How to maintain my batteries while I wait....

ROTTEN · July 2016

posting this here now since didnt get any help in off-grid forum.

Hello friends.
I got my batteries and they are sitting.
my solar setup is on hold for a moment and I wanna be sure my batteries dont
go bad from sitting idle..

I have them stored inside in climate controlled shed, sitting at 70'F on wood.

they are Trojans 6 volt 300 some amp hours.

If anyone can link me to a charger that can use to run a maintenance cycle on
each of my batteries one at a time, that would be wonderful.

Thank in advance.

Is it as easy as just getting a car charger that has 6volt?
or should I link 2 batteries together to get 12volt and just use a car charger???

vtmaps · July 2016

Many/most car chargers are not suitable for deep cycle batteries... even if they have a "deep cycle" setting. Look for one with adjustable settings for absorb and float. You should run an absorb cycle every week on the batteries. No need to float... just disconnect them for a week until you are ready to run another absorb cycle.

--vtMaps

edit: are these batteries brand new, as in unformed plates? If so, you need to cycle them a bit before putting them in maintenance/storage mode.

GreenPowerManiac · July 2016

Would suggest hooking up All batts in parallel with a small wind turbine. That way it's like a trickle charger during anytime of the day/night. It works. Mine act this way whenever the wind blows. About 15-20v and 2-3 amps most of the time. Perfect !

ROTTEN · July 2016

@vtmaps

Yes they are brand new. They been sitting for about 7weeks now, and I'm concerned that I need to for sure get some kind of cycling going on.

BB. · July 2016

You need to get them charged ASAP (if flooded cell lead acid batteries). And if they are warm/hot environment, you may need to recharge them more often than once per month.

You need a minimum of 5% to 10% (10% is Trojan's spec, if I recall correctly) rate of charge... For 2x 6 volt @ 300 AH batteries, that is 15-30 amps minimum per pair (if you use a 12 volt charger, and charge one string per time).

Do you have grid power or will this be a genset? Most "utility" type battery chargers have very poor power factor and require an "oversized" genset to power them. A car charger will work to at least get these guys back fully charged (you should use a hydrometer to ensure that the batteries are charged--There are so many brands/models of car chargers to know how they will work--Many will tend to over charge batteries if left on all the time).

If genset, what brand/model/rating of genset will you be using? Can you run a recharging cycle once per month on them?

Once you get the batteries recharged again (>90% state of charge)--You can put solar panels on them. 1% rate of charge minimum, and you could probably get away without a charge controller (for flooded cell batteries, and you monitor water levels).

A 2% or greater rate of charge (float service) needs a charge controller. Say you have 4 batteries... You can use a 12 volt or 24 volt configuration (sort of depends on solar panels you pick and MPPT or PWM charge controller). The basic requirement for long term floating:

4 * 7.5 volts charging * 300 AH * 1/0.77 panel+controller derating * 0.02 rate of charge = 234 Watt array minimum recommended (float service)

You could get away with 1% float charge--But I would keep a close eye on specific gravity to ensure that they are staying charged.

-Bill

ROTTEN · July 2016

Thank you so much I knew I needed to give them some juice. I have grid power that I can use.

ROTTEN · July 2016

BB. said:

You need to get them charged ASAP (if flooded cell lead acid batteries). And if they are warm/hot environment, you may need to recharge them more often than once per month.

You need a minimum of 5% to 10% (10% is Trojan's spec, if I recall correctly) rate of charge... For 2x 6 volt @ 300 AH batteries, that is 15-30 amps minimum per pair (if you use a 12 volt charger, and charge one string per time).

Do you have grid power or will this be a genset? Most "utility" type battery chargers have very poor power factor and require an "oversized" genset to power them. A car charger will work to at least get these guys back fully charged (you should use a hydrometer to ensure that the batteries are charged--There are so many brands/models of car chargers to know how they will work--Many will tend to over charge batteries if left on all the time).

If genset, what brand/model/rating of genset will you be using? Can you run a recharging cycle once per month on them?

Once you get the batteries recharged again (>90% state of charge)--You can put solar panels on them. 1% rate of charge minimum, and you could probably get away without a charge controller (for flooded cell batteries, and you monitor water levels).

