Battery blues. Or why I am never as clever as I thought I was.

[GILow]

Hi Cruisers,

I am in a mental bind over my battery bank. A quick summary is this: in about three and a half years from now (when my son has finished year 12) we will set off for a round Oz trip, plus maybe Vanuatu, NZ etc on a trip likely to be between one to three years in duration depending on how much we enjoy it.

The boat is a very low power consumption vessel and even the most pessimistic power budget tells me we will get away with a 400AH house battery bank, assuming 200AH useable capacity, though I would prefer to fit 600AH to nurse the batteries a little, as weight is not a concern.

We have 280 watts of solar and a large wind generator (300 watts) plus a decent quality 100 amp alternator to charge things. All currently work as they should, I have completely rewired the boat from scratch. The solar controller understands practically any battery chemistry and is programmable so battery choices are flexible. The wind gen is a fixed charge profile so requires manual monitoring. The alternator is externally regulated and manually switched.

The boat is currently a total dock queen, and because it will be a number of years before we got going I decided to be a cheapskate and bought a pair of really cheap 12v 120AH AGMs from a big online retailer here in Oz. My idea was that they would do for weekend sailing, then when we were ready to go I would toss them, fit 6 Trojan T105s, reprogram the solar regulator and get going.

Alas the AGMs have gone toes up in a year. (Probably less than a year actually, I only noticed they were dead when I did a longer than usual trip to Kangaroo Island recently.)

So now I have a dilemma. I am back to a situation where I don't want to fit the "real" battery bank because then it will have been sitting for more than three years before we use it, but the current battery bank can't even service the boat as a weekender. To complicate things, I need to be able to cannibalise the house battery bank in an emergency to create 24 volts if the engine bank dies, so that means at least two 12 v batteries are needed in the house bank.

Oh yeah, batteries are horribly expensive in Oz. current best price for the T105 I have been able to find is about AU$260 each. And I'd need four of those to create 24 volts.

What would you do in my situation?

Matt


Sent from my iPhone using Cruisers Sailing Forum

[transmitterdan]

The first thing I would do is figure out why the new AGMs died. They should last 5 years; even the cheap ones. Until you know what is happening and because you need batteries now I would get the cheapest flooded deep cycle batteries you can find. Don't get AGM or some other expensive batteries until you get the problems sorted.

Most common cause of early failure of AGM is under or over charging.

[skipmac]

First, like Dan said, find out why the AGMs died.

Have you checked on golf cart batteries instead of Trojans? In the US there are a number of manufacturers that make 6V batteries very comparable to Trojan but for less money. Maybe there's an Australian battery maker that has an option.

[Pete7]

I don't follow the logic of fitting AGMs if its only a dock queen sailing at weekends. Instead I would chose flooded lead acid which you can add water to and top up occasionally. A pair of 100AH should do for weekend sailing for the next 3 years. Since you have solar this should keep things sweet whilst you are not on board.

Is the combination of wind and solar over charging? Try just the solar assuming it is well regulated with a PWM or MPPT regulator.

[barnakiel]

I would buy car grade 12Volt batteries and live with them then replace them.

They normally last me about three+ years in house use. Green points collect them for recycling. Prob noblem.

b.

[Terra Nova]

Originally Posted by GILow

...I decided to be a cheapskate and bought a pair of really cheap 12v 120AH AGMs...
the AGMs have gone toes up in a year...
What would you do in my situation?
...

I would stop being a cheapskate while expecting different results.

[socaldmax]

Originally Posted by transmitterdan

The first thing I would do is figure out why the new AGMs died. They should last 5 years; even the cheap ones. Until you know what is happening and because you need batteries now I would get the cheapest flooded deep cycle batteries you can find. Don't get AGM or some other expensive batteries until you get the problems sorted.

Most common cause of early failure of AGM is under or over charging.

Yes, I agree, find out why the AGMs died so quickly and fix that first.

Then I'd find out what kind of warranty they had and get them replaced, even the junk ones usually have a 2 or 3 yr warranty. Don't wait too long, get your free or prorated replacements while you can, this way you don't pay any more for batteries that should have lasted the duration.

There's a possibility that you didn't do anything wrong, if you got a battery with a bad cell, it could have dragged the entire bank down with no negligence on your part.

[S/V Alchemy]

AGMs have different charging requirements entirely from flooded lead-acid (FLA) "standard" batteries. They are the most expensive, pointless choice for a "dock queen".

For long hauls, you want user-serviceable (as in watering and measuring SG to determine the true state of charge (SOC) of the batteries. You have all the components at hand save for the right batteries. I concur that car batteries, well-tended, will serve you until you get your "voyaging set".

It pays to educate yourself in this regard and I would start with this fellow, who posts here: Measuring A Lead Acid Battery State of Charge Photo Gallery by Compass Marine How To at pbase.com

If "weight isn't an issue", you may wish to go big, as I have in the last month. These total 1575 Ah of capacity, but I intend on drawing them down to no more than 75% SOC in normal usage, not the 50% that people assume is customary. Why? For the greatly increased cycles, which translate to a greatly increased lifespan. Sometimes not having to buy, or to shift, batteries is the best savings of all.

[Cadence]

I wouldn't worry about expensive batteries. If space is not an issue go to a truck /lorie / semi supplier and get some 8Ds. Keep water in them and worry about expensive batteries later.

