Cranking battery and directly wired electronics

For those of you who have their graphs hardwired to the cranking battery, when your battery isn't charging or the engine isn't running, does the power connection drain the battery while the boat sits? If so, how long before the battery is drained enough to not be able to turn over a HPDI engine? Group 27 interstate battery, fairly new. Thanks!

Mine are hardwired but I'm a little confused. Are you talking about after you pull it off the lake and remove the graphs? I pulled an older group 24 out of my boat, which really wasn't bad just old, and bought a group 27 Interstate cranking battery. My boat has been parked 2 weeks and the battery must have been pretty well drained because it took it much longer to charge than my 2 group 27 deep cycle batteries I bought from Sam's about a year ago. On the lake with and HDS-8 at the console and HDS-7 at the bow the battery drains quicker than my old one. I'm a little disappointed with the Interstate battery. I wouldn't think there wouldn't be a drain from the power cord while it is parked with the graphs removed and the accessory and power switches off.

Wellllllll, alrighty then. Totally not how I had read it so here's an edit.

I always turn my graphs to stand by. Seems to help. Running you livewell pumps on time also helps.

Sorry for the confusion, I meant in your garage, storage facility, etc. Here is my scenario, 5 months ago I bought an interstate 27 cranking battery. I leave my boat in a storage facility, but on a charger. When I fish, I leave my boat at my house overnight the night prior, at most for 12 hours and it's off the charger. I've never had an issue and wouldn't think there would be an issue, but the last two trips when I launch, my graph tells me I'm at 12.7 volts, but when I go to turn the engine over it drops to 8 volts and won't turn the motor over. I've had to jump the battery, but when I do and warm the engine up, it runs all day with graphs on/live-wells running etc. and it always turns over. I called interstate about the issue and they told me to bring the battery in. I charged the battery full, got the boat, hooked it up to ears and tried to turn the engine over and it again dropped to 8 volts. I brought the battery to interstate, they ran a test, and then a load test and said the battery seemed fine. They're doing more testing in the next day with it, and going to tell me the results tomorrow.

When you engage a starter that won't turn over with the attached battery, you've started a downward spiral. A stopped starter motor is essentially like a dead short. That effective dead short is going to drag the voltage down in an instant because the battery doesn't have enough energy to deliver to spin the starter with that compression load on it.

They may say the battery meets spec, but I'd say it's a crappy one.

There are some electronics modules that do draw a small amount of power. I believe that I saw at least one version of the LSS boxes with a spec in the milliamps, but that would not kill your battery overnight.

Sorry but ur first problem is a interstate battery

Please expand on your observation.

Be aware if you have an external GPS networked and that network draws power directly from the boats battery, the GPS receiver will remain on all the time and drawing power. I believe its recommend to install a switch between the battery and NMEA-2000 buss.

I'm hoping it's just a bad battery, and a replacement will fix the issue. I run a HB 1199 and HB 999, so the LSS isn't something I'd deal with. Wish I would have gone with the group 31 agm in the first place, but I was in a tight squeeze and the previous battery that came with the boat was an interstate so I picked the same one up because it was in stock.

I run interstates thru out all the boats I have owned. Only had an issue once with my cranking battery dying at the end of 4 days straight, the last two running everything in the boat, live wells, electronics and lights. At the end of the second tournament day main would barely crank and graphs. 998 and 1199, would not stay on. With this being said took the battery in and had it load tested, it tested good. They then did cell test and I had one bad cell. Make sure and check each cell. Never had another issue with interstate.

Don't know if you have them but if you have power poles you need to get a cutoff switch so the bluetooth isn't searching for signal which over time could run down battery.

That is very true. But, he seems to indicate that while the boat is in storage, the charger is plugged in 24/7. The PP load won't hurt anything while that charger is active. He brings it home Friday evening to fish on Saturday morning. The PP bluetooth should lower it's power consumption after no activity, so I do not think that small drain overnight is a culprit for killing his battery so readily.

A test he has not mentioned is whether the cells have been checked with a good hydrometer (not a cheapie pencil-size tube version). A bad cell will typically show itself via such a test.