A 2% or greater rate of charge (float service) needs a charge controller. Say you have 4 batteries... You can use a 12 volt or 24 volt configuration (sort of depends on solar panels you pick and MPPT or PWM charge controller). The basic requirement for long term floating:
4 * 7.5 volts charging * 300 AH * 1/0.77 panel+controller derating * 0.02 rate of charge = 234 Watt array minimum recommended (float service)
You could get away with 1% float charge--But I would keep a close eye on specific gravity to ensure that they are staying charged.

-Bill

Bill, REALLY appreciate the feed back bro.... thats exactly the kinda details and info im looking for.
Im still very new to all this and in the mix of building my solar setup this season... in like 2 months behind on everythign though..
go figure... but regardless of that.. I do needa maintaine these batteries since I got them.

Just checked when I bought them, they been sitting for 8 weeks in a climate controlled building that is
70'F steady.

Last I tested them, their voltage was 6.30v

https://www.amazon.com/Extreme-Max-1229-4000-Intelligent-Maintainer/dp/B00K72C1T4/ref=sr_1_1?ie=UTF8&qid=1467922726&sr=8-1&keywords=12volt+float+battery+charger

would that maintainer be something of use? Or am im going to need to look for something better?
I can just get 2 of those babies and run 2 strings at time, I have 8 batteries total.

ROTTEN · July 2016

The batteries I got are

Trojan L16RE-B 370 AH Deep Cycle Battery

lead-acid

Raj174 · July 2016

That maintenance charger will not do the job. If I were you I'd buy a 48V 20 - 30 amp charger and get those batteries charged up as soon as possible. At 8 weeks without charge, battery life can be impacted. Here is a 25 amp charger that will do. Chose something else if you would like, but I would keep it between 20 and 30 charging amps.

https://www.amazon.com/Schumacher-INC-4825A-Amp-Digital-Charger/dp/B009YP8PH2/ref=sr_1_12?ie=UTF8&qid=1467947301&sr=8-12&keywords=48+volt+battery+chargers

That's about 7% of your battery bank capacity, and like Bill said between 5 and 10% is necessary. I would look at it as an investment, not only for this issue, but just incase you have a problem with your inverter/charger in the future, you will have a way to keep the batteries charged.

Of course, a 6/12 volt 30 amp charger will work also, but each one or two will have to be charged several hours each.

BB. · July 2016

I would not bother with the Extreme Max.. It is only 0.75 amp output. You need something like 3.7 amps per battery string... If you want 1% minimum, you are looking at 3.7 amps minimum.

That is one of the problems with large battery banks--You need a large amount of current to keep the battery bank happy.

If you have Grid Available--You can go with Iota chargers (and the IQ4/AL1--Depending on Iota model--module if you want to leave the chargers on 24x7). Note, these are just random examples on my part:

http://www.solar-electric.com/ioen12vo90am.html

There is a new series of Iota inverters that looks interesting:

http://www.solar-electric.com/iota-engineering-sdc1-120-12-75-battery-charger.html

Don't know much about them, but could work nicer on a genset vs the old (non-PFC) models.

You probably should pick these types of chargers based on your eventual off grid battery configuration (12/24/48 volts--guessing you are looking at 2x strings @ 24 volts?). And, if you will use 120/240 VAC input power, and if you will have a backup genset (size charger to genset and size genset to charger).

-Bill

ROTTEN · July 2016

I was planning on running 1 string, 48volt.

BB. · July 2016

Planning on a backup AC genset?

-Bill

South Africa · July 2016

FWIW, Trojan batteries, lead acid, according to my local supplier can stand up to 6 months with no charge, but recommends not more than 3-4 just to be safe.

ROTTEN · July 2016

BB. said:

Planning on a backup AC genset?

