bilge Bilge pump voltage

[ronnietucker]

I used my submerged bilge pump a couple of weeks ago to remove a couple of cm of water from the bilge and it worked fine. This week, nothing.

 

When I flick the switch to put the bilge pump on the voltage at the connector block shows as being only 10.8V. Strange. Could it be a faulty switch, or just that the pump has copped it?

 

I don't know the make of the pump I'm afraid as someone before me has put it in a very awkward place. Making it hard to get it out.

[Alan de Enfield]

16 minutes ago, ronnietucker said:

When I flick the switch to put the bilge pump on the voltage at the connector block shows as being only 10.8V

 

Try testing the voltage at the battery terminals, what are you getting ? then

Try switching on the bilge pump and testing the battery voltage at the battery terminals, what voltage are you getting ?

 

It could be :

1) The battery is flat.

2) The bilge pump sucked up some crud last time and has jammed the impellor causing a huge stalled load current draw.

 

If the battery is ok - from memory you have an outboard - will it start the engine, then you will need to get the bilge pump out, clean the impellor and try again.

[Tony Brooks]

24 minutes ago, ronnietucker said:

I used my submerged bilge pump a couple of weeks ago to remove a couple of cm of water from the bilge and it worked fine. This week, nothing.

 

When I flick the switch to put the bilge pump on the voltage at the connector block shows as being only 10.8V. Strange. Could it be a faulty switch, or just that the pump has copped it?

 

I don't know the make of the pump I'm afraid as someone before me has put it in a very awkward place. Making it hard to get it out.

10.8V is a flat battery and it is not clear if that 10.8 is with the motor attempting to operate or not. As Alan asked whet is the voltage at the lead of the battery terminals with the pump turned on AND off. That will help decide if its a battery or wiring fault.

 

Does the pump had a float switch plus manual override. If a float switch jammed up the pump would run 24/7 and flatten the battery and potentially eventually burn the motor out.

 

 

[ronnietucker]

38 minutes ago, Alan de Enfield said:

Try testing the voltage at the battery terminals, what are you getting ?

I'm off the boat at the moment, but when I tried the pump the battery was at 13.1V with the switch off. I have a solar panel keeping my batteries topped up. Hence, why I thought 10.8V was a bit odd when I know the battery is full.

31 minutes ago, Tony Brooks said:

whet is the voltage at the lead of the battery terminals with the pump turned on AND off

It would have been 13.V (roughly) with the pump switch off. Not sure of the battery voltage with the pump on.

32 minutes ago, Tony Brooks said:

Does the pump had a float switch plus manual override.

No idea. I've never seen the elusive wee beastie. I'm hoping I can reach it by unscrewing the table hole, plate, thing, in the floor. If not, I may have to just disconnect it, leave it there, and connect a new one. Which reminds me, I'll need to measure the area to make sure a new one (if needed) would fit.

34 minutes ago, Tony Brooks said:

If a float switch jammed up the pump would run 24/7 and flatten the battery

I keep the pump switched off.

 

I'll fight with it again next week and try and get battery voltages with the switch off and on.

 

Thanks for the advice!

[Tony Brooks]

Some bilge pumps can be switched "off" yet still  turn themselves on with a  float or electronic switch when needed although they should be wired to a three position switch (auto - off - run) I have known some that are not. Just be aware.

[Alan de Enfield]

Just now, ronnietucker said:

I'm off the boat at the moment, but when I tried the pump the battery was at 13.1V with the switch off. I have a solar panel keeping my batteries topped up. Hence, why I thought 10.8V was a bit odd when I know the battery is full.

That is not the battery voltage - it is the output voltage of the solar panels.

To get the battery voltage, cover the solar panels, wait for 1hr (or longer - 2 is better) switch on a load ( a light or something on for a couple of minutes), switch it off and then test the battery voltage. This gets rid of the 'surface voltage' and allows you to take a true reading of battery voltage.

 

What is the water level like in the battery ?

Is the battery warm when on charge ?

Are the end walls or side walls of the battery slightly 'bowed' outwards ?

 

As I described in an earlier thread - it is not really 'voltage' that we need but Ah.

 

From the other thread :

 

It doesn't matter - if the battery is knackered you could go on a 24 hour cruise.

