Care and Feeding of AGMs (Was: Honda City)

[Jeff Owen <Jeffrey.Owen@FOODSCIENCE.AFISC.CSIRO.AU>]

Bill Dube' wrote
>>Any idea why Hawker recommended *not* using regulators or pairing the
>>batteries?

 >       I doubt that Hawker would make this recommendation. It goes
>completely against the grain. I suspect that your local distributor, not
>Hawker, made these incorrect recomendations. Your pack will go south in no
>time if you don't run regs. Hawker publishes a very complete EV applications
>booklet. As I recall, it says to buddy up parallel strings at least every
>other battery (24 volts.) I'm not sure if it says explicitly to run regs.

Before my car was first charged I asked the local distributor about
regulators. He was told by Hawker not to use them. I then rang Hawker (not
cheap from Australia) to speak to Kalyan Jana who is the author of the EV
application book. He was not available and I spoke to Bill or Phill Schumard
(not sure of the name due to American accent). He told me they did not
recommend the regulators as they had not tested them. He also said that
testing a few would not be sufficient as they would not indicate possible
variations in performance and manufacture from what I assume are small
manufacturers without approved QA programs in place. He did not appear to be
against the concept of regulators.

The second edition of the EV application handbook mentions equalizing links
between strings, but from memory, does not mention regulators.

The third edition of the handbook does not mention equalizing links (from
memory so shoot me if I am wrong) or regulators.

On Friday I rang Hawker and spoke to Phill/Bill again. He was confident
about the batteries being able to handle 16V and suggested that I let the
charger run the full cycle every 2 weeks. He also told me they had gone off
the buddy arrangement as they believed variations in batteries along each
string would average out to produce a more equal current in each string
(this is my interpretation of what he said). The local agent also told me
that the 15.6 - 16 V was OK for say up to an hour.

As Bill Dube' points out, voltages between batteries vary wildly during
charging but when tested after sitting overnight, they are all within 0.01
or 0.02 volts of each other.

My batteries are in 3 packs of 24V, 24V and 72V parallel strings. As
regulators are the most cost effective form of battery management, it is
likely I will be fitting them in the near future. To halve the number of
regulators, I will be connecting the batteries into buddy pairs with a light
gauge wire.

Jeff Owen
Brisbane
Australia



Care and Feeding of AGMs (Was: Honda City)