Boiled Batteries!

[Trev]

We parked our boat in the marina at the end of October last year. We had cruised during the summer 2011 and we left it without a hook up relying on the solar panels (2 x 136W & 2 x 68W) which run thro an MPPT controller. We made regular trips to the boat over winter and the Sgauge reading was never below 90%. Plugging into the mains we always left the batts at 100% before we left.

 

We recently returned to the boat to the smell of sulphur to find that two of the four 135amp batts were seriously gassing off and the SGauge reading was down to 32%.

 

We hadnt left anything on to drain the batteries and hadnt done anything different on previous visits to the boat.

 

The carbon monoxide detector was showing 22ppm so we disconnected the boiling batteries.

 

The solar panels were still showing as putting amps into the batteries. Not an excessive amount I think is was 4 or 5 amps. I will be replacing them all at some point but I cant work out what caused the failure so as not to have it happen again.

 

Anyone got any thoughts or had a similar experience?

Thanks

Trev.

[Guest]

We parked our boat in the marina at the end of October last year. We had cruised during the summer 2011 and we left it without a hook up relying on the solar panels (2 x 136W & 2 x 68W) which run thro an MPPT controller. We made regular trips to the boat over winter and the Sgauge reading was never below 90%. Plugging into the mains we always left the batts at 100% before we left.

 

We recently returned to the boat to the smell of sulphur to find that two of the four 135amp batts were seriously gassing off and the SGauge reading was down to 32%.

 

We hadnt left anything on to drain the batteries and hadnt done anything different on previous visits to the boat.

 

The carbon monoxide detector was showing 22ppm so we disconnected the boiling batteries.

 

The solar panels were still showing as putting amps into the batteries. Not an excessive amount I think is was 4 or 5 amps. I will be replacing them all at some point but I cant work out what caused the failure so as not to have it happen again.

 

Anyone got any thoughts or had a similar experience?

Thanks

Trev.

 

It sounds like either your charger (assuming it was on) has over charged them but the most likely cause is that the 2 batteries that are boiling have suffered and internal short and basically your charger is putting more volts in than they can take. One other possible cause I've seen suggested is poor connections across the wiring of the bank

 

One of ours failed like this but whilst under charge from the alternator though but others have reported similar failures whilst under mains charge, it normally initiates a discussion about the wisdom of leaving batteries on charge from a mains charger but we do exactly the same as you - (minus the solar ans SG)

 

There are some tests you can carry out but others with better knowledge than me will be along shortly.

 

How old is the bank?

Edited August 21, 2012 by The Dog House

[Pretty Funked Up]

Initial thoughts would be the solar controller has done a funny and completely over charged the batts OR just pure coincidence that it 'was their time to go' (the batteries i mean).

[Trev]

The four Numax batts were only two years old and only being charged by the solar panels. Two had boiled dry but and one was warm but not boiling. The other batt seemed ok.

My solar controller was bought from fleabay, Germany. Had no problems with it since fitting.

 

I think in future I will disconnect all charging to the batteries and isolate them and just turn up once a month and put a charge in them.

Trev.

[by'eck]

We parked our boat in the marina at the end of October last year. We had cruised during the summer 2011 and we left it without a hook up relying on the solar panels (2 x 136W & 2 x 68W) which run thro an MPPT controller. We made regular trips to the boat over winter and the Sgauge reading was never below 90%. Plugging into the mains we always left the batts at 100% before we left.

 

We recently returned to the boat to the smell of sulphur to find that two of the four 135amp batts were seriously gassing off and the SGauge reading was down to 32%.

 

We hadnt left anything on to drain the batteries and hadnt done anything different on previous visits to the boat.

 

The carbon monoxide detector was showing 22ppm so we disconnected the boiling batteries.

 

The solar panels were still showing as putting amps into the batteries. Not an excessive amount I think is was 4 or 5 amps. I will be replacing them all at some point but I cant work out what caused the failure so as not to have it happen again.

 

Anyone got any thoughts or had a similar experience?

Thanks

Trev.

 

This problem comes up time and again and is well documented on this forum. The answer is usually the same - a cell gone short circuit leaving a 10 volt battery in a 12 volt bank being charged as such. With a low or disconnected charge source, the faulty battery(s) will drag the others down hence the low SOC reading.

 

Despite the suggestions its very unlikely to be a charge controller problem.

[Guest]

The four Numax batts were only two years old and only being charged by the solar panels. Two had boiled dry but and one was warm but not boiling. The other batt seemed ok.

My solar controller was bought from fleabay, Germany. Had no problems with it since fitting.

 

I think in future I will disconnect all charging to the batteries and isolate them and just turn up once a month and put a charge in them.

Trev.

 

They could still have been overcharged even with solar (as PFU says) but my money is on a battery fault - you will need to get them checked out properly (and with the advice of someone better than me) before you but them back on charge, they can actually explode - are any of the battery sides bulging?