Imagine a 4 litre bucket which is 3/4 full of mud and stones (equivalent to your batteries with a load of sulphate) you can only put in 1 litre of water and it is full - no matter how much water you pour into the bucket it will just not hold any more

 

Once a sulphated battery(s) tells the alternator 'hey - stop, I'm full now" the alternator will stop putting any more 'leccy into the battery.

If your capacity is very low, it could be that the battery is fully charged after 1 hour engine running.

 

I postulate that you have not been 'living off the batteries' you have been living off the external supply (shore-line and solar).

We (knowingly) did the same for some time - it saved buying new batteries and we were not intending to move.

 

I think that you need to understand that there are two totally separate criteria when talking about batteries.

 

1) Capacity - measured in Ah and basically the bigger and heavier the battery the higher the capacity. for example a 100 Ah battery would (in theory) run a 1 amp load for 100 hours, or a 100 amp load for 1 hour, or any other permutation.

 

2) Voltage - (irrespective of capacity) 12 volt lead acid batteries will be 12 volts (that is a bit of a misnomer as they are around 12.8v when fully charged, and they will be charged at anything up to 14+ volts, the surface charge (until it is absorbed into the plates) can also be (say) 14v). 

 

You can have a tiny, tiny  battery maybe the size of matchbox - it will still be "12v" but the capacity is probably 'milli-amp hours'.

As far as we boaters are concerned we need 'capacity' not voltage, so as our 100Ah battery ages and gets clogged up, the capacity reduces to 75Ah, then, 50Ah, then 25Ah …………. (but will still be at "12v").

We measure the capacity as the time taken for the battery to go 'flat', when the capacity no longer supports our usage patterns the batteries are replaced - they still show 12v but they no longer have the 'power' we need.

 

We measure the state of charge of the battery by measuring the voltage, eg 12.2 volts = approx. 50% charged, 12.8v = 100% charged, and the charging current, so that when the charging current has remained at 1% of battery capacity (so charging at 1 amp for a 100Ah battery) and not changed for an hour, AND the charger voltage is around 14.4v you can say the battery is charged.

[lampini]

4 minutes ago, Alan de Enfield said:

That is not the battery voltage - it is the output voltage of the solar panels.

To get the battery voltage, cover the solar panels, wait for 1hr (or longer - 2 is better) switch on a load ( a light or something on for a couple of minutes), switch it off and then test the battery voltage. This gets rid of the 'surface voltage' and allows you to take a true reading of battery voltage.

 

What is the water level like in the battery ?

Is the battery warm when on charge ?

Are the end walls or side walls of the battery slightly 'bowed' outwards ?

 

As I described in an earlier thread - it is not really 'voltage' that we need but Ah.

 

From the other thread :

 

It doesn't matter - if the battery is knackered you could go on a 24 hour cruise.

Imagine a 4 litre bucket which is 3/4 full of mud and stones (equivalent to your batteries with a load of sulphate) you can only put in 1 litre of water and it is full - no matter how much water you pour into the bucket it will just not hold any more

 

Once a sulphated battery(s) tells the alternator 'hey - stop, I'm full now" the alternator will stop putting any more 'leccy into the battery.

If your capacity is very low, it could be that the battery is fully charged after 1 hour engine running.

 

I postulate that you have not been 'living off the batteries' you have been living off the external supply (shore-line and solar).

We (knowingly) did the same for some time - it saved buying new batteries and we were not intending to move.

 

I think that you need to understand that there are two totally separate criteria when talking about batteries.

 

1) Capacity - measured in Ah and basically the bigger and heavier the battery the higher the capacity. for example a 100 Ah battery would (in theory) run a 1 amp load for 100 hours, or a 100 amp load for 1 hour, or any other permutation.

 

2) Voltage - (irrespective of capacity) 12 volt lead acid batteries will be 12 volts (that is a bit of a misnomer as they are around 12.8v when fully charged, and they will be charged at anything up to 14+ volts, the surface charge (until it is absorbed into the plates) can also be (say) 14v). 

 

You can have a tiny, tiny  battery maybe the size of matchbox - it will still be "12v" but the capacity is probably 'milli-amp hours'.

As far as we boaters are concerned we need 'capacity' not voltage, so as our 100Ah battery ages and gets clogged up, the capacity reduces to 75Ah, then, 50Ah, then 25Ah …………. (but will still be at "12v").

