Batteries-warm weather boat storage

[BayMan]

I plan to haul and store my boat for 4-6 months this summer. In Florida. It's going to be hot.
How do I keep my batteries from draining and dying in the heat? I should be able to connect a trickle charger but won't have the typical 30a or 50a power. I have a bank of 4 6v batteries for my house bank and separate 12v batteries for starter and bow thruster/windlass. I will disconnect all negative leads to remove any power drain. I will not be able to check on them periodically and can't count on the storage yard to do so.

Thanks

 

[Don S/V ILLusion]

I infer you can't remove them for storage in a controlled environment which as I'm sure you know is the preferable alternative.

Absent that, what most of us do during the off season (summer) is trickle charge them in-situ. The 'northerners' don't know what battery problems are during their lay-up time.

 

[Benny17441]

Even if you disconnect the batteries and remove all loads you will still have to contend with a rate of self discharge. A month or two would perhaps be fine but 4 to 6 months will induce some sulfation. See if you can procure a reliable connection to have a 120V 15A extension cord to provide power to a trickle charger. The alternative might be a solar panel and controller. Regarding the heat, it has been my experience that during the summer months distilled water needs to be added to the batteries to maintain the level to cover the cell plates. There are some automatic battery watering systems in the market; I have not used any of them and don't know how reliable they might be but perhaps it is something to consider to keep up the electrolyte level.

 

[BayMan]

It won't be easy but perhaps what I simply have to do is get to the boat at least once during storage to check on everything, not just the batteries.

 

[Stu Jackson]

See if you can procure a reliable connection to have a 120V 15A extension cord to provide power to a trickle charger. The alternative might be a solar panel and controller.

Benny's right about the options, although constant trickle charging also causes sulphation. Man, boating and those pesky options...

 

[Bill Roosa]

I'd throw them in the trunk and take them home. even if you have to leave them under the deck or in the rain it will be better for them as you can check on them and recharge as needed. As a cautionary tale, if you have a rain water leak into the cabin you can take the smallest battery with you when yo do visit the boat to run the bilge pump.

 

[seadaddler]

I go up north
for 3 months and have solar keep them charged and have a friend stop and check the
fluid in batteries 1 or 2 times while I am gone but I do have 2 solar panels mounted on my arch since 2010
and love them when cruising.
Nick

 

[JamesG161]

I would have thought the yard would have supplied power, even a cord. I would be more concerned about the mildew inside your cabin. A dehumidifier and extension to your Inverter/Charger would do all but the Start Battery, which is much more easily removed.
Doesn't your Hunter model have a solar panel to trickle the Start Battery? BTW my new start battery cost ≈$90, but I don't have a bow thruster.
Jim...

 

[Maine Sail]

Remove them and store them at home in a cool location, room temp or below is optimal with cooler being more healthy. Heat above 80F shortens the life out of lead acid batteries whether they are fully charged or not. If float charging them make sure your charger has an on-battery temp sensor to drop the charge voltage based on actual battery temp..

This quote is directly from one of the Sandia National labs studies I have on my hard drive. Sandia is perhaps the foremost leader in the field of lead acid battery research.

Sandia National Labs:
"The optimum operating temperature for the lead-acid battery is 25°C (77°F). As a guideline, every 8°C (15°F) rise in temperature will cut the battery life in half."

If the mast is up use the main sheet to lower them to the ground or just make 4 trips up and down the ladder. Why shorten the life of your bank over 20 minutes work....

 

[walt]

I leave approximately $205 worth of lead acid batteries (6V) on a 20W solar panel/ charge controller in the boat over the summer in one of the hottest cities on the planet (Arizona). Im gone for about 6 months of the year but come back during the summer and trailer the boat for a week or so. The charge controller has temp compensation but its not reading the battery temp directly.

From talking to people around here, the heat results in car batteries lasting maybe 2/3 as long as they do in a cooler climate and I have been storing the batteries in the boat like this for enough years now that I think that number is ballpark enough.

So.. my yearly cost for just leaving the batteries in the boat is on the order of $17. For that $17, I dont have to remove the batteries twice, then put the batteries back in twice and then go through the hassle of finding a cool place to keep them. That is a huge bargain- well worth it!!! If it were a safety issue.. it would be a different story (however not screwing up my back also goes in the "safety" category).

What has been harder on the batteries is the little things like the solar panel getting blown so that its output is reduced and then you come back and find the batteries discharged. If you were around, you would have noticed and corrected this quickly - but you are not around and the battery might sit there discharged for a long time.

 

[LeeandRick]

If you can't do any of the above then go down to Harbor Freight and get cheap trickle charge solar (PV) panels. About $12 bucks each (less if you have the 20% off coupon). Buy enough to charge the individual banks so you don't have to add wire to the panel. Alternative, if you trust yard security, is to move them all to the cockpit under a tarp with solar chargers. Just don't connect batteries together that haven't been connected together before. Unless the batteries are getting near the end of their life, they should survive 4 months with no additional water. At least that's my experience from the last 20 years in the RV solar business.

