Killed my batteries?

Bill1972

Howdy!

I rent a yurt up in the woods of western Washington, and inherited 4 batteries from the previous owner who didn't want to move them. Hence, free for me! (no identifiable name on batteries, apparently huge & heavy deep cycles, previous owner said ~225AH each, 1.5 years old when i inherited them 6 mo. ago - wired for 12v)

I don't have a lot of $$, so I got a pair of 140w panels and a morningstar prostar 30amp charge controller after I moved in to charge them up. I know thats way too little to recharge the batts properly but I figured if i used my Honda EU2000 for any large loads, and just sipped the batts with my laptop & LED lights it would be OK til I could afford upgrades all around.

Well, that worked fine over summer & fall when the sun was good - never went below 12.6v after weekends use, and was always back up to 13v when i came back the next weekend. But thats changed...winter, clouds, shading from trees, and after a few weekends of that (and 35 degree weather this last weekend) my last couple weekends have brought the bank down to 12.2/12.3v under load overnight.

I kinda panicked and hooked up an auto battery charger I had laying around (it says it has a 6a, 10a, & 50a charging rates) and have run it a couple times all day at 6a (charger says not to use the 10a or 50a settings for charging) and it did seem to get back up to 12.9vs before the charger kicked into its equivalent to a 'maintain' stage. But then, under what used to seem like a modest load (laptop + led lights) ...it goes back down to 12.3 or 12.4 volts again overnight.

I know need to stop the madness and get a good charger (prob an invertor/charger) as well as much more solar, an MPPT, move to 24v, and a good generator for a backup. Prob can afford this by late Spring. (Learned my lesson, probably the best & only way that will stick with me, and once I do that I'll prob also just get a new batt bank cause I have probably killed these, eh? )


But is there any hope in the short term for these batteries?

- Is it safe this next weekend to run the battery charger at its higher 10a or even 50a setting if I stay alert & monitor the temperature of the wires and batteries for heat or outgassing?

- Should I bother next-day air shipping a decent but inexpensive charger (say, an Iota) to run via my Honda EU2000 generator for charging instead, or just do my best with the auto charger and patience?

- Is the Honda EU2000 even capable of driving an iota charger? (the honda says it has 13.3amp rating on its 120v AC, but iota seem to go to 15amps and way waaaay higher. i am unclear how to figure this out, and also why I didnt use the 10a or 50a settings on the el cheapo charger...i dont want to blow anything up....



Any thoughts welcome!

CALLD

Re: Killed my batteries?

Hi Bill,

Your assumption that you don't have enough PV is correct as you want at least a tenth of the batteries AH capacity charging current. For a 225AH 12V battery that is 22.5 amps. 2x140w panels wired in parallel will give you about 16amps in full sunshine, about 6 or 7 amps short. That is with no load.

Your batteries also need to reach between 14 and 16v during a charging cycle to reach full charge unless you are just keeping them on standby. For standby use they should be kept between 13.5 and 14v. Lower temperatures require higher charging voltage.

What's encouraging though is that your batteries appear to be keeping their loaded voltage above 12v which suggests they may still be in good condition. That is however assuming they are holding those voltages under a decent load of about 20 amps or so after a few hours of use with no additional charging supply...

Bill1972

Re: Killed my batteries?

Thank you for the response Calld! So there *might* be some hope for them yet! It will be until Thursday night before I can get back up there and fire up the generator again, but do you have any thoughts on a suitable action plan for possible recovery from this? i.e., for best short term charging strategy?

I am reading every thread I can, and things are starting to make a little more sense as i read them now that I have some real-world experience, but the first thing I am doing is *zero* load on the batts until i can get them in some way charged. If nothing else, I'll continue to use the el cheapo auto battery charger at 6a thursday night when I get there and let it run until it kicks into its maintenence cycle again.

Think I should bother getting a 'real' (but relatively inexpensive charger like an iota mailed out to me? (as i read threads, it seems that my Honda EU2000 is 13.3amps of AC, so as long as i get a charger that doesn't exceed that on the AC side, then the *DC* amps it outputs are different, and wont exceed the Honda's capacity?)

Or alternatively, I can just limp along with the el cheapo auto battery charger and (maybe, if safe) set it to 10a to quicken the charging?

