❀ Vacation: Leave batteries hooked up or no???

cupcake · June 2014

Hi pals,

OK - if I wanted to leave for say 1 month - is it proper to leave the off-grid system hooked up to the controller and batteries while I'm away for 1 month?

In other words, unplug the inverter, and just have the panels feeding the batteries via the charge controller...

Is this proper?

OR should I just unhook everything and let 5 12volt parallel-wired batteries sit for 1 month?

Thanks as always everyone...

-- cake in a cup

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

Disconnect all loads.

If you trust your charging setup--Leave it connected. Make sure that the battery bank will spend most of its time in float. The battery bank will not need much in the way of charging current (1-2% typical maximum current of 20 Hour battery bank capacity).

If you are gone less than 1 month, and the batteries are in good shape and not too hot (say less than 25C/77F), then you are OK with turning everything off (disconnecting charge controller from battery bank). A flooded cell lead acid battery in good shape should be fine with up to 1 month between charging cycles.

If the charging system does over charge the battery (and boil it dry)--That could be a fire hazard (and kill the bank).

-Bill

inetdog · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

If you charge the batteries fully before you leave and make sure that there are no residual loads, you should be able to leave them disconnected for a month without damage.
But if you trust your panels and charge controller, it will be better to leave them connected to the CC, although you may want to open the switch or wiring to your inverter just in case. Remember that some inverters have a high parasitic draw even when there is no load on their output.

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

BB. wrote: »

Disconnect all loads.

If you trust your charging setup--Leave it connected. Make sure that the battery bank will spend most of its time in float. The battery bank will not need much in the way of charging current (1-2% typical maximum current of 20 Hour battery bank capacity).

If you are gone less than 1 month, and the batteries are in good shape and not too hot (say less than 25C/77F), then you are OK with turning everything off (disconnecting charge controller from battery bank). A flooded cell lead acid battery in good shape should be fine with up to 1 month between charging cycles.

If the charging system does over charge the battery (and boil it dry)--That could be a fire hazard (and kill the bank).

-Bill

I should mention that I am in the desert.... inside temps will reach 105 degrees or higher potenitally...

knowing this, would you unhook the batteries or not?

No loads will be left on (inverter, etc) -- just the charging system (controler) IF that is what is recommended....

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

cupcake wrote: »

I should mention that I am in the desert.... inside temps will reach 105 degrees or higher potenitally...

knowing this, would you unhook the batteries or not?

No loads will be left on (inverter, etc) -- just the charging system (controler) IF that is what is recommended....

How might I objectify 'trusting' my charging system? ...

under normal use (using loads day in and day out..) it charges just fine... bulk, absorb, float, repeat...

but I've never just left it hooked up without draning/using the batteries (loads applied)

and its the desert so its full sun constantly if that matters...and heat near the battery banks will get up in the 100's

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

In general, as temperature rises, self discharge increases too... Does it follow the rule of 2x for every 10C--I don't remember--But if it does, then a battery averaging ~95F (10C + 25C standard temperature) would suggest a 2x faster self discharge rate or only ~2 week between charging cycles (and a battery that will only last ~1/2 as long as a battery kept at 77F/25C).

So--I would leave the charger+panels connected. And I would think about dropping the absorb voltage set points a bit and reduce the absorb timer (if used in this controller)... You do not want the battery to be excessively charged when you go.

How is your water usage? If you only add water roughly every 2 months--Then the charging voltage/time is probably just fine.

-Bill

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

BB. wrote: »

In general, as temperature rises, self discharge increases too... Does it follow the rule of 2x for every 10C--I don't remember--But if it does, then a battery averaging ~95F (10C + 25C standard temperature) would suggest a 2x faster self discharge rate or only ~2 week between charging cycles (and a battery that will only last ~1/2 as long as a battery kept at 77F/25C).

So--I would leave the charger+panels connected. And I would think about dropping the absorb voltage set points a bit and reduce the absorb timer (if used in this controller)... You do not want the battery to be excessively charged when you go.

How is your water usage? If you only add water roughly every 2 months--Then the charging voltage/time is probably just fine.

-Bill

Thanks bill...

The batteries are sealed...
The controller is the mornigstar mppt60...set for sealed type batteries..

So just leave it hooked up?

Thanxx

--cake

Cariboocoot · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

And now from someone who actually has batteries and actually leaves them unattended for six months at a time ...

