Battery Life for a bilge pump

P

pij27

Well-Known Member
Joined
22 May 2016
Messages
125
Location
Ryde Isle of Wight
Visit site
I am considering fitting an electric bilge pump to my 18ft boat. It will have a float switch and be connected to a 12V battery, I will not have a shore supply. Does anyone have any ideas how long a 45Ah battery should last, weather depending, to help keep the boat water level low? I am also considering fitting a solar panel, but not sure what sort of value this would be.
The initial set up will be with the bilge dry, then fitting the switch and pimp to the boat and a fully charged battery. Should this last a little while, or should I be looking to charge the battery every few weeks? I know that weather will pose a big part of this equation, but just trying to get a feel for this.

Thanks

Peter
 
You need to look up the current requirements of the bilge pump you are considering. You can then calculated how many hours of continuous running you would get out of half the capacity of the battery so around 25Ah. The big imponderable would then be how often and for how long the bilge pump will kick in .... only you can estimate that as it depends upon how watertight your boat is. :)

Richard
 
How long is a piece of string? I suggest you need a solar panel and/or wind turbine (plus regulator) to keep the battery charged, and ideally you want two batteries; an engine start battery plus a "domestic" battery, with a 1/2/both switch. That kind of setup is common. You could measure the actual drain over a 24 hour period, which would give a better idea of what you need. It's a common issue.
 
As Richard wrote, you'll need to do the simple sums, and then guess how much the pump might have to shift over a typical period. For guidance, the smaller pumps draw around 2A, so would offer around 12hours service on the battery you mention. Trouble is the battery has no idea what's good for it. If left to its own devices it would just carry on powering the pump until it was dead flat, which would seriously reduce its lifespan. So the frequency at which you're able to check it would be another important factor.

In assessing the pump, do bear in mind that its stated rating will be at zero head. The accompanying literature should tell you how fast it pumps with a head to work against.

Is it an open boat, by any chance? If so, does it have any sort of cover?
 
What sort of boat?
Does it leak?
Does it let the rain in?

I know people with open RIBs etc, and mildly leaky wooden boats who find a small solar panel very useful with a bilge pump and car battery setup.
Such boat still need looking at regularly though.
 
macd said:
...but perhaps not so common on 18 footers ;)
Click to expand...

Maybe not, but depending on how it's used and what it's got, electrical requirements can be similar for an 18 footer and a 30 footer. Mine's only 23', but I have solar panels, and two batteries, as well as shore power and mains charger.
 
lw395 said:
What sort of boat?
Does it leak?
Does it let the rain in?
Click to expand...

From another thread, it's a Seafarer 19, a centreboard dinghy-with-a-lid with a large open cockpit and small cuddy/cabin. So while not quite an open boat, it might as well be one for the purposes of this thread.

(For Elton - no inboard and battery system, presumably a hand-start outboard if anything.)

Pete
 
prv said:
From another thread, it's a Seafarer 19, a centreboard dinghy-with-a-lid with a large open cockpit and small cuddy/cabin. So while not quite an open boat, it might as well be one for the purposes of this thread.

(For Elton - no inboard and battery system, presumably a hand-start outboard if anything.)

Pete
Click to expand...

Then the first thing to do is to get a cover made to keep out as much rain as possible.
Most of the problem then disappears.
Even with solar charging and plenty of battery, bilge pumps can still fail due to causes beyond our control, been there!....
 
So from the replies a good cover and then pump and battery setup with a secondary charging system. This should at least give me a good chance of keeping water level down when not around the boat. Thanks
 
If the only water entering the boat is rain into an open boat then a 45Ah battery will last for a long time, by back of an envelop calculation suggests you would need less than 20Ah of usable capacity for a year of rain.
 
bedouin said:
If the only water entering the boat is rain into an open boat then a 45Ah battery will last for a long time, by back of an envelop calculation suggests you would need less than 20Ah of usable capacity for a year of rain.
Click to expand...

Similar calculation on the back of an envelope here. ........ consumption by the bilge pump probably less that the self discharge rate.

It would be bad for the battery not to recharge it though. The problem will be that during the wetter months of the year charging from a small solar panel will probably not keep the battery fully charged.

Overall a 5 watt panel might be big enough, and that wont need a regulator when used with a 45 Ah battery. A 10 watt panel should be more than adequate but that will need a regulator.
 
Hi Vic I would go 10w without a regulator on a decent sized battery but no more. However OP main concern is that the battey may be flattened and so destroyed. I suggest get an old car battery perhaps from ascrapper's yard and see how it goes. Check with a volt meter after a while and after rain to get a feel for how long it will last. Yes I think a solar panel would be good. ol'will
 
A serious downpour can dump a lot of water into an open boat. I had a flattish bottomed 18' open boat, a few years ago a heavy downpour in May got the water almost to the inboard's dipstick and made the whole thing very unstable. got a cover made and installed a little pump. All OK after then.
 
pij27 said:
I am considering fitting an electric bilge pump to my 18ft boat. It will have a float switch and be connected to a 12V battery, I will not have a shore supply. Does anyone have any ideas how long a 45Ah battery should last, weather depending, to help keep the boat water level low? I am also considering fitting a solar panel, but not sure what sort of value this would be.
The initial set up will be with the bilge dry, then fitting the switch and pimp to the boat and a fully charged battery. Should this last a little while, or should I be looking to charge the battery every few weeks? I know that weather will pose a big part of this equation, but just trying to get a feel for this.

Thanks

Peter
Click to expand...

First I would get rid of the requirement for a pimp:), then consider the products shown in these links ;
www.gaelforcemarine.co.uk/en/ie/Dra...cDiNIU25Bswg3MoRSU0rWs5NZxEP1vhgaAhhFEALw_wcB
www.securefixdirect.com/wave-powered-bilge-pump---wind-natural-nature-suction-boat-marine-1122-p.asp
also, if you Google "bilge pump powered by wave action" you will come across links to multiple threads on the on these fora.
 
You must log in or register to reply here.

Other threads that may be of interest

W
Battery suicide
Replies
17
Views
604
Refueler
Refueler
P
Adding fuses to my batteries
2 3 4
Replies
61
Views
2K
AngusMcDoon
AngusMcDoon
P
Old AGM battery.
Replies
9
Views
308
samfieldhouse
samfieldhouse
webcraft
Resetting SmartShunt to 100%
Replies
7
Views
346
webcraft
webcraft

Share this page

Top