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

----- 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

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.


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