Battery drain on 09 330 express

Dhmako2

Dhmako2

Member
Joined
Mar 2, 2019
Messages
7
Reaction score
4
Points
3
Age
64
Model
Express 330
Good evening I would appreciate any insight as to what type of batteries or charging system I should use on my almost stock 09 330 express. I seem to loose battery power over night even if I leave main dc power switch off. It does not occur if I cut battery switches to off. New interstate marine cranking batteries and all terminals clean and tight. My battery charger is the usual 2 bank 15 A charger from GW. Should I change to dual deep/starting batteries or up grade my charger or both. Any suggestions are welcome. Thanks David
 
Have you diagnosed what is causing the batteries to be drawn down so fast? That's the first step. It would be silly to replace things without first finding out what the issue is.

What do you mean by "lose power overnight"?

-- What is the resting battery voltage and charging voltage (via engines and charger). Test and report back on that. Test directly at the batteries.
-- Fully charge and then load test the batteries
-- Do an amp draw test on each battery. If there is excessive draw, start pulling fuses till you find the offending circuit.

What is the "main dc power switch"?

That boat only came with a 2-bank, 15A charger from Grady? Wow, that's pretty small. Do you not have a third bank (house)? Or is one of the engine batteries also the house? If so, that should be a DP battery.
 
  • Like
Reactions: Dhmako2
There are things directly wired to the batteries that could be draining your batteries. I'd start by checking the pumps. Could you have a stuck float switch or a pump that is running? Maybe start removing some of the direct connection items and see if you can isolate.GW recommends starting batteries versus deep cycle or hybrid ones. How old are the batteries? 5-7 years is usually the norm to replace. Maybe you have a weak bank or battery? Always change in pairs is my recommendation.
 
It is a two bank charger for (4) total batteries in (2) pairs (batteries wired in parallel). It is 15A per bank, 30A I believe (Guest Charger).
 
DennisG01 said:
Have you diagnosed what is causing the batteries to be drawn down so fast? That's the first step. It would be silly to replace things without first finding out what the issue is.

What do you mean by "lose power overnight"?

-- What is the resting battery voltage and charging voltage (via engines and charger). Test and report back on that. Test directly at the batteries.
-- Fully charge and then load test the batteries
-- Do an amp draw test on each battery. If there is excessive draw, start pulling fuses till you find the offending circuit.

What is the "main dc power switch"?

That boat only came with a 2-bank, 15A charger from Grady? Wow, that's pretty small. Do you not have a third bank (house)? Or is one of the engine batteries also the house? If so, that should be a DP battery.
Click to expand...

Thanks for the quick followup. I will have to run the circuit by circuit evaluation to find out the answer. But great suggestion on what to look for. Yes GW only installs a 2 bank 15 charger since the battery layout is two batteries for each bank and the house runs from either bank ( depends ) on battery switch positions. Also the generator starts on the starboard bank I will get some answers soon and let you know. Thanks again
 
If you are absolutely sure the problem doesn't occur when the battery switches are OFF then you have a current draw on one or more of the circuits powered by the DC panel switches. It could be a pump running, the fridge, stove, lights, accessories etc. You can leave the main breaker switch on and make sure all the branch breakers are off and see what happens. A faster way is to turn off the main breaker with the battery switches on and measure the battery voltage at the battery. What ever it is, when you turn on the main DC breaker, that voltage will drop if there is any load. Use a decent digital voltmeter since the drop could be small but noticeable. Have two people do the testing makes it easier, one watches the voltmeter and the other runs though turning the breaker on and off.
Let us know what you find
 
"It does not occur if I cut battery switches to off."

I'll throw some things out there...

Most likely there are 3 fused circuits directly off the battery not effected by the switches. Fwd bilge pump, aft bilge pump, and "Memory".
A pump my be running or stuck.
The memory to the stereo may be drawing down old batteries.
Someone may have powered the stereo (or something else)with the memory wire and it is on and drawing down the battery
 
But *both* battery banks are draining to zero? And just to be sure: your battery switches are *not* in the BOTH position, right?

I can't think of any scenario where something off the DC panel can drain both battery banks, unless the switches are set to BOTH.
 
Does it go dead if you have the DC main off in the cabin at the top of the 12volt panel? If it does, The only other things connected to the battery switches are the motors, generator, and the power going up to your hardtop electronics box. It’s not the bilge pumps because they bypass the battery switches. Are your key switches turned off when it drains down. If so. I suspect something hooked to the electronics box power? Spot light, VHF, other things powered up there?
 
You must log in or register to reply here.