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thingstodo · 04-08-2012, 02:27 AM

As usual, I don't appear to see the forest for the trees. I'm searching for a power supply to run on the bench ... to simulate a 'battery pack' that I already HAVE. My lovely wife ... to the rescue yet again ... after patiently listening to me describe the problems with the 24V power supply, asked me why I wasn't using that 'pack' of batteries in the garage.

- These are a set of 60 old gel-cells (12 'shelves' of 5 batteries each) from an Un-interruptible power supply at work. The batteries failed the automatic battery test about 3 years ago and could not last for the 20 minute minimum required, so they were to be sent to the battery recycler. I intercepted them and said I could use them for a few projects before they eventually made it to the recycler.

My wife continued - 'If you're not going to use them, can we get rid of them?' ... Hmmmm ... They don't have the capacity (7.2 A-h each when new) to use in the truck, but they should be fine for testing. Of the original 60 cells, only 40 will still hold a charge ... the rest DID make it to the recycler. I'm not a battery guy, so if the battery charger I'm using stops charging and goes into 'float', then the battery is likely OK in my books. If the battery charger never 'finishes', the battery goes to the recycler.

Two 12V gel-cells in series is 25.2V - and should work well for supplying the grinder with enough current to drive the encoder. On the plus side, I have incentive to add PLC control of the contactors. In fact, I can go through the pre-charge cycle, activate the contactor to bypass the pre-charge resistor, measure the current going into the grinder (that will require the fabrication of a shunt resistor ...) measure the voltage of the 'battery pack', and the PLC output will 'run down' the batteries in a realistic way. GREAT IDEA!

I still need a 24V battery charger to charge these batteries back up, but they should only need charging once or twice a day. (I could use two 12V chargers if I have to since the batteries are not matched, right?) I have a bunch of the batteries, so I could likely just switch batteries when I'm testing and do the charging offline. I only seem to work on this for an hour at a time anyway.

Well, that's it for today.

04-08-2012, 02:27 AM	#89 (permalink)
thingstodo Master EcoModder Join Date: Sep 2010 Location: Saskatoon, canada Posts: 1,488 Ford Prefect - '18 Ford F150 XLT XTR Tess - '22 Tesla Y LR Thanks: 749 Thanked 565 Times in 447 Posts	The new Simulated Truck Motor - part 3 As usual, I don't appear to see the forest for the trees. I'm searching for a power supply to run on the bench ... to simulate a 'battery pack' that I already HAVE. My lovely wife ... to the rescue yet again ... after patiently listening to me describe the problems with the 24V power supply, asked me why I wasn't using that 'pack' of batteries in the garage. - These are a set of 60 old gel-cells (12 'shelves' of 5 batteries each) from an Un-interruptible power supply at work. The batteries failed the automatic battery test about 3 years ago and could not last for the 20 minute minimum required, so they were to be sent to the battery recycler. I intercepted them and said I could use them for a few projects before they eventually made it to the recycler. My wife continued - 'If you're not going to use them, can we get rid of them?' ... Hmmmm ... They don't have the capacity (7.2 A-h each when new) to use in the truck, but they should be fine for testing. Of the original 60 cells, only 40 will still hold a charge ... the rest DID make it to the recycler. I'm not a battery guy, so if the battery charger I'm using stops charging and goes into 'float', then the battery is likely OK in my books. If the battery charger never 'finishes', the battery goes to the recycler. Two 12V gel-cells in series is 25.2V - and should work well for supplying the grinder with enough current to drive the encoder. On the plus side, I have incentive to add PLC control of the contactors. In fact, I can go through the pre-charge cycle, activate the contactor to bypass the pre-charge resistor, measure the current going into the grinder (that will require the fabrication of a shunt resistor ...) measure the voltage of the 'battery pack', and the PLC output will 'run down' the batteries in a realistic way. GREAT IDEA! I still need a 24V battery charger to charge these batteries back up, but they should only need charging once or twice a day. (I could use two 12V chargers if I have to since the batteries are not matched, right?) I have a bunch of the batteries, so I could likely just switch batteries when I'm testing and do the charging offline. I only seem to work on this for an hour at a time anyway. Well, that's it for today.