QT1
Active Member
- Oct 20, 2016
- 649
- Boat Info
- 1990 350 Sundancer, "Quality Time II".
- Engines
- 454 Mercruisers, performance parts modified by PO.
Starting from Bow to Stern, can someone tell me what each battery's job is?
3 batteries, 88 WE 300: What does each do?
- Thread starter QT1
- Start date
JVM225
Well-Known Member
The way that Sea Ray set them up, and assuming nobody changed things around, one just starts the port motor and the other two start the starboard motor and power all the 12 volt stuff on the boat.
I'm not sure how they are positioned in your boat, but it's easy enough to figure them out. Even if there were a diagram there is no guarantee that a previous owner didn't move them around.
The port motor battery should be easy enough to ID by following the positive cable. It's run to the port starter.
The two starboard batteries go to a battery switch marked "off" "1" "2" "both".
Put the switch on "1" with the stereo playing loud enough to hear. Take the negative lead off of one of the batteries if the radio goes off then that's "1". If it keeps playing the other battery is "1".
I'm not sure how they are positioned in your boat, but it's easy enough to figure them out. Even if there were a diagram there is no guarantee that a previous owner didn't move them around.
The port motor battery should be easy enough to ID by following the positive cable. It's run to the port starter.
The two starboard batteries go to a battery switch marked "off" "1" "2" "both".
Put the switch on "1" with the stereo playing loud enough to hear. Take the negative lead off of one of the batteries if the radio goes off then that's "1". If it keeps playing the other battery is "1".
QT1
Active Member
- Oct 20, 2016
- 649
- Boat Info
- 1990 350 Sundancer, "Quality Time II".
- Engines
- 454 Mercruisers, performance parts modified by PO.
Thanks a bunch JVM225! That gives me some insight on what type of batteries I want to replace in the near future.
johngus
Member
- Dec 27, 2008
- 248
- Boat Info
- 1988 300 Weekender
- Engines
- Twin 350 Chevy
Straight Inboards
the reasoning behind this setup is the house never runs off the port engine battery,this way at anchor even if you did run down the hose battery there is still a dedicated battery to start the port engine.thats why there is a jumpstart switch at the helm.after starting the port engine you can jump start the starboard.
QT1
Active Member
- Oct 20, 2016
- 649
- Boat Info
- 1990 350 Sundancer, "Quality Time II".
- Engines
- 454 Mercruisers, performance parts modified by PO.
This is why this is a great forum for 300 WE owners! Thanks for the info.
QT1
Active Member
- Oct 20, 2016
- 649
- Boat Info
- 1990 350 Sundancer, "Quality Time II".
- Engines
- 454 Mercruisers, performance parts modified by PO.
You were right, battery one is only for the port engine. 2 and 3 are starboard and house. Thanks.
SCORPIO
Well-Known Member
My Sundancer has two battery switches, one is just ON/OFF the other is the three position switch. Is the ON/OFF switch just for the port engine start battery? Never played with it much, usually just turn it ON and set other switch to Both and everything works.
trflgrl
Active Member
- Jun 23, 2014
- 982
- Boat Info
- 1989 Sundancer 300
- Engines
- Twin 350 Merc/Alpha 1 Gen 1; Quicksilver 4.0 gen
Most likely. I have two battery switches, both with 1/2/both/off, but the first switch operates as if it's solely an on/off. To know for sure, test like JVM says, or....
When I first got the boat, I turned off both switches, then turned switch 1 to each position and tested both engines and other systems, logging what did and didn't work. Then I left switch 1 off and turned switch 2 to each position and logged those outcomes. That gave me basic mapping of the most critical systems without tracing wires (PITA to be in and out of the bilge), but obviously there's more than one way to skin a cat! We found that our stereo was running off the port starting battery and chose to rearrange.
Bt Doctur
Well-Known Member
Drawing engine batteries down to useless is never a good idea, Dedicate your engine batteries and dedicate the house battery(s)
Should you port battery go weak/bad/dry/shorted the cross-over switch is useless. If you have a electric operated hatch verify what battery runs that too.
Should you port battery go weak/bad/dry/shorted the cross-over switch is useless. If you have a electric operated hatch verify what battery runs that too.
JVM225
Well-Known Member
My guess would be yes, the on/off switch is just for the port battery and the 3 position switch is for the starboard bank.
Easy way to check is to turn that one off and try to start the port motor.
My old 87 300 didn't come with a switch for the port motor, but I added a simple on/off switch for that battery.
My routine for the stbd bank was always run the boat on "Both", and when I got to where I dropped the hook I would switch to either "1" or "2" then put it back on "both" when I was ready to start the motors for the return trip home.
I tried to remember to alternate the battery I used to power things during a day on the hook.
Last edited:
QT1
Active Member
- Oct 20, 2016
- 649
- Boat Info
- 1990 350 Sundancer, "Quality Time II".
- Engines
- 454 Mercruisers, performance parts modified by PO.
The port battery (#1) and #2 battery are brand new.
