Trickle charging a marine battery?

[Sojourner]

Wondering if any of you boat or PWC owners have found it beneficial (or necessary) to maintain your battery year-round using a trickle charger. I recently got advice from the service department where I take my PWC to always use a trickle charger, even in the summer and even when the battery is brand new. This was surprising to hear, as I'd assumed the battery would only need to be maintained via trickle charge during the off-season (Oct-Apr).

I've never used a trickle charger consistently, for long periods, on any vehicle. And during the off-season, I've always just disconnected the negative terminal of boat batteries. It's much easier to do this than to setup a trickle charger, especially for my PWC where the battery is in a very tight spot, difficult to access, and would have to be fully removed and replaced multiple times throughout the summer if I were diligent about this.

What do you think? Is trickle charging always best? How do you maintain your marine batteries?

 

[njhowie]

In season, assuming you're using it every few weeks, I don't see the necessity...unless, maybe you have it docked/moored in the water and it is powering a bilge pump or other accessories.

As far as battery accessibility, you could just leave the leads (eyelet wire) always attached, and put the coupling in a more readily accessible location - it's usually a couple feet of wire (they also sell extension cables if you need to go further from the battery). Then you can easily connect the trickle charger when needed.

 

[travelover]

I think the key is to not let it get below 50% charge or about 12.0 volts. Some battery maintainers periodically give it a high voltage shot to prevent sulfation, which I guess, could extend battery life.


https://www.crownbattery.com/news/sulfation-and-battery-maintenance

 

[ExFlyBoy5]

Wondering if any of you boat or PWC owners have found it beneficial (or necessary) to maintain your battery year-round using a trickle charger. I recently got advice from the service department where I take my PWC to always use a trickle charger, even in the summer and even when the battery is brand new. This was surprising to hear, as I'd assumed the battery would only need to be maintained via trickle charge during the off-season (Oct-Apr).

I've never used a trickle charger consistently, for long periods, on any vehicle. And during the off-season, I've always just disconnected the negative terminal of boat batteries. It's much easier to do this than to setup a trickle charger, especially for my PWC where the battery is in a very tight spot, difficult to access, and would have to be fully removed and replaced multiple times throughout the summer if I were diligent about this.

What do you think? Is trickle charging always best? How do you maintain your marine batteries?

We used on our boat that was kept in a slip. The advantage was that we didn't have to worry about the battery being dead if we went out and no being there to help us out. It was a convenience thing for us...didn't have to disconnect/reconnect the battery everytime we went to the boat which could be a pain, especially in the dark. When it wasn't in the slip, we just kept it disconnected.

 

[pb4uski]

Wondering if any of you boat or PWC owners have found it beneficial (or necessary) to maintain your battery year-round using a trickle charger. I recently got advice from the service department where I take my PWC to always use a trickle charger, even in the summer and even when the battery is brand new. This was surprising to hear, as I'd assumed the battery would only need to be maintained via trickle charge during the off-season (Oct-Apr).

I've never used a trickle charger consistently, for long periods, on any vehicle. And during the off-season, I've always just disconnected the negative terminal of boat batteries. It's much easier to do this than to setup a trickle charger, especially for my PWC where the battery is in a very tight spot, difficult to access, and would have to be fully removed and replaced multiple times throughout the summer if I were diligent about this.

What do you think? Is trickle charging always best? How do you maintain your marine batteries?

Never done that in over 50 years with boats of all kinds. I do store my two marine batteries indoors over the winter then in the spring I trickle charge them overnight before reinstalling them in the boat or jetski. Never even considered trickle charging them during the season... seems like overkill to me based on my experience.

For some of our vehicles (car, golf cart, tractors) that are stored indoors I just disconnect the negative terminal then in the spring reconnect and try to fire it up. If it starts ok then I let it idle for 20 minutes or so to charge... if it has a hard time starting then I'll put the charger on it overnight.

 

[NW-Bound]

The general recommendation from lead-acid battery makers is to keep a battery in storage at a float voltage of 2.25V/cell, or 13.5V for a 12V battery.

