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CA95 fried selenium rectifier

ballbearian

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Location
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Rode to Boonesboro, 12 miles, 60mph, no problem. Stopped, then nothing juice wise. Started with kick starter, made it home and a total battery drain.


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2 year old SLA 6volt would not charge up ( I haven't "pushed" it with the 2amp charger, only the 1amp). So, I did not put a meter between the ground strap and negative battery terminal to see if there was a short but I pulled the OEM rectifier and started to put in an ebay modern silicone one. These ebay rectifiers are not very robust, it seems. If it cooks too, then maybe a Vintage Honda Shop regulator/ rectifier as voltage is not specific in rectifiers AFAIK.

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New battery arrived, so will do short test at battery. If anyone has advice on a durable fix here, please chime in.
 
Did you mount it on a heat sink? Where is the ground wire? I've used those small square bridge rectifiers for years, they're normally pretty much bullet proof.
 
Did you mount it on a heat sink? Where is the ground wire? I've used those small square bridge rectifiers for years, they're normally pretty much bullet proof.


Mounting bolt is the ground on both the OEM and the replacement.

I've fried 2 of these small ones, one on a CT90 and yesterday one on a 305 Dream.
 
Rode to Boonesboro, 12 miles, 60mph, no problem. Stopped, then nothing juice wise. Started with kick starter, made it home and a total battery drain.


2 year old SLA 6volt would not charge up ( I haven't "pushed" it with the 2amp charger, only the 1amp). So, I did not put a meter between the ground strap and negative battery terminal to see if there was a short but I pulled the OEM rectifier and started to put in an ebay modern silicone one. These ebay rectifiers are not very robust, it seems. If it cooks too, then maybe a Vintage Honda Shop regulator/ rectifier as voltage is not specific in rectifiers AFAIK.


New battery arrived, so will do short test at battery. If anyone has advice on a durable fix here, please chime in.





That modern rectifier looks like the one I just bought from an EBay seller, yet mine has a fourth green ground terminal looped to the mounting bolt. Hopefully this isn't an issue in moving to a modern unit from the selenium original?



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That modern rectifier looks like the one I just bought from an EBay seller, yet mine has a fourth green ground terminal looped to the mounting bolt. Hopefully this isn't an issue in moving to a modern unit from the selenium original?


Same as mine essentially. On mine the guy went cheap and just bent that terminal so it is pinched to the mounting/gound bolt. I think the main problem is the bolt to bare frame was not optimal and the ground strap to battery terminal wasn't either. I'm going with the words of wisdom given here by Mike in Idaho and Steve (66Sprint) that sometimes the factory way needs help and that help is going to be a dedicated and redundant ground wire running from rectifier ground to battery negative. I had this problem before on a '76 CT90 that fried the rectifier (solder even seeped out) due to insufficient ground pathway through the frame back to battery negative on high beam. I should have learned my lesson then but thought I could get away with it because I think I'm that good at taking care of minor details like clean ground mounts and battery negative terminal connections. Yum, yum, humble pie.

Beware repainted frame or powder coated builders.

I'm giving this treatment to both bikes that had charging fails on the last two rides, '65 Dream and '63 Benly. Glad I got a new tube of dielectric grease too.
 
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Same as mine essentially. On mine the guy went cheap and just bent that terminal so it is pinched to the mounting/gound bolt. I think the main problem is the bolt to bare frame was not optimal and the ground strap to battery terminal wasn't either. I'm going with the words of wisdom given here by Mike in Idaho and Steve (66Sprint) that sometimes the factory way needs help and that help is going to be a dedicated and redundant ground wire running from rectifier ground to battery negative. I had this problem before on a '76 CT90 that fried the rectifier (solder even seeped out) due to insufficient ground pathway through the frame back to battery negative on high beam. I should have learned my lesson then but thought I could get away with it because I think I'm that good at taking care of minor details like clean ground mounts and battery negative terminal connections. Yum, yum, humble pie.

Beware repainted frame or powder coated builders.

I'm giving this treatment to both bikes that had charging fails on the last two rides, '65 Dream and '63 Benly. Glad I got a new tube of dielectric grease too.

Ok, As I will be paint the frame etc I will run a separate ground from the terminal mounting bolt directly to the battery ground. Thanks for the heads up on your issue.

The Ebay seller did offer a lifetime warranty on his part. I just can't find him on there anymore. ;)
 
Ok, As I will be paint the frame etc I will run a separate ground from the terminal mounting bolt directly to the battery ground. Thanks for the heads up on your issue.

The Ebay seller did offer a lifetime warranty on his part. I just can't find him on there anymore. ;)

I would still remove paint for any mount grounds shown in the wiring diagram as well as using an extra wire.

Braintarp is the ebay seller I've used, he has many configurations available but all the basic rectifiers have 4 terminals on the block, just depends the colors of wires and type of connectors and how many are wired. Like Jim said, " you can't have too many grounds, ever"
 
I would still remove paint for any mount grounds shown in the wiring diagram as well as using an extra wire.