[leftbrainstuff]

Originally Posted by GILow

Hi Cruisers,

I am in a mental bind over my battery bank. A quick summary is this: in about three and a half years from now (when my son has finished year 12) we will set off for a round Oz trip, plus maybe Vanuatu, NZ etc on a trip likely to be between one to three years in duration depending on how much we enjoy it.

The boat is a very low power consumption vessel and even the most pessimistic power budget tells me we will get away with a 400AH house battery bank, assuming 200AH useable capacity, though I would prefer to fit 600AH to nurse the batteries a little, as weight is not a concern.

We have 280 watts of solar and a large wind generator (300 watts) plus a decent quality 100 amp alternator to charge things. All currently work as they should, I have completely rewired the boat from scratch. The solar controller understands practically any battery chemistry and is programmable so battery choices are flexible. The wind gen is a fixed charge profile so requires manual monitoring. The alternator is externally regulated and manually switched.

The boat is currently a total dock queen, and because it will be a number of years before we got going I decided to be a cheapskate and bought a pair of really cheap 12v 120AH AGMs from a big online retailer here in Oz. My idea was that they would do for weekend sailing, then when we were ready to go I would toss them, fit 6 Trojan T105s, reprogram the solar regulator and get going.

Alas the AGMs have gone toes up in a year. (Probably less than a year actually, I only noticed they were dead when I did a longer than usual trip to Kangaroo Island recently.)

So now I have a dilemma. I am back to a situation where I don't want to fit the "real" battery bank because then it will have been sitting for more than three years before we use it, but the current battery bank can't even service the boat as a weekender. To complicate things, I need to be able to cannibalise the house battery bank in an emergency to create 24 volts if the engine bank dies, so that means at least two 12 v batteries are needed in the house bank.

Oh yeah, batteries are horribly expensive in Oz. current best price for the T105 I have been able to find is about AU$260 each. And I'd need four of those to create 24 volts.

What would you do in my situation?

Matt


Sent from my iPhone using Cruisers Sailing Forum

Our T105s are 9 years old and still going strong. They are quite thirsty now as they get near end of life.

Why not replace with cheap FLA. They will get you through a few years with your current use.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[lordgeoff]

And get a warranty refund on the batteries?

[Bell1938]

Hello GILow,

I am also in Oz and looking at new batteries myself for a new (to me) vessel for the same sort of duty as you describe and had just about decided on a pair of 120AH AGMs, so your post is timely.
Would you mind telling me what brand/supplier these batteries were?

[CapnBazza]

I am thinking about these ... OFF Grid Solar Deep Cycle AGM Battery 6V 320AH FOR 12V 24V 48V Battery Bank | eBay . Currently doing a refit, my All Rounders have expired after 6 years. Also contemplating LiFePO 150ah at about AUD$1700.

[reed1v]

would check for a short somewhere. Turn all off and check to see if there is any draw on your batteries. Secondly, selectively turn on the normal stuff one by one, like bilge pump, etc and see what the draw is. Batteries do not die on their own unless they are cracked. You got a slow draw somewhere in the system.

[Uncle Bob]

Originally Posted by GILow

Hi Cruisers,

I am in a mental bind over my battery bank. A quick summary is this: in about three and a half years from now (when my son has finished year 12) we will set off for a round Oz trip, plus maybe Vanuatu, NZ etc on a trip likely to be between one to three years in duration depending on how much we enjoy it.

The boat is a very low power consumption vessel and even the most pessimistic power budget tells me we will get away with a 400AH house battery bank, assuming 200AH useable capacity, though I would prefer to fit 600AH to nurse the batteries a little, as weight is not a concern.

We have 280 watts of solar and a large wind generator (300 watts) plus a decent quality 100 amp alternator to charge things. All currently work as they should, I have completely rewired the boat from scratch. The solar controller understands practically any battery chemistry and is programmable so battery choices are flexible. The wind gen is a fixed charge profile so requires manual monitoring. The alternator is externally regulated and manually switched.

The boat is currently a total dock queen, and because it will be a number of years before we got going I decided to be a cheapskate and bought a pair of really cheap 12v 120AH AGMs from a big online retailer here in Oz. My idea was that they would do for weekend sailing, then when we were ready to go I would toss them, fit 6 Trojan T105s, reprogram the solar regulator and get going.

Alas the AGMs have gone toes up in a year. (Probably less than a year actually, I only noticed they were dead when I did a longer than usual trip to Kangaroo Island recently.)

So now I have a dilemma. I am back to a situation where I don't want to fit the "real" battery bank because then it will have been sitting for more than three years before we use it, but the current battery bank can't even service the boat as a weekender. To complicate things, I need to be able to cannibalise the house battery bank in an emergency to create 24 volts if the engine bank dies, so that means at least two 12 v batteries are needed in the house bank.

Oh yeah, batteries are horribly expensive in Oz. current best price for the T105 I have been able to find is about AU$260 each. And I'd need four of those to create 24 volts.

What would you do in my situation?

Matt


Sent from my iPhone using Cruisers Sailing Forum

Hi, having been down a similar path not so long ago, I ended up buying a set of six 235 ah Supercharge golf cart batteries from an online seller, based here in Sydney, for $200.00 each. They work perfectly, run the fridge 24/7 and rarely drop below 13 volts being charged from 190 watts of solar.
Works really well for me, and I should get at least 7 years from them (touch wood)
So what would I do ? I would spend the money and get a reasonable set of flooded lead golf cart batteries, set them up correctly and enjoy all the benefits now, not wondering if they were going to do the job.