GregOddity
Well-Known Member
yes, it's the second button from the left beneath the dial, I was going to make a photo for you but the wife is using it to measure the infrared emissions from the LED light in the freezer.
starter battery flat after couple of hours
- Thread starter vasant
- Start date
yes, it's the second button from the left beneath the dial, I was going to make a photo for you but the wife is using it to measure the infrared emissions from the LED light in the freezer.
wotayottie
Well-Known Member
No one can diagnose a wiring problem without details of the wiring diagram and sight of the installation itself. So if as seems likely from your post you personally dont understand electrics, then best hire an electrician to come along and sort your problem.
A battery can go flat for at least two reasons - an internal short or an external one. Either way, if the battery is flat and you hand crank the enf=gine, no way will the battery be charged in half an hour. Or even 2 hours.
vasant
Well-Known Member
Actually i hold a MSC degree in electrical engineering, but you are right that this is not a meanigfull measure in terms of troubleshooting engine electrics for which indeed i have little experience.
NEvertheless thanks all i guess i will run diagnostics on the battery first for the case I am unlicky with batteries and proceed with checking drains. Next i will connect the voltmeter to monitor the situation. if i find something i will update here as i do always.
halcyon
Well-Known Member
You are under charging the battery, result surface charge. It will take
It will take 1 - 10 hours depending on charging system fitted to engine to top up battery to the maximum system will allow. Running for short periods gives a limited charge which combined with running battery flat will over a period will result in sulphation, which results in surface charge. The effect gives you power for a short period then flat battery.
Fit a voltmeter and ammeter, when you read 14.2/1.4 volt and 1 or 2 amps depending on alternator / battery size show you have a full battery, or as full as your system will give you.
Brian
vasant
Well-Known Member
Τhanks, makes sense. I actually recently used the engine quite a lot so one week ago i was running it for 2 hours and apart cranking its not used for anything else. So I assumed that would be enough.... Nevertheless it would maybe make improve to conenct it to my solar panel to keep it topped up during the week.
scottie
Well-Known Member
You could buy a boat for less!
GregOddity
Well-Known Member
It does seem you’re only partially charging your batteries and if you do this continuously, or even just store the battery with a partial charge, it can cause sulphating, and that may give you results like you have.
Tranona
Well-Known Member
Suggest you take the battery off the boat and fully charge it with a mains charger. As others have said it is difficult to get it fully charged with the engine in the short period you tend to use it. However, once fully charged the demands just for starting the engine are low and easily replaced in a short period of running. Discharge when unused is low so the battery should have no problems (assuming it is a decent size) starting the engine even after a period of no use.
The problems usually arise when the battery is used to power other things on the boat which will discharge it, hence the importance of keeping an engine start separate from the domestics.
The problems usually arise when the battery is used to power other things on the boat which will discharge it, hence the importance of keeping an engine start separate from the domestics.
GregOddity
Well-Known Member
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halcyon
Well-Known Member
Would do no harm, as would getting battery bench charged and checked, also check regulation voltage for alternator.
PaulRainbow
Well-Known Member
From the description in post #1 it doesn't sound like the battery is going flat at all. If it's a separate starter battery and the engine isn't running there are very few things that could drain a battery in such a short space of time, without burning something out, which means it wouldn't recover. The battery also isn't going to charge back up from not even having a light to being able to start the engine in such a short time.
I'd be looking for a bad connection.
I'd be looking for a bad connection.
jac
Well-Known Member
Given that it's a new battery and the old one also died, my suspicion would one of - a) that it's somehow powering the domestics side as well. and isn't purely used for engine start or b) that the alternator isn't charging it.
a is possibly more likely - maybe an old 1,2, both set up with some stuff wired to whichever bank was most convenient??
Assuming that the engine starts within a few seconds of being turned over it's hard to see that it could be drained by much more than a couple of Ah even if glowplugs are in use. That should be replaced by most alternators fairly quickly.
Quick and dirty test - turn on some obvious domestics, your domestic bank and your engine start battery, them turn off the domestic bank. if the lights or instruments or whatever stay on then the engine start is powering them and they need to be switched over to the correct bank.
If not, then when the engine is running at cruising rpm ( whilst tied alongside) measure the voltage at the engine start and domestic banks. If your alternator is only putting out say 13.4 volts then your batteries are not getting charged. If the raised voltage is only showing on the domestic bank then the alternator is only charging that bank and what has happened has been that your engine start has slowly discharged as the power needed to start the engine hasn't been replaced. Unlikely though given you managed to recharge it but maybe a faulty VSR or a VSR wired the wrong way round. They should only start charging the domestic bank once the engine start is full.
a is possibly more likely - maybe an old 1,2, both set up with some stuff wired to whichever bank was most convenient??
Assuming that the engine starts within a few seconds of being turned over it's hard to see that it could be drained by much more than a couple of Ah even if glowplugs are in use. That should be replaced by most alternators fairly quickly.