Braintarp is the ebay seller I've used, he has many configurations available but all the basic rectifiers have 4 terminals on the block, just depends the colors of wires and type of connectors and how many are wired. Like Jim said, " you can't have too many grounds, ever"

Which combo regulator/rectifier did you choose for a replacement on your bikes? I have looked at the ones that are the Kohler clones on Amazon that are reasonably priced. There are the ones from a Honda place, possibly Bill Silvers website? The fellow I used was Chev58SS on EBay for the straight rectifier.

As you suggested in your other post I will be running the electronic ignition plus LED headlights and signals, so a stable 12+ volts would be desirable vs spiked voltage.
 
Which combo regulator/rectifier did you choose for a replacement on your bikes? I have looked at the ones that are the Kohler clones on Amazon that are reasonably priced. There are the ones from a Honda place, possibly Bill Silvers website? The fellow I used was Chev58SS on EBay for the straight rectifier.

As you suggested in your other post I will be running the electronic ignition plus LED headlights and signals, so a stable 12+ volts would be desirable vs spiked voltage.

We always recommend this one from Sparck Moto, Matthew (VHT member Sonreir) gives great support for all the stuff he sells at both Sparck Moto and Vintage Connections, all good quality stuff.
 
We always recommend this one from Sparck Moto, Matthew (VHT member Sonreir) gives great support for all the stuff he sells at both Sparck Moto and Vintage Connections, all good quality stuff.

Honestly, I had forgot/neglected to check them out. Thanks for the reminder because they have a bunch of stuff that I can use. They even have a 6volt rec/reg combo unit for the Benly CA95. They also have little LED accessory lights to integrate into the Dreams turn signal set up to keep Charles (and me) from forgetting to turn off the turn signals. Like the Mennonite community around these parts, we need to support our own. Heck, with our beards we even look like them. As long as we don't all ride black bikes, we shouldn't get mistaken.(y)
 
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Selenium senility is setting in, I'm afraid. These are going on a wind chime.

I'm gonna get Spark's 6 volt reg/rect combo and some of his DIY LED dash light pigtails for a home brew turn indicator for the Dreams (I'm tired of following space cadet Charles eternal turn signals). Charles is going to get his EI unit from Spark's.
 
Added to this older thread because I didn't finish the planned work but had to do it since I fried another rectifier. I had poor grounds on the lighting circuit and that did it. The new Sparcxmoto unit went in and because it's larger I just relocated it to the left side panel tool area. This time I ran a ground from the headlight, speedo housing too all the way back to the battery. I guess the flickering speedo light wasn't due to cheap LED bulbs but a bad ground.
3rd time the MightyMax AGM 6volt has been drained flat and it revived, and for about $20 ea., I'm impressed.

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All mine are 12v but I use a heat sink with those solid state rectifiers. What ever I have in my computer parts box.

The heat sink on this one is probably overkill but I use these on all my bikes without issue.
 

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All mine are 12v but I use a heat sink with those solid state rectifiers. Whatever I have in my computer parts box.

The heat sink on this one is probably overkill but I use these on all my bikes without issue.

The one that died was not on a heat sink but there really wasn't much room for that in the original location up inside the hollow body of this frame. One leg of it burnt that was attached to the lighting coil.
 
The one that died was not on a heat sink but there really wasn't much room for that in the original location up inside the hollow body of this frame. One leg of it burnt that was attached to the lighting coil.

Well there's no telling with those cheap rectifiers. Maybe I've just been lucky. You mentioned your 6v battery has been robust.
I have a 6v Motobatt in my XL250s that is going on 7 years old and has gone flat several times and has outlasted all the other 12v batteries in my other bikes.
 
Well there's no telling with those cheap rectifiers. Maybe I've just been lucky. You mentioned your 6v battery has been robust.
I have a 6v Motobatt in my XL250s that is going on 7 years old and has gone flat several times and has outlasted all the other 12v batteries in my other bikes.

6volts rock. Each cell is probably built more rugged, or at least is relatively larger, than a comparable 12 , thus lasting longer.
 
I found that Gel battery's (like Motobatt) in combination with the selenium rectifiers isn't a good combination. These battery's cannot stand the high voltages (at high RPM's) that the selenium rectifier is producing. This is due a too low internal resistance of the modern battery's. One leads to another, the battery goes down, and takes the rectifier with it. The best solution is to stay with the old fashioned lead-acid battery with refill openings when using the standard selenium rectifier.

The whole system without a voltage regulator is a balanced system, if out of balance, issue's will arise due to higher voltages then the battery can handle (no regulated voltage), with a predictable outcome. Not having a voltage regulator made it also necessary for Honda to design a complex day-night system with a different coil setup during the night. This way the system stays in balance depending on the load (illumination / resistance of battery).
 
I found that Gel battery's (like Motobatt) in combination with the selenium rectifiers isn't a good combination. These battery's cannot stand the high voltages (at high RPM's) that the selenium rectifier is producing. This is due a too low internal resistance of the modern battery's. One leads to another, the battery goes down, and takes the rectifier with it. The best solution is to stay with the old fashioned lead-acid battery with refill openings when using the standard selenium rectifier.

