On 10/10/2016 23:25, Stephen Wolstenholme wrote:
A friend has a disabled buggy for short distance trips. It is supposed
to do 25 to 30 miles on fully charged batteries. Last week it stopped
dead after about 10 miles. It was retrieved by the insurance company
and taken to the workshop for repair. A fuse had blown and so both
batteries needed replacing. Can anyone explain how a fuse blowing
results in the batteries needing to be replaced. They are sealed lead
acid batteries.

Any ideas?

Would the workshop receive more money if they decide that the batteries
need replacing, even if the batteries are ok? Changing the batteries
would be a quick and simple job involving very little labour or
knowledge, and the mark-up on the replacement batteries might be quite
large. That might be one explanation why the workshop decided to replace
them.

In fairness to the workshop, many people abuse batteries without mercy,
running them into deep discharge and then leaving them to sulfate, or
making them boiling hot with heavy currents for long durations.
Determining with certainty whether the batteries are just a bit flat or
have been damaged through abuse may be a very time-consuming job and
require much experience and knowledge, and if the batteries are found to
be good, then it would likely be unprofitable also. They may also be
uncertain about the condition of the batteries, and may fear that they
would make the customer unhappy if the batteries are bad and they don't
replace them.

The workshop may even think that performing an unnecessary battery
replacement is a way of doing the owner a favour, if an insurance
company is paying.

The fact that the batteries were able to blow the fuse is if anything a
sign that they might be in good health. A really knackered battery might
not be able to produce enough current to blow the fuse, depending on the
fuse rating.

If the owner is allowed to hang onto the old batteries then that would
be nice, but I expect the workshop wants to sell them for the scrap
value. In the event that the problem happens again with the new
batteries, that will show that it was some other problem.