battery weight

[seabeagle]

Quick question. Are dry cell batteries like the Optima brand lighter than an equally rated lead acid battery?

[Stephen Williams]

I don't have an exact answer to your question, although I do have one of each and they seem about the same.

But, I do want to tell you to go ahead and move the batteries from the stern to under the seats. I did that a couple of days ago, and BOY, what a difference. I also lengthened the fuel line so that my 6 Gal tank can go underneath the forward berth. I had moved the tank previously just to test the weigh effect, and it didn't seem to do much, so I now can give credit for much better balance to the movement of the batteries. I also have a 6 HP Mercury hanging off the stern on a separate bracket which adds weight to the stern, but I would never want to give up the security of that extra engine!! Steve

[Desolation Cruiser]

I believe the Optima batteries are actually a gel cell battery not a dry cell.
They are still a lead acid battery. The acid is in a gel form vs. liquid.
Similar CCA batteries will weigh approximatly the same gel or liquid acid.

[Dreamer]

The Optima Batteries are actually an AGM Battery (Absorbed Glass Mat). The weight is similar but the charging voltage can be up to 15v. The Blue Top 35 series is a great start battery.

[mcc272]

The best way to figure things out is to go to the web site for the battery manufacturer and do a careful comparison of the specs. www.optimabatteries.com. Lifeline is another brand of AGM battery. I have used Lifelines for years on several boats as well as Optimas which I use as my starting battery. If you are using the batteries as the house bank, you are more concerned with the capacity of the battery than the CCA which is more of a starting question. For capacity, there is no free lunch, weight wise and the heavier the battery, the greater the capacity. For comparison, an Optima Blue Top D31M weighs in at 59.8 lbs and has a capacity of 75AH (C/20 rate). The Lifeline GPL-31T which is the same case size (that is the 31 number) has a capacity of 105AH measured the same way and weighs in at 69.0 lbs. Assuming a maximum 50% draw down (although I prefer to draw down less) the lifeline has an extra 15AH of useable capacity which is not insignificant. Since both Optima and Lifeline are AGMs, they can be charged together as the charging requirements are very similar.

AGMs cost a lot more than wet cell lead acid batteries but they never have to be checked, take a charge at a faster rate and since there is nothing to spill even if the case were to break, they do not need to be installed in a battery box. They can even be installed on their sides.

The real question you have to ask yourself with AGMs is whether the benefits are worth the significant additional cost.

Jim

[FtBiggy]

Just thought I would add that Odyssey Battery's are used by the Coast Guard, according to the web site, www.odysseysoutheast.com
Good details, weight, CCA's etc. on site. Certainly an area where you need to always get the BEST available.

[toyman]

I have 2 Optima grp 31 in my van and have been very happy with them. I have a Prosine 2.0 inverter that will charge them at 100A when they are down, contrary to sage advise from the net, Optima says "no problem" with the high amp charge rate as long as the temp. is monitored. I will have AGM's in the FanCdory when the factory batteries go "Toes up", just a lot cleaner and easier to maintain.

[Chuck S]

Battery power is directly related to the weight of the battery. The amount of lead (or other metal). Lightweight batteries are lightweight performers. The only benefit Optimas have is their very sturdy construction. Great for offshore powerboat or off road racing. Not much power for running your anchor light and VHF all night.

Since the engines on our boats take little starting amperage you can use deep cycles for both starting and house batteries. Buy these by Reserve Capacity, not cold cranking amps. You'll find the Optimas are low in RC.

-- Chuck

[marvin4239]

I'd definately go with the AGM's for the 16, mounted under the passenger seat they are hard to access for checking fluid level. I particuarly like the Sears AGM's they are expensive and some argue they are twice as much as lead acid but it you figure the cost difference over a three year span they really aren't that much and Sears offers a full (not prorated) replacement for three years.

[Sea Wolf]