Rectifier Diode Heatsink - Page 1
Forum section: electronics / beginners

author: metrologist
author_rank: Super Contributor
timestamp: March 18, 2025, 04:16:06 am
content: I bought some 6A10, 10A10, 20A10 R-6 diodes mostly to repair some old battery chargers. Does this style require heatsinking? I haven't seen any in my searches.Also Amazon. It took a few orders before they got delivered. Probably counterfeit, so I want to test them. The easiest way I can think of is just hooking it to a CC power supply (the popular DC-DC converter type). I suppose that will make my supply sweat.

author: Konkedout
author_rank: Frequent Contributor
timestamp: March 18, 2025, 05:47:37 am
content: Link to some datasheets? That takes some detective work for us, without even being sure of the manufacturer. I was just digging through some old diode samples. There are manufacturers whom many of us have probably never heard of. EDI, EDAL, Taitron, Collmer, Central for example. I have quite the bag of Motorola (or maybe ON Semi) MUR410s which are not so useful these days.If you look at the datasheets, those will usually specify how the diode is to be cooled in order to get the rated current capability. Often that is a test condition which is difficult to apply in a real design.How much current will you be flowing through the diodes?Axial diodes are frequently specified to be soldered to a significant copper land area for adequate heat sinking at rated current. Stud mounted diodes as well as TO220 etc also need to be heat sunk to get close to the ratings. But I would not normally recommend running at much over 50%, unless you are being very careful about it.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: March 18, 2025, 05:58:07 am
content: If you run a high current test (e.g., 10A+), your CC power supply might struggle if it isn’t rated high enough. Most DC-DC converters (like buck modules) will heat up if they push their max-rated current for too long. Consider using a bench power supply with proper cooling or a large heatsink on your DC-DC module.

author: metrologist
author_rank: Super Contributor
timestamp: March 18, 2025, 04:18:10 pm
content: It's one of those RuiDeng converters, the 5015 model with heatsink and fan, and a 36V10A switch supply. I can't really stress the 20A diode, but the 6 and 10...But the DC-DC converter will be converting 36V down to around a volt or less at high current. I think that's bad for the converter.

author: Konkedout
author_rank: Frequent Contributor
timestamp: March 18, 2025, 04:33:02 pm
content: YOU SAID "It's one of those RuiDeng converters"I have been designing power supplies since 1980. I have no idea what you are talking about. You might as well have said "Barthwarp Defabrilator."Other posters provide a link or a datasheet even when it is less necessary. If you want help, I think you ought to provide a link or a datasheet. Be as specific as possible.

author: madires
author_rank: Super Contributor
timestamp: March 18, 2025, 04:43:25 pm
content: Diode Heatsink Design: Best Practices for Thermal Management

author: metrologist
author_rank: Super Contributor
timestamp: March 19, 2025, 07:33:49 pm
content: Quote from: Konkedout on March 18, 2025, 04:33:02 pmI didn't think I'd find one but it was easy using google...This is the exact model:https://www.gotronic.fr/pj2-14966---dps5015-1959.pdf

author: metrologist
author_rank: Super Contributor
timestamp: March 19, 2025, 07:44:12 pm
content: Quote from: madires on March 18, 2025, 04:43:25 pmIt's the round axial ones, like these:https://www.amazon.com/MCIGICM-Rectifier-Electronic-Silicon-Diodes/dp/B07Q7YNZZFI've never seen a heatsink for/on them. In particular, the 20A one is the same size as the 6A one. 20A seems like a lot, but then I guess it's only dissipating 20W, so maybe they're designed to not need a heatsink.

author: madires
author_rank: Super Contributor
timestamp: March 19, 2025, 08:04:37 pm
content: You can also calculate how much power dissipation the diode can handle in a specific environment without a heatsink before blowing up. If the diode can't handle the required power dissipation consider forced ventilation or a different diode which can be easily mounted on a heatsink.

author: metrologist
author_rank: Super Contributor
timestamp: March 19, 2025, 10:47:37 pm
content: Quote from: madires on March 19, 2025, 08:04:37 pmYou have too much faith in me. What specs do I use? There's a thermal resistance spec of 10 deg C./W and operating temp 150C max, so does that mean it can dissipate max of 15W, or to whatever degrees over ambient? There is a temperature derating curve.https://www.mdddiodes.com/wp-content/uploads/2022/08/R610A10000AA0A.pdfI'm not sure what to be considering because 12V 20A seems different than 400V 20AI suspect the old Sears battery charger uses an axial diode just like I have floating in the air.The 6 amp uses selenium rectifier diodes which I've heard degrade.