If you have an Outback or Midnite controller with RTS simply check the charge and electrolyte level before you go, turn off all the DC loads, and be happy.

If you have another brand of controller (one which does not limit Absorb time by Bulk time) and/or do not have an RTS you'll want to change the settings to reduce Absorb time and Float Voltage. The Morningstar is one of these controllers.

Your batteries are sealed so you can't check the electrolyte level. All you can do is turn the Voltages down (you're looking at constant Float level basically) and limit the Absorb time to minimum (the batteries will not be discharged so they don't really need charging). Since these are cheap batteries, you're taking a gamble anyway.

zoneblue · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

If you have AGMs then its a no brainer, depower the entire system, and sleep easy while your away.

I monitor my system closer than average, and hence fairly confident that ive seen the worst it can do. But ill still be throwing all three main breakers when we go away next month, that is for sure.

PNjunction · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

Tip: doublecheck what the actual voltage is when using the "sealed" configuration. Most of the Morningstar stuff I've used sealed is really meant for GEL, which has about a 14.1v absorb.

This may not be appropriate for your flooded or agm batteries, so always compare the voltage to make sure that the canned "sealed" setting is actually the proper one to use for your batteries! ie, most flooded and sealed agm's like to see 14.4v, and some even higher.

mike95490 · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

And most of the MS gear, can be re-programmed pretty easily.

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

OK guys... I am still un-clear on the correct answer here...

Q: Would 5 fully charges 12v 'deep cycle' batteries last 1 month sitting 'on the shelf' unhooked?

I mean...don't these batteries sit for months at a time on store shelves?

What sayeth the forum?

Thankxxx as always,

--cup of cake

zoneblue · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

This was answered above. AGM remain charged for long periods. 6 months or so. Not so flooded which must be kept charged.

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

It depends... More or less, a good set of flooded cell lead acid batteries can sit on a ~70-77 degree F shelf for around 1 month and have an assumed state of charge of ~75% at the end of the month.

As the batteries go below this level (approximately), they begin to sulfate faster and faster.

If they are are hotter by 18F (10C), then they can discharge around 2x faster, and should not sit for more than 2 weeks. If the battery is -18F cooler, then it could set for ~2 months.

Anyway--Why it is always suggested that you get "fresh batteries" that have >12.40 volts on the shelf.

AGM batteries, because they have much lower self discharge, can store uncharged longer.

-Bill

niel · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

normally for an agm i'd say go ahead and unhook the batteries for a month, but i'm not sure of autozone's specs on them and how they may compare to brands we are more familiar with. they may lean more towards car starting batteries and even though they are agm types they may not fair as well in the self discharge area. this would be something you'd rather test for yourself without being away from it before it goes too low.

be on the safe side and charge them up fully and then drop the absorb charge voltage down to the float charge voltage. this keeps the batteries floating rather than overcharging. either way you try it all dc loads to the batteries need disconnected including your inverter just to be on the safe side.

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

niel wrote: »

normally for an agm i'd say go ahead and unhook the batteries for a month, but i'm not sure of autozone's specs on them and how they may compare to brands we are more familiar with. they may lean more towards car starting batteries and even though they are agm types they may not fair as well in the self discharge area. this would be something you'd rather test for yourself without being away from it before it goes too low.

be on the safe side and charge them up fully and then drop the absorb charge voltage down to the float charge voltage. this keeps the batteries floating rather than overcharging. either way you try it all dc loads to the batteries need disconnected including your inverter just to be on the safe side.

I have 5 AUTOZONE 'deep-cycle' batteries hooked in parallell.........

they look like this:

Attachment not found.

Are these OK to sit for 1 month?

IF NOT:

HOW can I go about tweaking and adjusting the absorb rate on the Morningstar MPPT-60 charge controller?? I see no info on this in the manufactureers instructions....

Thanks guys!

--cakey

zoneblue · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

I thought you said they were AGM... Those do not look like AGMs.

Turn all loads off, set the controller to absorb=float voltage, or absorb time to 2mins (if you want to mess with it), and call it good.

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

zoneblue wrote: »

I thought you said they were AGM... Those do not look like AGMs.

Turn all loads off, set the controller to absorb=float voltage, or absorb time to 2mins (if you want to mess with it), and call it good.