Ultimately, once i think I have it as charged as i can possibly get it w/the equipment I have, I'll probably disconnect all the batteries...check specific gravity in each cell...clean all the connectors...etc. and start doing some record keeping before delicately adding a teensy bit of load to it again.

softdown

Re: Killed my batteries?

Bill, I don't think you have killed your batteries at all. It is January and many of us are struggling with low battery voltage. Everything is working against us: cloudy weather, super short days, we are spending time indoors on our computer and the router may use more power than you think, and cold batteries show less voltage.

Some good news is that you can very easily charge this battery bank at 10 amps without undue damage. In fact, I might recommend at least 20 amps, or more, for this size of bank. But 10 amps puts you squarely in the ideal operating range of your generator. So you can relax this year and look forward to spring when things will likely normalize.

I use my industrial Shumacher charger at 40 amps with a similarly sized battery bank. It is roughly equivalent to using 4 amps on a regular car battery. i.e.- my battery bank is at least ten times as "large" as a regular car battery. I would not be opposed to the 60 amp setting but my genset doesn't readily output that much. Don't continually ask more of your genset than it is designed for. Gensets also lose power as altitude gains.

Bill1972

Re: Killed my batteries?

Thanks, optimism is encouraging!! (despite the grey skies and lack of sun!

if they are dead (I tend to be a pessimist) i will chalk it up to a very good lesson learned, that will prompt me to educate myself much MUCH further into this arcane art/science.

I'll try the 10a charging setting once i am up there, taking care to observe temps/outgassing (if any) to be safe, and give it a good long charge. And again the next day, possibly i will have time to disconnect/test specific gravity/clean/reconnect as well...and then charge again if need be.

if they yet live, I will put the ~$200 i was thinking of using for a shortterm charger into what I really need to get in Spring....more solar, big MPPT, good quality invertor/charger, and a larger genset. Gonna be expensive, but this time around I will know a bit more about all of this.

Thanks all!!

softdown

Re: Killed my batteries?

12.0 volts is roughly a 50% state of charge. You should be able to dip down to a 20% state of charge with deep cycle batteries. That is, after all, what they are designed to do.

For long term storage? Try to keep them at 12.5 volts or better. The lower the volts, the more sulfidization occurs. This kills the battery.

If you said that your batteries were at 11.2 volts for a period, then your fears would likely be true. Thats my take anyway.

Use these batteries as long as you can. There are 100 ways to destroy a battery bank. Don't learn with an expensive set. Your battery array sounds pretty good to me. Huge and heavy deep cycles are exactly what you want.

Bill1972

Re: Killed my batteries?

Oh yes, I really do like this set...assuming they can be recovered it was certainly a godsend to have them just left 'at my doorstep' as it were. Big $$ savings I can really use. I wish I had done a bit more research as it was turning from fall to winter of course. (he said, sheepishly)


I am now amusing myself by reading some of the other 'battery dead!!' threads, and realizing I was not as smart as I thought I was. Better late knowledge then no knowledge though...and kind assistance from the community!!

Edit: after reading yet more threads, I can see I should have gotten a battery meter on Day 1, so now I will probably order a Bogart Engineering Trimetric meter + shunt for delivery ASAP. Their site is great, has some really good docs i found to be useful like http://www.bogartengineering.com/sites/default/files/images/high-res/QuickReference%20TM2030%20finalwithimages031814Reference-2.pdf and also http://www.bogartengineering.com/sites/default/files/docs/TM-2030%20Users%20Instructions6-20-14.pdf (particularly section 7, "...Important information about battery charging to keep from killing your batteries..." LOL)

Also, in light of Callds voltage/charging recommendations, I think I will spend the most time next researching quality inverter/chargers so as to insure I have the most flexibility in how i charge...followed closely by determining the best generator to get as a main. That way i will always have a *well* charged battery no matter the weather/cold, and then once the sun is getting ready to be out again, I can finally put the cherry on the top of the ice cream bowl by acquiring an *appropriately* sized PV array w/MPPT controller.

westbranch

Re: Killed my batteries?

Hi Bill, here are a few tricks I learned on my old AGM 1100Ah ex-Telco battery.