[bottle]

The four Numax batts were only two years old and only being charged by the solar panels. Two had boiled dry but and one was warm but not boiling. The other batt seemed ok.

My solar controller was bought from fleabay, Germany. Had no problems with it since fitting.

 

I think in future I will disconnect all charging to the batteries and isolate them and just turn up once a month and put a charge in them.

Trev.

 

Mine lasted two and a half years, depending on your usage they may well be at the end of their life.

 

A cell going 'short' can happen any time but usually as a battery gets old.

 

I am with by'eck on this one.

[nb Innisfree]

I think in future I will disconnect all charging to the batteries and isolate them and just turn up once a month and put a charge in them.

Trev.

 

Having cc'd for 5 years we have never had to leave the boat for long so when we were forced to stop ccing and leave our boat on a mooring next to shorepower I topped up the batts for a few days and decided to take a chance and leave shore power disconnected and batts isolated when we left the boat. When we revisited a few months later batts were still at 98% SoC. (Batts are 5 yr old AGMs with less than 50% capacity left)

[smileypete]

We parked our boat in the marina at the end of October last year. We had cruised during the summer 2011 and we left it without a hook up relying on the solar panels (2 x 136W & 2 x 68W) which run thro an MPPT controller. We made regular trips to the boat over winter and the Sgauge reading was never below 90%. Plugging into the mains we always left the batts at 100% before we left.

 

We recently returned to the boat to the smell of sulphur to find that two of the four 135amp batts were seriously gassing off and the SGauge reading was down to 32%.

 

We hadnt left anything on to drain the batteries and hadnt done anything different on previous visits to the boat.

 

The carbon monoxide detector was showing 22ppm so we disconnected the boiling batteries.

 

The solar panels were still showing as putting amps into the batteries. Not an excessive amount I think is was 4 or 5 amps. I will be replacing them all at some point but I cant work out what caused the failure so as not to have it happen again.

 

Anyone got any thoughts or had a similar experience?

A few questions...

 

What charging voltage is your solar controller set up to? Are these sealed batts or 'open' ones? Are they in they in a trad engine room or under a cruiser stern deck (hotter environment)

 

If you have a battery hydrometer it might be helpful to know the specific gravity of the batts that haven't boiled dry. Can you remember when were they last topped up? Do you normally top them up 'just above the plates'?

 

cheers, Pete.

~smpt~

[luctor et emergo]

Are your positive and negative connections on opposite sides of the bank, or on the same battery?

[ditchcrawler]

Are your positive and negative connections on opposite sides of the bank, or on the same battery?

They even had that in Waterways World this month and mentions the Smartgauge site

[Trev]

Thanks for your replies. The MPPT controller is an IVT and I'm not sure about what charging voltage it is set to? The batts are wet open and I have always kept them topped up above the plates. They are in a ventilated box in the back of a trad stern not tucked away where they could overheat.

I am going to test the sg of the two remaining batts today.

 

The batteries are/were connected via batt cable with the positive feed on the first batt and the negative feed/return on the last batt.

I have seen WW yet. What did it say about the batt connections?

Thanks

Trev

[WotEver]

I have seen WW yet. What did it say about the batt connections?

Me neither, but if it mentioned the SG site then it was probably this page.

 

Tony

[smileypete]

Thanks for your replies. The MPPT controller is an IVT and I'm not sure about what charging voltage it is set to? The batts are wet open and I have always kept them topped up above the plates. They are in a ventilated box in the back of a trad stern not tucked away where they could overheat.

I am going to test the sg of the two remaining batts today.

With the 135Ah batts there can be a huge gap between the top of the batt plates and the bottom of the batt filler hole. So without knowing the level the batts were supplied with, a hydrometer will help tell if the acid on a fully charged batt is getting too strong or too weak. Linky on specific gravity:

 

http://www.engineersedge.com/battery/specific_gravity_battery.htm

 

Anyway I think the common causes of batt overheating come down to one or a combination of:

 

Shorted cell

Poor terminal post connections

Charge voltage too high (also defective temp sensor)

Charge current too high (also poor bank connections)

Ambient temp too high

Batt SG too high - maybe

Batt old or in poor condition.

 

If the boat is left unattended, a 10 amp charger should be enough to keep up with a bilge pump, 12V fridge.

 

cheers, Pete.

~smpt~

Edited August 22, 2012 by smileypete

[bizzard]

Mounted on the uxter plate next to the engine all shut in and cooking away in stinking hot conditions under a hot ''in summer'' steel deck is in my opinion diabolical conditions for batteries, all contributing to them overheating, gassing off their electrolite and going off bang. Too hot for alternators too in my opinion. And in an appalling position to maintain them and their connections especially on the W/beams. If i had a wide-bean no way would i have batteries down there when there's loads of room for vented boxes on the after deck.