Boiling Battery

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freespirit

Boiling Battery

Lead

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Posts: 10

05/30/07 13:14:22

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Has anyone experienced a boiling battery? On Free Spirit this week we had one almost start a fire! sail # 408 is a three cabin Mark I model, with two batteries under the port aft birth. It was one of these two. The other is on a circuit shared with with the 3rd battery under a solon settee. We noticed the port aft cabin was hot and checked to find the boiling battery. The 2x4 wood braces in the battery compartment were charred. Any ideas as to causes, remedies and future sensing that could be added would be helpful. At this point we are assuming that the batttery would not hold the charge and the charger just kept trying to charge it. We are in the process of replacing the battery for starters. Thanks Free Spirit. sail #408

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Izablue2

#1

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Posts: 122

05/30/07 14:25:24

The same thing happened to me! I am in the process of replacing all the batteries and the 2x4 hold downs.

Most of the cells were dry or severly low and the hold downs were not burned by temp but rather by the acid.

The batteries were checked about 4 weeks ago. They were tired but showed no signs of imploding. My first thought was regarding the charger. I have a Charles 40 amp. Visual inspection showd nothing dramatic. When the new house batteries were installed, the charger seemsed to function fine.

As with Freespirit... what's happening?

Mark
Izablue, #835/3

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sashay567

#2

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Posts: 194

05/30/07 15:39:44

There is a phenomenon called thermal runaway. Basically, a cell shorts in the battery causing a drop in voltage. The charger senses the drop in voltage and begins bulk charging. The bulk charging causes the battery to heat up (as does the shorted cell). As the battery heats, the voltage continues to drop causing the charger to increase charging current... which causes more heat, more heat causes the voltage to drop more, and so on.

Thermal runaway can be prevented by battery temperature sensors which will limit charging currents as the battery heats up. You, of course, have to have a charger which supports battery temp sensors. The triggering event is usually a cell shorting. Cells can short due to age, going dry, or manufacturing defect. If the battery is part of a large bank, a cell shorting will cause all the other batteries in the bank to discharge into the shorted cell, causing intense overheating and boiling.

Rodney Kidd, C-42 #567 Sashay, 2 Cabin Fin, Marina Village, Alameda, CA

Last Edited By: sashay567 05/30/07 15:42:01. Edited 1 time.

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pwinterfeld

#3

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Posts: 108

05/30/07 15:53:54

There is a phenomenon called thermal runaway. Basically, a cell shorts in the battery causing a drop in voltage. The charger senses the drop in voltage and begins bulk charging. The bulk charging causes the battery to heat up (as does the shorted cell). As the battery heats, the voltage continues to drop causing the charger to increase charging current... which causes more heat, more heat causes the voltage to drop more, and so on.
Izablue2

Thank you for the explanation - its the best ever

Peter
C'est la Vie
Hull #746

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Izablue2

#4

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Posts: 122

05/30/07 16:49:27

Awesome... I,m going to check the info booklet that came with the charger and see if in fact it has a thermal sensor.

Thanks again

mark
Izablue, #835/3

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tinolanza

#5

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Posts: 213

05/30/07 21:55:02

Our batteries are charged via a Heart Interface 2000 with a temperature sensor. But there is only one sensor. So I have isolated all our batteries and when leaving the boat for extended periods make sure we are only charging the battery with the sensor. A lesson learned after frying the second battery on the house bank while the sensor was on the first one.

Tino Lanza, Dancing Dolphin (#739/3 cabin pullman, Westlake Village, CA)

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nickwigen

#6

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Posts: 216

05/31/07 06:03:37

Sashay described the thermal runaway accurately. Another thing to look for is the charger. The older ferro-resonant chargers can lose their regulation ability by some mechanism I don't have full information on. Until a several years ago the FR chargers were standard and can be identified by their weight (many pounds) and the buzz sound they emit. I learned this after replacing the batteries in our Cal 31 with Trojan T-105s. About 2 months later I went aboard and was greeted with a nasty hot battery smell. The batteries were at 15.5 volts, hot to the touch and the plates were dry. I replaced the charger with a new smart charger, refilled the batteries with distilled water and everthing was fine. I thought the batteries had been destroyed but they were still going strong 5 years later when we sold the boat. As I was hauling the old charger up the dock I met a local boat mechanic who surmised my situation in about 5 seconds. He'd seen 3 other cases of the same thing.

Odds are the problem is the thermal runaway but keep an eye on the charger also. One big advantage to the new charger was I now only added water every 6 months (could have gone a year) With the old Buzz-Box it was every 3 months.

Nick Wigen
Ursa Minor #178 FK, 3-Cabin
Portland, Oregon

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dbnonsense

#7

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Posts: 139

05/31/07 10:46:00

We had the same situation , boiled 2 4yr old house batteries but not the windlass battery even thou the battery switch was on all. We had a Charles 40 amp charger 4 yrs old with a 5 year warranty.
I called Charles who advised to send the charger back to them to evaluate, did that and 10 days later UPS delivered a new charger with a 5 year warranty !!! I do not know the reason but rather "suspect" a battery shorted and contributed to the demise of the charger.

Dave Zeuli Common Sense #810

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freespirit

#8

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Posts: 10

06/01/07 11:14:56

The battery charger is a Newmar HDM 50 and is no longer made. Newmar is recommending a repacement with a PT40 CE. We have removed the old battery and are running on the second bank. A new battery on order at the moment. Will keep you informed of progress.

thanks for all the advice.

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cathyinct

#9

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Posts: 310

06/02/07 13:06:54

So, if one keeps the batteries topped off with distilled water, is this boiling issue a non issue -- or is it still a charger problem ? Thanks for reminding me about the windlass battery

CAthy in CT

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freespirit

#10

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Posts: 10

07/13/07 09:43:03

Here is the latest on Free Spirit. Newmar, the battery charger company, confirmed my analysis that there new chargers only monitor a single battery bank. This is not good enough for the 42 with two banks. We are also seperated into two compartments. They go on to state: "the HDM 50 is good for live aboard situations where you are drawing a load off the battery banks at all times." The HDM 50 was supplied with my 42 and is no longer made.

So we just changed the boiling battery out and are keeping the battery switch on "all" when on shore power. We are now shutting down the charger at night when we stay aboard. We are also searching for simple temperture sensors that can be placed in each battery compartment and provide at least an audio indicator of a "hot" battery. All seems to be functioning OK with the new battery.

Thanks again for all the advice.

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