I used a car battery charger at first 2-10-15A to just keep it in float mode as I assembled my system.
then to get a good charge I got a used 40A Xantrex TrueCharge, great piece of kit and you should consider the down side of a combined unit failing, ie you might also want a standby charger only...

I only had a Honda 1000i generator at the time and it would not run the X charger if it was 'testing' the charge state of the battery, just too much load for a 6 A gen set.

A little trick:
What I found was that if I used the car charger for about 15 minutes it would get rid of that huge deficit (or alternatively, give it a flash of surface charge) and then the 1000W Honda could handle the demand of the TrueCharge, and run all day on 1/2 US Gal.
Later on when I got a 3000W gen I ran it for 15 minutes and then switched to the 1000W, all with the 40A TrueCharge.
Your 2000W would handle 40A @ 12 v

PS think through all your possible loads before committing to a different voltage
pps Don.t confuse Battery voltage Amps and 110V input amps to the charger, it's easy to do

hth

Vic

Re: Killed my batteries?

Hi Bill..,

Couple of things;

Battery voltage is not a very good indicator of SOC of a battery. For voltage to be a fairly accurate indication of SOC, the battery needs to be Rested for 3 - 6 hours with NO charge or discharge. AND, the voltage reading should be temperature compensated at about -- 5 millivolts per cell, per degree C. For a 12 V system this is 0.03 V per degree C change from 25 C (77F). Add for temperatures that are below 25 C, and subtract for temps above 25 C. Your batteries may now be cool/cold, and the voltage that you are measuring might be implying to you that they are more fully charged than they actually are.

Your charge sources really should have ability to compensate the charge voltage for the actual temperature of the battery. An Auto charger is good to use if it is the only thing that you have to charge the batteries at the time. Most of them will not really have a sufficiently high charge voltage to finish charging cool/cold batteries, unless the charger has some compensation of charge voltage.

Since you have Flooded batteries, YES!! the Hydrometer is the Gold Standard of SOC determination. Get a good one, and always rinse it several times with Distilled Water when you are finished with the measuring session.

Battery Monitors are a good ROUGH indication of approximate SOC, they are better if they are carefully Calibrated. Calibration will change over a period of time. Some are mislead by what they feel that a battery monitor appears to be telling them.

If your four batteries are actually 225-ish Ah, and 6 V batteries (probably Golf Cart batts. if so), then it would seem that you have two parallel strings of two batteries in series. This should yield close to about 450 Ah for the set of four, IMO.

This should change your equation for the minimum recommended current for charging them, and mean that your two 140 Watt PVs are a fairly small charge source, indeed -- probably less than 18 Amps in perfect sun.

You may be familiar with all of this, to the extent that it is correct. FWIW, Good Luck. Opinions, Vic

mike95490

Re: Killed my batteries?

I have a VEC1093 12V Charger that has switchable output amps, 5,10,20 & 40A settings. Selectable to Deep Cycle, AGM, car...... and has an EQ setting. You may want to invest in something like that, a smart charger, that has settings for deep cycle or car batteries, different amp rates, and EQ settings.

But note, most of these "smart" spark proof chargers, will not activate their clip leads, till they have greater than 8 volts from a battery. If your battery is really dead, it wont try to charge it. I would pass on the Iota, as it's not portable, and has no EQ setting.

Bill1972

Re: Killed my batteries?

Just wanted to respond back with an update...and a hearty Thank You to everyone who took the time to reply back with advice and tidbits of information. As I get more real world experiences, it is leavened with concrete facts and knowledge from this and other threads, and maybe someday i can even be considered competent enough to return the favor and answer questions & give advice here too.

Weekend-before-last I tore my battery system down to the basics, checked for any corrosion, cleaned all the connections, refilled cells where needed (not much distilled water required) checked specific gravity, (adjusted #s for 40 degrees F, seemed OK) and then cleaned & reconnected everything. I used my generic auto-battery charger at its 10a setting for a couple hours and then set it to its 6a setting for a few more hours until its internal circuitry switched to whatever its 'maintain' threshhold is....and then let well enough alone, presuming that it was as charged as i was going to get that visit.

