Lead-Acid Batteries as Ballast

[Bahama]

The maintainable lead-acid batteries provide the longest life (over the SLA) and are the most efficient cost effective solution. They're great except that they require filling them with distilled water and some periodic equalizing charging (every 10 to 40 days), and they can leak if not sealed well.

I've been reading about how to make your own batteries--my interest in this was to design a tailored system that would fit perfectly in to my bilge area, provide for easy maintenance (e.g. a hydrocap design, automatic water filling from a single distilled water reserve, and would include sensors for water level, temperature, voltage and capacity for all batteries).

Essentially, I want to design a "Sealed Lead-Acid (SLA)" system (lead-selenium seems best see page 10: http://www.alcad.com/pdf/everystandb...emdeserves.pdf ) with removable seals, hydrocaps, and the sensors plus automated water filling describe above.

If any can point me to any sites that offer good advice regarding building your own batteries, that would be great. I plan to do a quality job on this by using the thick solid lead-antimony plates that are at least as thick or thicker than the largest Rolls-Surrette (which is .265" thick) and to pour them into an interlocking waffle pattern to maximize the surface area. I've forged many metals and lead is very easy to melt and pour. I'm also pretty good with electronics and feel confident to design the electronics needed to communicate with a nice MasterVolt power control system.

Once I get pouring the lead, it makes sense to just pour some extra plates to save and use for later repairs if needed, and otherwise just to use as replacements when they go bad (which sounds like they'd last for 15 to 20 years with plates that thick and maintained well).

For those who like to point out risks: I understand the system designed would need to be sealed safe and tight. That mixing battery acid with salt water is a nice way to make deadly chlorine gas. That boats can potentially be rolled over. etc. All true, and all manageable with good design. Thick triple walled plastic encased inside a metal sealed container for example, and provide all venting straight to the deck with dual safety seals to protect against water flowing in.

If you have some suggestions regarding how to design a safe battery box and containment box for the bank, I'd love to hear it; otherwise I plan to just look at the Rolls marine battery designs. This is a nice link that I found: http://www.battcon.com/PapersFinal20...09FINAL_12.pdf

[Submarine Tom]

Check out this site:

http://members.shaw.ca/Craig-C/news/TENews2.html

-Tom

[Bahama]

Originally Posted by Submarine Tom

Check out this site:

http://members.shaw.ca/Craig-C/news/TENews2.html

-Tom

Thanks. I definitely want to learn how to make a mold and then pour the plastic into the mold to make my battery cases. I'll have to learn if the ABS plastic is best or if another material would be better. Since I plan to seal the entire battery bank into waterproof metal case (that has been plated/painted to protect against corrosion, the plastic doesn't have to protect against being dinged by falling objects, just strong enough to not crack or leak. I'll still do a double or triple layer if I can.

I also plan to use hydrocaps to limit the water lose, but I need to devise a way that I can protect these hydrocaps while I'm equalizing the batteries (so that they don't get damaged)--my best thought is to have a simple slide valve or ball valve made of plastic that will slide closed automatically during equalization and then reopen afterwards. This would seal the batteries and still retain some water while not letting the hydrocap burn out.

I found a couple sources for the lead-selenium. I am guessing that batteries are a pretty competitive business and so i'm not anticipating some huge savings in money (sometime when you look into building it yourself, it can cost more). But I estimate the cost of doing something like a Surrette Rolls 4-KS-25P would be about $1050 and they can be bought for $1350, so there may be some savings there--what is key to me is being able to custom fit and design what I want. If I can find a Surrette Rolls that will find into the space that I want, then I may go with that, but otherwise, since it looks like I can do this custom for less money, I may make my own--especially since I can put in some extra sensors that would not come with a production battery.