 

[walt]

Sandia National Labs:
"The optimum operating temperature for the lead-acid battery is 25°C (77°F). As a guideline, every 8°C (15°F) rise in temperature will cut the battery life in half."

This sounds bad.. but you have to consider that the elevated temps are not happening ALL YEAR, just a portion of the year. For 3/4 of the year, in my case, the batteries will be at much lower temps and for months of that time, well bellow an average of 77F. The above is true.. but it does not at all mean that if you leave the batteries on the boat for a summer, that you will shorten the overall life time by 1/2 or more. It is only during the time that they are very hot that you get the shorter life. For my application in Arizona, I think the 2/3 lifetime is ballpark. The cost for the reduced battery life is an overall small expense especially when I compare it to my out of pocket costs for a hernia operation.

 

[Ron20324]

Take anything of value off the boat. An-out-of-state boat on the hard is an invite for break-ins & theft.

 

[BayMan]

Latest thought is to use a converter plug to plug my 30a shore cord into storage yards 110v 3 prong socket. Plugged in my onboard xantrex charger should keep batteries alive. Should have enough amps available to run a dehumidifier to combat mold. Not much I can do about the heat. I don't dare leave a port open due to rain.
I have no place to take them so removing batteries is not an option.

 

[LeeandRick]

Sandia National Labs:
"The optimum operating temperature for the lead-acid battery is 25°C (77°F). As a guideline, every 8°C (15°F) rise in temperature will cut the battery life in half."

.

I would like to read the paper on that one. Do you have the reference. My friend Tom M. headed up most of the battery research at Sandia the 25 years I lived in ABQ and passed along a lot of papers when I got into the solar biz. I didn't see that info or maybe missed it.

 

[Maine Sail]

I would like to read the paper on that one. Do you have the reference. My friend Tom M. headed up most of the battery research at Sandia the 25 years I lived in ABQ and passed along a lot of papers when I got into the solar biz. I didn't see that info or maybe missed it.

Is that T. Hund? I have a bunch of his papers including some Sandia no longer allow downloaded. When I get home Monday I can dig that paper up.

 

[walt]

This reference doesnt tell where that number comes from - but its the same numbers you can find on this link http://batteryuniversity.com/learn/article/how_heat_and_harsh_loading_reduces_battery_life Might be some difference from battery technology.. but no doubt that heat degrades the battery life time. The question is.. how bad is it really over the life of a battery given seasonal and daily temp fluctuations and different use patterns.

Rick and I both are in Lake Havasu which really gets HOT in the summer so might be somewhat of a benchmark to compare to. Likely for the OP in FL, its not as hot as Havasu is - you could compare with the link below. My data point is just from asking people who live here about car batteries and I think they dont last as long as in colder climates but its not a huge deal. Car batteries have it worse than boat batteries being right under a metal hood that must get just blazing hot here in the summer and near a hot motor. My experience.. leaving the batteries in the boat is not something to get all excited about.. and they probably wont last as long but the alternative of taking them out of the boat and finding some cool place for them is a way worse alternative (would I drive them back and forth to Denver four times a year.. NOPE). However, I also dont heavily use my batteries and I also dont measure them even remotely as accurately as Maine Sail does for capacity.

If I do decide to take the two batteries out, Rick, do you think your wife would be OK if I left them in your kitchen for the next six months? (Ok.. maybe NOT a good idea).

http://www.usclimatedata.com/climate/lake-havasu-city/arizona/united-states/usaz0372

 

[walt]

From the battery university link.. (VRLA are sealed lead acid batteries)

What I get from that web site (see quotes below) is that if you keep a boat in a place with a hot climate, the standard flooded lead acid batteries are a better choice than sealed lead acid batteries. The data point of half the life for each 15F rise in temp is for a VRLA battery and likely fairly old data. Link again http://batteryuniversity.com/learn/article/how_heat_and_harsh_loading_reduces_battery_life

Flooded lead acid batteries are one of the most reliable systems and are well suited for hot climates. With good maintenance these batteries last up to 20 years. The disadvantages are the need for watering and good ventilation.

When VRLA was introduced in the 1980s, manufacturers claimed similar life expectancy to the flooded systems, and the telecom industry was enticed to switch to these maintenance-free batteries. By mid-1990 it became apparent that the life of VRLA did not live up to the flooded type; the typical service life of the VRLA is 5–10 years, less than half of the flooded equivalent. It was furthermore noticed that exposing VRLA batteries to temperatures above 40°C (104°F) could cause a thermal runaway due to dry-out.

As a guideline, each 8°C (15°F) rise in temperature cuts the life of a sealed lead acid battery in half. This means that a VRLA battery for stationary applications specified to last for 10 years at 25°C (77°F) would only live 5 years if continuously exposed to 33°C (92°F) and 30 months if kept at a constant desert temperature of 41°C (106°F). Once the battery is damaged by heat, the capacity cannot be restored.