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  #11  
Old 01-29-2020, 10:32 PM
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RED caddy RED caddy is offline
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There was a couple in my old MSC paper catalog, other than those, I find 'em in yard sales and auctions. I use an old commercial schneider for electric rust removal and jump starting big diesel's (200 amp starter boost) Brought many a "ruint" battery back to life.

I ain't smart enough to re wire and such, so I take good care of what I have.
Leaving them out in the rain is as good as letting out the magic smoke...

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  #12  
Old 02-03-2020, 06:16 AM
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The really practical problem with a smart charger is that most of them will not identify and charge a battery with a voltage below 7 or so volts. I've rescued many a battery from the junk yard with an old analog charger that doesn't care.
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  #13  
Old 02-03-2020, 12:12 PM
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That can be an issue but batteries that discharged are usually pretty much done for the job they were meant to do.
Remember that the original simple chargers had selenium rectifiers these have a built in resistance which acts like a current limit er and allows the simple charger to charge dead batteries. you knew when they faied it smells like rotten eggs.
I am not sure that you can even buy them today.
Silicon rectifiers have almost no current limiting built in so the simple design noes not work and needs to be changed to deal with this evolving to the smart charger.
If you start with 100 batteries and dumb chargers then add up replacement cost over say 10 years you will get a cost per year for batteries.
Run a parallel set of batteries under the same conditions using smart chargers and compare the yearly battery cost.

All I do in that situation is set up the charger on the dead battery then jump a good battery to it for a second or so the terminal voltage comes up and charging starts.

This is like all such discussions about how the old way was better..
remember 6 volt batteries .
generators
vacuum windshield wipers
starter switches on the floor
suicide doors.
using your arm for signaling
non syncro manual transmissions.
These were all state of the art back then.
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  #14  
Old 02-03-2020, 12:33 PM
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What's wrong with 6 volt systems? Heck, even computers these days use a mix of 12v and 5v supply, it can't be that bad.

I know the old Ford tractor I had was 6 volt, used to average about 8-10 years out of a battery. It was tough for a while to find chargers that would top it up if needed though, so made sure I looked after the one charger I had that would do 6 or 12 volt batteries.
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  #15  
Old 02-03-2020, 03:21 PM
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Quote:
Originally Posted by greywynd View Post
What's wrong with 6 volt systems? Heck, even computers these days use a mix of 12v and 5v supply, it can't be that bad.



I know the old Ford tractor I had was 6 volt, used to average about 8-10 years out of a battery. It was tough for a while to find chargers that would top it up if needed though, so made sure I looked after the one charger I had that would do 6 or 12 volt batteries.


One thing nice about the old 6 volt systems was when you put a 12v battery, it really turned the motor over great so started easier. My dad wrapped about 10’ of heavy wire around a broom stick to help dampen the starting. Thinking about it now, probably would have been better using a lighter gauge wire and allow the heat in the wire slow it down. I can’t ever recall burning up the starter though. Put a Delco 40 amp single wire alternator on it for charging.


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  #16  
Old 02-04-2020, 05:11 PM
nelstomlinson nelstomlinson is offline
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I've been rereading my old text books. I think I can build a rectifier using SCRs which will also regulate output voltage. I can switch in different Zener diodes to let me select different output voltages, and I could even put in a series resistor to make a little heat and drop voltage when the current gets too high.

I'd probably want to drop about 2 volts with that series resistor at 50A, so 4 0.01Ohm resistors in series would do that, and each would dissipate 50^2*0.01=25W. 50W resistors are pretty cheap on fleabay.

This might work.
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