There are battery maintainers that will supply that voltage, and can be hooked up to the battery indefinitely.

Many battery chargers put out a higher voltage and will overcharge the battery if left on for a long time. This is not good.

For more details, see: https://batteryuniversity.com/article/bu-403-charging-lead-acid.

 

[RobbieB]

I would do it if it was easy. I waited too long and ruined 2 perfectly good batteries. I did have an excuse (lame one), I needed to get a 100 foot extension cord because the dock plugs didn't work except for the one at the meter box.

I would say once a month minimum and if it's easy (short cord) I would leave one of those little (750 mA) automatic units on all the time. Or hang a 15 watt solar panel on it.

 

[OldShooter]

After having a dead house generator battery or two that I had carefully connected to inexpensive trickle chargers, I did a more serious look at the problem (from an MSEE background). What I came up with is this one: https://www.optimabatteries.com/products/digital-400/ The web page is not really informative, but the manual (https://sqlvawbi4pg46k2imi.blob.cor...ault-document-library/digital400_warranty.pdf) goes into more detail about its testing functions and automatic battery reconditioning functions.

I have had it for a couple of years and so far the generator battery seems to be just fine. I have no way, though, to really test the claimed features. Just going on engineering judgment and faith.

 

[street]

People around here install a trickle charger on a time clock and charge periodical and don't have to remember to charge them is does what is programed.

 

[Bamaman]

I use car batteries on my boat as I don't have any trolling motor or high power sound system. When I go to start it in the Spring, it has always started just fine. If it was low, I'd just charge it with my 15 amp auto battery charger.

I might remove my boat battery for the winter and put a Battery Tender on it--if we lived in a colder climate than the Mid South.

I am a believer in using the trickle charger on any PWC battery or motorcycle battery, however.

 

[Venturer]

On my motorcycle I have always used a Battery Tender. I had a 1999 Yamaha RSVenture that was 9 years old before it died. Its funny that in my online club had a joke going about which old Venture battery was going to die 1st. between mine and a fellow in Huntsville Al. that also had a 1999. He ended up winning by 3 months,but mine went out one day about 2miles from home, and his wentout one day about 20 miles from his home. Anyway yes I'm abeliever in the battery tenders, and keep one on my bike,riding mower, and on my camper all winter when I bring the battery home for storage.

 

[Sojourner]

Thanks to all for your replies and suggestions. I think I'm going to end up just disconnecting the negative terminal and then recharging it after any idle periods (two+ weeks) during the summer. I'll take the battery completely out and bring it inside during the winter to keep it on a trickle charger.

 

[Midpack]

I owned boats up north for 25 years. In season I used the boat once or twice a week, so never charged the 2 batteries. Had lead acid first few boats, but gel cells for the last few. Stored batteries in my basement, not sitting on concrete, from mid Oct thru mid Apr every year. I fully charged the both batteries in mid Oct and never again all winter until mid Apr when I was ready to reinstall them on the boat - though they weren't very low in Apr. Never had a single issue in 25 years. I used to replace them every 5 years or so, so may be different if you run batteries until they die...

 

[HenryD]

I keep mine on a charger/maintainer only because it's in a slip, in case the bilge pump needs to run a lot. I am running dehumidifiers on the shore power anyway, so might as well. Batteries are disconnected for the winter when it's out of the water. Gel house and FLA start.

 

[ERD50]

The general recommendation from lead-acid battery makers is to keep a battery in storage at a float voltage of 2.25V/cell, or 13.5V for a 12V battery.

There are battery maintainers that will supply that voltage, and can be hooked up to the battery indefinitely.

Many battery chargers put out a higher voltage and will overcharge the battery if left on for a long time. This is not good.

For more details, see: https://batteryuniversity.com/article/bu-403-charging-lead-acid.

This is the key. If the voltage drops too low, it will lead to sulfation of the plates that reduces output tremendously, and is essentially irreversible. This happens very quickly below ~ 10.2 V.

Having the battery disconnected does help - there's no drain on it other than self-discharge. If the initial charge keeps it above 11.6V over the storage time, I guess that would be OK. Also, you need to keep the electrolyte topped off, as needed.

