That diode will probably net you a 700mv drop.  Two in series 1400mv.

Pensionerd

On Tue, Mar 15, 2011 at 7:39 AM, mark drillock <mdrillock@cox.net> wrote:

> I have a simple setup with a 1314 and the 125ah led acid deep cycle. The
> aux battery sees about 14.5 volts while I am driving. My battery did not
> experience any loss of water but it did lose at least half of it's rated
> capacity in less than a year. Whether this problem is due to charging
> method or simply a poor battery is a question I would like to answer but
> can't.
>
> My current plan is to put in a switched voltage drop to let me reduce
> the charging voltage on long drives, after some initial period of full
> voltage to allow fast charging. I plan to use a big diode for the
> voltage drop.
>
> Mark
>
>
>
>
> David Beierl wrote:
>
>> At 10:04 PM 3/14/2011, Daryl Christensen wrote:
>>
>>> OK�My van charges at about 13.6 to 13.8 or9 max. All the spiffy
>>> temp/voltage AGM battery chargers I see are 120V AC input..
>>> Is there an onboard �charger widget� for upping the charge voltage to
>>> the 14.4 the AGB batts need?
>>>
>>
>> Yes, but you're not going to like it. Because getting up there is easy
>> (at least on Bosch alternators) - drop-in adjustable regulators are easy
>> to get. It's getting back down that's the problem, 'cause if you keep
>> the voltage up there you'll boil the thing dry.
>>
>