Forum for discussion of MG and MGB motorsports, historic and current (SCCA, NASA, VARA, etc) car preparation, engine, bodywork, suspension, drivetrain modification.
Has anyone tried a motorcycle battery in their race car? Most motorcycle batteries are sealed AGM style (can be mounted at any angle) and are less than half the weight of a group 26 size battery and have up to 310 CCA. I still run an alternator (for enduros). Do you think this type of battery is adequate (starting/spark etc) and can handle being used in a circuit with a 55 amp alternator?
Don't try starting with a small battery. You might hook up a jumper port to start the car but if you spin and stall, you're toast. A gear reduction starter draws less current than the Lucas so that helps some. But there are gel batteries out there that are lighter and will work. You might also try a 62 series automotive battery - pretty small but 550 CCA. Basil
I always go the opposite direction, build the car light enough to use use hog, serious CCA battery like a Optima, nothing like having a battery that will actually crank your car :) it would also depend on whether you use a charging system in your race car or not, I don't, I fiquire it's one less thing to buy or break or rob hp, and my only fee for not having a charging system is hooking up the charger in between sessions. I know of one vintage B racer who has two failures because of a elaborate charging system, I just don't see the need for carrying extra stuff around that can break. Truth is wiith a fully charged Optima you could probably run all weekend on a full charge, but hooking up the trinkle charger is just part of my routine and simple enough to do.
Bill, HapX2. Your alternator weighs more than you'll save in battery weight. I ran a 1000 amp or so Orbital in my SCCA car. Mounted it as best I could for weight distribution. I had two batteries which I kept charged and changed them out Sun. AM after that days cold start. Knew that I was good to go. You could change out before the start of an enduro, should be good for 1 hour, maybe not three.
Nice to see your smiling face here.
FWIW, one of my customers ran the 3 hour HSR enduro at Sebring on a Optima and no alternator.
Obviously, lots of racers get by fine without an alternator. Probably MOST racers...
I'll play devil's advocate:
With an alternator you'll have ~13.1 volts feeding into your ignition system. Without alternator, best case is ~12.6 volts. Period. (Doesn't matter how big your Optima battery is.) However, ~12.0 volts at the ignition system seems more likely because of voltage drop in cables/connections. Don't forget the ground side of the circuit! Less voltage-in must result in less spark at the spark plug, right? How much less spark will surely depend on the ignition system. (Coil choice? MSD? etc.)
People pay a lot of money for trick ignition parts, but I'm starting to wonder if simply feeding basic ignition parts higher voltage might make sense. Someone should test this on a dyno, and determine if less spark under load and thus less horsepower really happen as input voltage drops.
The wheels are great. I squeezed on 205/55s. First with Avons (only because they spelled tyres the british way), now Kuhmo. I called Superlite directly in Australia yesterday to get another set of spline drive 14x6, they want 310(Aus. $) per wheel (285 US) but $450 Aus. for shipping. The wheel price was reasonable, but do you think that shipping rate was a little high?
William, one of the biggest problems we had with the Superlite spline adpaters is the spline were often broached off center and would not fit the hubs, it was a huge issue, we would get like 100 adpaters from them and maybe half of them were machined properly, we ended up going to the very people we use now to make the VTO wheel to make us adpaters that were properly made. The very last set of splined drive Superlite we sold were assembled by Superlite, sure enough the customer called us and told us two wheels would not fit on the splined hubs, luckily we had exaclty two adapters made by the third party to send him and correct the problem. If it were me, I would be leary of just ordering a set from Superlite, you are almost guranteed atleast one fo the adpater will be machine wrong, from what I understand a place in Australia, other than Superlite makes the adapters for them.
We and Superlite together came up with the idea of the splined drive wheel, Peter, then CEO of Superlite had the idea to put the adapter on the backside, I was given the chore to help the Superlite engineering department to fiquire hw the proper backspacing with the now adapter bolted to the backside, which took .400" of backspacing away, I fought and fought with these guys, they kept sending me prototypes they would not work, bottom line they had to make a new mold with a greater positieve offset to make up for the adpater, it was like pulling hens teeth with these guys to get the wheel right, it took well over a year to get this done.
We don't run an alternator in either of our cars. We both have the Hawker Odyssey PC 925 batteries, I think it was originally made for Yamaha Rhino Utility vehicles. No problems lasting for an entire enduro, just make sure you buy the Hawker battery charger, otherwise they do not get fully charged on conventional chargers.
Always good to see another racer on the site,
Stirling
About 6 years ago I was looking for a battery and because I'm a budget racer, aka cheap bastard, decided to see how little I could spend. So I went to the local Batteries+ and found something called a Werker sealed gel cell. It's only 31 ah it measures 6x8x5 so it takes up about 1/2 of an MGA battery tray. I run a low amp alternator (historic group requirement), oem lucas starter and have never had an issue. If your interested the part number is WKG12-31J. I think I paid about $30 for it.
FWIW
I forgot to mention that I run an Optima Red Top in my passenger floor board. I don't have a charging system either - or a passenger seat.
x2 with Dave, although my car is not balanced yet. Right now it is just lead bricks attached to the floor boards.
I have had good results using an U1 (BCI spec.) AGM wheel chair battery. There several manufacturers that make these batteries, including Panasonic. They have @ 320 CCA/34 amp hr.s and weigh @ 18-20 lbs. One of the best features is that it charges and discharges very reliably. They cost @ $75-$100. There is a battery recycling center in my area that sells reconditioned units for @ $20. All in all it has been an effective solution for my application.
Being a charter member of the "Budget Racers League" (AKA cheap basterds) I'm running a used Optima from a Civic one of our customers brought back to the store as "defective" ( he really had a bad alternator but that's another tale). As per procedure, the battery was offered for sale as "used" for $45.
That was 4 years ago. I'm still waiting for it to let me down :thumbsup:
I use an Odyssey PC 680MJT
PC 680MJT Specs:
* 680 cranking amps for 5 seconds
* 595 cranking amps for 10 seconds
* 525 cranking amps for 20 seconds
* Short circuit current over 1800A
* 17 amp hours
* 25 minute reserve capacity with 25amp load
* With metal jacket and automotive terminals
* Length 7 1/4"
* Width 3 1/8"
* Height 7 3/8" to top of terminal
* Weight 16 lbs
http://www.amazon.com/Odyssey-PC680MJT-Automotive-LTV-Battery/dp/B000XEF3DM
If I were going to forgo the charging system, I would use a 16 volt battery, especially with electronic ignition.
