MacGregorSailors.com

Batteries should be attached firmly to prevent spillage and damage from being banged around.

Worrying about "explosion/fire" from batteries ranks just under worrying about International Space Station decaying orbit and landing on you in risk management.

Now from you I consider that a very strange comment! I thought you were a very experienced and wise sailor.

How many of you smoke in or near the cabin of your boats with a potentially gassing lead/acid battery next to your naked flames?? The gas is HYDROGEN. It goes 'big bang' when lit.

I will say no more on this subject but please don't come crying to me when you are blown to bits. I have a sealed gel battery which will be located in the cockpit so I feel safe and no I don't smoke.

You have to push a lot of current through a battery to make a lot of hydrogen and even then its doesnt sit around like LP, propane, petrol, etc - it merrily follows its entropic destiny to the heavens. You wont go boom just sitting in the cockpit.

I would worry much more about a smoker starting a fire from combustibles than battery gas...but we are all free to choose our worries I guess...

God help your customers in your new career!

hey PAC: how about a little history of battery explosions on a a GUINEA for your efforts. stew

Pacamac-uk wrote:God help your customers in your new career!

God bless us one and all,
And God bless Tiny Tim.

About 5000 and boats delivered with wet batteries and bilge mounts....how many exploding incidents ???
I guess we could take a poll.....

I have an old battery here maybe I should put it on the charger and se if I can duplicate the last blow up, which far from blowing anyhing to bits just split the battery, I was doing a lot of cutting for a long time with a 9 inch angle grinder just forgot about the battery.
I would be far more worried about gas or fuel being used or just in bottles or tanks below deck.
There was a boat blown up last week here in Melbourne two people were killed and two injured the boat almost desintegrated, they turned the key on after filling with fuel and boom.
Even handling fuel above deck in the cockpit is potentially dangerous which is why we have extinguishers above and below decks.

I have no way of knowing how many Macs have 'exploded', if any, but this could be more by luck than anything else! There are several explosion and fire incidents in boats every year in the UK and this has directly lead to changes to the boat safety schemes/licensing applied to UK boats. Only last weekend I was sailing in Plymouth Sound when a mayday was heard and the fireboat and lifeboat went out to a motor boat that had suffered an explosion and fire. The cause was not identified on the VHF but this shows that it can happen.

Below is a quote from a marine survey website on safety concerns on batteries.....

'Battery Safety

Batteries constitute an underestimated danger onboard boats. A fully charged battery contains a tremendous amount of stored energy-more than enough to melt in half a spanner placed carelessly across the terminals. A battery's electrolyte solution of sulphuric acid will eat through clothing and cause severe burns. Take great care with battery acid. Any splashes should be immediately and liberally doused with water.

The battery compartment should be well ventilated. When being charged or rapidly discharged, batteries emit explosive, lighter than air gases-hydrogen and oxygen. Never generate sparks around a charging battery, or one that is being rapidly discharged, such as during long engine cranking. Batteries can explode spraying acid in all directions.

Batteries also emit corrosive fumes. Never install electronic equipment near a battery compartment. The equipment will likely suffer irreparable damage.

Batteries should be kept in well-built, acid proof (plastic, fibreglass, or epoxy saturated plywood) boxes with secure, vented lids. Ventilation is important not just to remove explosive gases, but to dissipate heat generated during rapid charging. Because of this, the degree of ventilation may well have a significant impact on charging times. It will also prolong battery life by keeping batteries cool. As long as the batteries don’t freeze, the cooler the temperature the longer the battery life.'

If you are all comfortable sleeping, and cooking in a possibly enclosed compartment with an explosive gas producing battery then may you all sleep well. I know what I would do.

Yes hydrogen is flamable but it is also lighter than air (Remember the Hindenburg).
In order to get a build up of hydrogen to explosive levels would require an air tight enclosure. I know my battery compartment and boat are not "airtight". I agree with Kelly East that the hydrogen coming off a single battery being charged will be smal and disipate quickly in the air. If I were running a charger on dead batteries it would be prudent to leave a small opening at the gangway or a solar vent. But this would be an extreme case. Under normal circumstances the hydrogen will rise in small amounts and be dissipated to the environment.
I think the main confusion with hydrogen from the batteries versus other explosive agents is build up. It would take an effort of totally enclosed air tight containment over an extended period and then a spark at the moment of opening the containment to achieve an explosion with hydrogen. The heavier than air elements are a different story as they can build up slowly over time and just be sitting there waiting for a spark to come along at any time.
In conclusion, I agree with Kelly East.

Came across this article. Something to think about here regarding other things that come from batteries:

Using Liquid Batteries

Liquid batteries should be located in a cool, well ventilated space, preferably not in living quarters because of emissions of arsine and stabine gasses.
The batteries should be secured so that movement is not possible in expected conditions. This means more than a single nylon strap with plastic buckles routed over the top of the battery. Batteries should not be enclosed so tightly, however, that normal expansion and contraction of the case is impeded.
The batteries should be mounted in a watertight tray big enough to hold all of the electrolyte in the event of battery case fracture.
The battery should be maintained with a charging system, (charger, alternator, etc.), that actually measures battery temperature and corrects the applied voltage accordingly.
An instrumentation system should be connected to the battery that provides alarms for the following abnormal conditions:
high battery voltage;
low battery voltage;
high battery temperature;
high battery current; and
low state of charge.
If multi-step charging is used, the systems should be designed so that it trips from the absorption voltage to the float voltage based on Volts and Amps through the battery, rather than just timing the absorption charge.