More detail here: https://www.kendrickastro.com/lvc.html

The truth is that any lead acid battery, be it a Gel Cell, AGM or flooded batteries such as DCBs, should be cut-off at 11.6 volts. Not doing so increases the risk of damage to the battery and if taken down deep enough into the batteries charge, will ruin the battery.

.... Stored batteries in my basement, not sitting on concrete, ...

The advice to not place the battery on concrete is an ancient myth. A search will provide many reliable sources on the subject. If anything, if the battery is kept a bit cooler by being placed on a cold concrete floor, that actually slows the aging process.

-ERD50

 

[NW-Bound]

The advice to not place the battery on concrete is an ancient myth. A search will provide many reliable sources on the subject. If anything, if the battery is kept a bit cooler by being placed on a cold concrete floor, that actually slows the aging process.

-ERD50

I have read about the above myth. I wonder what explanation has been given about some physical phenomena that could happen to a battery and that would shorten its life if treated this way.

 

[Midpack]

The advice to not place the battery on concrete is an ancient myth. A search will provide many reliable sources on the subject. If anything, if the battery is kept a bit cooler by being placed on a cold concrete floor, that actually slows the aging process.

Not a myth exactly, just way out of date admittedly.

it used to be that batteries would discharge faster when stored on concrete, but newer technology put the kibosh on this phenomenon. Yet the belief persists.

A hundred years ago, this rule-of-thumb was quite useful, as the case around the battery was made of wood and the electrical cells were glass. If the concrete floor underneath was wet, the wooden case would swell, causing the glass cells to break.

Subsequent batteries would sometimes lack a case altogether, allowing electrical discharges into the concrete. Then came porous rubber cases which contained carbon atoms: this also created electrical activity between the cells in the presence of moisture, leading to prematurely discharged batteries.

 

[ncbill]

Ummm...the reproduction lead acid batteries I've seen with vintage vehicles have had 12V batteries with glass cases...you could see the lead plates inside.

Did the actual original batteries not have glass cases?

 

[NW-Bound]

Lead-acid batteries only last so long, no matter how you pamper them.

I had 2 marine batteries in my class C motorhome. When I installed lithium batteries, I removed them to the garage, and put them on a battery maintainer. Being 12V, they would work in my cars as starting batteries, and they were of the right size too. And that's what I intended to save them for.

They lasted 4 years sitting there doing nothing. Then, one day I took them out to my solar shed to power some auxiliary equipment while I was reconfiguring the lithium bank. They worked for a few days, then quit. Prior to being idled on the battery maintainer, they were used in the RV for only 1 year.

Lead-acid batteries are lousy. At least that applies to the regular flooded batteries. I have no experience with the better and more expensive AGM type to know.

 

[ncbill]

Lead-acid batteries only last so long, no matter how you pamper them.

I had 2 marine batteries in my class C motorhome. When I installed lithium batteries, I removed them to the garage, and put them on a battery maintainer. Being 12V, they would work in my cars as starting batteries, and they were of the right size too. And that's what I intended to save them for.

They lasted 4 years sitting there doing nothing. Then, one day I took them out to my solar shed to power some auxiliary equipment while I was reconfiguring the lithium bank. They worked for a few days, then quit. Prior to being idled on the battery maintainer, they were used in the RV for only 1 year.

Lead-acid batteries are lousy. At least that applies to the regular flooded batteries. I have no experience with the better and more expensive AGM type to know.

Yep, I just dumped one of these which needed new batteries ($100+):

https://xantrex.com/products/backup-power/xpower-powerpack-1500/

in favor of:

https://smile.amazon.com/gp/product/B08P5SFV4D

I calculate the latter has around 75% the useable capacity of the former, based on 50% depth-of-discharge (DOD) for lead-acid versus 80% DOD for LFP.