Quick and dirty test - turn on some obvious domestics, your domestic bank and your engine start battery, them turn off the domestic bank. if the lights or instruments or whatever stay on then the engine start is powering them and they need to be switched over to the correct bank.
If not, then when the engine is running at cruising rpm ( whilst tied alongside) measure the voltage at the engine start and domestic banks. If your alternator is only putting out say 13.4 volts then your batteries are not getting charged. If the raised voltage is only showing on the domestic bank then the alternator is only charging that bank and what has happened has been that your engine start has slowly discharged as the power needed to start the engine hasn't been replaced. Unlikely though given you managed to recharge it but maybe a faulty VSR or a VSR wired the wrong way round. They should only start charging the domestic bank once the engine start is full.
vasant
Well-Known Member
well indeed another interesting point.
I wdefinetely will check whether any domestic appliance is connected , but chances are low. Moreover there is no high consuming application the boat is small. On the other hand its old so wiring that might be 40 years old can have issues. Then however its to answer why this happens randomly....
i am not sure if in the switch there is some voltage controlled switch . That is when tried to crank light went on but didnt crank immediately after not even the lights started. This would also explain the relatively fast charging. If there is something that when battery goes lets say below 12.0 V cuts it off this would explain how after short time voltage is up again.
PaulRainbow
Well-Known Member
Very, very doubtful on the starter circuit. Beware of the red herrings regarding domestic equipment draining the battery, or 1-2-both switches. Unless you have some extremely greedy domestics there should be no way to flatten a battery in two hours, or to recharge it in 30 mins.
I'd still be looking for bad connections. Remove every battery cable at the batteries, starter, engine block etc and give them a good clean. Any one of those can cause the problems you describe, the connection isn't perfect, you turn the ignition switch on and the lights come on (just enough continuity for those) you turn to the start position and the contact is too poor for the current needed to start the engine, not only does the engine not start but the lights all go out. You crank it or jump start it (or in the case of a car you tow it) and it starts, vibration makes the faulty connection contact a bit better and next time you turn the key it starts.
Seen it a million times.
vasant
Well-Known Member
thanks, i think this will be next project to swap cabling etc. will have a look to it.
BTW i dont have one switch for both batteries, i have two switches one for each battery.
PaulRainbow
Well-Known Member
Good man :encouragement:
You could add a 3rd switch to link the two for emergency starting, rather than use the cranking handle
vasant
Well-Known Member
Good man :encouragement:
You could add a 3rd switch to link the two for emergency starting, rather than use the cranking handle
well actually i got as present las year a set of cables i have placed in the boat that i used for jump start
RichardS
N/A
An ever better man! :encouragement:
That is the most cost-effective solution and those cables can be very useful for other things as well, as I've found out.
Richard
VicS
Well-Known Member
TAKE CARE when using jump leads. It is possible for small spark produced when connecting or disconnecting them to ignite hydrogen gas given off by the batteries.
The chance of it happening is small but it can, and from time to time does, happen. A battery exploding in your face will spoil your weekend and probably the rest of your life.
The instructions when using jump leads on cars are always to make the final connection and break the first connection ( a negative) away from the battery itself. That ensures that there is no spark at a battery terminal. A similar precaution may not be so easy to achieve in a boat.
wotayottie
Well-Known Member
I'm astounded Vasant. Dont they do simple volts , amps, watts and DC in electrical engineering these days? Sorry that sounds unhelpful and maybe even rude and it isnt meant to be. But with an MSC in electrical engineering I would expect you to be providing the answer not the questions.
Anyway, to try and be more helpful:
1/ the charge current that a battery will accept depends on its state of charge. So foe example I found that my battery bank might take 45 amps when half flat but 6 hours later this was down to maybe 5 amps and the batteries were just beginning to become fully charged as measured by hydrometer. No way would a flat lead acid battery charge up in an hour.
2/ It could well be that you have mistakenly been allowing the battery to remain badly undercharged and this definitely damages its ability to hold charge. It may now be knackered .
3/ Batteries can fail in a number of ways and an internal short is one of them. In that case the battery will lose charge without anything drawing current from it - the losses could be entirely internal. Lead acid batteries do that to some degree anyay. They have a self discharge rate but usually its pretty low.
4/ the other alternative is that you have a discharge via the wiring.
If I were tackling the job my first step would be to remove the battery completely, take it home , put it on the battery charger for a day or more and then monitor it measuring its voltage every few hours. Is it self discharging or not? If it isnt then I would take it to my local garage and ask them to do a discharge test on it to test its capacity. Alternatively use a known resistance ( a headlight bulb for example) and discharge the battery down to 12.2 volts through that resistance measureing the time it takes. That will give you a rough number for its capavcity to decide if it is bu66ered or not.
If the battery is OK and with it fully charged its back to the boat. I would try to find hwre and how it was discharging. You can ofetn get a hint from what gets warm with the the battery conected but nothing switched on. Or you can bung an ameter in circuit and measure whats happening. That would also allow you to check the alternator output both amps and volts.
At this point its a detective hunt, taking fuses out of circuit and measuring the drain until you find the culprit.