What is flattening my battery?

Thepipdoc

Thepipdoc

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I inadvertantly left my battery isolator switch in the "1" position for 23hrs.
When I left the boat it was showing 12.5 volts but when I returned 23hrs later it was showing 11.4 volts.
I checked to see what could be drawing current form it and there were 3 devices that were left switched on.
1. The depth sounder - constantly displaying the depth
2. The water system - if a tap was turned on or the toilet flushed it would pump water (though no one was on board so it wasn't).
3.The electric toilet was left switched so that it could be activated if flushed (though no one was on board so it wasn't).

Could either of these items be flattening the battery just by being left in the "ON" position?

Thanks
 
Hard to say for sure what's causing the drain, the sounder would use a bit. If you suspect that you may have something that's imposing a sneaky drain on your power, hook an ammeter up and switch everything off. If you have a current draw, you'll have to poke around and find what it is.

A good investment is a clip on ammeter. You can easily clip it on to various places in the boat as required and easily isolate problems. I recently had a charging problem, a minute or so with the clip on ammeter soon pinpointed the problem.

One of these will do you :

http://cgi.ebay.co.uk/Sealey-BT98-1..._Measurement_Equipment_ET&hash=item2a071db775

Also available in 75-0-75 Shop around for the best price.
 
Do you have CO2 detectors ? Ihad a malfunctioning unit a few years back that ate batteries. It could empty a 130ah battery in a week before I discovered the problem.
 
I agree the way forward is to check current with an ammeter but the clip on one in the link is barely sensitive enough to measure the sort of current you may be looking for unless its is a pretty big battery you have knocked flat in 23 hours.

None of the items you mention should flatten a battery in that time.

The water system should not use anything unless it is losing pressure and the pump cut in periodically.
The toilet should not use any unless it is flushed

Check what current the echosounder takes ... mine only take 0.1 amps
 
Last edited:
Battery Monitor

How about the NASA battery monitor, it's easy to wire in and will tell you what is being drawn and what is left in the batteries.

I switched everything off, it read 0.1A, then turned things on and off to see what drew what. Once the unit has "learned" the batteries it's connected it works out what you have left

Good luck

Ian
 
All sensible suggestion so far and some I hadn't really considered till now.

One of the batteries is only 2 weeks old and the other, the one that went flat, is about 3 months old.

I have had another thought...... the boat was converted to run on LPG 12 years ago ( from New) and part of the conversion includes a solenoid to each gas vapouriser that controls the gas. Would the solenoids be using power?
 
Thepipdoc said:
All sensible suggestion so far and some I hadn't really considered till now.

One of the batteries is only 2 weeks old and the other, the one that went flat, is about 3 months old.

I have had another thought...... the boat was converted to run on LPG 12 years ago ( from New) and part of the conversion includes a solenoid to each gas vapouriser that controls the gas. Would the solenoids be using power?
Click to expand...

How big is the battery that went flat ?
 
Thepipdoc said:
110ah
Click to expand...

Given that the battery was nearly flat, you're looking at a big drain. Maybe something in the 4 amp region, assuming the battery is in good shape. I know it's only three months old, but still a possibility that it could be faulty.

I appreciate VicS's comment that the voltmeter i linked to may not be the best thing for finding very small "leaks", in this case it should do the job nicely. At £18.45 it's certainly no ill store to have in the toolbox.
 
PaulGooch said:
Given that the battery was nearly flat, you're looking at a big drain. Maybe something in the 4 amp region, assuming the battery is in good shape. I know it's only three months old, but still a possibility that it could be faulty.

I appreciate VicS's comment that the voltmeter i linked to may not be the best thing for finding very small "leaks", in this case it should do the job nicely. At £18.45 it's certainly no ill store to have in the toolbox.
Click to expand...

Thanks for the advice - presumably if I were to temporarily rig a meter between the battery positive+ terminal I should be able to measure what (if any) current is being drawn of the battery and switch on/off the various appliances till I find which one is causing the big drain?
 
Thepipdoc said:
Thanks for the advice - presumably if I were to temporarily rig a meter between the battery positive+ terminal I should be able to measure what (if any) current is being drawn of the battery and switch on/off the various appliances till I find which one is causing the big drain?
Click to expand...

Yes. If you have an ammeter you can do that. If you have to purchase an ammeter, the type i linked to just clips over the cable, no need to disconnect anything.
 
Thepipdoc said:
All sensible suggestion so far and some I hadn't really considered till now.

One of the batteries is only 2 weeks old and the other, the one that went flat, is about 3 months old.

I have had another thought...... the boat was converted to run on LPG 12 years ago ( from New) and part of the conversion includes a solenoid to each gas vapouriser that controls the gas. Would the solenoids be using power?
Click to expand...

Yes it really could be the solenoids.

I have a solenoid operated / spring return valve to open the heater flow to my heater matrix, and that uses a good couple of amps IIRC.
So depending upon the size and number of them this could easily be the source of your problem.
 
Thepipdoc said:
All sensible suggestion so far and some I hadn't really considered till now.

One of the batteries is only 2 weeks old and the other, the one that went flat, is about 3 months old.

I have had another thought...... the boat was converted to run on LPG 12 years ago ( from New) and part of the conversion includes a solenoid to each gas vapouriser that controls the gas. Would the solenoids be using power?
Click to expand...

Are the solenoids activated by just having the power on, i suspect they wouldn't open until you turn the ignition on.
 
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