Extracting hydrogen from battery comp .

clyst

clyst

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Hi guys , I run two banks of two trojan T 145 s and need to extract the hydrogen given off whilst charging . I can extract it from the compartment via trunking and would like to use a solar sealed fan to assist rather than relying on natural ventilation . Can anyone recommend a suitable solar fan . Cheers Terry
 
Don't the cells have catalytic combiners in their filler caps.
Do you really boil the cells while charging them?
 
RAI said:
Don't the cells have catalytic combiners in their filler caps.
Do you really boil the cells while charging them?
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ITYWF They are conventional wet flooded batteries which will release small quantities of hydrogen (and oxygen) during charging.
 
IIRC isn't there an increased risk of a hydrogen explosion when mixed with air in a certain stoichiometric ratio ? To avoid any problem you need to remove hydrogen either as plain hydrogen (i.e. small quantities) or with masses of diluting air, but in both cases with an ATEX certified fan.


If you can perceive hydrogen (how ?) when charging2 x 2 x 145Ah batteries, then something is out of spec somewhere. Sorting that problem first should remove the need for complicated extraction tubing and fan.
 
It's lighter than air so any vents would need to be at the top of the compartment - I don't think an extractor fan would be necessary unless you intend to regularly boil the batteries to death!
(And, unless it was an intrinsically safe, non sparking one, it could create a source of ignition in a space where there would otherwise be none)
We're talking relatively small volumes of gas so practically any vent as long as it vents upwards would be sufficient
 
sarabande said:
IIRC isn't there an increased risk of a hydrogen explosion when mixed with air in a certain stoichiometric ratio ? To avoid any problem you need to remove hydrogen either as plain hydrogen (i.e. small quantities) or with masses of diluting air, but in both cases with an ATEX certified fan.
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Hydrogen forms an explosive mixture with air between 4.0 vol % and 75.6 vol %. It does not have to be a stoichiometric ratio.

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My boat, with two boxed in battery compartments, is fitted with a flameproof fan and ducting, to extract any build up of hydrogen etc. A boat berthed in a marina might be fast charging her batteries immediately prior to starting the engine. A spark at the batteries could lead to an explosion. My boat is on a mooring or at anchor, so in my case, the situation doesn't arise, but I can see how it could. If my boat had shore power, and if I had recently been charging, I would run the fan for a few minutes before starting the engine, just in case.
 
VicS said:
Hydrogen forms an explosive mixture with air between 4.0 vol % and 75.6 vol %. It does not have to be a stoichiometric ratio.

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I had a similar problem as my battery box was underneath the berth in my aft. cabin. The underside of the locker became badly stained after a couple of years. I was switched to Trojans and re-built the box with a sealed lid and put in ventilation. I did do calculations to get an idea of the rate of hydrogen evolution at peak voltage and also calculated the free volume above the batteries. I found a computer fan was well able to shift enough air to guarantee that it would never reach the lower explosive limit.

All a bit OTT as I really just wanted to remove corrosive vapour and that's closely related to evolution of hydrogen.

Don't bother with a solar powered fan.
It is a battery and so power is readily available. Gassing takes place during charging and becomes worse at higher voltages. You only need to run the fan when charging the batteries and that could be in the middle of the night when there's no sunshine.

You could connect the fan to only run when the engine is running but that doesn't help with solar or mains charging. My fan is triggered by voltage and is off until charging begins and runs at half speed until voltage rises above the point gassing becomes significant. It then runs at full speed.

I imagine the circuitry doesn't need to be very complex. Something to measure voltage and trigger a 6V feed from one battery until a threshold is reach. Then power switches to 12V. I was lucky to have a SmartGauge fitted and only needed to buy a diode to achieve this result. I'll see if I can find a simple circuit to achieve the same result.

Ducting for my fan was really cheap. I bought 2 pieces of 100mm pipe and 2 125>100mm reducers for a few pounds (total £5.68). The pipe fitted a spare Eber heater outlet and the fan fitted inside the 125mm section of the reducer. Just a matter of fitting a 4" computer fan inside a reducer, joining to the other reducer with duct tape and connecting 100mm pipes to either end.

100 Round Pipe 100mm x 350mm
125 Round Ducting Reducer 125-100mm
 
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Has anyone actually experienced a genuine hydrogen explosion? Every battery explosion I've seen photos of looks like a good old-fashioned steam explosion, caused by an internal short circuit. It is incredibly difficult to keep hydrogen in! It diffuses at an enormous rate, it is lighter than air by a lot, and it will even pass through most solid materials. If you know of a reliable way to stop hydrogen from leaking, I know a lot of people who want to talk to you. Seriously, worrying about a hydrogen build up is in the same league as worrying about suffocating yourself with your own farts, unless you have made extreme efforts to keep it in.

