Help with smoothing DC power supply

spec said:

and I think a 30A rectifier is big.

any pics?

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bountyhunter said:

Actually, 30A rectifiers are plentiful.

https://www.westfloridacomponents.com/DI055/MBR2545CT+30A+30+Amp+45V+Schottky+Diode+Rectifier.html

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bountyhunter said:

The problem is, with so much power dissipated, the TO-220 package isn't practical. It has to be the metal type which are pricey and a pain to mount. I don't have my Motorola data books anymore or I would look up some.

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bountyhunter said:

I always liked the TO-220 as long as the power dissipation wasn't more than maybe 15W. It was convenient because I could just solder the tab down to the copper PCB and get a pretty good thermal connect.

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Tony Stewart said:

This thread could have been answered in one answer, if you provided the much needed current measurements or expected ratings for battery, motor and charger for average and max.

My guess is the charger barely just keeps up to idle motor motor/gear load current with moderate use. I suspect the peak/average load current may be 20x bigger, but then my best guess of duty cycle of a clay pigeon motor is 2% so the overall demand might be 20*0.02 or 40% more .. thus doubling your battery capacity or charger current may be two workable solutions.

The choice is limited by your lack of given constraints for cost or availability of free solutions.

Commercial solutions would consider battery chemistry, electrolytics and pulse current rates for optimal stability and lifetime. The charger ought to be capable of supplying most of the peak current to reduce the aging of battery, while the battery smoothens the voltage. But this is a tradeoff between short term economy and long term reliability.

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• In addition to adequate bulk charger, the Battery brand/model, condition, environmental temp. and preventive maintenance also affects results to make battery trouble free.
• In general for CCA to match surge load of car starters, the ESR of the battery must be <25% of starter winding resistance to cause < 5V drop from 12.5 to 7.5V where CCA is measured at 0'C
• Your motor DCR and battery ESR are also important. SoC of the battery also causes ESR to rise sharply so draining a battery under heavy load, increases heat rise in cells and aging effects.
• Thus a cheap galvo battery meter with zener or LDO to give a battery SoC meter from 11 to 15V would be a good idea. Where 14V is suggested with 14.2 max for float charge and 12.5V for 100% SoC after small load without charger , 12V for 50% SoC and 11.5V for <10% SoC .
• So using a 50uA analog meter with 11V zener is in series with small ammeter using 20k Ohms/V to Vbat or similar can be useful to monitor battery voltage. or an automotive ammeter...
• Keeping the battery beween 12V ( 50%SoC) and 14V ( float charge voltage) and average battery current low will permit the lead acid car battery to last 5~10yrs. Otherwise much less.

spec said:

I meant pics of your equipment and I misinterpreted the term hokey puck. I imagined you were a hockey buff, especially because of your avatar, and had built some sort of machine for propelling hockey pucks, at a goal for example, for practice. I was thinking that the puck would be going at some speed with all that power.

spec

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tcmtech said:

Not sure how you associated my avatar with hockey? It's the Joker from the animated series 'The Batman' from a number of years ago.

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