits between sessions. Since I am a true believer of Murrphy's law, I hook the jumper plug directly to the battery. This way you have less to forget on those hecktic race weekends. Hope this helps Allan

[Brian]

I hook the jumper battery to the car side of the master switch so that I can start and run the car just on the jumper battery. To me, that saves the car battery for the race. You have to remember to switch on the master switch when charging and when you unplug the jump battery.

Of course, now that I use Odyssey PC-680 batteries I don't actually use a jumper battery anymore, and I haven't wired one in on the Lola.

Brian

[Allan T. Chou]

Hi Brian; I really like your way of using the jumper to start the car, and I tried figuring out the wiring for it many yaers ago, but herein lies the main problem that confronted me. The master has to kill the engine when off as well as the dash kill switch independently of each other. Subsequently, If you wire the master to energize the ignition on the car side (when off to start the car with the jumper battery only), it will do two things. One it defeats the dash kill switch when the master is on, and when you are just charging/engine off it heats up the coil which I think is a bad thing. The only way I could figure out the independent double kill switch system was to use the master to power the starter motor and to power the ignition through the dash kill switch. This way switch off the dash switch, engine stops, switch off the master, and the engine also stops. Outside of using a battery cut off for the car battery (which I feared would accidentally be switched off at the least opportune moment (Murrphy's law)) I could not figure it out without compromising the double kill switch, nor energizing the ignition when just charging. Can you explain the wiring you had? Would love to incorporate it into my cars. Thanks Allan

[stephen wilson]

My car also works the same as Brian's. I think the key is that my master switch is wired into the ground wire, straight from the battery, and grounded to the frame on the other side. The jump plug has a ground directly to the chassis, bypassing the master. The dash Ignition switch still works while using the internal or external battery

[Brian]

Allan, I just bypass the master switch, basically. if I have the master interupting ground or live, I just hook the jump battery in on the car side of the switch. If I have the switch off, the car works exactly the same as normal, just off the jump battery not the car battery. If I have the master switch on, both batteries are in parallel.

On my dash all I typically have is a switch for coil (ignition), rain light, push button for start. On sports racer, I add a fuel pump switch. No "dash kill switch".

It all just kind of works, I haven't had any problems with doing it this way. Now I'm worried...

Brian

[Allan T. Chou]

Damn, I get it!!! Car side of Master switch is connected to the starter motor, jumper battery, dash kill switch which powers the coil and starter button. Master off, Dash on to start the car without the car battery, Master on, Dash off to charge the battery between sessions. Both Master and Dash kill switch will work independently. Can't believe I didn't see this before. Must have over thought it lol. But I do have to admit that I had to draw it out a few times before I got it right. Thanks for making me focus on this again. I attached the drawing of the circut. Now to re-wire all my cars

[Mike Jones]

Thank you all for the great information. Brian, I still don't have an engine. I am waiting to see what the damages are before getting the headers made. My spousal unit will be gone this weekend so I should get some stuff done.

Thanks again-

Mike

[Brian]

Allan, what I do differently than you is bring the positive feed to the dash (to the starter switch, usually, or a three way connector/splitter) and feed the coil through a separate switch, rain light through a separate switch, and any accessories (like fuel pump) through a separate switch. I don't use a "master" switch like you do. The reason is to have the coil as isolated as possible, with minimum potential impact from any other device. May be a moot point, but there you go. This also lets me crank the engine without having ignition or fuel on, etc.

On the FFord, i use no fuses or breakers (I am actually using 95% OEM Lola wiring harness, I changed out about two connectors and one battery lead, plus the master switch). On the NTM B/SR, I used marine breakers for everything. On a Mini Cooper S that I just re-wired, I used a marine breaker for fuel and rain light, but ran ignition direct. Nothing like consistency...

Brian

[Murray]

Attached is the wiring plan I use on my Lolas. This set-up allows operating with the Pit battery and the on-board battery isolated. It also allows using the starter to crank up oil pressure with the ignition offl. It also turns on the transponder anytime the ignition is on. One other feature is wiring with a short section of 22 AWG to act as a fuse only if a big short occures. The rest of the wire is 18 AWG which keeps from burning up the entire harness in case of a short.

[Allan T. Chou]

Hi Murray, for some strange reason, this system had eluded me for quite some time. Possibly not just giving it enough thought. But I do like the efficient use of 6 or 8 heavy guage battery wires and using the master to ground the system in your schematic. One thing though, why use 22 Ga for 7" and then step it up to a 18 Ga. wire for the coil/dash? wouldn't a in line fuse be safer? No fire potential. Thanks Allan

[Murray]

Hi Allan;
Yes a fuse would work. I just don't like fuses much. A short piece of smaller AWG wire becomes a fuse link. It will melt in half before you start melting the insulation on the rest of the harness. It allows an intermittant short of quite a bit of current without blowing. It is kind of a slo-blow system . I don't use fuses for simplicity and it removes one more thing that could go bad.
I did not show the gage of the battery cables, but I use 8 AWG from the pit battery to the starter and from the on-board battery to the Main Shut off switch and to the starter. Everything else is 18AWG.