Batteries (Life Span)

[mbianka]

To make batteries last you should remember the voting motto of Chicago politics but, instead of "Vote early and often" you should charge your battery bank early and often. Don't let discharged batteries sit around for days in that state. Charge them as soon as you can. Also don't discharge them too deeply as that will decrease the number of charge cycles the batteries will give you.
I have a 48 volt AGM bank for my electric propulsion system. I never let them get under 70% charge before I crank up the Honda generator to either operate in a hybrid mode or start charging them back up to 100%. After five years they are still going strong. I also use solar panels and a wind turbine to keep them charged up in between uses.

[belizesailor]

Yes, batteries are definitely murdered, but I have not managed to murder my 8 year old house bank yet. SeaGel 12V 8D gels installed in 2004. They do appear to be losing a little capacity, but are still quite adequate for our use.

I think a good charging system, and good power management, make all the difference. I run a NextStep regulator and a custom wired paralleling system with 2 alternators (2 engines). Does a fine job. MorningStar PWM regulator for solar panels.

[DeepFrz]

I am not sure one should consider all inexpensive batteries to have cheap construction. Yes it is a competitive world out there.

Very true.

[belizesailor]

Originally Posted by foggysail

....
I am not sure one should consider all inexpensive batteries to have cheap construction. Yes it is a competitive world out there...

True, but all batteries are definitely not created equal and quality construction makes a huge difference in service life.

I had a charter company install cheap no-name batteries in my boat once and they only lasted a couple of seasons.

Also, on rare occasions you do run into good deals. For example, I just happened to be in the right place at the right time recently when a relatively new cell tower installation was being decommissioned. I picked up 5 AGMs, which tested out at almost full capacity, for the equivalent of about US$70 each. Added them to my house bank at home (off grid).

[Randyonr3]

Originally Posted by colemj

Are you cruising and cycling the batteries, or living aboard almost always on a charger?

If the batteries have never been below 12.6V, you either have a fantastic off-grid charging system and live where there is limitless solar, wind and/or fuel, or use almost no electricity, or are plugged into a shore power charger most of the time.

If you are running off a shore power charger, you could get by with a $35 Walmart battery for 10yrs.

Our batteries have.never been on a shore charge. We opperate off of two 130 watt panels atop our bimini and a 4-winds charger. And of corse the motor which has a 140 amp alt from cruising direct with a smart charge regularter... When re building systems in the boat, we opted to spend more for cost effective systems. Our reffer is a good example as we opted to spend more and installed the "cool blue" from technotics. All lighting is diode including running lights and our water heater is on demand propane
Every couple months, we shut down each battery individual to let the battery settle and surface charge drop. On the last inspection (shutdown)-all batteries read between 12.7 and 12.8..

[colemj]

Originally Posted by Randyonr3

Our batteries have.never been on a shore charge. We opperate off of two 130 watt panels atop our bimini and a 4-winds charger. And of corse the motor which has a 140 amp alt from cruising direct with a smart charge regularter... When re building systems in the boat, we opted to spend more for cost effective systems. Our reffer is a good example as we opted to spend more and installed the "cool blue" from technotics. All lighting is diode including running lights and our water heater is on demand propane
Every couple months, we shut down each battery individual to let the battery settle and surface charge drop. On the last inspection (shutdown)-all batteries read between 12.7 and 12.8..

Ah, that is different information than your original post. Most certainly your batteries have seen voltages below 12.6V while operating.

I don't think you have the data to say they are at 90% of original capacity. Even mostly consumed batteries will charge up and give high resting voltages. Actually, I think for AGMs, the resting voltage should be higher than you see since the self-discharge rate is so low.

The proof of the pudding is how long they will sustain a discharge, not how high the resting voltage is.

With 8 batteries and low daily draw, it is very likely that your batteries have lost considerable capacity in the past 10yrs, but even at this much lower capacity they still fulfill your power needs.

You would need to do a proper load test or run-down test to determine actual capacity left.

I truly do hope they are still at 90% and you get another 10yrs out of them. But that would be against all odds and if forced to make a wager, I would bet against them.

Mark

[AbenF]

I had a set of Surrettes that lasted around 14 years of fairly hard use - we had no solar so our cruising time was deep cycling and rarely topping up because who wants to listen to a generator? If I was heading around the world, I'd definitely go with them again. When it was time to replace them we went with much cheaper Interstates, and although our deep cycling days are over, we have 9 years on them and they're still testing out quite well. So I guess you just have to pay for how much abuse you expect to dish out versus how much you'll need to rely on them. Might be that just having a good set of solars adds a few years all by itself.

Regarding the "murder" charge (pun intended) - when I see batteries pulled out of boats that rarely leave the dock, I figure half of them died of natural causes, and the other half were killed by improper charger connections.