-Bill

I got a Magnum inverter that has charging capability for when the sun isn't shining and the batteries need charge.
Was told by my local solar guy that I'd be able to plug in AC-DC power for backup or a generator. I was going to go with AC backup at first then by the generator a little while after

BB. · July 2016

OK... Say 48 volt bank, 10% rate of charge (~37 amps @ 48 volts charging current), then you would be looking at a genset minimum ratings somewhere around:

59 volts charging * 370 AH battery bank * 0.10 rate of charge * 1/0.80 charge eff * 1/0.80 PF * 1/0.80 genset derate = 4,264 VA rated genset "worst case"
4,264 VA / 240 VAC nominal = 17.8 Amp rated (minimum) branch circuit (worst case) ~ 20 amp
59 volts charging * 370 AH battery bank * 0.10 rate of charge * 1/0.90 charge eff * 1/0.95 PF * 1/0.80 genset derate = 3,192 VA rated genset "best case"
3,192 VA / 240 VAC = 13.3 Amp rated branch circuit minimum (best case) ~ 15 amp

Just how the basic math works out--You have to plug in "your numbers" (exact charger ratings, your 5% to ~20% rate of charge choice, etc.).

-Bill

ROTTEN · July 2016

Ok...so I don't really understand what that math means though...what numbers do I use then to determine what sized charger I need?

BB. · July 2016

Do you want to buy a single inexpensive car charger (6 or 6/12 volt) for now--And move it from battery to battery (say you charge all of them once per month, ~8-24 hours per battery or battery pair)?

Or do you want to buy a (for example) a 48 volt charger (same as your battery bank voltage for the magnum inverter-charger)? And wire up the batteries (at least with temporary wiring)? Are you able to wire up a 240 VAC @ 20 amp (minimum) branch circuit for your battery charger?

-Bill

ROTTEN · July 2016

If and when I get a back up generator..will that be plugged into the 48v charger then into the Mangum investor?

My concern with that is...I was told by the local solar guy that the invertor I bought had a built in charger for my battery bank and I just needed to plug my generator straight into the invertor and it is smart enough to handle it.

Just don't wanna buy a 200-300 clam charger if I'll end up with it collecting dust after I finish this build.

If a $50 car charger can get the job done in the mean time that would be great. I'd tie 2 batteries together to get 12v, if going that route.
I don't mind spending a few minutes checking them and switching strings once a day for 4 days, doing that only 1 time a month..I can't handle that.

Just wanna spend responsibly and have items that can be of good use after the fact.

Know what I mean?

ROTTEN · July 2016

Excuse the autocorrect.....invertor. not investor.

Raj174 · July 2016

The inverter/charger can charge the batteries from the grid if grid connected or from a generator input. A stand-alone 48 volt charger would connect directly to the batteries. It is not a necessity. You certainly can use a 6/12 volt 30 or so amp charger to keep your batteries charged until they are put into service.

BB. · July 2016

You probably will be OK with the car charger--They tend to over charge a battery (when set to higher charging currents). Just monitor charging voltage/specific gravity and you should be fine.

You could connect up the program (as needed) the Magnum--But that may take more time than you are prepared to do at this time (wire up 120/240 VAC branch circuit, programming, etc. for temporary connections).

-Bill

ROTTEN · July 2016

BB. said:

You probably will be OK with the car charger--They tend to over charge a battery (when set to higher charging currents). Just monitor charging voltage/specific gravity and you should be fine.

You could connect up the program (as needed) the Magnum--But that may take more time than you are prepared to do at this time (wire up 120/240 VAC branch circuit, programming, etc. for temporary connections).

-Bill

Thanks a lot Bill, really appreciate the help my friend. I plan on being able to monitor the batteries for sure.

BB. · July 2016

Just be careful of sparks (when using the battery clips from the charger)--You don't want to ignite the hydrogen inside the battery cells.

And the usual warnings (old clothes, no jewellery, eye/face protection, be careful of polarity with batteries/charger, rinse hydrometer a few times with distilled water after use, etc.).

-Bill

tabbycat · July 2016

I wouldn't trust an unattended high output multi-stage charger. If a cell should fail the charger would assume the batteries should be charged at maximum output leading to thermal runaway. It is much safer to use a low output float charger if it is unattended. Ask me how I know this.

ROTTEN · July 2016

BB. said:

Just be careful of sparks (when using the battery clips from the charger)--You don't want to ignite the hydrogen inside the battery cells.