 

[ERD50]

Yep, I just dumped one of these which needed new batteries ($100+):

https://xantrex.com/products/backup-power/xpower-powerpack-1500/

in favor of:

https://smile.amazon.com/gp/product/B08P5SFV4D

I calculate the latter has around 75% the useable capacity of the former, based on 50% depth-of-discharge (DOD) for lead-acid versus 80% DOD for LFP.

I'd prefer LFP as well, but I don't think your watt-hour and DOD calculations are relevant.

I'm pretty sure that the lead-acid 51 Amp-Hours ( ~ 600 watt-hours at 12V), and the LFP 299 watt-hours, are both based on the appropriate DOD for the chemistry. IOW, those DOD numbers are already 'baked in the cake', and you are double counting to apply them a second time.

-ERD50

 

[ncbill]

I'd prefer LFP as well, but I don't think your watt-hour and DOD calculations are relevant.

I'm pretty sure that the lead-acid 51 Amp-Hours ( ~ 600 watt-hours at 12V), and the LFP 299 watt-hours, are both based on the appropriate DOD for the chemistry. IOW, those DOD numbers are already 'baked in the cake', and you are double counting to apply them a second time.

-ERD50

I don't believe so, at least for the lead-acid power pack I referenced.

It uses three 18Ah, 12VDC lead-acid batteries like this in parallel (so 54 AH, ~650WH):

https://infinisia.com/products/emer...8000mah-t4-terminal-agm-sla-one-year-warranty

Notice that battery is labeled as 216WH (18AH x 12VDC)...its entire capacity, not 50%.

So the useable capacity (assuming you want to keep reusing them) of those three batteries is parallel is only ~325WH.

Obviously I'm assuming a reasonable rate of discharge for each as well.

 

[ERD50]

I don't believe so, at least for the lead-acid power pack I referenced.

It uses three 18Ah, 12VDC lead-acid batteries like this in parallel (so 54 AH, ~650WH):

https://infinisia.com/products/emer...8000mah-t4-terminal-agm-sla-one-year-warranty

Notice that battery is labeled as 216WH (18AH x 12VDC)...its entire capacity, not 50%.

So the useable capacity (assuming you want to keep reusing them) of those three batteries is parallel is only ~325WH.

Obviously I'm assuming a reasonable rate of discharge for each as well.

OK, I see what you are saying. I guess it depends how you are going to use it. If it was only an occasional emergency use, then using the full capacity of the lead-acid would probably be OK? But if you are using it fairly often, then I guess they do recommend only 50% discharge.

edit/add: And this reference spells it out pretty clearly, agreeing with your 50% number -

https://www.solarips.com/blog/2021/january/battery-storage-101-what-is-depth-of-discharge-/



-ERD50

 

[youbet]

I owned boats up north for 25 years. In season I used the boat once or twice a week, so never charged the 2 batteries. Had lead acid first few boats, but gel cells for the last few. Stored batteries in my basement, not sitting on concrete, from mid Oct thru mid Apr every year. I fully charged the both batteries in mid Oct and never again all winter until mid Apr when I was ready to reinstall them on the boat - though they weren't very low in Apr. Never had a single issue in 25 years. I used to replace them every 5 years or so, so may be different if you run batteries until they die...

https://www.mcgill.ca/oss/article/g...oncrete-truth-about-batteries-stored-concrete

Have you heard the one about batteries discharging when stored on concrete? Apparently, some people have taken to storing 12V batteries—the kind used in electric wheel chairs and emergency lighting systems—on wooden shelves to maximize their life expectancy. Is there a spark of truth to this or is this claim dead in the water?

A bit of research reveals this to be a zombie truth: it used to be that batteries would discharge faster when stored on concrete, but newer technology put the kibosh on this phenomenon. Yet the belief persists.

The myth that modern batteries (lead-acid, gel or lithium) shouldn't sit on concrete has been debunked for the most part. Admittedly, my storage spot still has couple of 2 x 4's on the floor where I sit my RV battery but that's just because I put them there long ago and haven't been motivated to get rid of them since they aren't doing any harm.

The real villian in battery storage is heat.

 

[Sunset]

How about a very small solar panel to trickle charge the battery, just leave it connected to the battery all the time on the boat?