Can someone explain to me please...

[lisilou]

in simple terms why my batteries are draining.
Scenario as it stands: Boats been on hard for couple of weeks with no shore power. Batteries switched off so no draw from them over that time. Plugged her into shore power today back on berth, switched batts back on and batt charger. TV on, fridges on, the usual 'liveaboard' requirements being used tonight. After about 4 hours, the lights start to dim and the odd short bleep from what I think is one of the co2 alarms (no co2 leak just a warning that the charge is running low). Clearly the domestic is being run down despite the batt charger up and running.
Now my question is this...surely if the boats plugged into shore power and thats all working fine and the battery charger is switched on then that should in turn provide enough charge (and get it back up to full charge) for the domestic battery to do its stuff?
What am I missing here?
Had to run the engines to get the charge up and the starbrd engine was dead so had to flip the switch to swap charge to get that one started.
That's brought the charge up quite a bit but I can see the voltage gauge dropping slowly but surely.
How come?
L
(I apologise if this is a stupid question but I'd really like to know)

 

[Momac]

Sounds like the battery charger has become faulty or possibly it has blown a fuse.

 

[rafiki_]

Lisa, look for the simple things first. Is the shore power working? Sounds not to me, so see if it has tripped out?

 

[lisilou]

Volts slowly climbing again now so I'm guessing it's had a chance to recoup some charge. It's a mystery to me tbh.
L

 

[rbcoomer]

How much power can the charger deliver? If it can only provide say 50A and you're drawing 55A then the batteries will slowly drain. You need a charger that can provide what you are using plus a bit extra to charge the batteries... It's easy to underestimate power draw at 12V or 24V!

 

[lisilou]

Raf... shore powers fine. All 230v stuff (TV and other socket stuff etc) working no probs but the lights are on the 12v DC thingy. It's getting back to normal now and I get that batteries need time to get back up to full charge but I just would've assumed that as I'm plugged into shore power...the batts wouldn't need that time.
As I'm typing this, I'm answering my own questions so excuse my ramblings.
L

 

[rafiki_]

Ok Lisa, good. Sounds like the batts just needed a bit of oooomph. Good luck.

 

[lisilou]

How much power can the charger deliver? If it can only provide say 50A and you're drawing 55A then the batteries will slowly drain. You need a charger that can provide what you are using plus a bit extra to charge the batteries... It's easy to underestimate power draw at 12V or 24V!

You're right rb...if I stop to think about it, I get to boat, shes not been charging for 2 weeks, I plug her in, switch the chargers on, then turn every appliance on plus the tv plus the lights etc etc. Of course it's not gonna cope straight off.
Thanks fellas...at least I know there's no problem (aside from me being a bit blonde!!!)
L

 

[rbcoomer]

You're right rb...if I stop to think about it, I get to boat, shes not been charging for 2 weeks, I plug her in, switch the chargers on, then turn every appliance on plus the tv plus the lights etc etc. Of course it's not gonna cope straight off.
Thanks fellas...at least I know there's no problem (aside from me being a bit blonde!!!)
L

Probably worth warming the motors up anyway if they've not run for a while and the batteries will charge quicker on the alternator. (Although I'd run up to operating temperature not just a short idle)

 

[lisilou]

Probably worth warming the motors up anyway if they've not run for a while and the batteries will charge quicker on the alternator. (Although I'd run up to operating temperature not just a short idle)

Thanks rb...I'll do that first thing tomoro.
L

 

[oGaryo]

Lisa, I think RBcoomer's given you the answer, if you're drawing more than the charger can deliver in terms of servicing the demand from the electrics you have switched on + trying to charge the batteries it'll not charge the batteries or will charge them slowly. Leave as much off as you can overnight and give them a good charge.

Also, are you sure someone's not hammered the batteries whilst it's been on the hard or maybe they're simply getting to that stage in their life where you need to consider swapping one or more of them out with the stint on the hard tipping the duff one(s) over the edge?

Finally, i'd advise getting a battery condition tester on all of them, then you'll know for sure if you have one or more duff ones in the bank.. I had one bad'un identified by Tom during the survey and did nothing about it... ended up knackering the one next to it as it dragged it down over a short time = having to replace 2 batteries rather than 1

G

 

[lisilou]

Good call Gary...thanks. They're 4 years old and possibly don't get consistent enough long runs to keep them happy so maybe they are coming to the end of their life. Will get them checked I think.
Ta for that.
L

 

[oceanfroggie]

Check the water level in the batteries. It's an other possibility.

 

[lisilou]

Check the water level in the batteries. It's an other possibility.

Thanks OF...are they not sealed units tho? (oh so much I still need to learn)
L

 

[Bandit]

Check the obvious, electrolyte level , charger etc.

My recent problem both engines running full chat but ending up with low domestics was a poor battery connection.

 

[lisilou]

Thanks Bandit.
L

 

[rafiki_]

Thanks OF...are they not sealed units tho? (oh so much I still need to learn)
L

You can still get sealed or unsealed Lisa. Check if there are caps on the top surface of the batts. If not, there should be a colour tell tale. Green is good!

 

[volvopaul]

Check the obvious, electrolyte level , charger etc.

My recent problem both engines running full chat but ending up with low domestics was a poor battery connection.

Sounds to me like your ready for a new set of domestic batteries

 

[lanerboy]

Lisa mine were not holding charge on my old boat i checked the levels and they were all low so i topped them all up with distilled water then thet were fine after a few days charge when the chargers on a lot they do loose water if they are that type our floor cleaner at work goes on charge every day and we have to top them up every month

 

[lisilou]

Hmmm....gonna seek out my batteries tomoro and check them. Great help as always guys...thankyou. Got a feeling it's time to replace them. heyho...that's boating