Monday, 7 May 2018

Non-functioning bilge pump turns out to be dead starter battery

When we came to the boat last month for a brief stopover I was perturbed to find that the bilge pump didn't work. It was the sort with an in-built float switch; there was enough water down there for it to have operated, but when I removed it and pressed the manual override it made a pathetic small noise and did nothing else.

Oh well, time to buy a new bilge pump, I thought. A new pump obtained, I installed it and ... the same result. It was only then that I thought of checking the voltage at the pump. 6V. Surely there must be shome mistake! I traced the wire back to the circuit breaker and then to the starter battery. Yup, only 6V there too.

Then I had my only bright idea of the day: I wired the bilge pump to the domestic battery bank. This is constantly being topped up by the solar panels so should be a better bet than the starter battery anyway. When we got home I ordered a new starter battery.

I fitted it yesterday - not an easy job as it lives in a wooden box tucked away on the swim and secured by inch-high steel upstands. All now seems tickety-boo. I have now installed a dedicated voltmeter so I can keep an eye on the battery's performance.

Today, then, we set off on our first trip of the year, travelling from Fazeley to Atherstone (above Lock 9). We're on our way to Debdale Wharf for blacking.

No photos, sorry, as I'm writing this on my telephone.


Halfie said...

Er ... must be my age! I had forgotten that I'd written the previous post. Sorry for putting you through it all over again.

Nick said...

We decided a while ago to put the automatic bilge pump on the domestics not the starters. I think we have too many boat wiring traditions that are still based on a caravan towed behind a car!

There are several benefits I can see - at least:
a) the domestics have far more capacity if something causes a lot of water to come in
b) domestic batteries are designed to be run down and come up again
c) you have top-up from the solar
d) if the float switch sticks and flattens the batteries, you can start off the engine battery and recharge the domestics.

Halfie said...

Nick, all good points except I don't think any lead-acid battery would take kindly to being completely flattened. Can domestics take a deep discharge better than a starter battery?