Some of you may recall that I've got an old K&W BC-20 charger trying to
charge a 132v (used to be 144v) pack, which should not (and in my
observation, does not) work very well. Some very knowledgeable folks
have said it's good only to 108v, or 120 with the LB-20 booster. So far
this has all sounded very reasonable, as in my experience the charger
will only bring the pack up to about 140-145v.
This morning I really got in and looked at the way things were wired up
for the first time. It appears that it is wired with a larger
transformer in an LB-20-style boosting role.
Specifically, there is a Signal Transformer model MPI-900-40 wired up
exactly the way the BC-20 manual shows an LB-20, except that the MPI is
using 2 20v outputs together in series rather than just the one 20v
output of the LB-20. Here's the pdf of the manual, which has a good
diagram of it: http://evdl.org/docs/bc-20.pdf
I also found a loose connection from the plug to the MPI. Complete with
burn marks. Awesome. This may be related to the truck flipping the
breaker this morning when I plugged it in, which is what prompted me to
take a more serious look at where the wires were going.
So...this brings me to a few questions:
1. Should this transformer + K&W setup work for a pack of my size? It
seems logical enough I suppose, assuming he also changed out the
internal resistor (haven't had a chance to check, and not sure what the
value should be as the target voltage is higher than the table goes in
the manual) and assuming the other components in the BC-20 can take the
extra voltage. Since the vehicle is pretty old, I guess they can.
2. How bad is it that I've got minor burns on my input terminal strip
for the transformer? I tightened up the connection and it works again,
though I didn't try for long.
3. Is this dangerous?
I'm still in the market for a new charger, no doubt about that. But I
hope I can still keep limping around on this one for a minute. I do need
to move the truck about 6 miles this week (from my old house to my new
one) which believe it or not will probably require a charge in the
middle. I'm not really equipped to tow it.
Thanks again for all the help everybody's been giving me.
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