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fastcat435 · 13-08-2008, 02:51

Quote:

Originally Posted by ireaney

Well said Gord, I am getting fed up of someone discussing their dirty washing in public, this is not the idea of the forum, as we have to read all this to get to the information that we want.

Case Closed and besides this thread was on saving weight.

Greetings to all.

Gideon

BigCat · 13-08-2008, 07:22

Quote:

Originally Posted by Aussiesuede

It's not just 'Fully Charging' that represents the problem, it's the entire cycling memory. If you don't automate the recharge cycle to start recharging at the same points of discharge, you're going to shorten the life of a deep cycle AGM battery rather noticably. A real PITA if you ask me. When considering battery life (without even getting into the weight savings) the additional cost for Lithium Polymer seems more than reasonable imo. Under no circumstances would I allow a non polymer Lithium ion battery anywhere near a boat though. But the polymer lithium Phosphate & Magnesium's are actually a decent deal when looking at a 'non-spill' , 'non gaseous' battery.

Can you give us a link or two for these batteries? I can't seem to find any. Thanks!

fastcat435 · 13-08-2008, 07:36

Quote:

Originally Posted by BigCat

Can you give us a link or two for these batteries? I can't seem to find any. Thanks!

Lithium Phosphate Battery - Energy Storage Systems

Saft web site

greetings

Therapy · 13-08-2008, 07:58

Quote:

Originally Posted by yeloya

The fact that Gideon is representing SF or not, from when on, etc. does not really matter.

yeloya

Actually, in the long run, it does. IMO.

**Hud3** · 13-08-2008, 08:41

But not in a thread on the subject of "Saving Weight". Let's all try to keep on topic, please.

Aussiesuede · 13-08-2008, 09:38

Quote:

Originally Posted by BigCat

Can you give us a link or two for these batteries? I can't seem to find any. Thanks!

The Valence Batteries Gideon referenced are currently the best choice imo and they are Lithium Phosphate Polymer. There are benefits to using Lithium Magnesium Polymer in a larger custom battery bank (ie, full electric instead of hybrid) but the phosphate's are better in the smaller form factors we're accustomed to. The best of the standard form factor magnesium's I've found are the 'Torqueedo's' . The real benefit to magnesium vs phosphate is they don't 'self discharge' when not used. Sit em for a year unused and the power that remains stored is above 90%.

torqeedo: Produktbeschreibung

Personally I think the future lay in magnesium chloride batteries which use seawater as their electrolyte, therefore reducing weight by over 70%. The problem with this technology is the current state of the precious metals market. It's simply too expensive to produce using silver as the anode, therefore there are no takers to develop the technology, even though it's fared well in field tests and has been put to limited use with success in the defense industry.

NRDC Technology offer-MAGNESIUM* SILVER CHLORIDE SEA WATER ACTIVATED BATTERY

Obviously eliminating onboard storage of electrolyte would provide the greatest weight savings...

Zach · 13-08-2008, 09:53

I've been doing some searching around... Haven't found a whole lot that suggests putting lead acids in the living space is overly dangerous. (Heck, my starting battery is under the bottom step of the companionway. A whole 10 inches away from the berths... for what, 47 years?

)

Been pondering mounting the batteries in a "dorade" box of sorts. Even if things go inverted, the lid would become a catch pan... still vented.

BigCat · 13-08-2008, 10:02

Quote:

Originally Posted by Aussiesuede

The Valence Batteries Gideon referenced are currently the best choice imo and they are Lithium Phosphate Polymer. There are benefits to using Lithium Magnesium Polymer in a larger custom battery bank (ie, full electric instead of hybrid) but the phosphate's are better in the smaller form factors we're accustomed to. The best of the standard form factor magnesium's I've found are the 'Torqueedo's' . The real benefit to magnesium vs phosphate is they don't 'self discharge' when not used. Sit em for a year unused and the power that remains stored is above 90%.

torqeedo: Produktbeschreibung

So, in Torqueedo batteries, apparently, you are limited to a maximum of 332 amp hours at 24 volts for a cost of $2,800, if I correctly understand this link: Torqeedo POWER 26-77 UI BATTERY AND ACCESSORIES (207-2203)

I haven't come upon any pricing for Valence batteries. Where do you buy them?