And the usual warnings (old clothes, no jewellery, eye/face protection, be careful of polarity with batteries/charger, rinse hydrometer a few times with distilled water after use, etc.).

-Bill

https://www.amazon.com/Schumacher-SC-1200A-CA-SpeedCharge-Maintainer/dp/B000BQSIWK/ref=sr_1_2?ie=UTF8&qid=1468417336&sr=8-2&keywords=12v+car+battery+charger

OK, i found that charger on amazon, looks pretty decent and just about what I'll be needing.
I know the batteries are not dead, so it shouldnt take to long to get 2 batteries up to charge with this, no?

I just purchased my own battery hydrometer too for testing the electrolyte.

BB. · July 2016

These are pretty big batteries... a 5% rate of charge (about the minimum for active cycling batteries) of 370 AH would be 18.5 volts--A fairly larger "car battery charger" continuous rating.

If you want something smaller, I would suggest a 2% rate of charge as absolute minimum for your needs (~7.4 amps). If you do have a shorted cell, 2% will not fry the rest of the string (can run pretty hot--You will still need to monitor to insure that everything is working well).

I have a Battery Minder brand this is I think, and older discontinued model):

https://www.amazon.com/BatteryMINDer-Volt-Amp-Battery-Charger/dp/B000JFLSL6

I have it on my in-laws' car (with a lot of phantom loads in modern car, computers, cell phone, Lowjack, etc.) and it would take a battery dead in 6 weeks of not-driving. The Battery Minder has worked well (keeps battery charged, does not "boil dry" like some cheaper float chargers did)--But they just leave the charger connected for months at a time (don't drive much any more).

And the battery minder is (was) NOT CHEAP. But they were "burning through batteries" about once per year without it.

The charger you are looking at--I would be careful and not leave it connected for days/weeks at a time. These new "smart" chargers seem to have issues with controlling their output voltage at times (taking AGM batteries over 16 volts charging--a Big NEVER).

Just watch how it works (at least until you "trust" it). Disconnect when the batteries are charged. Repeat once per month (may need 12-24 hours to recharge each set of batteries).

-Bill

ROTTEN · July 2016

I was planning on only leaving the charger on the batteries till they were fully charged, then disconnect the charger... as to
not have to worry about watching the batteries and what not...

literally, I have the batteries in my work area, so I can check them easily every 30mins and when im not working I can check them easily every hour or 2.

If you believe that BatteryMINDer is the best bet for me for trying to keep it safe but also not spending a shit load
extra on something that is only temporary... know what i mean?

Im all about safety, dont get me wrong im not trying to cut corners here, just trying to keep my batteries from dying
on me while i build their housing and put up the solar array. (mount is in the mail finally)

BB. · July 2016

The battery tender is probably too expensive to justify for this temporary usage.

Monitor your charger and batteries, and you should be fine.

-Bill

ROTTEN · July 2016

BB. said:

The battery tender is probably too expensive to justify for this temporary usage.

Monitor your charger and batteries, and you should be fine.

-Bill

That's what I'm thinking. I'll be watching them closely.

ROTTEN · July 2016

So hell yea. That battery charger I posted from amazon worked perfectly. Exactly what I needed. Cheap and effective.

I have it set to 12amp lead acid and it pumped the batteries to about 14.25v is what the highest I seen it hit, the electrolyte was bubbling ever so slightly.

They finished charge and stayed in float for a few hours at I think...12.80v... something like that.

Can't wait to get this setup done... lol

ROTTEN · July 2016

ok just wanted to come back with an update to let everyone know
that I had 100% success using a 50 clam smart car battery charger.

Has 3 to 12 amp charging ability.

It charged up 2 of my batteries in about 24hours. Now im just letting them sit for a few weeks before I hit them
with some charge again.

I DO NOT LEAVE THE CHARGER PLUGGED IN AND CONNECTED TO THE BATTERIES.
I WOULDNT TRUST A 50 DOLLAR CAR CHARGER ON MY 600 DOLLAR BATTERIES.

Thanks for everyones help.

How to maintain my batteries while I wait....

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