FLA battery storage question

[Mendigo Diver]

Hi.
I have four Trojan batteries (6V 450Ah used in series parallel), I need to store them for 10 to 12 months and am looking for advise, I was thinking to remove them from the system and connect a float charger to them, hopefully someone will come occasionally to check the water levels but I recon if they go on to float fully charged and full of water there should not be much gassing. To maintain a float would a 10Amp smart charger be sufficient? I haven't bought a charger for this yet but the 10A ones are fairly cheap.
Thanks
Jon

 

[SolGato]

Take a look at the NOCO Genius 2x4. I would want intelligent independent charging for each battery.

If the batteries are in good health and topped off, 2A should get the trickle charging job done.

If you can remove them and store in an ideal climate per the manufacturers specs, they won’t need as much supervision with regard to levels.

 

[Zonker]

Yes, should be OK but "hopefully" is not much of a plan. Have a jug of distilled water handy and find somebody to check them every 3-4 months. Even if you have to pay then $20 for 5 minutes work.

 

[mckenzie.keith]

I think those pulse de-sulphating battery maintainers would be a good idea. Like the BatteryMINDer 1510. I haven't used one of these but I have heard very good things about them.

BatteryMINDer® Model 1510: 12-Volt 1.5 Amp Maintenance Charger/Desulfator Including a 10 Year Warranty

Battery MINDer's 1510 12 volt desulfating battery charger maintainer can extend the life of a battery up to four times its normal span.

www.batteryminders.com

 

[DDW]

I have been talked into purchasing, and then tested a desulfating device. It was snake oil - until they publish a test run by a reputable university who wasn't paid for the work, save your money.

There are some battery chargers that have a 4th state, "storage", which drops the voltage below float voltages to minimize evaporation. The Victron Smart charger in 5A or 10A for example is a great one. It will go into storage for a week, then wake up and do a very short absorb charge, then back to float and storage. I would not bottom fish the charger market, you need only google fires caused by cheap chargers to be a little concerned.

 

[Mendigo Diver]

Thanks for the info guys. The batteries will be removed with distilled water and a baster sat next to them so my guy wont have to do much other than turn up (though I will also make a plan with the boatyard to be sure). I like the look of the NOCO 10A charger (just big enough to be useful in future as well), the batteries are 2 years old and seem very balanced so I will charge them as a bank.

 

[Leeroy Jenkins]

Winter Battery Storage & Self Discharge Characteristics - Marine How To

December 11, 2012 After having a discussion with one of my customers, about leaving his battery charger running on-board all winter, a practice I am certainly not a huge fan of, and one his boat yard specifically prohibits, I decided to venture into this article.

marinehowto.com

Worth a read.
According to the article you could probably just charge them to 100%, disconnect them, top up the electrolyte and walk away.

 

[Mendigo Diver]

Very interesting article, thank you, though I now have more to think about!

 

[mckenzie.keith]

I have been talked into purchasing, and then tested a desulfating device. It was snake oil - until they publish a test run by a reputable university who wasn't paid for the work, save your money.

There are some battery chargers that have a 4th state, "storage", which drops the voltage below float voltages to minimize evaporation. The Victron Smart charger in 5A or 10A for example is a great one. It will go into storage for a week, then wake up and do a very short absorb charge, then back to float and storage. I would not bottom fish the charger market, you need only google fires caused by cheap chargers to be a little concerned.

I think the battery mindr things work. But I have not tested them.

 

[Will1073]

My own boat, I would charge them to 100%, remove the negative cables, and fill em up.

Some yacht clubs in my area are starting to not allow boats to be charged unattended when on the hard. Insurance conditions apparently

 

[don54321]

A lead acid battery engineer (and one of his colleagues) at East Penn (Deka), one the the largest Lead Acid battery manufacturers, recommended the cheapest of the dashboard type solar panel to me. He told me that even the smallest charge & discharge current helps minimize sulfation, and the the amp or 2 of charge is plenty to compensate for self discharge. He said that leaving a battery disconnected was not healthy for the battery. At these super low charge rates, you are not generating significant heat "boiling" off water. I don't think that this is an issue at all. This of course is assuming healthy batteries to start. If using a battery maintainer, smaller is better for this application. 10A is way overkill. With modern smart chargers with stages, supposedly they should back themselves down, but I would be inclined to buy a 1.5 or 2A model from a top brand as reliability of the charger becomes an issue. It can't be expensive. A bigger charger, if too aggressive, could be a problem, for no apparent purpose. You are not going to damage anything with a ~1A charge rate. The other question is storage temperature. Best to keep temperatures moderate. High temps will promote water loss and age the batteries. I plan to use a 20W best case (<2A) dashboard solar charger, to maintain a car battery over the summer ~4 months for the first time this season, on this same advice. We will see how it goes.

Don

 

[El Borracho]

A lead acid battery engineer …

An engineer wouldn’t say that the water “boils” off. Certainly not from “heat”. During charging chemically liberated gasses are created and vented. That reduces the water content of the electrolyte. The forming bubbles can also ablate the plate materials. A very accurate manufacturer-specified temperature compensated float voltage (not so much a current) can avoid the problem but is unlikely to be completely successful in the marine environment.

My choice would be to leave them disconnected. Each 3 months fully charge and add water if necessary. More often if the climate is hot. If battery temperature is on the cool side (10°C) then each 6 months would suffice.

 

[don54321]

"Boils off" was of course not a literal Boil. Overcharging absolutely contributes to loss of water. As it happens I am an electrical engineer, with an electronic test equipment manufacturer and East Penn DEKA (one of the biggest lead acid battery manufacturers) is my customer. I know very little about chemistry and not much about lead acid batteries, but I do know a goodly number of research engineers at DEKA. When visiting DEKA's research center, in Kutztown, PA, (not to be confused with their factory / HQ down the road) on a routine support call, I asked exactly the question posed here, and the recommendation was the cheap dash top type solar panels for a car sitting dormant. Furthermore, they indicated that the very slight load of the alarm system and other sustaining electronics was a net benefit to the battery and recommended not to disconnect the battery, just use the dash top solar panel. This was not the opinion of 1 guy, but also his colleague, part of the same conversation. Although I have no personal battery expertise, I would assume that the guys designing the batteries know their stuff. Now as this was in regard to a typical automotive battery, I did not ask about maintaining water levels, as people do not water modern automotive batteries. Much of what I do for a living puts me in contact with experts in their respective fields. It's an opportunity for me to ask some questions of my own, and I am not in the habit of challenging their recommendations as this is their specialty. Feel free to have your own opinions.

 

[Mendigo Diver]

Thanks everyone for the input. After reading a fair bit on this now I have changed my mind about charging, as previously stated there are many possible problems at worst fire and at best someone un-plugging the shore power.
I will charge/top up/equalize them and put them in the bilges which will remain the coolest spot through summer.
I will try to remember to give you an update at the end of the year as to how it went
Jon