Ventilation of Battery Compartment

[James S]

Thats the one I have and it works great.....Thanks again ChrarlieJ

[Roy M]

CharlieJ: Thanks! Just what I'm looking for. And I don't have to go out, buy parts and assemble it before installing it. Life is good.

[sailvayu]

I was hoping to not get back into this but I wanted to answer Jim about production boats and just add my final thoughts.

I do not know of any production boats that use a active ventilation system for the batteries. Most have there batteries installed in the engine compartment or cockpit locker with passive ventilation. I have looked at several of the European boats with batteries installed in the living space. Recently I looked at a 2005 Bavaria 36 with the batteries under the port and starboard settee's. No boxes, no covers, no ventilation. There was acid in the bottom of the locker and the wood above was stained. No equipment could be stowed here because it would be sitting in acid. Terminals were not covered so equipment could short out the terminals.

Come on guys this boils down to common sense. Batteries are a source of high power they can produce poisonous gases, then can leak acid, they can explode, they can start fires. Maybe under normal conditions none of this will happen and as we all know nothing ever goes wrong on a boat right?

My point in all this was not to nit pik the rules and regulations but to think about doing things in a safe and seamanship matter. Maybe you can get away with 8 batteries under your settee with no ventilation or ventilation into the cabin. But maybe it would be safer if you follow the basic guild lines set out by those who have spent a lot of time researching this stuff.

Also you need to consider resale of your boat. Installations not meeting ABYC are likely to get written up in a survey. Your argument for not doing things the way they should be will not likely impress a buyer.

I stand by common sense and doing things for worst case conditions not best. Batteries are a source of some potential problems. Maybe you will never have any of those problems but i do not think that is an excuse for at least not trying to protect yourself form the what could happen.

OK I am done you can all make your own decisions, but if I come and survey your boat and the batteries do not meet basic safety standards I will write it up.

Fair Winds
Wayne Canning, AMS
projectboatzen.com

[bobfnbw]

Your points are valid.
I have seen many bad battery installs as well.
But you have to understand that just because you write it up in a survey, does't always mean anything. The new or prospective owner has the choice at that time to take it or leave it, or fix it or not fix it. True the insurance company may make him fix it.. but not all boats are insured.

I think that most of us would agree that a large lead acid battery is a dangerous thing.
The proper steps must be taken to keep things from going bad, but that there is little that can be done to make 100% sure that this can't happen. But a prudent seaman would take steps to ensure that t he batterys are secured, the terminals, covered, the area vented in some way, passive or active, and the chance of leakage minimized.
Bob.

[sailvayu]

Originally Posted by bobfnbw

But you have to understand that just because you write it up in a survey, does't always mean anything. The new or prospective owner has the choice at that time to take it or leave it, or fix it or not fix it. True the insurance company may make him fix it.. but not all boats are insured.

Bob.

HA! aint that the truth lol I have surveyed the same boat and written the same crap up all 3 times for 3 different owners lol.

Hey at least I did what I was paid for!

And surprisingly most Insurance does not require it gets fixed but I am guessing if there is a lose due to something in the report not fixed the insured will be on their own.

But I am humble and know only too well I do not have all the answers and begrudgingly admit I do not know everything (but i will deny it if asked lol)

And thanks for helping me remain humble lol (I will remember this lol)

Wayne Canning, AMS
projectboatzen.com

[Roy M]

sailvayu: Nolo illigitimi carborundum.

[CharlieJ]

Here is the multi-stage charging algorithm from a major inverter/charger manufacturer. Hopefully this will clear up any confusion caused by earlier posts in this thread.

Charging Algorithm.pdf Views: 254 Size: 31.6 KB ">Multi-IRJDSUNE9932123321222xxeww-Stage-IRJDSUNE9932123321222xxeww-Charging-IRJDSUNE9932123321222xxeww-Algorithm.pdf

[cal40john]

Originally Posted by CharlieJ

Here is the multi-stage charging algorithm from a major inverter/charger manufacturer. Hopefully this will clear up any confusion caused by earlier posts in this thread.

Attachment 11712

That must be a simplified graph or I don't understand how multistage charging works. The argument is the a constant voltage charger starts backing off the current too early leading to longer charging times. Well this graph shows the max current being reached at a lower voltage than the absorbed. Seems to me that a constant voltage device would achieve the same thing under this profile. Also unless the battery were horribly discharged I would think that the current output from the device would achieve maximum much earlier then stay constant for a longer time. In addition I've never seen a charger say it drops to battery is full so no current output. Float is what you put into your battery to maintain it.

Basically I don't think the above graph is very accurate.

John

ars5 charge profile showing during bulk charge higher voltage allowed
page67-ars5

mc612 manual showing max bulk charge voltage of 14.60 volts dropping to 14.40 volts for absorption charge for deep cycle flooded program.

http://www.balmar.net/PDF/2005-mc-612-manual.pdf

neither shows the current output

[CharlieJ]

John-
The graph I posted in Post #67 is correct for that I/C. Balmar uses a 200 mV difference to transition from bulk to absorption for a couple of reasons. My posting in #67 and in this post is to clarify that voltage is held constant during the absorption stage and current naturally decays off as the battery resistance increases with increasing state of charge. Other posters disputed that the absorption stage was a constant voltage stage, hence the reason for my clarifications.

Here is another charging profile from another major charger and inverter/charger manufacturer showing that, at least as designed, the voltage is constant during the absorption stage.