I'd be more worried about lack of ventilation causing heat to build up resulting in the battery plates warping, and hence to the steam explosion mentioned above than about any explosion caused by the evolution of hydrogen.
 
AntarcticPilot said:
Has anyone actually experienced a genuine hydrogen explosion? Every battery explosion I've seen photos of looks like a good old-fashioned steam explosion, caused by an internal short circuit. It is incredibly difficult to keep hydrogen in! It diffuses at an enormous rate, it is lighter than air by a lot, and it will even pass through most solid materials. If you know of a reliable way to stop hydrogen from leaking, I know a lot of people who want to talk to you. Seriously, worrying about a hydrogen build up is in the same league as worrying about suffocating yourself with your own farts, unless you have made extreme efforts to keep it in.

I'd be more worried about lack of ventilation causing heat to build up resulting in the battery plates warping, and hence to the steam explosion mentioned above than about any explosion caused by the evolution of hydrogen.
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I charged one in my garage at home and sometime after disconnecting it a spark from an agle grinder caused the battery to explode fortumately behind me as the acid splashed about a bit.

Some batteries have a connection for a small bore pipe which presumably could be positioned to vent in a safe area.
 
Mistroma said:
You could connect the fan to only run when the engine is running but that doesn't help with solar or mains charging. My fan is triggered by voltage and is off until charging begins and runs at half speed until voltage rises above the point gassing becomes significant. It then runs at full speed.
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I have something similar. I have a Smartguage system that has a discrete output when actively charging that runs a computer fan to ventilate the house batteries. It's off when the charger is in float. In my quirky installation the fan also runs when the fridge compressor is running to ventilate it's enclosure.
 
Hoolie said:
I have something similar. I have a Smartguage system that has a discrete output when actively charging that runs a computer fan to ventilate the house batteries. It's off when the charger is in float. In my quirky installation the fan also runs when the fridge compressor is running to ventilate it's enclosure.
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I also have Smartbank for charging and that pulses 12V to the relays to reduce power needed. The relays effectively use a 6V supply and that what I use to supply the fan. Charging starts, relays are energised to combine battery banks and fan gets power from the relay feed. SmartGuage alarm trips when voltage gets high enough and supplies 12V to the fan. The only extra part I needed was a diode to stop 12V and 6V supplies meeting in the middle.:D:D

I suspect you are just using Smartgauge to switch 12V on above a set-point and off otherwise. I only bothered with the extra 1/2 speed option because it only required a diode and I had one lying around. I was mostly venting corrosive vapour and hydrogen venting was a useful side-effect.

OP didn't mention Smartgauge but would only need a simple voltage sensitive switch to achieve the same result. A basic circuit with a resistor, diode and mosfet etc. would probably be fine. Or buy something off the shelf if you can find something like this E1040 1A Voltage Sensitive Switch.
 
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2Tizwoz said:
I charged one in my garage at home and sometime after disconnecting it a spark from an agle grinder caused the battery to explode fortumately behind me as the acid splashed about a bit.

Some batteries have a connection for a small bore pipe which presumably could be positioned to vent in a safe area.
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That is a very enclosed spaced compared with an engine compartment and the battery did not not so much as explode but instead had a min pop spraying acid. Nasty but not likely to wreck a yacht or set fire to it. On submarines the issue might be different
 
AntarcticPilot said:
Has anyone actually experienced a genuine hydrogen explosion? Every battery explosion I've seen photos of looks like a good old-fashioned steam explosion, caused by an internal short circuit. It is incredibly difficult to keep hydrogen in! It diffuses at an enormous rate, it is lighter than air by a lot, and it will even pass through most solid materials. If you know of a reliable way to stop hydrogen from leaking, I know a lot of people who want to talk to you. Seriously, worrying about a hydrogen build up is in the same league as worrying about suffocating yourself with your own farts, unless you have made extreme efforts to keep it in.

I'd be more worried about lack of ventilation causing heat to build up resulting in the battery plates warping, and hence to the steam explosion mentioned above than about any explosion caused by the evolution of hydrogen.
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There are a lot of anal retentives on here, so it's a real possibility. :ROFLMAO:
 
WOW thanks for all your replies ....... certainly gives me lots to think about. Thank you .
 
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