Huge 1500w to 6000w starter-battery eliminators?

Discussion in 'The Projects Forum' started by DMahalko, May 21, 2011.

  1. DMahalko

    Thread Starter AAC Fanatic!

    Oct 5, 2008
    This is a project originating from annoyance. I have a friend who has a lot of engine-driven equipment with lead-acid starting batteries. Farm tractors, lawn mowers, loaders, trucks, you name it.

    The problem is, the stuff doesn't get used all that often, so more often than not, the lead acid battery is dead, corroded and just plain shot, plus it sat outside and froze in the dead state which wrecked it, and they have to go fork out money for yet more new batteries.

    I suppose everything could be outfitted with float chargers, but I am looking around to see if there are any other options. One possibility is to just get rid of the lead acid batteries completely, and use a power supply possibly coupled with some supercapacitors for starter current buffering.

    So for that big diesel loader with 400A worth of starter batteries, yank them out, and stick in a switching power supply with a couple farads worth of supercapacitors. To start the huge diesel engine, plug in a 250v power cord to heat the glow plugs and kick it off, then unplug when it is running.

    When the machine isn't needed, the switching supply and supercaps won't degrade and have to be replaced if the machine isn't run for another year or so, sitting dead and frozen to -40C in the winter.

    Though, insanely huge switching power supplies over 1500 watts appear to be "uncommon" to say the least.

    I am thinking that probably the way to go would be to use hot-pluggable server power supplies which are already designed to be compact, and use a bunch of them in parallel feeding a common fused power bus.

    If each supply is rated for 1500 watts separately, then combine four of them to start the big diesel loader, with them all drawing from a common 220v power source with 30A of capacity.

    With used/obsolete server power supplies it should be possible to build a fairly compact "battery eliminator" that can easily fit within the battery box of the existing equipment and can stay installed permanently.


    This could add security to job sites if all big equipment is outfitted this way, and a large portable generator and power cord is left in the back of the company pickup truck for starting equipment in the morning. Without that power source, the equipment is stone dead at night, and very difficult to steal even if keyswitches are replaced with simple starter buttons.

    And... no more lead-acid batteries to replace or maintain.

    - Dale Mahalko
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    OR just put some solar panel 'trickle chargers' on the units to maintain the batteries while the equipment is not being used.
  3. someonesdad

    Senior Member

    Jul 7, 2009
    Do the numbers -- they don't make sense. Let's say you have to crank at 400 A for five seconds to get something started -- that's 2000 coul. Suppose you have a capacitor of 10 F. At 15 volts, that means you've got 150 coul -- more than an order of magnitude short. And, don't forget, the voltage drops as you pull charge off the capacitor, so even if you could get a 100 F capacitor, you've also got to have some heavy duty voltage regulation.

    Trickle chargers make a whole lot more sense, both work-wise and economically.
  4. K7GUH


    Jan 28, 2011
    You can buy a lot of float chargers for $200.00. Let's see you come up with a 1500 watt battery eliminator for anywhere near that little. In any case, a fleet of equipment like that requires routine checking and maintenance, such as starting the engine once a month and keeping the batteries from freezing. If that's too much trouble, then replace the batteries once a year and pay for engine overhauls more often than would be required by a program of proper maintenance. TANSTAAFL.
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    Remove the batteries when not in use and store them indoors.

    Re-install when needed.
  6. Adjuster

    Late Member

    Dec 26, 2010
    Anyone using a tractor, lawn mower etc. would be in a difficult situation if the engine stalled away from base, with no battery available for re-starting. Some smaller machines might be equipped with manual cranking arrangements, but for the bigger ones it would mean fetching a generator or a battery, or towing the stranded machine back to the starting generator.

    I would think the resulting delays would end up leading to reduced productivity, as well as causing a lot of unnecessary grief to whoever had to use the system.