Cold Cranking Amps oddity

Gallery, Projects and General > How do I??

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awemawson:
Steve, some years ago I had a little 'works truck' that had a 24v bank of fork lift cells under the load space as the power source. When I got it the cells were fairly sulphated, and although improved by a few charge / discharge cycles were in a bad way. I drained and replaced the H2SO4 having done as you suggested and rinsed what would come from the bottom. I bought a little device that self powered off the battery shocked it at intervals with a high voltage high energy pulse. Nowadays this same technique is employed in 'battery maintainers' that you can buy for laying up cars.

After a week of this treatment I got the batteries back to 95% of their rated capacity. I made a dummy load from a length of heavy galvanised fence wire wrapped around a bit of asbestos flue, and tuned to the correct resistance for a 10 hour discharge - even rigged up a chart recorder to plot the voltage under discharge. An entirely satisfactory result. Used the truck for many years and it held charge and worked fine.

I still have the little 'shocker box' awaiting repair. I stupidly put it across a battery with wrong polarity and it wasn't much amused :lol:

Pete W.:
Hi there, Andrew and Stuart.

Andrew, maybe if you canvas a few airlines, you'll find one that'll do you a swap for a nice Lithium Ion battery! :lol: :lol: :lol:

Stuart, the 1.5 volt cell (U2 to oldies like me, aliter D-size) ought still to be available. I think you were referring to the 15 volt battery that's used on the high Ohms range. I did manage to buy one a couple of years ago. Also, there used to be a mini DC-to-DC converter (from a third-party supplier) that tapped off the 1.5 volt cell and produced the necessary 15 volts. I haven't seen any reference to those for decades. It was never very clear to me how you switched the converter on and off - maybe some modification to the AVO wiring was required.

I bought my AVO 8 Mk 2 for £32 10s 0d from Watts' Radio in the Apple Market, Kingston upon Thames, still got the receipt somewhere!

awemawson:

--- Quote from: hermetic on June 07, 2014, 08:42:57 AM --- I know what you mean about tractor batteries, I recently bought a new one for my Fordson diesel major. I leave it with a cheapo Lidl anti frost maintaining charger on it, and it is kept in a nice warm shed, covered with all sorts of junk to keep it warm, and almost never used, but the day is coming...........................
Phil

--- End quote ---

The Diesel Major is usually a very good starter. One trick is a rope wrapped around the flat belt side pulley (if you have one) and just pull start it like a lawn mower! Just make sure it's out of gear or you may not get to do it twice. Mine was happy with an old battery out of my Landrover - and it didn't even have a charging set up. The generator was fitted but not wired up. Just put it on charge every few months.

lordedmond:
Pete

Yes that's the one real odd voltage weren't they

The old D type :doh:

I still have it for but it's not used

I now use a fluke for the bits I do now

But that mk 8 was the job for tuning rf circuits for a dip and peak digital do dahs do not cut it

Anyway let's not take Andrews thread OT

Stuart

dsquire:
Andrew

When I lived in Northern Ontario winter temperature dropped way below 0. When the temp was at the extreme we would turn the headlights on for a minute before trying to start the car. Now turn the light off and wait another minute then hit the starter. If the car isn't running in 30 seconds then you are probably going to need a boost to get started.

When you initially discharged the battery this would cause heat. Now that the battery is warmed up you will get a higher reading and more cold cranking power. :D :D

Cheers :beer:

Don

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