Battery Blues

[Dr_Dan]

Need some expert advice.

A couple of weeks ago, somehow, some electronics were left on in the boat after a trip. After realizing this more than a few days later, checked the voltage on the batteries, which read 11.4v. No worries I thought, that’s plenty. Off for the next trip a little later, down to the ramp, and motor doesn’t start. BUGGER IT! No power in the batteries. Get home, charge them up, put them back in the boat, and it starts no worries. Run it for a little bit on the muffs, shows a good 13v afterwards. WOOHOO! Disconect the isolator key so some dingbat (being me) can’t drain the batteries again

So this morning, less than a week after hooking up the batteries, again trundle down to the ramp before sparrows full of anticipation at getting out amongst some mackies. Back the trailer down, and what do you know, won’t start! BUGGER IT! No power, would just lose all its’ power and not haven enough to crank over the motor.

Question is:
1) When I put the batteries on the charger, they only charged up to what appeared to be 50% on the gauge. Old little charger supercheap special. How do I know if it’s the charger or batteries that are playing up?
2) Why would it lose power when the isolator switch was turned off?
3) Why do we insist on torturing ourselves with boats???
:-[ :-[

[dnej]

How old are the batteries
David

[Dr_Dan]

Don't know, have only in the last couple of months bought the boat.

[tenzing]

Have you thought of getting a new charger that stays in the boat and you can leave it on full time. CHECK THE C-TEK MULTI 7000. Worth checking the battery with a hydrometer first and check that they dont need replacing.
Brendan

Ps when I bought my boat I pulled the battery out on suspicion. just not worth the risk as far as i'm concerned

[Blaster Bretty]

yep my guess would be the batterie's for sure. Your voltage check say's 13v after charging but if the batterie's are stuffed they wont hold a charge for very long, hate to be out on the water and they let go on you .

Bretty

[dnej]

Yep,need to have the batteries checked.You can buy the necessary hydrometer (http://www.epa.qld.gov.au/media/parks_and_forests/marine_parks/go_slow_map_Mar06.pdf)
from super cheap,very cheaply.
Dont be fooled into thinking there is not a proble.
Also a multi meter would be handy
David

[Dr_Dan]

Cheers all. Thought that would be the case! if it's just replacing a couple of batteries i'm happy!

[FNQCairns]

Dan where do your electronics power from? if before the isolator and at the battery terminals??

cheers fnq

[Dr_Dan]

from after isolator i think?

[FNQCairns]

Thats ok then. I have seen different, where the isolator will cut ignition and say the guages but not the fitted electronics/lights etc as they run direct from the battery terminals which also is the best place to hook them up to very often, catch 22.

cheers fnq

[yettifish]

You will need to get the battery tested by using a hydrometer first to check how charged it is then load test with a loadmeter to see if it is capable of holding any charge. Sounds very much like the battery has seen better days.

[QF3 MROCP]

Cheers all. Thought that would be the case! if it's just replacing a couple of batteries i'm happy!

Dr_....
switch on all the electrics on the boat and the voltage should not fall blow 11.4v. Also with the hydrometer a fully charged battery should read 1.25 on the scale and discharged at 1.15

These are the the two testing methods - on load voltage and Specific gravity test with the hydrometer. Negative results, you need to go and start talking about a new battery and make sure the amp hours match if not better the total amps required from all the power guzzlers on board.

Watts (Power) = amps x volts

so if it's a 12v system and you have onboard 120 watts consumption, thats equal to 10 amps and if the battery is a 60amp/hr unit, then you have 6 hours of battery life.

So, don't leave the DVD, Coffee maker, fridge, radio (25w), senseround hifi, gps, radar, motor idle, spot lights on all at the time (just a high level critic ;))