Higher than 12v Batteries

[dereklola]

On the Stack tach problem thread Steve Demeter said "If the battery voltage drops to 11.9999999 volts, it does go crazy though".

Are 14v or 16v racing batteries available and if so does anyone have any specific recommendations? I haven't done a seach yet simply because it's a bit late tonight.

I had what I now think was a battery voltage problem with my Electromotive ignition last weekend. The SBS 30 battery works fine for sprint races (say 20 minutes) but after 55 mins of an enduro I was limited to 6000rpm versus 9000 normally (vintage Atlantic with BDD). Electromotive says I must keep at least 12v available - bit difficult with 12v battery and no charging system.

Anyone?

[Rick Kirchner]

If you have trouble with the electronics on the car, then try two batteries - like an SBS-30 to run the fuel pumps, starter, and coil, and then a smaller 12V battery to run the sensitive electronics. They don't draw much current but are voltage sensitive. Using the starter and high capacity pumps really sucks the power out of the bigger battery, but the components they run are not really voltage sensitive. The smaller battery should run all your electronics for hours. You have to be careful to ensure the two systems don't touch anywhere except at ground. You might have to use an optoisolator for the tach input but you'll have to test to see.

[dereklola]

Thx Rick.

Actually the Electromotive ignition is the big amp user simply because the 2 coils are integral with the unit but this morning I too have been thinking of using a second battery and be-damned the extra weight! Question then is whether to run them both separately as Rick suggested - one for the ignition, the other for the rest (fuel pump, instruments and occasional start) - or run all from one and be able to switch over to the other if/when necessary. Probably wise to find room for a volt meter as well - but goodness knows where.

I did find a 14v battery from http://www.twracing.com (they sell it as a slave battery to avoid drawing down the car battery). I'm trying to contact them to get more info - their email didn't work. And I found 16v TurboStart batteries from New Castle Battery http://www.batterycentralmall.com/Ba...cing/S16V.html This is no heavier than two SBS-30s but is physically far too big to get in the Lola unless I leave out the driver.

Anyone got any opinion on the best way to use dual batteries? Or any other good ideas?

[kea]

Derek,
How about using the SBS 40?
Keith

[Rick Kirchner]

Here's another couple of suggestions: The dash and ignition manufacturer should be able to give you an estimate of both typical and max current draw. Along with some info from SBS, you should be able to predict how long the battery should last. The wild card is how much the starter takes off of the battery to begin with. If SBS can give you an internal resistance, then the voltage drop and the time it takes to start the motor will tell you how many AH are gone. It's all just a SWAG of course, because there are so many variables here.

You could try some testing - you'll need to simulate the trigger signal for the ignition, but you should be able to run all the car electronics on the "bench" (plugs out of that expensive cossie) monitoring the supply voltage until you hear the thing start to hiccup. That would tell you how long everything can run without using the starter.

I'm almost of the opinion that there's something a little bit wrong somewhere. Does your start cart back-charge the SBS? If it does, they don't like that at all - either the SBS will get a large inrush from the jump battery or the jump battery will get charged from the SBS. I have the jump battery and the onboard battery isolated via the main switch. I start the car and get it warm from the jump battery, and then it's just two easy starts via the onboard to get to the grid and out on the track. If I have two crew members, one will pull the jump plug as the other turns the master switch - that works too.

The other suggestion is to add an alternator with an in-line current limiter to charge the SBS (no more than 2A I think). For a vintage car, that's really a trouble-free setup. The alternator on the Zetec cars is pretty slick.

[dereklola]

Rick

Appreciate all your ideas. I do use a jump battery to warm up and start, even on the false grid, and keep the on-board SBS isolated during that time - just switching over at the last minute. Last weekend I didn't have my usual crew and ended up having to crank on the SBS quite a bit at the start of the enduro race.

Maybe just a combination of events. I'll go through everything and try again next time. Never had these problems with my old Howard ignition - maybe I shouldn't have gone modern!

Thx again.

[stonebridge20]

Derek, I ran a Baker bettery I got from Coleman machine in my RT-1 with the Electramotive and started the car on the false grid every time without a jumper.. Never had ignition issues with the baker. We ran a sbs40 in Handshy's March when we did all the enduros and never had a problem. Either of those will do the trick. Bye the way.....The Baker is only $91 from Coleman!

Good luck, Mike Agnifilo

[Ray Grienke]

Another issue to consider is using the proper charger for gel cell batteries. Got several from Keith Averill and they solved some low voltage problems we were having.