Battery flat, help!!!!

Dazzler66 · 19 July 2021, 13:23

Hi, completely new to Ribbing so be gentle with me. I have just purchased a Zodiac Pro with 40HP Mariner engine. Purchased a new battery for it and last tome I took it out it started first time. Took it out down to Christchurch in Dorset at the weekend, put it in the water and nothing, no electric and wasn’t firing at all. I have since tested the battery snd it’s got no / minimal charge. I forgot to add that after the last time I used it 3 weeks ago I never disconnected the battery and so it was left exposed to the elements and lots of rain. So my question is, are you supposed to disconnect the battery after you moor it up and then recharge it before you next use it? Or is there something potentially drawing on the battery power even though it’s not in use. Like I said, I’m a complete novice 😭

jeffstevens763@g · 19 July 2021, 13:30

Water is a great conductor for electricity if it’s had a dead short the battery will be goosed

paulbrown22 · 19 July 2021, 13:56

Assuming the brand new battery is covered up in a console/box (and not underwater) and hasn't just shorted itself out completely, I'd check the obvious sort of things first. Are any lights/bilge pumps/other accessories left on/live when you've switched off the engine and packed up the boat? Even if the bilge pump is an auto unit, if there's been lots of rain and it's been correctly activating itself, possibly that has drained the battery? Check the current draw at rest with the engine off in your "closed down" state, is there a permanent draw indicating something is still connected?

Jon Tallis · 19 July 2021, 14:51

Hi Dazzler and welcome to Ribnet.
Your engine alone shouldn't draw any current when it is keyed off, however you don't mention if you have any other electrics on board - they may/will if left switched on.

You mentioned left out in the rain etc.... I'm my experience a bit of rain shouldn't discharge a battery (I have electric fences for my horses running off 12v batteries and they last weeks between charges, out in all weathers), however if you submerge it you'll kill it. That said having a boat battery exposed to spray etc is very poor practice (as others have said, salt water is a very good conductor). If it isn't already, your battery should be in a console or battery box and we'll secured.

You may of course just have a duff battery..

Best way forward from here....
* Get your battery tested and confirm its OK.
* Recharge it fully
* Put it back in a proper battery box, secured to the deck if it isn't already.
* Fit a proper, marine rated battery isolator switch, or as an interim, take off one of the terminals when you leave the boat. If it still discharges, your battery is goosed (but a tester should be able to tell you this anyway

Jon Tallis · 19 July 2021, 14:55

Picking up Paul's comment above, if you boat is kept afloat and you want your bilge pump operating, clearly you need to have this live to the battery, via a fuse of course. You can prevent it from completely discharging the battery by fitting a battery saver on the bilge pump circuit. You could also install a small solar charger

Dazzler66 · 19 July 2021, 17:47

I forgot to mention that I have no other electric items on the boat, no bilge pump etc. I had left the battery connected and whilst it is sat in a battery case the cover had been removed due to the kids playing around on it!!! So I’m thinking the likely culprit here is that the battery is screwed. I’m going to get a charger tommorow and see if it will charge and hold the charge

HDAV · 19 July 2021, 21:03

Get a multi meter check voltage when resting if under 9v it’s likely flat, does OB have charging circuit fitted? Or just elec strat?

Jon Tallis · 19 July 2021, 21:41

Sorry HDAV, whilst you're right, under 9v resting means it's very definitely flat, othe than that, resting voltage means next to nothing for engine starting ability. Battery needs to be tested on a drop tester to show it can still generate current.
Never known an electric start OB without an ability to charge its own battery.... still... Every day's a school day....

paulbrown22 · 19 July 2021, 21:46

Quote:

Originally Posted by Jon Tallis

Never known an electric start OB without an ability to charge its own battery....

That's assuming the alternator/stator is actually working properly, something I meant to suggest previously is checked, in case he's running the engine and it's not actually charging the battery.

HDAV · 19 July 2021, 22:01

Under 9v means it’s likely toast……… seen a leisure batt in a camper at 0.75v I don’t think it was possible but pointless charging that…..

A flat battery won’t start the motor but a sulphate battery won’t hold charge, used a ctek to resurrect one once but the charger cost as much as the battery would…..already had charger so it was a win!

I would check voltage running too known bad regulators kill 2-3 battlers before things were checked that’s possibly £200 wasted