The whole system without a voltage regulator is a balanced system, if out of balance, issue's will arise due to higher voltages then the battery can handle (no regulated voltage), with a predictable outcome. Not having a voltage regulator made it also necessary for Honda to design a complex day-night system with a different coil setup during the night. This way the system stays in balance depending on the load (illumination / resistance of battery).


Right you are, Jensen. The smaller 6volt systems are very prone to these overcharging issues (the CT90 owners know this), blown headlamps from dead batteries are common. AGM batteries are not as capable of handling excessive higher voltages and will swell and fail. This can happen by extended hours of high rpm riding, and for this reason some who ride CT90's like that will use the acid fill batteries. Most selenium rectifiers have been replaced by the modern silicone type, which are more efficient and thus can contribute to the overcharging situation. A good lead acid battery is preferred for these folks.

That said, the CA95 presents it's own challenges due to the unique shape of the 6volt OEM lead acid battery, they are long and thin. They are also pretty expensive and do not last as long as the 6volt AGM batteries designed for mobility chairs and kids ride on toys and they are relatively inexpensive. I have yet to ruin one of these AGMs, even when I initially was still using the original selenium rectifier, although I did have some overcurrent damage at the negative battery connection due to an improvised smaller gauge wire and female spades used to attach to the male spade battery connections. I have now modified clamps directly to the male spade battery terminals and use the original bolt connections of the original wiring harness.

My recent silicone rectifier failure was due to poor ground return of the headlight and the small speedo illumination lamp, and no doubt made worse by the poor location and lack of heat sink. It was certainly grounded directly to the battery negative. The battery then discharged from the shorted rectifier, not the other way around.

Here is a pic showing the skinny long battery required for the CA95 and my modified connections to the battery spade connections, which are working quite well. I plan on temporarily mounting a voltage meter on the handlebars to monitor some real time and extended charging performance.


zQXBQg0.jpg




I need to update this pic showing the newer MightyMax brand of battery and my dual direct redundant grounding connections.
 
Here are our two runners before a 40 mile ride. A late '65 and my early 62. Everything went as it should with bright headlamps (stock 25/35watt incandescent) and taillamps. Next day voltage check was 6.41, just right.

The MightyMax ML12-6 (12Ah, 6volt) available on amazon is definitely the way to go for these CA95's, if one makes the battery terminal clamps.

DwVq6Jp.jpg
 
I'm a bit bemused by this. I understand Jensen's point about the 'balanced' system that Honda built, but that was surely a compromise / kludge, using the technology available at the time.

I've always thought that a modern sealed AGM battery, used in combination with a modern combined rectifier / regulator, along with fresh wire and connectors, was the ideal upgrade for these bikes. Set up so that full ( was headlight ) output from the stator being used all the time.

My three 175's are running like this without issues. In fact, the little 12v 5ah battery on the SL175 is coping fine being used with an electric starter, makes me think that the other two don't need their 12ah batteries with the modern kit, after all, my CB600 only has a 7ah battery to turn over a much larger engine ( and much higher output from the stator, 0.34kw at 5k rpm, whatever that means...)
 
My three 175's are running like this without issues. In fact, the little 12v 5ah battery on the SL175 is coping fine being used with an electric starter, makes me think that the other two don't need their 12ah batteries with the modern kit, after all, my CB600 only has a 7ah battery to turn over a much larger engine.

And when the bikes are in good tune they take so short a time on the starter to begin running, I can see why the 5 amp battery is adequate. In fact, before going on vacation last fall I wondered about my then nearly 6 year old lithium ion battery in the 450 possibly aging out and bought an AGM of the exact same size to take along as a spare just in case. Though it weighs at least a pound more than the lithium ion version, it could have been used in the same battery box I fabbed up for the bike and probably would have turned the starter motor had I chosen to keep the electric start. In hindsight I should have considered that, but then again maybe the AGM of that size might not have existed in late 2016 either.
 
I'm a bit bemused by this. I understand Jensen's point about the 'balanced' system that Honda built, but that was surely a compromise / kludge, using the technology available at the time.

I've always thought that a modern sealed AGM battery, used in combination with a modern combined rectifier / regulator, along with fresh wire and connectors, was the ideal upgrade for these bikes. Set up so that full ( was headlight ) output from the stator being used all the time.

My three 175's are running like this without issues. In fact, the little 12v 5ah battery on the SL175 is coping fine being used with an electric starter, makes me think that the other two don't need their 12ah batteries with the modern kit, after all, my CB600 only has a 7ah battery to turn over a much larger engine.

We must deal with availability issues and improvements to keep these old girls happy. Honda earned their good reputation back in the day.

I'll take your healthy 5ah over a neglected 12 any day.
 
Here are our two runners before a 40 mile ride. A late '65 and my early 62. Everything went as it should with bright headlamps (stock 25/35watt incandescent) and taillamps. Next day voltage check was 6.41, just right.

The MightyMax ML12-6 (12Ah, 6volt) available on amazon is definitely the way to go for these CA95's, if one makes the battery terminal clamps.

Tom,I like the photo taken against the wall with that classic sign Free Air (y)
 
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