No.. I don't know where AGM came from... I never said that... 5 autozone sealed deep-cycle batteries..

anyway -- does ANYONE know how to set the absorb voltage on the Morningstar MPPT-60 controller? I've had no luck reading the instruction manual as I don't see any mention of how to do this...

THanks

--cakey

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

The manual switch method, on page 19 of the PDF file:

http://www.morningstarcorp.com/wp-content/uploads/2014/02/MS-ZMAN-TSMPPT-304560A_v05.11.pdf

Or--You can get a computer interface (possibly a remote display) and program exact values (and other settings).

-Bill

smatthew · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

Where do you get "Sealed" from. The only Sealed batteries are AGM.

So your CC settings are wrong..... and have been for some time.

cupcake wrote: »

No.. I don't know where AGM came from... I never said that... 5 autozone sealed deep-cycle batteries..

anyway -- does ANYONE know how to set the absorb voltage on the Morningstar MPPT-60 controller? I've had no luck reading the instruction manual as I don't see any mention of how to do this...

THanks

--cakey

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

smatthew wrote: »

Where do you get "Sealed" from. The only Sealed batteries are AGM.

So your CC settings are wrong..... and have been for some time.

OK - so what do you call an Autozone deep-cycle battery that cannot have water added to it... sealed? or something else?

Enlighten me...

--cake of cup

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

BB. wrote: »

The manual switch method, on page 19 of the PDF file:

http://www.morningstarcorp.com/wp-content/uploads/2014/02/MS-ZMAN-TSMPPT-304560A_v05.11.pdf

Or--You can get a computer interface (possibly a remote display) and program exact values (and other settings).

-Bill

OK, so the whole idea is to keep everything at float voltage the whole time right? So basically set it at a steady 13.7 volts ...

do I have this correct?

thankx

--cup

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

Typically sealed deep cycle batteries are AGM--Although, they could be GEL too.

These are also known as VRLA (valve regulated lead acid) batteries (aka "sealed").

And there are are "maintenance free" automotive (and marine?) batteries.

These batteries are flooded cell and not sealed--And you do not need to add water to them in normal service (the caps may appear to be "sealed"--but the few I worked with, you can still pop the caps off and measure the specific gravity and even add water). However, due to additives to the lead plates, they use very little water under normal usage (they can still be over charged and need water added--ask me how I know

).

If this is the right battery:

Duralast/Marine battery

Does not appear to be a sealed/AGM/GEL battery... Just "leak less" vent caps.

Duralast Marine and RV Batteries are designed to get you and keep you on the water! Duralast Marine Batteries are manufactured with the Cold Cranking Amps, Reserve Capacity and vibration resistance to keep you operating in the demanding Marine and RV environments.
Patented grid manufacturing technology produces grids engineered to be more efficient for optimal performance

Best-in-Class vent caps are engineered to be safer and reduce leakage and corrosion

Solidium™ welds are designed to stop corrosion and prevent premature failure

Lifespan™ negative paste is formulated to improve performance and battery life

Sometimes it is difficult to tell exactly what battery you have with a "house brand". There are a few major battery mfg. and they will build to spec. for the stores.

-Bill

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

cupcake wrote: »

OK, so the whole idea is to keep everything at float voltage the whole time right? So basically set it at a steady 13.7 volts ...

do I have this correct?

If you have no (cycling) loads on the battery bank--Then that will "float" the batteries and not use very much water--All good things.

-Bill

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

BB. wrote: »

Typically sealed deep cycle batteries are AGM--Although, they could be GEL too.

These are also known as VRLA (valve regulated lead acid) batteries (aka "sealed").

And there are are "maintenance free" automotive (and marine?) batteries.

These batteries are flooded cell and not sealed--And you do not need to add water to them in normal service (the caps may appear to be "sealed"--but the few I worked with, you can still pop the caps off and measure the specific gravity and even add water). However, due to additives to the lead plates, they use very little water under normal usage (they can still be over charged and need water added--ask me how I know).

If this is the right battery:

Duralast/Marine battery

Does not appear to be a sealed/AGM/GEL battery... Just "leak less" vent caps.

Sometimes it is difficult to tell exactly what battery you have with a "house brand". There are a few major battery mfg. and they will build to spec. for the stores.

-Bill

So let me get this straight -- You are saying I have a FLOODED battery now?

SO I need to change the CC settings to flooded??

Is this correct?