We measure the capacity as the time taken for the battery to go 'flat', when the capacity no longer supports our usage patterns the batteries are replaced - they still show 12v but they no longer have the 'power' we need.

 

We measure the state of charge of the battery by measuring the voltage, eg 12.2 volts = approx. 50% charged, 12.8v = 100% charged, and the charging current, so that when the charging current has remained at 1% of battery capacity (so charging at 1 amp for a 100Ah battery) and not changed for an hour, AND the charger voltage is around 14.4v you can say the battery is charged.

Yes, this WAS proper helpful! ?

[Tony Brooks]

18 minutes ago, ronnietucker said:

I'm off the boat at the moment, but when I tried the pump the battery was at 13.1V with the switch off. I have a solar panel keeping my batteries topped up. Hence, why I thought 10.8V was a bit odd when I know the battery is full.

 

It would have been 13.V (roughly) with the pump switch off. Not sure of the battery voltage with the pump on.

 

13.1 V with a charging source running seems very low to me unless it was a  dull day so that is all solar could produce. It suggests the batteries are pulling the charging voltage down because they are well discharged.

 

If the voltage stays the same then its probably a fuse, faulty switch, broken wire, or a open circuit in the pump motor fault. If it drops then its probably well discharged batteries, on your reading and with the further information I suspect the latter but why I am not so sure.

Edited September 9, 2018 by Tony Brooks

[ronnietucker]

4 minutes ago, Tony Brooks said:

13.1 V with a charging source running seems very low to me unless it was a  dull day

Scotland. Say no more.    I think I was getting about 0.5A for most of Saturday.  

 

Sorry, confusion was mine. The starter battery was 13.1V, my second battery was about 12.6V (from memory). The first battery is for starting the engine and nothing else. The second battery is for my lights, pumps, etc.. The solar panel keeps the first battery topped up and when the first battery is full a VSR passes any charge to the second battery. I'm not connected to shore power.

 

But I'll check for voltages and switches on/off next week when I'm down at the boat again.

[Tony Brooks]

6 minutes ago, ronnietucker said:

Scotland. Say no more.    I think I was getting about 0.5A for most of Saturday.  

 

Sorry, confusion was mine. The starter battery was 13.1V, my second battery was about 12.6V (from memory). The first battery is for starting the engine and nothing else. The second battery is for my lights, pumps, etc.. The solar panel keeps the first battery topped up and when the first battery is full a VSR passes any charge to the second battery. I'm not connected to shore power.

 

But I'll check for voltages and switches on/off next week when I'm down at the boat again.

 

Sorry but that is NOT how a VSR works. The VSR has an pre-set "turn on" voltage and another pre-set "turn off" voltage. The voltages do vary a bit but typically around 13.6 to 13.8 volts turn on and around 13.2 to 13.4 volts turn off. Check the date for your own VSR. A discharged battery will hold the charging voltage down but it is very unlikely to be fully charged when the turn on threshold is reached, especially with just solar input. The battery may be between 60% and 80% of fully charged but fully charged it will not be.

 

12.6V with a charge source running is worse, flat battery wise, than 13.1V. Which battery is the bilge pump linked to?  I think it is still more likely a flat battery problem than anything else at present but I wait to see..

[ronnietucker]

I did some tinkering with the bilge pump yesterday.

 

Battery 1 (engine starter only) and disconnected from the 100W solar panel: 12.8V

Battery 2 (all lighting, pumps, etc.) and disconnected from the solar panel: 12.7V

 

I have to assume that Battery 2 is functioning OK as it will run the pump which delivers water from the tank to the tap. Similarly, it works the 12V LED lighting.

 

I managed to get the bilge pump out from under the floor eventually, and I'll buy a new one since it's only £15 for a replacement. No major money loss if it turns out to be something else.

[ronnietucker]

Yep. Turns out it was a faulty pump after all.

Bought a similar model, fitted it, and it worked first time.

Hoorah!

[WotEver]

1 hour ago, ronnietucker said:

Yep. Turns out it was a faulty pump after all.

Bought a similar model, fitted it, and it worked first time.

Hoorah!

We went through three in as many months then the next one lasted until we sold the boat... just bad luck I guess.