From: Ed Kirkley (mojoedd@bellsouth.net)
Date: Sat Feb 23 2002 - 06:16:43 PST
Jeff,
I understand the wording of your message and in that setup I tend to agree.
On the other hand in a two 12 volt battery system with two alternators that
each provide power to one battery, (such as my CUCV), I wouldn't think that
this would apply?
Best Regards,
Ed Kirkley KG4OUJ
1984 M1009
M103 Trailer
----- Original Message -----
From: <TacticalTruck@aol.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Saturday, February 23, 2002 09:08
Subject: Re: [MV] CHEAP (er) 24 to 12 volt converters, if you care
>
> In a message dated 2/22/02 10:56:38 AM, amnon@deltaforce.net writes:
>
> >This may be a stupid question, but why can't one just run wires from one
> >battery to get 12V?
>
> Let me quote from "Battery Equalizer Application Notes" by Mark Endres,
> Project Engineer Sure Power Industries, Inc.
> "The 24V system normally consists of two-12V batteries connected in
> series, with a 24V alternator providing power. It seems the most logical
> place to to obtain 12V power is the junction between the two batteries.
> However, a problem arises if the system is constructed in this fashion.
> "Consider the situation when the engine is off (alternator is not
> generating), and 12V power is used. Load current comes only from the 12V
"low
> side or A" battery, none of which is being furnished by the top or "high
side
> or B" battery. After a time, the 12V loads will discharge the "A" battery
> while leaving the "B" battery charged up. Since the "B" battery has not
been
> discharged it will not need any electrical current to recharge it;
however,
> the "A" battery will.
> "When the engine is started and the alternator furnishes current to
the
> load and to charge the "A" battery. All the current now flows throught the
> "B" battery, since it is in series with the load and "A" battery.
> "When this happens, a condition exists where the "B" battery
overcharges
> because it does not need recharging, and the "A" battery does not get the
> charge it requires. Charging current for the "A" battery is impeded by the
> already charged "B" battery and reduced by the amount of current that
flows
> to the load. Even if there were no load at this point, the same problem
would
> exist due to the imbalance of the battery charges.
> "When operating the system in this manner, the life of the batteries
is
> dramatically shortened. The "A" battery fails prematurely because lead
> sulfite builds up on the battery plates, reducing the capacity. The "B"
> battery fails when its electrolyte "gasses" and evaporates and damage
occurs
> to its plates and separators in the dry battery cells as a result of ov
> ercharging. Failure time can be as short as a few weeks for heavy 12V
loads.
> "If there is no 12V load, a 24V system with a two battery "stack" can
> operate well without an equalizer. However, the batteries must be of the
same
> type and age. Without a battery equalizer, current draw from one battery
and
> not the other will cause an imbalance. This imbalance accumulates over
time.
> Because the effects of the imbalance are cumulative, battery degradation
> occurs even with very small loads, such as a radio, clock or small lamp"
> The paper goes on to describe how their converter/equalizer works and
the
> benefits of their system. Again, I have some new surplus 25 amp units for
> sale for $150.
> Jeff
> TacticalTruck.com
>
> ===Mil-Veh is a member-supported mailing list===
> To unsubscribe, send e-mail to: <mil-veh-off@mil-veh.org>
> To switch to the DIGEST mode, send e-mail to <mil-veh-digest@mil-veh.org>
> To reach a human, contact <ack@mil-veh.org>
This archive was generated by hypermail 2.1.4 : Mon Apr 08 2002 - 00:24:30 PDT