If the batteries suddenly spike from 11.5V to 14.5V when connected to the
charger, that is an indication that the batteries are worn out. A battery
that is good takes time to discharge and little longer to charge. There
are a lot of variables, such as the size of batteries vs. size of charger.
Generally batteries should be kept above 12.2V, otherwise they have short
life. Thousands of boats have A/B fridge systems (including mine), all
have battery chargers, they work reliably without add'tl equipment.
Lee Haefele
Nauticat 33 Alesto
"GBM" wrote in message
news

"Larry" wrote

Hmm...Interesting. The only way I know of it making a "voltage spike" is
if it is connected to a battery with an open cell. Batteries absorb the
spikes, normally. It's how they charge...(c;


I think they were talking about higher than normal charger output voltages
in 15+v range that some chargers may put out under certain conditions.

Regarding spikes - Don't we get a "spike" when we turn on the charger?
Instead of say 11.5v, we suddenly have 14.5 or whatever. Anyway, that's
what my voltmeter tells me!

GBM