BigCat · 13-08-2008, 10:03

Quote:

Originally Posted by Zach

I've been doing some searching around... Haven't found a whole lot that suggests putting lead acids in the living space is overly dangerous. (Heck, my starting battery is under the bottom step of the companionway. A whole 10 inches away from the berths... for what, 47 years?

)

Been pondering mounting the batteries in a "dorade" box of sorts. Even if things go inverted, the lid would become a catch pan... still vented.

The USCG requires a 3" vent for commercial boats' battery compartments.

Aussiesuede · 13-08-2008, 10:49

Quote:

Originally Posted by BigCat

So, in Torqueedo batteries, apparently, you are limited to a maximum of 332 amp hours at 24 volts for a cost of $2,800, if I correctly understand this link: Torqeedo POWER 26-77 UI BATTERY AND ACCESSORIES (207-2203)

I haven't come upon any pricing for Valence batteries. Where do you buy them?

To my understanding, Valence currently has no distribution network and all purchases are factory direct. Gideon can comment better on this as he's purchased quite a few of them. The last price point I'm aware of is about a year old and it was about $1500 /unit. Again, Gideon would offer a better idea of current costs (if he's allowed to disclose it). Make no bones about it, they are NOT cheap. Ones primary goal would have to be weight and space savings, as primary at this point. Considering that Valence has just received a $70million & $20 million contract for dedicated commercial electric vehicles, we should finally start to see the prices drop a bit (but are likely realistically about 3 years away from any significant reductions imo)

Their batteries are on average double the capacity @ 2/3rds the weight of lead acid. With an estimated recharge capacity of 2000 cycles (10 year replacement schedule) @ Full capacity, which is another of it's benefits (the battery performance does not degrade with usage like lead acid).

ldrhawke · 13-08-2008, 11:14

It looks like it loses 4% of capacity per year.

Quote:

Normally, the capacity of a lithium battery system changes with the passing of time after its production. A lithium battery thereby loses around 4% of its capacity per annum. This ageing process is not significantly changed during use by the number of cycles. The batteries also do not have any memory effect. However, the lifetime of the battery changes dependent on the storage temperature and the charge state during storage. To increase the lifetime of the battery it should be discharged when possible if stored for a longer period of time and it should be stored in a cool environment. On the other hand, a long storage time in fully-charged state at high temperatures, e.g. over 105 ° F, reduces the lifetime of the battery.

IMHO, Saving 20 lbs per battery and paying and additional $700 to $1000 per battery over even AGM's to save 20 lbs, or 80 lbs in a four battery bank isn't a bargain. Plus it looks like it takes at least 6 hours to recharge, which means you will quickly eliminate any real dollar and weight savings in additional fuel consumed to charge the batteries.

I think a lot more analysis needs to be made and more questioned answered before I would even consider taking the next step in high tech batteries at this stage of development and pricing. There are a lot of easier ways to save 100 lbs.

Just jump up in the air every few minutes and take your body weight off the boat..............

Nordic cat · 13-08-2008, 11:31

Don't you need a special charger for the lithium batteries? Something with the maximum voltage I think.

Alan

BigCat · 13-08-2008, 11:33

Quote:

Originally Posted by ldrhawke

It looks like it loses 4% of capacity per year.

IMHO, Saving 20 lbs per battery and paying and additional $700 to $1000 per battery over even AGM's to save 20 lbs, or 80 lbs in a four battery bank isn't a bargain. Plus it looks like it takes at least 6 hours to recharge, which means you will quickly eliminate any real dollar and weight savings in additional fuel consumed to charge the batteries.

I think a lot more analysis needs to be made and more questioned answered before I would even consider taking the next step in high tech batteries at this stage of development and pricing. There are a lot of easier ways to save 100 lbs.

Just jump up in the air every few minutes and take your body weight off the boat..............

The bottom line for me is that we are best off with the old fashioned lead acid batteries, with water saver caps, as there are drawbacks to the AGM and Gel batteries besides price. See: Battery Accessories & Maintenance .