battery draining how do i check???

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rowey2006

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www.birdcareuk.com
hi all
just a quick question
my battery may have a current drain how do i check with the volt meter if there is?

i.e volt meter on terminals are giving a nice 12.6v but which setting do i use on the volt meter to see if there is something draining the batery.

your help would be great
thanks marc
 
You need an ammeter to check this or at least a multimeter with current ranges.

The ammeter will have to go in series with the battery lead. So make sure nothing is switched on. Disconnect one of the leads and connect the ammeter to the vacant battery terminal and the disconnected lead. BUT make sure the meter is swiched to, and its lead connected for, the highest current range first, often 20 amps If no reading work your way down through the ranges (reconnecting the meter lead to the appropriate socket as you do so)

With a sensitive meter you are almost certain to get a low reading eventually.


WHEN YOU HAVE FINISHED make sure you switch the meter off or switch it to a volts range before using it again or you'll foget and connect it to a power source and blow the shunts! If it is a meter with a separate socket for the highest amps range make sure you do not leave the lead in that socket!

I am sorry but people asking basic questions like this give me the heeby jeebies a bit. If you no not have the knowledge to do something as simple as checking the current in a circuit then maybe you should not be tinkering with the electrics. I'm not wanting to sound patronising as I realise that you have to start on the learning curve somewhere (and really that was in your O level or GCSE science lessons) but please be careful and if you are unsure of yourself ask for more help or get someone who knows a bit more to help you.
 
If you are like me and dont have GCSE's or O levels then join the numb nuts society I will start it off. OR like me get hold of a book called the The Electrical Bible or something like that and it will talk you through all aspects of electrical boating needs ( without the smart arsed remarks).
 
[ QUOTE ]
without the smart arsed remarks

[/ QUOTE ] I am sorry you want to take that attitude. What i said was not intened to be smart arsed. I answered the question that was asked in the best way I could but also expresed some some reservations and did so with apologies for doing so. I would not like to hear that someone had done damge to their electrical system or blown their battery up in their face due to their own lack of understanding of basic electrics or my inadequate instructions. Prhaps the only sound advice is to say "Get someone who knows what they are upto to check it all out."

Your advice to get a good book on the subject is good but does not help with the immediate problem
 
Yes Marc that is the symbol for the DC current ranges. You will see that the DC volts ranges are maked with a V and and the same lines. The AC volts ranges are marked with V ~. Inexpensive mulimeters do not usually have AC current ranges but If they did they would be maked A~


My meters have 10 amps as the highest range I notice (not 20 as I implied previously) and to use it the positve lead has to be moved to a separate socket as well as the range being selected on the switch.
 
Ensure that every thing IS switched OFF, disconnect the negatives from all batteries, from the neg battery post put you meter (12 volt range) between it and the negative cable. in theory should be nothing, is there is you have a circuit, Leave the meter connected, now disconnect every circuit one at a time until you find the culprit. If you feel that you cannot deal with the fault its time to call the pro`s. Good luck.
 
That's another way of doing it but with the meter on the 12 volt range. Its is probably safer in fact but a modern digital voltmeter is so sensitive I suspect you will almost certainly get a reading.

The advantage of checking the actual current flowing is that one can then decide if there is a problem worth investigating or whether it's a small leakage can be ignored

Disconnecting circuits one at a time is easy to say but almost certainly more complex to do. Ultimately if a significant current flow is detected then that is the way forward though.

BTW Marc until someone buys you the "12volt Bible" for Xmas you may find the electrical notes HERE useful.
 
Where exactly in Vic's reply did you read any "smart arsed remark"? His advice was 100% correct and also made the point that working with 12 V batteries can be dangerous ,especially to members of the "Numb nuts Society"
 
right done what you have said!
please check what i have done to make sure!

made sure nothing is switched on.
positive cable connected to battery + post.
negative cable removed from battery -post.
turned on multimeter to A-and three dots under the - and at the 20m setting.
put the black wire from the multimeter to the battery - post
and the red wire from the multimeter to the boats negative cable that would have gone on the battery - post.

iam i right so far hope so.

the meter reading with all the above read 0.00

if i have done this correct please let me know and i havent got a battery drain which is good as iam just checking that i havent.

regards
marc.
p.s thanks for the help for a simple job done rather than get a pro out to say nothing up but thats 50 quid for my trouble.
 
no i havent got a problem. i just dont use the boat often enough and with no electric hook up i want to make sure the batterys are not getting drained from a little 12volt gremling
i dont want to be buying new batterys if they get drained to zero volts.
i just wanted to know how to check it
if i have done everything ok on last reply i have no problems and i have learnt something.

marc.
 
In that case,why don't you just disconnect the batteries when you are not on the boat?that way you can be sure that there can't be any current drain.
 
Just a thought - while you have the ammeter hooked up it is useful to do a "load check" on your DC various circuits. To do this you can switch on individual loads one at a time and make a note of the ammeter reading. Then you will have a list of each circuit (like nav lights, cabin lights etc.). This way you can have a better feel for how your battery is loaded under the different circumstances and how long you can expect your battery to last (assume you can only use 50% of the total AH capacity).

The total load is sum of the individual loads asuming they are on 100% duty cycle which doesn't work for fridges and autopilots as they have loads that switch on and off.

Last year I bought a battery monitor which constantly shows battery load and also AH remaining as a % and also time remaining before reaching 50% discharge. NASA have brought out a relatively low cost unit (less than half the cost of mine which was a BMV unit) and if you are having battery problems these units are very helpful as it will give you charge current also.
 
Reasonable idea, but NOT with the meter set to 20mA which seems to be how he's done it, VicS' sensible advice to start with the highest current range being ignored apparently. With no fault present, no problem so no damage done in this case. Try switching on lights or other loads drawing significant current and goodbye meter! (Or it's internal fuse anyway - which is probably non standard making finding a replacement difficult.)
 
I think some of this may underline my reservations at the beginning however if there is 0.00 indicated on the 20mA range then there is is no problem (or he has blown the fuse anyway!)

BTW My little multimeters take 250mA quick blow 20mmx5mm fuses which I bought from Maplin, like the meters. The 10 amp range is however unfused.
 
The meter will survive the current rating of it's maximum setting regardless of the range selected so a meter capable of measuring 10 A (most common) will be fine even if the meter is set to 20mA range (probably just show 99.99 or Over-range). I must admit I did assume that the range would be adjusted upwards to the max when making load measurements.

I do admit that Vics first comments were spot-on - and seems to have answered the basic point.
 
[ QUOTE ]
I do admit that Vics first comments were spot-on - and seems to have answered the basic point

[/ QUOTE ]

Thanks, nice to get something right now and then! Won't last SWMBO comes home tomorrow after a weekend away.
 
thanks all for the comments

my multimeter is probably the same as yours, i did have it set on the 10a first and went down to 20ma thus quoting fine setting on the meter. and no i havent blown the fuse.

thanks again
can i use the same proccedure on a car??

marc
 
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