Battery storage


Chuck_Kim_Joy
 

Greetings All,

I have posted this on the victron forum without a clear consensus so here it goes. I will be hauling out and storing boat for appx 7 months this winter. I have a skylla I charger, solar and victron mppt and victron agms. Agms have self discharge at less than 2% per month at 20c. In theory I could fully charge and be OK with turning them off. Or set mppt to storage mode and hope I don't overcharge and bake them. Any advice? Thanks and all the best!

Chuck and Kim 

sv Joy #388 Ionion, Greece


Gerhard Mueller
 

If the batteries are in good condition any charger will slow down charging automaticly when the batteries are fully charged. This is a physical rule because of the changing inner resistance of a battery.
--
Gerhard Mueller
Amel Sharki #60
Currently North Sea, Germany


Dean Gillies
 

You won't get a consensus on this question, only opinions.

If you are only away from the boat for 6 months and, barring world events that may prevent you returning to the boat, (don't ask!) and you don't have anything onboard that needs power, then turn everything off and DISCONNECT the batteries.
You will sleep easier.

If you are away longer than 6 months then consider leaving them on float charge, but of course there's always the chance that something goes wrong, no-one on board etc. maybe you don't sleep quite so easy.

Personally, I turn off my LFP system and put my AGM batteries into solar float during the winter. This allows me to run an internet connection which I use to monitor the boat. I sleep pretty well because I know what is going on when I'm 13000 miles away.




Sent from my iPhone X

--
Dean Gillies
SV Stella *****,  Amel 54-154


Bill Kinney
 

Chuck,

"Storage" mode in the Victron world does two things.  It reduces the "float voltage" and it periodically cycles the batteries through an absorption cycle.  

Looking at the manual for my old Lifeline AGM's, they recommend letting the batteries sit--not charging--and applying "boost charge" every 90 days at between 28.8 to 30.0 Volts, basically a normal absorption cycle to bring the batteries back to 100% charged.  I haven't seen any similar details for exact strorage recommendations from Victron in the battery documentation, other than to use the default AGM setting on their chargers.

I don't know how much control you have over the particular model of MPPT you have, but this Lifeline's recommendations be created by setting a low float voltage (~24.1V or 24.2V) which would basically shut down charging unless the batteries drop below about 75% or so.  Keep the absorption voltage set at its normal level, and the "Storage mode" absorption repeat interval to 90 days (Victron Default for this is 7 days).  This pretty much replicates what Lifeline recommends for their batteries.

All that said...  if I had Victron AGM batteries, and a Victron MPPT, If it was my boat, I would use the Victron MPPT Default storage mode when set to the AGM battery defaults unless I had a very good reason for doing something else. A properly functioning MPPT will never overcharge the batteries if the charging parameters are set up correctly.

Bill Kinney
SM160,  Harmonie
Port Louis, Grenada
http://www.cruisingconsulting.com


Chuck_Kim_Joy
 

Hi Bill,
Thanks for your reply. Here is a snap of the victron mppt settings. I mispoke regarding a storage mode setting for the mppt. I have the storage voltages (not float) for my batteries 26.4-27v. I can set to that. No repeat intervals as you described. I had or the guardianage in Martinique had fried my last set of wet cells (1 year old) charging from an old Morningstar pmw solar controller. So I am a bit paranoid. 
I hope you and Karen are enjoying Grenada. Another month and you're free to meander North. 


Cheers,
Chuck and Kim 
Joy #388

On Thu, Sep 29, 2022 at 4:06 PM Bill Kinney <cruisingconsulting@...> wrote:
Chuck,

"Storage" mode in the Victron world does two things.  It reduces the "float voltage" and it periodically cycles the batteries through an absorption cycle.  

Looking at the manual for my old Lifeline AGM's, they recommend letting the batteries sit--not charging--and applying "boost charge" every 90 days at between 28.8 to 30.0 Volts, basically a normal absorption cycle to bring the batteries back to 100% charged.  I haven't seen any similar details for exact strorage recommendations from Victron in the battery documentation, other than to use the default AGM setting on their chargers.

I don't know how much control you have over the particular model of MPPT you have, but this Lifeline's recommendations be created by setting a low float voltage (~24.1V or 24.2V) which would basically shut down charging unless the batteries drop below about 75% or so.  Keep the absorption voltage set at its normal level, and the "Storage mode" absorption repeat interval to 90 days (Victron Default for this is 7 days).  This pretty much replicates what Lifeline recommends for their batteries.

All that said...  if I had Victron AGM batteries, and a Victron MPPT, If it was my boat, I would use the Victron MPPT Default storage mode when set to the AGM battery defaults unless I had a very good reason for doing something else. A properly functioning MPPT will never overcharge the batteries if the charging parameters are set up correctly.

Bill Kinney
SM160,  Harmonie
Port Louis, Grenada
http://www.cruisingconsulting.com


Chuck_Kim_Joy
 

Thanks Dean,
It will be closer to 7 months. I feel most comfortable turning everything off. I was hoping someone had recent experience fully charging and turning off victron supercycle agms and letting them discharge over that length of time. I do have a good victron mppt that can be programmed. Just a bit nervous to over or under charge. All the best!
Chuck and Kim 
sv Joy #388

On Thu, Sep 29, 2022 at 3:53 PM Dean Gillies <stella@...> wrote:
You won't get a consensus on this question, only opinions.

If you are only away from the boat for 6 months and, barring world events that may prevent you returning to the boat, (don't ask!) and you don't have anything onboard that needs power, then turn everything off and DISCONNECT the batteries.
You will sleep easier.

If you are away longer than 6 months then consider leaving them on float charge, but of course there's always the chance that something goes wrong, no-one on board etc.  maybe you don't sleep quite so easy.

