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Re: [EVDL] Modified K&W BC-20 questions (primary input leads)

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Re: [EVDL] Modified K&W BC-20 questions (primary input leads)


I agree with Roland about the loose connections on the
terminal strip being the cause for the burns.

>From the photos it looks like the transformer does not
have a screw-down type terminal, but s spade-terminal
strip with push-in contacts adjacent to the spade connectors.

Most often after several years the spade (also called Fast-on)
lose their spring force and start to lose contact, OR they
corrode, get a bad contact resistance and then lose the
spring due to over-heating.
Loss of spring means loss of contact, which will cause heat
and burn it up in short order.

When you remove the wires you will be able to see how they
connect and make sure they are clean and tight, then this
part of the problem should be solved.

Now if the BC-20 survived the interrupting primary input
and if that is the reason the breaker blew, that is to be
seen as soon as you get the wires back on.


Cor van de Water
Systems Architect
Proxim Wireless Corporation
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Second Life:

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Roland Wiench
Sent: Thursday, October 04, 2007 11:32 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Modified K&W BC-20 questions (primary input leads)

When wire connections are burn like this, this is normally cause by a loose connections and/or the terminals were connected up with out cleaning the a dull tarnish surface that may be on the transformers connections which causes a higher resistance.

It is best to use a torque wrench on these type of connections. Normally a
1/2 grade 5 bolt takes 50 ftlbs, a 3/8 at 35 ftlbs and a 5/16 at about 25 ftlbs if it's a straight through bolt with a nut. If it's a set screw type of terminal, then your manual should tell you want the torque should be.

If this terminals are a solder on connection or the connection was compress incorrectly by using only one point type crimp, then I would cut off these terminal lugs and have new heavy duty tin plated copper terminal lugs crimp on.

NAPA auto stores sell very heavy duty spec grade un-insulated wire terminals that they keep in the back shelf's. I got 100 each 2/0 size wire terminals for about $2.50 each. They may have two or three crimping guild lines that is mark on the barrel. If there is two guild lines, then you crimp first next to the cable and then the second crimp next to the bolt hole. If you crimp next to the bolt hole section first, then the cable may push out some.

If it's has three guild lines, then crimp in the center guild line first, the second by the wire and third at the bolt hole section.

The NAPA auto store, I go to can either crimp the wire terminals on the cables which may be a hydraulic crimper, or you can rent a hand crimper from
them. Make sure you slip on the heavy duty heat shrink that has a sealent
in it first before you install the terminal.

It looks like there are un-plated thin copper wire terminals are use on your battery links. You will have to watch these connections very closely, as copper to lead will increase in turnish at the contact point which may increase in resistance. After a while, bright copper will turn dark, to a green color and then to something looking like white frosted coating. I would give them a very good cleaning and torque them also.

A very good terminal coating I use, is that tool dip liquid compound make by LocTite. It should be listed as acid proof and can be use on batteries.


----- Original Message -----
From: "Hunter Cook" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Thursday, October 04, 2007 9:58 AM
Subject: Re: [EVDL] Modified K&W BC-20 questions (primary input leads)

> Thanks for the advice, Roland.
> I don't think it's that serious...the transformer looks like it's fine
> to me. The burns are just on the input terminal, which I'm thinking I
> should be able to replace independent of the transformer. I don't know
> if it's glued on or's on there tight. Figure I'll drop by
> radioshack today and see if they've got something similar.
> I put some pictures of it up in case you or anybody else wants to have a
> look:
> Thanks
> Hunter
Roland Wiench wrote:
> >
> >
> > ----- Original Message -----
> > From: "Hunter Cook" <[email protected]>
> > To: "Electric Vehicle Discussion List" <[email protected]>
> > Sent: Wednesday, October 03, 2007 9:49 AM
> > Subject: Re: [EVDL] Modified K&W BC-20 questions
> >
> >
> > > Roland-
> > >
> > > Very interesting history there...basically just shows that for at
> > > least
> > > the last 30 years you've been a lot harder core than me. Not that any
> > > more proof was necessary ;-)
> > >
> > > My batteries do not look "super clean." I suppose it's time I tested
> > > for
> > > leakage. But the first thing on my mind today is what to do about my
> > > burned up primary input connections on the boost transformer.
> > >
> > > Thanks again for all your help,
> > >
> > > Hunter
> >
> > Hello Hunter,
> >
> > If the primary input leads go's directly into the transformer windings
> > and
> > the insulation is brittle or gone, you could remove the transformer and
> > take
> > it to a motor shop. It may be as simple as re-enameling the core, if
> > the
> > transformer test out ok.
> >
> > If the transformer is a one winding core, then they have a winding
> > machine
> > that counts the number of windings as it is remove from the core, and
> > than
> > winds new wire on the core. Takes less than 30 minutes to do.
> >
> > If the leads terminate to a bolt in transformer tab, then you can
> > replace
> > these leads with some good high temperature motor leads, that I normally
> > get
> > from a motor shop. This type of wire is fine multi strand wire. A No 10
> > AWG
> > may be 52 strand with a 105 C rating or more.
> >
> > Use a non-insulated solid wire terminal and heat shrink. Sometimes, I
> > had
> > transformers or motor leads insulation burn off, and I was able to
> > insulated
> > with a 3M high temperature glass tape by wrapping the wire twice half
> > lapping the tape. This makes four layers.
> >
> > If the lead wire has no terminal points and the copper wire itself looks
> > brittle, sometimes I could cut the wires leaving about 1 inch from the
> > windings and use a non-insulated solid wire inline splice to a flexible
> > motor lead wire and heat shrink and glass wrap that connection.
> >
> > I also spray all these transformer connections with motor enamel spray
> > you
> > can also get from a motor shop. Its not the bake on type.
> >
> > If you ever brake down a DC brush type motor, which I do about every ten
> > years, for cleaning, inspecting or replacing the brushes, I use this
> > spray
> > on motor enamel to recoat all the field windings, the front of the
> > commentator down to the motor shaft and the motor shaft up to the
> > bearing
> > surfaces.
> >
> > When a motor is brand new and never been run, I record the ohm values of
> > the
> > motor terminals to the motor frame which should read over 20 meg ohms.
> > The
> > commentator windings to the field windings (with the jumpers remove,
> > should
> > also read over 20 meg ohms.
> >
> > As time goes on, the brush dust inside the motor will increase the
> > conductance and it may get down to 50 k ohms or less which you may get
> > arc
> > over. The its time to clean the motor. Enameling these areas on the
> > commentator and motor shaft has increase resistance which allow the
> > motor to
> > go over 15 years with no brush replacements.
> >
> > Roland
> >
> > _______________________________________________
> > For subscription options, see
> >
> _______________________________________________
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