I'm running two batteries with a switch (Atwood) which has connectors for
the Field from an alternator. I was led to believe that by connecting these
two small terminals to the proper wires I could switch batteries in mid
stream. Questions: 1. Why does this switch have printed (molded) "do not
switch with engine running"? 2. I have a 200 Merc 2 stroke which has no
alternator, rather a "rectifier" for the charging circuit. Is there a
procedure to hook this up and be able to switch batteries while engine is
running?
LD

I am not familiar with that switch but you can test it.... To switch
while the engine is running you need a MAKE BEFORE BREAK switch. Which
means that when you go from BAT 1 to BOTH, you never loose connection as
well as from BOTH to Bat 2. Just connect a volt meter to it and turn
the switch SLOWLY and see if you loose voltage. (Analog meter is better
if you have one)



LD wrote:

I'm running two batteries with a switch (Atwood) which has connectors for
the Field from an alternator. I was led to believe that by connecting these
two small terminals to the proper wires I could switch batteries in mid
stream. Questions: 1. Why does this switch have printed (molded) "do not
switch with engine running"? 2. I have a 200 Merc 2 stroke which has no
alternator, rather a "rectifier" for the charging circuit. Is there a
procedure to hook this up and be able to switch batteries while engine is
running?
LD

Ed wrote in :

I am not familiar with that switch but you can test it.... To switch
while the engine is running you need a MAKE BEFORE BREAK switch. Which
means that when you go from BAT 1 to BOTH, you never loose connection as
well as from BOTH to Bat 2. Just connect a volt meter to it and turn
the switch SLOWLY and see if you loose voltage. (Analog meter is better
if you have one)


I'd like to make a simpler suggestion......

Hook the starting battery straight to the battery leads from the engine's
rectifiers (all negative leads, of course, hook to the negative ground on
all the batteries). Now, get a simple ON-OFF battery switch from Waste
Marine (mine's 350A) and hook it from the starting battery's + terminal to
the house battery's + terminal, so you can separate them whenever the
engine is not running, and parallel them for charging from the outboard's
simple charging circuit. This switch also allows you to "jump start" the
engine from the house batteries if the starting battery fails.

As none of the electrical loads are EVER disconnected from the batteries
and only connected to the alternator's BIG VOLTAGE pulses with no battery,
problem solved.

on-off
switch (on position)
|
Engine/alternator + ---|---------------------|-------house panel +
| |
Starting House
Battery Battery
| |
Engine/alternator - ---|-------------------------|-------house ground


Come aboard boat....
Start engine........
Switch to ON position
Both batteries charge
Stop engine after use
Switch to OFF position
Discharge only house battery with house loads...
Start engine....(only on starting battery still charged)
Switch to ON position (to reconnect house to charging)
Run around recharging house and starting
Stop engine...
Switch to OFF to separate batteries for storage so they don't discharge
each other.....Unless you're at a dock with the AC charger going on the
house batteries, then leave switch ON so AC charger charges both.

The house and electronics is ALWAYS connected to the house batteries.
The electronics on the engine is ALWAYS connected to the starting battery.
No open circuit high voltage can exist to destroy anything.
Use the panel breakers like everybody does to secure boat and turn
everything off....

My electronics shop in a 1989 Chevy stepvan is wired this way. Works
great....I don't open the switch unless:
A - I'm storing the van for a few days
B - I'm going to load the house batteries with my 1KW inverter or 800 watt
DJ stereo system.
The house batteries are two 6V, L-16 golf cart monsters in series.
The starting batteries are two red AGM starting batteries in parallel.
It's worked this way nearly 2 years with no problems....(c;

Larry