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RE: [PSUBS-MAILIST] Battery pods - connected or isolated from the cabin?



Title: Battery pods - connected or isolated from the cabin?
Has anybody done any tests to see how much hydrogen is given off by the AGM batteries?
 
Brian
-----Original Message-----
From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org]On Behalf Of Smyth, Alec
Sent: Monday, February 11, 2008 7:51 PM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Battery pods - connected or isolated from the cabin?

Hi all,

I'm building my battery pods and wondered if I could pick your brains.

On the K-350, I believe the battery pods are mounted on pipes that go through the pressure hull, thereby connecting the pods to the cabin. They can be isolated with screw-on caps. I presume Kittredge's reason was to allow forced ventilation during charging. Also, Busby explains that if you use hydrocaps in a sealed pod, the caps can consume the little O2 available in the pod during discharge (i.e., a dive), at which point they would cease to work and start releasing hydrogen that can quickly reach an explosive concentration. One approach to prevent this was to add O2 to the pods before diving.

Kittredge was no doubt designing for lead-acid batteries. But these days with AGM batteries, I'm wondering if the same issues are still of concern, or whether I can just make the pods truly isolated. I suspect the latter, because I'm not aware of the pods on modern submersibles being piped to the cabin. Perhaps I'd have to remove the pod endcap on land to charge the batteries. If so I'd be unable to charge afloat, but frankly I don't envision doing that, because I don't care for leaving the boat in the water for extended periods. Over days, condensation really starts collecting inside.

I can see several safety advantages in keeping these spaces truly isolated. Any opinions?


Thanks,

Alec



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