Multi stage charging algorithm #2.pdf

[cal40john]

Originally Posted by CharlieJ

John-
The graph I posted in Post #67 is correct for that I/C. Balmar uses a 200 mV difference to transition from bulk to absorption for a couple of reasons. My posting in #67 and in this post is to clarify that voltage is held constant during the absorption stage and current naturally decays off as the battery resistance increases with increasing state of charge. Other posters disputed that the absorption stage was a constant voltage stage, hence the reason for my clarifications.

Here is another charging profile from another major charger and inverter/charger manufacturer showing that, at least as designed, the voltage is constant during the absorption stage.

Attachment 11810

OK, I didn't know before what you were concentrating on. I agree completely with what you say about the absorption stage.

What I have finally come to understand is that there are 3 stage chargers that I would actually call 2 stage. The transition from bulk to acceptance is no more fancy than what an internally regulated alternator would do if set to that voltage.

I'm going to start another thread, since this is far afield of ventilation.

John

[Julien de Tilly]

Hello everyone,

My turn to revive this old but necessary and learned discussion.

I am planning to do a complete electrical refit on my sailboat (Hughes 29) this coming spring and I want to do things the right way. I am still not sure wether I will opt for wet-cells or AGM batteries, but they will be stored under one of the settee in the main cabin (the only large enough and readily accessible place onboard). I understand that in any way they will need to be contained in an overboard-discharging ventilated box, according to ABYC 10.7.9-10.

10.7.9 - A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery.

10.7.10 - Battery boxes, whose cover forms a pocket over the battery, shall be vented at the uppermost portion of the cover.

Note to 10.7.9 and 10.7.10: These requirements also apply to installation of all batteries wether they employ removable caps, non-removable caps, are "sealed" or "maintenance free" batteries, or have pressure regulated valve vent systems with immobilized electrolyte (gel and AGM batteries).

What I am not sure to clearly get from the previous discussion, is how this could be made while complying at the same type with ABYC 10.7.2, which states that:

10.7.2 - Provision shall be made to contain incidental leakage and spillage of electrolyte.

The way I understand this, the box is in first place required to contain electrolyte that can be spilled due to (over)charging process, heeling/capsizing, battery case failure (freezing or explosion), etc.), and even if ABYC doesn't state it in this way, it thus seems important from what I read that battery boxes needs to be as "watertight" as possible to prevent such spillage, thus the venting issue becoming more and more important. Now, considering that venting (passive or active) seems to me to require at least two openings in the box - one on top (which could be dealt with without overthinking the whole thing) and one near the bottom for fresh air entry (which seems to me much more problematic, especially if we take into consideration the possibility of having large amount of electrolyte spilled in the event of battery case failure), how am I suppose to deal (or have you dealt) with that issue ?

I perfectly know (and hope) that this scenario is not likely to happen, but again in my mind rules are made to prevent risk. Or am I just to much overthinking all of this ?

Thanks a lot in advance to all the knowledgable person who makes this community so valuable.

[cal40john]

Originally Posted by Julien de Tilly

Hello everyone,

My turn to revive this old but necessary and learned discussion.

I am planning to do a complete electrical refit on my sailboat (Hughes 29) this coming spring and I want to do things the right way. I am still not sure wether I will opt for wet-cells or AGM batteries, but they will be stored under one of the settee in the main cabin (the only large enough and readily accessible place onboard). I understand that in any way they will need to be contained in an overboard-discharging ventilated box, according to ABYC 10.7.9-10.



What I am not sure to clearly get from the previous discussion, is how this could be made while complying at the same type with ABYC 10.7.2, which states that:



The way I understand this, the box is in first place required to contain electrolyte that can be spilled due to (over)charging process, heeling/capsizing, battery case failure (freezing or explosion), etc.), and even if ABYC doesn't state it in this way, it thus seems important from what I read that battery boxes needs to be as "watertight" as possible to prevent such spillage, thus the venting issue becoming more and more important. Now, considering that venting (passive or active) seems to me to require at least two openings in the box - one on top (which could be dealt with without overthinking the whole thing) and one near the bottom for fresh air entry (which seems to me much more problematic, especially if we take into consideration the possibility of having large amount of electrolyte spilled in the event of battery case failure), how am I suppose to deal (or have you dealt) with that issue ?

I perfectly know (and hope) that this scenario is not likely to happen, but again in my mind rules are made to prevent risk. Or am I just to much overthinking all of this ?

Thanks a lot in advance to all the knowledgable person who makes this community so valuable.

You are venting hydrogen, it will all be at the top of your box so no need for a bottom vent.

[john61ct]

Actually batt offgassing is very close to same weight as atmosphere, position NBD, either passive opening big enough, or a small active one will do anywhere.

[coopec43]

Originally Posted by john61ct

Actually batt offgassing is very close to same weight as atmosphere, position NBD, either passive opening big enough, or a small active one will do anywhere.

Would a gas detector designed for LPG pick up the "offgassing"?

I have a bilge blower in the same "compartment" as the batteries. Would it pay to have the bilge blower (and engine room blower) going when the motor is running and charging batteries?


Clive

[boatpoker]

ABYC requires a battery ventilation system. Nowhere does it say that such a system must be powered (fan). Hydrogen is the lightest known element and has a rate of ascent of 20m per second or 44.6mph. it needs no assistance from a fan.

An ungasketed hatch lid or a simple 1/2" pipe leading from above the batteries to outside would qualify as a "ventilation system" in my opinion.

There are those who believe that AGM's do not vent, I disagree. They sure as hell vent when they are cracked open.