Personally, I turn off my LFP system and put my AGM batteries into solar float during the winter. This allows me to run an internet connection which I use to monitor the boat.  I sleep pretty well because I know what is going on when I'm 13000 miles away.




X

--
Dean Gillies
SV Stella *****,  Amel 54-154






David Crisp
 

In line with Dean's comment, here's another opinion and my experience.
I had a brand new set of Victron batteries in 2020 and and for good reason ($$$) I am nurturing them.  WG has solar panels with Victron MPPT but I am wary of relying upon any devices when I am not on hand to monitor things (that from someone who spent 30 years in the tech' industry).  A couple of years ago I consulted with Victron technical support and they advised the batteries would be fine if fully disconnected for 6-9mths.  Consequently I physically disconnect the batteries on WG when I haul out for the winter.  
--
David Crisp
SV Wilna Grace
Amel 54 #58


Chuck_Kim_Joy
 

Thanks David. That is reassuring to hear. I guess if there was an event that prohibited me from getting back to my boat I could have someone in the yard connect and charge. So you disconnect each battery or just the switch?
Chuck 
Joy SM 388

On Fri, Sep 30, 2022 at 12:14 PM David Crisp <david@...> wrote:
In line with Dean's comment, here's another opinion and my experience.
I had a brand new set of Victron batteries in 2020 and and for good reason ($$$) I am nurturing them.  WG has solar panels with Victron MPPT but I am wary of relying upon any devices when I am not on hand to monitor things (that from someone who spent 30 years in the tech' industry).  A couple of years ago I consulted with Victron technical support and they advised the batteries would be fine if fully disconnected for 6-9mths.  Consequently I physically disconnect the batteries on WG when I haul out for the winter.  
--
David Crisp
SV Wilna Grace
Amel 54 #58


Denis Foster
 

Hello,

For the reasons exposed in the messages about storage. We have Gel batteries (no solar panels) and opted to disconnect all charges. Every fifteen days 48H of charge with Mastervolt Mass chargers that brings back to 100% charge. The amplitude is usually from 95% to 100%.

Our Sonneschein Gel batteries are now 11 years old and still working well.  We cruise about 7 months / year. I understood that what kills lead acid batteries of all technologies is not being charged to 100% more than 10-15 days. We try to go to a marina every two weeks for this and using the clothes washer. Our goal is to be over 75% charge all the time and use 2h generator/ day  (and / or alternator if motor sailing) to go back to 90-95% when not linked to shore power.

This method was developed empiracly.

Best regards.

Denis


John Meskauskas
 

Dean, I very much like your logic. Would you share how your circuit is wired?

John Meskauskas

On Sep 29, 2022, at 8:52 AM, Dean Gillies <stella@...> wrote:

You won't get a consensus on this question, only opinions.

If you are only away from the boat for 6 months and, barring world events that may prevent you returning to the boat, (don't ask!) and you don't have anything onboard that needs power, then turn everything off and DISCONNECT the batteries.
You will sleep easier.

If you are away longer than 6 months then consider leaving them on float charge, but of course there's always the chance that something goes wrong, no-one on board etc. maybe you don't sleep quite so easy.

Personally, I turn off my LFP system and put my AGM batteries into solar float during the winter. This allows me to run an internet connection which I use to monitor the boat. I sleep pretty well because I know what is going on when I'm 13000 miles away.




Sent from my iPhone X

--
Dean Gillies
SV Stella *****, Amel 54-154


Chuck_Kim_Joy
 

Thank you Denis. I appreciate your time to reply. I will consider this. 

All the best to you!
Chuck 
Joy SM 388 

On Fri, Sep 30, 2022 at 6:57 PM Denis Foster <deniswfoster@...> wrote:
Hello,

For the reasons exposed in the messages about storage. We have Gel batteries (no solar panels) and opted to disconnect all charges. Every fifteen days 48H of charge with Mastervolt Mass chargers that brings back to 100% charge. The amplitude is usually from 95% to 100%.

Our Sonneschein Gel batteries are now 11 years old and still working well.  We cruise about 7 months / year. I understood that what kills lead acid batteries of all technologies is not being charged to 100% more than 10-15 days. We try to go to a marina every two weeks for this and using the clothes washer. Our goal is to be over 75% charge all the time and use 2h generator/ day  (and / or alternator if motor sailing) to go back to 90-95% when not linked to shore power.

This method was developed empiracly.

Best regards.

Denis


Dean Gillies
 

On Sat, Oct 1, 2022 at 02:13 AM, John Meskauskas wrote:
Would you share how your circuit is wired?
John,
I assume you mean the battery part? Please see attached.
Best regards

--
Dean Gillies
SV Stella *****,  Amel 54-154


Dean Gillies
 

On Fri, Sep 30, 2022 at 07:47 PM, Chuck_Kim_Joy wrote:
So you disconnect each battery or just the switch?
Chuck,
As is often the case, the answer is "it depends"!

You should make sure that ALL loads are removed from the batteries. That "may" not be the case if you just use the switches.
If you are confident that your boat's wiring has nothing connected at all after turning off the main switches, then using the switches should in theory be fine. Of course, there is still the risk that one faulty battery which won't hold a charge long term can bring down the bank!  (Yes, I'm 3/4 Irish and have lived my life with Murphy lurking right behind me :-)

If you disconnect the battery pairs (often quickest to just remove the mid-point links), then it also encourages you to inspect and check your batteries on return.  It does however make it a little more difficult for someone to jump onboard and charge the batteries with the flip of a switch or two.
 
--
Dean Gillies
SV Stella *****,  Amel 54-154