Uploaded December 2022 | Updated September 2026, 2 weeks ago
In this video I take apart and repair an old heavy duty automotive battery charger that stopped working. If you own one of these older style chargers and it is not charging correctly, the problem is often simple to diagnose and fix. I will walk you step by step through the troubleshooting process, explain how the rectifier circuit works, and show how to replace failed diodes with a modern silicon bridge rectifier.
Older chargers like this can be very useful for starting cold cars or providing high current when newer lightweight chargers fall short. Along the way, I explain the principles of AC to DC conversion, the role of rectifiers, transformers, and ripple voltage, and why replacing outdated selenium rectifiers with silicon parts is a reliable upgrade.
By the end of this repair the charger is working perfectly again, delivering correct voltages and ready for real use. If you are interested in electronics repair, automotive tools, or just want to see how to bring vintage gear back to life, this detailed walkthrough will help.
Subscribe if you enjoy educational repair projects, vintage electronics, and hands-on demonstrations.
Chapters:
00:00 Introduction and problem overview
00:38 Should you fix an old charger or replace it
01:40 Why modern chargers differ from vintage units
02:40 Why I keep this 200 amp charger
03:40 Charger symptoms and first troubleshooting steps
04:30 Measuring output voltage and ripple
05:00 Diagnosing a failed rectifier diode
06:00 How a rectifier circuit works explained simply
07:00 Half wave vs full wave rectifier
08:00 Opening the charger to inspect components
08:45 Identifying the large transformer and control parts
09:20 Finding the old selenium rectifiers
09:50 Why replace with silicon rectifiers
10:30 Choosing a bridge rectifier module
11:00 Planning the wiring changes
11:40 Removing the thermal sensor and rectifiers
12:30 Preparing wires and connectors
14:00 Soldering and insulating connections
16:00 Mounting the new rectifier block
17:30 Adding thermal compound for heat management
19:30 Securing the rectifier in place
20:30 Final wiring connections completed
22:00 Trial fit and chassis mounting
24:00 Checking clearances and tightening connections
26:00 Applying thermal paste and finishing installation
28:30 Repair completed and reassembled
29:40 Powering on and voltage tests
30:40 Success: charger is fully functional again
31:20 Closing thoughts and invitation to subscribe
Production equipment I use or recommend:
barrywatson.com/recommended_equipment.html
Need a 12/24v smart battery charger?
Consider these units I use:
PCHH 12V 24V Car Battery Charger Heavy Duty, 0-15A Automatic
amzn.to/3SxDoIF (Nice build, and good display info)
YONHAN Battery Charger 10-Amp 12V and 24V Fully-Automatic
amzn.to/3OoSMoq (Works well and great value!)
Some electronic repair tools similar as used in this video:
Baomain Bridge Rectifier 200A 1600V Full Wave Diode Module
amzn.to/3UUgpJF
Fluke 107 Pocket Digital Multimeter
amzn.to/3jhddqI
Weller WP35 35-Watt Professional Soldering Iron
amzn.to/3htXSTb
60/40 Tin Lead Solder Wire with Rosin for Electrical Soldering
amzn.to/3BKBWd5
Weller WLACCBSH-02 Soldering Brass Sponge Tip Cleaner
amzn.to/3PCCFTF
Soldering Iron Holder Stand
amzn.to/3FCsNEO
High Performance Thermal Paste, Thermal Conductive Compound
amzn.to/3G2N1ZE
Klein Tools D202-6 Pliers, Diagonal Cutting Pliers
amzn.to/3G18sdu
IRWIN VISE-GRIP Wire Stripper
amzn.to/3jfs9oX
I suggest only purchasing products that you need or will help you achieve your goals.
I may receive a small referral commission if you purchase a linked product.
You still get the lowest price. There is no additional cost to you by using the provided links.
Thank you for supporting this channel.
In this video I take apart and repair an old heavy duty automotive battery charger that stopped working. If you own one of these older style chargers and it is not charging correctly, the problem is often simple to diagnose and fix. I will walk you step by step through the troubleshooting process, explain how the rectifier circuit works, and show how to replace failed diodes with a modern silicon bridge rectifier.
Older chargers like this can be very useful for starting cold cars or providing high current when newer lightweight chargers fall short. Along the way, I explain the principles of AC to DC conversion, the role of rectifiers, transformers, and ripple voltage, and why replacing outdated selenium rectifiers with silicon parts is a reliable upgrade.
By the end of this repair the charger is working perfectly again, delivering correct voltages and ready for real use. If you are interested in electronics repair, automotive tools, or just want to see how to bring vintage gear back to life, this detailed walkthrough will help.
Subscribe if you enjoy educational repair projects, vintage electronics, and hands-on demonstrations.
Chapters:
00:00 Introduction and problem overview
00:38 Should you fix an old charger or replace it
01:40 Why modern chargers differ from vintage units
02:40 Why I keep this 200 amp charger
03:40 Charger symptoms and first troubleshooting steps
04:30 Measuring output voltage and ripple
05:00 Diagnosing a failed rectifier diode
06:00 How a rectifier circuit works explained simply
07:00 Half wave vs full wave rectifier
08:00 Opening the charger to inspect components
08:45 Identifying the large transformer and control parts
09:20 Finding the old selenium rectifiers
09:50 Why replace with silicon rectifiers
10:30 Choosing a bridge rectifier module
11:00 Planning the wiring changes
11:40 Removing the thermal sensor and rectifiers
12:30 Preparing wires and connectors
14:00 Soldering and insulating connections
16:00 Mounting the new rectifier block
17:30 Adding thermal compound for heat management
19:30 Securing the rectifier in place
20:30 Final wiring connections completed
22:00 Trial fit and chassis mounting
24:00 Checking clearances and tightening connections
26:00 Applying thermal paste and finishing installation
28:30 Repair completed and reassembled
29:40 Powering on and voltage tests
30:40 Success: charger is fully functional again
31:20 Closing thoughts and invitation to subscribe
Production equipment I use or recommend:
barrywatson.com/recommended_equipment.html
Need a 12/24v smart battery charger?
Consider these units I use:
PCHH 12V 24V Car Battery Charger Heavy Duty, 0-15A Automatic
amzn.to/3SxDoIF (Nice build, and good display info)
YONHAN Battery Charger 10-Amp 12V and 24V Fully-Automatic
amzn.to/3OoSMoq (Works well and great value!)
Some electronic repair tools similar as used in this video:
Baomain Bridge Rectifier 200A 1600V Full Wave Diode Module
amzn.to/3UUgpJF
Fluke 107 Pocket Digital Multimeter
amzn.to/3jhddqI
Weller WP35 35-Watt Professional Soldering Iron
amzn.to/3htXSTb
60/40 Tin Lead Solder Wire with Rosin for Electrical Soldering
amzn.to/3BKBWd5
Weller WLACCBSH-02 Soldering Brass Sponge Tip Cleaner
amzn.to/3PCCFTF
Soldering Iron Holder Stand
amzn.to/3FCsNEO
High Performance Thermal Paste, Thermal Conductive Compound
amzn.to/3G2N1ZE
Klein Tools D202-6 Pliers, Diagonal Cutting Pliers
amzn.to/3G18sdu
IRWIN VISE-GRIP Wire Stripper
amzn.to/3jfs9oX
I suggest only purchasing products that you need or will help you achieve your goals.
I may receive a small referral commission if you purchase a linked product.
You still get the lowest price. There is no additional cost to you by using the provided links.
Thank you for supporting this channel.
