Battery advice

chriscraft · 11 October 2010, 00:49

The island where my RIB is berthed suffered 20 inches of rain in 3 days - an unprecedented amount even for the tropics. I was away for the week, and when I returned the battery which powered the bilge pump was flat, presumably from pumping overboard such a huge amount of rain. Worse, It won't re-charge using the engines, it remains flat as a proverbial. I have an 'on-off' swithch for each battery, and a third switch to gang the two batteries. Both batteries were installed new just 6 weeks ago. I replaced the original lead acid with AGM, which I thought was safer in a RIB. Is there any thing I can do to resurrect the dead battery (it wasn't cheap)? If I replace it, what should I replace it with? Another AGM would be throwing good money after bad if it can't recover from a discharge. I don't want to replace the other (good?) AGM at this stage. Can I gang an AGM battery with another type (if another type would be better to power the bilge pump in these circumstances). Any advice would be greatly appreciated.

Pikey Dave · 11 October 2010, 05:12

If the battery was immersed & water contaminated it, it's dead. If it's just severely discharged then a good battery charger/reconditioner such as a ctek should revive it. If it won't, try swapping it under warranty. If it's immersion that killed it, any other battery would have suffered the same fate if water got in to it. If if if.............

BogMonster · 11 October 2010, 10:10

also how about one of those solar chargers to keep it topped up?

though with 2 foot of rain in less than a week presumably the sun didn't put in much of an appearance

paul holder · 11 October 2010, 10:34

if this happens on a regular basis have look at the hawker gell rap traction .there is no vent required ,. place the battery in a ip64 box & gland each lead output

simsy · 11 October 2010, 13:40

To help recovery, use a power supply with limited current and ajustable voltage. (normal lab power supply).

Set to a low current, (around 100mA) and increase the voltage upto a max of 24 volts just to get it started, you may not reach 24 as the 100 mA current will limit it if it starts to charge. Voltage will be at 14 or so, within a few seconds/ mins... The capacity of the battery may be reduced however , as they do not like been deep discharged at all........

The battery reconditioner does some thing similar...

Battery never got wet , right?

jyasaki · 11 October 2010, 17:36

I would personally start off by trying to get some kind of warranty settlement. Most lead-acid batteries don't take to being run flat all that well. In truth, most don't like being run below about 50%, but that's a different thread, I think.

If you do want to try and revive them, you need something to get rid of the sulfating that has likely occurred between plates. There are several "conditioning" or desulfation chargers on the market that use a high frequency AC signal on top of the DC charge voltage that claim to break up the sulfates, but I haven't heard of any reviews (though I also haven't looked for them.)

Here's one:
http://www.batterystuff.com/battery-...ds/pulse-tech/

I, personally, figure on replacing the boat batteries every 3 or 4 years regardless of problems (not cheap, but considerably less expensive than needing a long tow if the motor won't start.)

jky

captnjack · 11 October 2010, 19:48

Does the boat not self drain?
Mine will accumulate some water but if I were leaving it outside I'd actually disconnect the bilge pump and just let a few cms of water persist in the bottom until I went to use it.

Ian Austin · 11 October 2010, 21:10

Chriscraft
AGM batteries are totaly sealed, so they can be totaly submersed (not ideal, but) if it has been totaly flattened out get a frequancy charger, these are what they are supposed to be charged with, like this :-
http://cgi.ebay.co.uk/GOLF-BATTERY-C...item3cb161c0c5
I have an AGM battery and the first one died because petrol melted the casing and let air in (they are vacuum sealed).

chriscraft · 11 October 2010, 23:53

Quote:

Originally Posted by captnjack

Does the boat not self drain?
Mine will accumulate some water but if I were leaving it outside I'd actually disconnect the bilge pump and just let a few cms of water persist in the bottom until I went to use it.

The boat self drains only on the move.
20" of rain is waist deep in town's main street, cars swept down hillsides and buildings and roads washed away. Without a bilge pump there would be more than a few cms of water in the bottom of the boat (the boat would more likely be on the bottom!)

captnjack · 12 October 2010, 03:33

Quote:

Originally Posted by chriscraft

The boat self drains only on the move.
20" of rain is waist deep in town's main street, cars swept down hillsides and buildings and roads washed away. Without a bilge pump there would be more than a few cms of water in the bottom of the boat (the boat would more likely be on the bottom!)

Are you sure? Does it have a flapper or an elephant truck? I mean its a RIB right? It'll sink lower into the water but I would expect the tubes to be no more than 1/3rd submerged. Most RIBs can completely flood and remain afloat. There is no battery in existence which is going to power a bilge pump for days keeping up with almost 2 feet of water inflow.