changing rectifier in battery charger

[Norm]

anyone to help me on this one ?

which one do I use ? and Which connections?
the original 4 is /was fastened to a  heat sink
5x2 inch aluminum plate at the back of the charger
I would like to use 3 as it would be a simple matter
to put the tabs of the red wires to the ~ of the rectifier
and bolt it to the heat sink ....do I really need the goop
between the heat sink and the rectifier ?
Now there is a disconnect tab on the heat sink that
goes directly to the positive clamp
the negative clamp goes thru a circuit breaker ammeter
and to the secondary of the transformer
now where do I connect the + and - of the rectifier ?
thanks for any help ......
Norm.
 

[Watt]

Norm, what charge amperage rating is the battery charger you got there?

That white stuff increased the thermal conductivity between the device and the heat sink.   

Are there any numbers on the components you have displayed numbered 1 to 4?

[tomw]

Norm;

So this charger has an on / off switch and a voltage select switch on the left side?

I think that black part with 2 connections you point to is a half wave rectifier and has a connection to the back plate which is the DC + ?

Without labels on the parts it is tough to be certain what is going on.

Tom

[Norm]

Norm;

So this charger has an on / off switch and a voltage select switch on the left side?

I think that black part with 2 connections you point to is a half wave rectifier and has a connection to the back plate which is the DC + ?

Without labels on the parts it is tough to be certain what is going on.

Tom

well for starters I hooked up 3, the 2 red wires to the ~s and the - and the + directly to the charge clamps
and clamped them to the terminals of the 75 amp/hr battery which was reading12.6 open voltage on the charger was 22 position switch was set for 2 amp .
 the voltage on the battery went up to 16,8 in about 20 seconds and the rectifier got too hot to touch
and started smelling just a trifle so I quickly pulled the plug voltage dropped on the battery and 3min later had dropped back  to original.

So I guess like you did the original is a half wave rectifier.
looked up the price and parts list rectifier and plate assembly ......
sorry but this part is no longer available
price for a whole new charger is $42    Sears......blah !

those diodes look similar to button diodes on alternators
so back to working on my battery holders and shelving this for now .
norm

[Bub73]

Norm;

 Don't use the negative on the bridge, just the positive wire to the + on the bridge and the two AC low voltage leads to the bridge ~ AC then put the negative wire back the way it was.
 This should give you half wave rectification with no connection to the bridge - minus.
 In full wave like you first had it the voltage was probably in excess of 24 volts DC .
Check the output at the cable clamps with your volt meter before hooking to a battery, if its much in excess of 15 volts don't use it, your #3 may have been damaged.

Hope this helps....
Bob

[tomw]

Norm;

 Don't use the negative on the bridge, just the positive wire to the + on the bridge and the two AC low voltage leads to the bridge ~ AC then put the negative wire back the way it was.
 This should give you half wave rectification with no connection to the bridge - minus.
 In full wave like you first had it the voltage was probably in excess of 24 volts DC .
Check the output at the cable clamps with your volt meter before hooking to a battery, if its much in excess of 15 volts don't use it, your #3 may have been damaged.

Hope this helps....
Bob

What Bob sed.

Tom

[rossw]

That white stuff increased the thermal conductivity between the device and the heat sink.   

Heatsink compound is an interesting thing.
It's better than air... but not as good as metal.
The perfect amount is just enough to completely eliminate any air spaces, but NOT to add goo between the metal surfaces.

What that means is: little more than a thin smear. Don't put it on like peanut butter, it'll be worse than not being there at all!

[Norm]

ok I found that the one rectifier works .....but no heatsink compound
and I can't find the heatsink right now anyways (so what else is new ...huh ?)
but I did hook it up and open voltage is like 9.6 on 10 amp setting .....why does the voltage go up to
13.5 when hooked to battery sla that reads 12.5 open voltage ?
or about 11 when hooked to an unloaded Amtek with 3.5 amp draw ?
Norm.

[Norm]

this when hooked up as a half-wave rectifier.
got warm pretty quick to a battery almost too hot to touch in about 10 seconds so enough until I get some heatsink compound.
Norm.

[ghurd]

Hey Norm.
You sure you don't have a couple little packets of heat sink compound?
Seems like something that would have ended up in an envelope I sent.
Stuff is expensive from RatShak.  If you don't find any laying around, let me know.
G-

[Norm]

No I'm pretty sure and yes I imagine the stuff is pretty expensive
when all I ever will need maybe in my life time is just a smear ...Huh ?
Things are goin great here but I could use a space like a built in front porch
....some plastic wrapped around and a table and a little 1000watt heater
Don't imagine you still had time to devote your full attention to PVC battery holders
but you probably realize the potential of their use ?
I use them everyday here.....like when I pedal charge 2 12 volt tubes in parallel
Since once you unhook from the doc Watson meter you lose all the data
I just unhook one at a time then hook another battery in parallel before I unhook the standby again.
and I was collecting enough that I had part of a kilowatt !took me 2 hrs. for it to register 0.04KWH !!
but that's not too bad the way I pedal If on a bicycle a person walking 3 1/2 MPH could keep up with me .
So at that rate ...about 10 weeks of 20 watt/hrs a day .
  I'm thinking of making a tester to simulate what it would be like to have those blades I have on a Amtek.
take a 20 " bike wheel .....drive it with a pulley in front and then the bike wheel turns a larger pulley
on the Ametek about a fifth of the speed of the motor or whatever it takes to put out like 14 volts
or 20 if charging a 18 volt battery .
So send a sample of that compound please ?
Thanks so much Glen....
Havin a lot of fun charging some batteries to replace in about 5 of Watt's cordless drill paks....about 5 of them.
I've learned a lot about charging batteries for these since a few years ago .....always learning....
BTW how'd the experiment go with those standby batteries for the solar lighting turn out ?
Norm.

[tomw]

Norm;

You can power the Doc with a separate battery to the one red lead and the ground, too.

Just saying.

Tom