Check and clean every connection too. Not that this IS the problem, but it surely could be.

Just curious, plugging it up at the house isn't an option?

Steez has a good point. Even a small resistance in a high-amps connection (starter) can have a huge impact on starting performance.

As to plugging in at the house for overnight: While that might get around the problem, I would not want to go on the water with a battery in such poor condition as you have described.

The cells are being tested this morning after it had to be on the charger over night. I'm hoping that discovers something. It's really not an option, unless I have a very very long extension cord. We will see when they call this morning if they discovered an issue. I'll make sure the connections are good and clean when I reconnect whatever battery I end up with!

Pretty self explanatory! JMO!

If it tests good, and you continue to have problems with it i'll exchange it for you if it's less than 12 mos old. You do need to have all gps units wired to a switch to completely shut off any draw.

If the voltage drops that much when you crank it, the battery is no good. That's why they load test them to determine if they are good or bad. At rest voltage by itself means nothing.

To be clear, your electronics isn't causing this - it's just telling you the problem exists:

1) The electronics includes the ability to read voltage. It is simply reporting what it sees happen.
2) If you removed the electronics from the boat, I'm very certain that the same no-crank issue will still occur.
3) If you put a voltmeter on the battery (instead of attaching electronics) it would tell you that the voltage is dropping when you try to crank the outboard - just like the electronics is already doing.

The battery needs a load test more so than a cell specific gravity test, though I bet it won't look good by either test method.

In my Phoenix they have two switches that cut off power to everything when your off the water so it avoids issues like this. No power destruction to anything just the batteries are charging.

Group 27 is a little on the small side for cranking and running accessories isn't it?

Same with me,6 boats later.

Not sure what size outboard you have, but do some research on the required CCA's for your outboard. My dealer put a Grp 24 in my boat to crank a 250 Pro XS, barely enough juice to crank it. It did okay, barely, but last month I bought Grp 31 AGM from Batteries Plus, it is a beast.

Another thing to look at is the order in which items are on your terminals. The motor leads should be first. And no wing nuts. I read on another board to get a terminal to clamp on and put the motor on it, all others on the threaded terminal.

If it was me, I would get the dealer who sold you the battery to give you an exchange even if they say it is good.

Good luck!

I have a similar problem with my Triton. I'm the second owner of the boat so I'm not as familiar with how it was wired originally. I have do have a main cut off for power and turn it off after being on the water each day before putting the batteries back on the charger. When the charger is on I show 13.0-14.0 volts holding steading in maintenance mode. When I take the charger off I show voltage of 13.5 and dropping. Something is drawing power from my cranking battery with the main in the off position. I'm still trying to diagnose my problem but you may want to take a look at what the voltage is doing on and off the charger.

Sooner,

If you have a drain on the battery when the battery disconnect switch is in the off position (as you claim), then there are other wires on the battery. One of those sets of wires will be that drain - if there is one.

You mention that you see this when you "take the charger off" where I will assume that means unplug an on-board charger? How fast does the voltage drop? A flooded cell battery won't hold 13.5 indefinitely without a charger active as that's higher than 100% charge. Most battery companies state 100% charge as 12.70-12.75V for conventional flooded cell lead acid batteries.

The 13.5V reading you see after unplugging or removing a charger is a "surface charge" from the elevated charging voltage that will dissipate in a few hours. Measure your battery after a rest period of 8-12 hours - no charging and no known load. If you see 12.7V, you're good and there is no mystery load draining the battery. A battery sitting on a bench would do the same thing.

Thanks Flippin!

Absolutely what this guy says. The motor cables should have as much contact to the battery lead as possible. It needs to be the first cable on. Even better is what he says about a dedicated terminal to post setup. Accessories can come second. They pull nowhere even close to the amps that a starter will pull. Put surface area for conducting amos where it is needed.

As far as the group size? Depends on the motor size, number of pistons, age, fuel injection, ECM required voltage, etc. my little old Mercury is carbed and well broke in, and a group 24 is still too small. A 27 in my boat is minimum for the starter and helix units.