--cake

ILFE · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

cupcake wrote: »

You are saying I have a FLOODED battery now?

cupcake wrote: »

Attachment not found.

Yes. I think we can safely say that is a flooded battery.

These are AGM batteries at AutoZone.

BB. · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

There are other AGM batteries too (gray box):

http://www.autozone.com/autozone/accessories/Specialty-and-Non-Automotive-Batteries/Marine-Battery/_/N-4ayy

It is also possible that this is the exact battery you have (looking at picture, lid color, description on side of battery):

http://www.autozone.com/autozone/accessories/Duralast-Marine-battery/_/N-25t6?itemIdentifier=644427_0_0_

In any case--The battery is pretty much the same flooded cell, and no detailed description. One battery is two pounds heavier than the other.

Float Voltage--Good enough for now--And on vacation, you could select sealed/AGM/GEL battery--It will charge at a lower voltage and use less water (14.2 to 14.4 volts or so).

When the place is occupied... You should get a glass hydrometer and measure/log the temperature corrected specific gravity. See how well they charge--If they seem low specific gravity "after charging"--Try raising charging voltage by 0.2 volts for a couple days. Probably max out at 14.8 volts and 4-6 hours maximum of absorb time.

It is difficult to tell as there are no details about the battery construction/charging requirements. You don't want to over charge them--Cause them to use too much water.

-Bill

vtmaps · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

BB. wrote: »

You should get a glass hydrometer and measure/log the temperature corrected specific gravity.

Very good advice... applicable to all flooded batteries.

Cupcake, you should also know that these batteries are NOT true deep cycle batteries... they are hybrids and will not have a long service life in a RE application.

Further, you should know that 5 batteries in parallel is unstable and will lead to premature failure of the entire bank.
short discussion here: http://www.wind-sun.com/ForumVB/showthread.php?14674

--vtMaps

zoneblue · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

Agree with vt. Your issue is actually not what to do with your bank while youre away, but that you need to much better understand your bank. This is really, really important. Its important because battery systems are dangerous. Its important because they can burn your house down if you dont understand them.

If you have 5 batterys in parallel, and cheap automotive grade batterys. What can happen? Well should one of them go faulty, a chunk of plate becomes exposed, of a piece falls to the bottom of the case, then it will short. This happens. It will short the other 4, whereupon they will proceed to dump several mega joules of store energy. That in turn may very likely send those cells into thermal runaway, where more heat means more amps until the battery litterally explodes.

Thats not something we want to see. Not on our watch.

Blackcherry04 · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

zoneblue wrote: »

Agree with vt. Your issue is actually not what to do with your bank while youre away, but that you need to much better understand your bank. This is really, really important. Its important because battery systems are dangerous. Its important because they can burn your house down if you dont understand them.

If you have 5 batterys in parallel, and cheap automotive grade batterys. What can happen? Well should one of them go faulty, a chunk of plate becomes exposed, of a piece falls to the bottom of the case, then it will short. This happens. It will short the other 4, whereupon they will proceed to dump several mega joules of store energy. That in turn may very likely send those cells into thermal runaway, where more heat means more amps until the battery litterally explodes.

Thats not something we want to see. Not on our watch.

Sounds like a story for Snopes.com.

cupcake · June 2014

Re: ❀ Vacation: Leave batteries hooked up or no???

zoneblue wrote: »

Agree with vt. Your issue is actually not what to do with your bank while youre away, but that you need to much better understand your bank. This is really, really important. Its important because battery systems are dangerous. Its important because they can burn your house down if you dont understand them.

If you have 5 batterys in parallel, and cheap automotive grade batterys. What can happen? Well should one of them go faulty, a chunk of plate becomes exposed, of a piece falls to the bottom of the case, then it will short. This happens. It will short the other 4, whereupon they will proceed to dump several mega joules of store energy. That in turn may very likely send those cells into thermal runaway, where more heat means more amps until the battery litterally explodes.

Thats not something we want to see. Not on our watch.

....or I can just use FUSES which are designed to prevent the.highly improbable doomsday scenario you mentioned...

I am certain I did not invent parallel battery systems and am.not breaking any records here...

..back on topic...

If these batteries sit on autozone shelves for months... won't leaving mine completely unhooked be ok too??

❀ Vacation: Leave batteries hooked up or no???

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&#10048; Vacation: Leave batteries hooked up or no???

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❀ Vacation: Leave batteries hooked up or no???