Using Gel Batteries

For the most part, gel batteries should be used exactly the same as liquid batteries. The possible exception is the requirement for an electrolyte container. First, gel batteries use a tougher case than typical liquid batteries, so case fractures are infrequent, and the electrolyte is much like a paste and will only ooze from a fracture. Obviously, using a container is playing it safe.

Case by Case Analysis


Keeping batteries cool is always, well cool! Typically gel batteries don't gas, but in the event they do, the same explosive mixture is produced. Planning for the day that the charging systems fails, and no one is around to hear the alarms from the instrumentation system is prudent ...provide plenty of ventilation.

Gel batteries are no more sensitive to temperature than liquid batteries, and might even be less sensitive regarding gas emissions. However, effects from gassing a liquid battery can be hidden by the addition of water to the cells. That can't be done with a gel battery. Conclusion: There is no safety difference related to temperature between gel and liquid batteries, just an economic difference.

Instrumentation System: Operating any electrical system without alarms is for risk takers, not for the prudent. Battery type makes no difference.

Well, there isnt so much to 'agree' or 'disagree' on with risk management since its a pretty personal thing what one accepts and what tries to mitigate.

Batteries do produce hydrogen and its absolutely prudent to keep sparks away from batteries at all times. The worst case estimate I found on the web for battery explosions links them almost exclusively to jump starting situations, with sparks from jumper cables being the cause of course. There were quite a few, estimate of 6000 per annum in North America. Of course, a jump start is a perfect storm of factors

- Heavily discharged battery
- Cables that generally have poor hardware, and cause sparks
- Bad human factors - generally person is stressed and will shortcut procedures and safety rules.

Found this on the Defender Website when looking at Battery Boxes:

USCG Code of Federal Regulations 183.420

Each installed battery must not move more than one inch in any direction when a pulling force of 90 pounds or twice the battery weight, whichever is less, is applied through the center of gravity of the battery as follows:
1. Vertically for a duration of one minute.
2. Horizontally and parallel to the boat’s center line for a duration of one minute fore and one minute aft.
3. Horizontally and perpendicular to the boat’s center line for a duration of one minute to starboard and one minute to port.
Each battery must be installed so that metallic objects cannot come in contact with the ungrounded battery terminals.
A vent system or other means must be provided to permit the discharge from the boat of hydrogen gas released by the battery.

I will assume this applies to our boats. What is the definition of "vent system"?

I am going to install two Group 27 batteries in my battery compartment behind the companionway ladder on my (I assume two will fit side by side...I currently have just the factory battery).

For those that have two batteries in that compartment. Is there hardware already in place to secure two batteries or will I need to get/fabricate something? If so, what recommendations do you have.

Looks like another option, from reading above posts, is to install the two batteries in the aft dinette seat area...I assume if I go that route I can buy two of the plastic battery boxes to "secure" the batteries. And I assume there would be no problem extending my current wiring from the battery compartment along the bilge into that compartment...any thoughts on that?

Any other thoughts about two batteries in the original compartment or under the seat would be welcome.

Thanks,
Jim

Jim
Consider for a moment that Roger is totally incompetant, there still have been a significant number of safety checks and Coast Guard inspections of the M in the last 3 or 4 years and the battery compartment has not been found to be a problem. It has a cover so tools etc can not be dropped onto the batteries - 1 major criteria, the batteries are secured - 2nd criteria, is vented or at least not solidly enclosed- 3rd criteria. Now consider that Roger is not incompetant and would respond to any complaint or citation by insurance, boat survayers (sp?) or Coast Guard inspectors and he still hasn't changed it, hasn't even add a hinge to keep the cover in place. Just a suggestion, not a criticism, but you might want to fixate on LED replacements for nav and interior lighting for a while, I think you have pretty much got your battery and wiring things sorted out.
Ron
on edit: You do not need the battery boxes when the batteries are in an enclosed compartment specifically designed for them

Ron,

Maybe you misundertand my position. I have no issues with Roger's design. In fact I am quite happy with it. And I have no concerns about the issues that some have over the battery compartment and its "access" to the bilge.

I only posted the USCG criteria because I happened to find it on the Defender website while researching my battery upgrade plans. And if I am going to upgrade I just want to make sure I am doing it "legally".

And of course I am hoping I become an "Assistant Deputy Vice Captain" or something when I hit 500 posts... (there...I admitted it!)

As far as my upgrade is concerned I plan to start "cruising" (4-5 days max) when I get back to the U.S. And thus I figured I would need a little bit more electrical power. After reading thousands of posts on this subject I have decided on my plan...and that includes 2 x Group 27 batteries (seem to be just a few more $ than a Group 24 so why not).

If the batteries will fit in the compartment...I will not worry about boxes...but I do need to ensure they are "secured" with a strap or something...not sure what is already in there...sure wish I had access to an so I could make a bunch of measurements and put my own eyes on these areas.

If they don't fit I will either go with smaller batteries (Group 24) or maybe go with the 27's in the dinette seat...in which case I would go ahead and get battery boxes...they are pretty cheap ($10) and it seems pretty easy.

LED nav lights are pretty far out there for me right now. Interior lights will not be an issue...mostly using AAA LED Light Pucks.

Bottom line is keep it simple, keep it cheap, and spend more time sailing than mod'ing. And I think my plan will fit all that criteria.

Thanks,
Jim