Battery drain

**J_ROW** · 09-06-2010, 05:09 PM

Does a HB 798 si have any drain on a battery if it is turned off but still plugged into the power plug? Haven't used my boat in two months but did recharge both troll motor and motor cranking battery after last use of it. When I got too the lake the motor battery was dead as a door nail. Jumped it off and ran down the lake a little ways and it charge right up enough to crank it. I know some motors put a drain on a battery when the have computer chips in them.

**flycaster** · 09-07-2010, 05:45 AM

I have a 997si and I have a plug in fuse in line with the depth finder. When I pull the boat I remove the fuse. When I go to replace the fuse I notice a small flicker at the fuse which indicates that there is a small current drain. The unit was turned of before removing the fuse and I have turn the unit on after replacing the fuse.
This keeps the battery from draining down when not in use.

**crappiedoc** · 09-07-2010, 06:33 AM

I believe the GPS is active all the time.

**J_ROW** · 09-07-2010, 07:30 AM

10-4. Never thought of the gps causing it. Oh well my son bought me a MK on board charger and we hooked it up yesterday , so that should solve the problem. Thanks for the come back and the info.

**CatFan** · 09-07-2010, 07:33 AM

After sitting that long without charging, the batteries are going to be pretty dead even if they aren't connected to anything. Batteries self-discharge all the time, and the effect is magnified during hot weather. Add in the draw from the motor and it was probably dead flat.

You shouldn't ever let a battery go more than 30 days without fully charging it and checking the electrolyte level.

**Barnacle Bill** · 09-07-2010, 08:30 AM

Originally Posted by CatFan

After sitting that long without charging, the batteries are going to be pretty dead even if they aren't connected to anything. Batteries self-discharge all the time, and the effect is magnified during hot weather. Add in the draw from the motor and it was probably dead flat.

You shouldn't ever let a battery go more than 30 days without fully charging it and checking the electrolyte level.

In 2 months? I don't think so. If that were the case there would be a awful lot of dead batteries sitting on autoparts shelves.

**crappiedoc** · 09-07-2010, 08:35 AM

Most batteries lose 1-2 amps per week

**beagle man** · 09-07-2010, 08:58 AM

I think you must have something on like you said, I know the lowrance structure scan is on all the time, and you must have it hooket to a swich or a main disconet controll or it will drain the battery. I leave my charger hooked up most of the time, not much worse getting to the lake and dead battery on board.

**chuckauten** · 09-07-2010, 09:00 AM

My drain was caused by my Minnkota auto pilot. I not undo the tm each time. Saves batterys. I can run two to three days on a charge when I use the tm each day. Eventually I am going to install a disconnect switch. Simalar to a knife switch.

Chuck

**CatFan** · 09-07-2010, 09:01 AM

Originally Posted by Barnacle Bill

In 2 months? I don't think so. If that were the case there would be a awful lot of dead batteries sitting on autoparts shelves.

There are a lot of dead batteries sitting on autoparts shelves. Always check the date before you buy.

A new lead-acid conventional battery loses about 15% of it's charge per month at ~86degrees F. 2 months without charging means you are at 70% state of charge. 70% may be well below what it takes to crank an outboard. If it was hotter, as it was here, the discharge rate would be worse.

The discharge rate gets worse as the battery ages. The worst part is that once the battery partially discharges and sits, it permanently loses capacity.

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