The next weekend I arrived, armed with an only-slightly-used Xantrex Truecharge 2/40a 12v charger that I did some horse trading for. It came with the battery temp sensor, and a remote display, so I felt pretty good about that acquisition. This last weekend the first thing I did was check the 'rested state' charge... 12.6v, and then tied in the Truecharge2 & fired it up, running it via my Honda eu2000.

It ran for ~6 hours, and as expected it went through its 3 stage charging routine...and as it got going i could see that voltages went much higher then I ever saw with the generic auto-battery charger - up to 14.2 or 14.3 at one point - before reaching its 'all charged' level, at which point I shut it down and turned the loads back on.

So much better this time...started the evening at 13.0v, used some lights, laptop, and a coffeemaker the next morning, and the next morning it was back to a v level I was used to seeing int he glory days of summer PV charging bliss...still 12.8v. (45-50 degrees F ambient temp in battery enclosure)

So I used some more power through the day and before leaving I fired up the Truecharge2 one last time before leaving and it only took about 2 hours this time to return the batteries to their 'fully charged' state. There have been a few sunny days around here lately, so hopefully when all is said and done my battery bank is now being maintained in a full charge state, and with the Truecharge2 & Honda EU2000 as a stopgap until i get more panels and the sun gets higher in the sky....

I think I am golden, for now.

THANKS ALL!!!!

BB.

Re: Killed my batteries?

Sounds good... Depending on the settings for the TC2 and the type of batteries you have--A flooded cell deep cycle battery may even go as high as 14.8 volts (or even higher if the battery bank is near freezing or below). Nature of the beast.

Also--Do you have the TC2 "bolted" to the battery bank (through a fuse or circuit breaker rated for the wiring size)--Or are you using alligator clips?

For a good/permanent solution, highly suggest you bolt up your TC2 charge controller connections. Alligator clips are not very reliable/rugged for use at high current levels.

-Bill

Bill1972

Re: Killed my batteries?

The default settings at boot up for the TC2 appeared to be fine for what I have - it sets itself to flooded lead/acid, 3-stage charging, and temp sense auto through the sensor. (temp sensor bolted to a negative terminal, per the manual) As far as the DC connections go, there are terminals on the TC2 (no built in wires or alligator clips) so I used some spare 3' 4awg battery cables that I have bolted to the battery terminals + & -. (the manual says 5' of 8 awg is OK for the 40a model...w/3% voltage drop...but I had the 4awg cables already there so what the heck, used them)

For the AC connections, there are just the 3 AC wires coming out of the TC2. I free-lanced this part, simply connecting them to a beefy extension cord end that I cut & spliced, running from the Honda generator. In this case, I didn't add any extra fuses or anything...but am expecting that since the Honda itself has its own fusing that should be OK until I get a more formal AC panel. (my AC loads come from a 2000w Xantrex Prowatt SW, wired also direct to battery posts)

I have a friend of my brothers who is a licensed electrician, and also does solar installs occasionally, and he is interested in visiting and camping out for a weekend soon, so he has promised to bring his 'medical bag' of tools and misc. parts...including good crimpers and such...to help me insure all my grounds, fuses, wiring, etc. are according to Hoyle. I'll buy wire, he'll provide expertise, and hopefully I'll get my wiring 'spaghetti' in good order...I'll probably try and get some even beefier battery wires, custom cut to the smallest length required, along with things like a bus bar, a shunt, and maybe a Trimetric battery capacity meter.

Future state (this spring/summer) will look lots different - prob move to 24v, get another medium sized battery bank, and certainly an MPPT controller and as many panels as i can afford by that time. (I may well keep the existing 12v system mostly intact and move it across to the other portion of the property where I am building a little treehouse/sleeping shelter thingy...

BB.

Re: Killed my batteries?

Sounds good. AC wiring is fine. The fusing/breaker I was typing about is on the DC side. Flooded Cell batteries can put an amazing amount of current into a dead short (hope for the best, prepare for the worse).

And glad to hear that the TC2-40 amp @ 12 volt charger is working well for you on the Honda eu2000i--It should be a very good match (efficient battery charger on the "small" Honda 1,600 watt genset).

