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Discussion Topic:
Two 6 volt batteries to increase cranking speed
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supereal |
07-14-2010 @ 8:42 AM
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Senior
Posts: 6819
Joined: Oct 2009
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We make up our cables from the stranded type used in welding equipment. Major vendors, such as C&G has them. Look at pages 136 and 137 in their online catalog at www.cgfordparts.com From your information, it appears that you are losing power between the battery and the starter somewhere in the circuit. Place a voltmeter across each leg of the system as you crank the starter. The reading will tell you the loss in that part of the circuit. In a 6 volt system, it doesn't take much resistance to lose most of the power. It is kind of like trying to water your garden with a hose full of holes. Six volt starters will run on 12 volts, but if cranking is prolonged, it is likely you will burn it up. We run a separate ground cable from the grounding point of the strap to one of the starter mounting bolts. A 12 volt cable with eyes on each end will do the job because it isn't rare for the connection between the face of the starter and the clutch housing to be poor, and the extra cable makes up the difference.
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36 Ford |
07-14-2010 @ 5:50 AM
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Member
Posts: 6
Joined: Jul 2010
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the problem is hot and cold. it turns but just too slow to start. I put all new cables on the truck as it is a full restoration. The cables are thick with the end sodered in connectors. it is a positive ground system so the positive cable is grounded to a nice bare spot on frame. I did run the negative connection thru a 300 amp disconnect switch. then back to starter. i have two starters, a stock from 36 which still works 6volt and i have a rebuilt 6 volt. my local starter company tells me the starters will work on 6 or 12 volts, the only disclaimer is 12 volts will where it out it if on it too long. thats why i say if i isolate system (not to fry the coil or gen) and I put 12 volt to starter direct it cranks really fast and starts no problem was even thinking about installing another tray with a 12 v battery connected directly to starter and floor switch. and just trickel charge that...and let 6 volt run system and make all those connections together. but again they did this in 36 so i would think i could make it work today. can you recommmend a battery cable size? thanks
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supereal |
07-13-2010 @ 9:00 PM
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Senior
Posts: 6819
Joined: Oct 2009
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Is your slow cranking both hot and cold? If hot only, the engine was likely set up too tight. Modern clearances will cause the problem. Are you sure your starter is actually for six volts? Six and 12 volt starters look the same. An Optima in good condition should turn over any engine with the high CCA power. Be sure the engine is grounded with a strong strap, and your battery cables are actually for 6 volts. Many sold today have thick insulation and 12 volt conductors.
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36 Ford |
07-13-2010 @ 5:58 PM
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Member
Posts: 6
Joined: Jul 2010
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ok just rebuilt flathead v8 and having a problem cranking the monster, With one 6 volt optima it cranks just enough to barely start it and other times to slow so it won't. This battery cranks out at 800 CA. was thinking about adding another in parrell, so system will still be 6 volt but can draw from another 800 CA battery. when I isolate system and put 12 volts to it, boy it spins like no ones business, starts everytime and really cranks anyone have any experience in this area or go this route.
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