-Bill

Bill1972

Re: Killed my batteries?

well, I don't yet have a fuse/breaker on the DC portion of the TC2. Thats pretty bad, I know - any misstep and i am gonna irretrievably fry the electronics - but I did make sure to do the wiring when my brother & dad were visiting that weekend (so there would be someone nearby in case of accident) and was *incredibly* careful as i connected/disconnected everything. (as a rule, during and after disconnecting/reconnecting wires, I fully wrap any exposed metal portions of the cables with black electrical tape until the last possible moment when I am actually connecting them, and of course insure the connections are firm & tight before moving to the next connection)

Am likely 'playing with fire' in that regard, but everything is currently stable and with a visit from the electrician really soon... (famous last words?)

BB.

Re: Killed my batteries?

Yea--Better safe than sorry. Remember that fusing/breakers are their to protect the wiring from overheating/causing a fire. It is not there to protect the electronics/loads (other than to prevent the loads from getting too much current and starting a fire themselves).

Not saying that you need to fuse the TC-2 today--But over the long term, it is safer to do it. 99.9% chance that you will never blow the fuse and never need that over current protection. That 0.1% of the time you needed the fuse--It would be sad if it was not there.

-Bill

Bill1972

Re: Killed my batteries?

True...hadn't really been thinking about the potential fire issue...but in that .1% possibility spread, I'll bet something like 'rogue squirrels nibbling on wires' would probably apply in my setting. Or else, 'tree or branch crashes through plywood during wind storm' and right into the wiring enclosure...

I don't have many kids that visit, at least not in winter, but thats undoubtedly another big risk. Anyway, within a couple weekends the lack of DC fuse issue will also be stamped out!!

Heh, it does make me wish that in high school I had taken the electronics/electrician elective courses when I had the chance!

BB.

Re: Killed my batteries?

I always wondered why I had an art class requirement (I suck at art), but there was no auto shop/shop class requirements (in the suburbs, every one needs a car--and even if you are never going to fix a car/repair a home, you need to understand the basics when hiring a repair shop/contractor).

Art--I can still see something and say its pretty without being able to draw it.

-Bill

techntrek

Re: Killed my batteries?

CALLD wrote: »

Your assumption that you don't have enough PV is correct as you want at least a tenth of the batteries AH capacity charging current. For a 225AH 12V battery that is 22.5 amps. 2x140w panels wired in parallel will give you about 16amps in full sunshine, about 6 or 7 amps short. That is with no load.

Not necessarily true if the load is light, as the OP says it is. I know the usual - and correct - recommendation is 10-15% charge rate, but that may only be correct for a system that is regularly drawn down to 50% SOC. Most of the systems designed here are like that. There has been some talk around here about the systems that are the exception, like one with a large battery but small load. Then you can get by with a smaller charge rate.

Alaska Man

Re: Killed my batteries?

Bill1972 wrote: »

True...hadn't really been thinking about the potential fire issue...but in that .1% possibility spread, I'll bet something like 'rogue squirrels nibbling on wires' would probably apply in my setting. Or else, 'tree or branch crashes through plywood during wind storm' and right into the wiring enclosure...

I don't have many kids that visit, at least not in winter, but thats undoubtedly another big risk. Anyway, within a couple weekends the lack of DC fuse issue will also be stamped out!!

Heh, it does make me wish that in high school I had taken the electronics/electrician elective courses when I had the chance!

I started out with Photovoltaic Design for Dummies and went from there. Before I went with our RE system I could wire a residential house, but that meant I was dangerous doing a Solar Install not educated on the subject. I've graduated to reading electrical engineering publications, so now I'm even more dangerous. ;-)

http://www.amazon.com/gp/product/047059893X/ref=as_li_tl?ie=UTF8&camp=211189&creative=373489&creativeASIN=047059893X&link_code=as3&tag=solar-power-outlet-20&linkId=Z6AZGLYPHNGXQI4K

2manytoyz

Re: Killed my batteries?

We have 6 TC 20A chargers at work. Very nice product. Glad it works well with your generator.

Initially you mentioned an Iota charger. I have a 75A model. It works great, but the power factor can eat your lunch. I have a slightly larger generator, a Yamaha EF2400iS. Good thing, the Iota charger draws a little over 13.5 Amps when initially charging the battery bank. Tapers off quickly though.





Just something to consider if you decide to get a larger charger...