Maybe my battery bank is ruined - seeking advice

Bloom

I have a cobbled together solar energy system at my remote cabin. 180W of 12V harbor freight panels wired to 24V, 90W to BT (MPPT) charge controller and seven marine batteries I picked up on a closeout deal. Not the best but it works.... until - a connection failed from my panels to the charge controller. Slowly my battery bank depleted and to add insult to injury, a friend using the cabin, not knowing any better sucked the remaining life out of the battery bank telling me that, "something must be wrong because the propane fridge stopped working on low dc right after I got there." UGGGHHH, and he tells me NOW, not then. Anyway, I went to my cabin to check it out and found the broken wire and fixed it. I also cleaned the panels, added water to my poor abused batteries, disconnected them and charged each one separately using a battery charger and generator.

My batteries seem sluggish and are reluctant to take a full charge. When I put a load on, they discharge rapidly. Are they wrecked?

Bloom

Blackcherry04

Re: Maybe my battery bank is ruined - seeking advice

Hard to tell. Are the Batteries the sealed type ?? You can take a generator and put large enough charger on them and see. you have 7 batteries and lets say they are 100 amp hr and trying to charge them to 8 -12 amps if that much from your 180 w worth of panels isn't going to work. You need to use a 50-60 amp charger on them at least. If they are not sealed use a hydrometer to check the SG's.

Bloom

Re: Maybe my battery bank is ruined - seeking advice

The batteries are plain old lead acid not sealed. And yes, they're 100ah. I have them connected in parallel at 12V. When I charged them, I disconnected them and charged each one separately. My MPPT controller seems to work well stepping down the 24V from my 90 watts of PV panels to charge the 12V batteries.

I don't understand your comment about not being able to charge the batteries from my panels. Could you please explain the 50-60amp charger needed? I'm still very low in the learning curve. Thanks for your help.

Bloom

Blackcherry04

Re: Maybe my battery bank is ruined - seeking advice

Bloom wrote: »

The batteries are plain old lead acid not sealed. And yes, they're 100ah. I have them connected in parallel at 12V. When I charged them, I disconnected them and charged each one separately. My MPPT controller seems to work well stepping down the 24V from my 90 watts of PV panels to charge the 12V batteries.

I don't understand your comment about not being able to charge the batteries from my panels. Could you please explain the 50-60amp charger needed? I'm still very low in the learning curve. Thanks for your help.

Bloom

If they are lead/acid you might be able to recover them depending how low they are. If you can charge each one thats ok, You can't charge them correctly because your panels do not produce enough power. You have 700 amp hrs of batteries, unless you are taking the bank apart to charge them from the panels.

Here is a video on how to use a hydrometer.

http://www.youtube.com/watch?v=SRcOqfL6GqQ

Bloom

Re: Maybe my battery bank is ruined - seeking advice

Thanks for the fast responses. And thanks for the link. One more question: What is the calculation to find the correct size battery bank for my solar panels? (I think that is backwards from the way it is normally approached.)

By the way, if my batteries are indeed wrecked; perhaps I should start fresh with a 500W 'kit'.

Thanks again,
Bloom

niel

Re: Maybe my battery bank is ruined - seeking advice

"......90W to BT (MPPT) charge controller."

what is a bt charge controller? if you meant bz then that is a problem as they are junk.

8n-bob

Re: Maybe my battery bank is ruined - seeking advice

Also from what I have learned here a bout solar charging

For minimum charge you need to have 5% charge current of the amp hour rating of your batt bank. So

You have 700 A/h of batt
700×.05=35 amps of charge

Now h
HF panels 180 watts ÷ 24 volts =7.5 amps
Thats if operating at 100% the best my panels give, and I have the same setup 4HF series/parallel to 24v, give 4.75a in bright direct sun maybe 5amps a few days in the summer.

I thought my batts were bad also just going down and down I have 6 golf cart batts 6V each serire paralleled together for 12V 660 A/h pulled 2 sets off for just 220 A/h and they are keeping thier charge.

Maybe t
You are frugal with electricity and thd the bank has a long time to recharge during the week. Your friend used a lot more power and now your batts are havjng trouble f
Recovering.

Thom

Re: Maybe my battery bank is ruined - seeking advice

8n-bob wrote: »

Also from what I have learned here a bout solar charging

For minimum charge you need to have 5% charge current of the amp hour rating of your batt bank. So

You have 700 A/h of batt
700×.05=35 amps of charge

Now h
HF panels 180 watts ÷ 24 volts =7.5 amps
Thats if operating at 100% the best my panels give, and I have the same setup 4HF series/parallel to 24v, give 4.75a in bright direct sun maybe 5amps a few days in the summer.

I thought my batts were bad also just going down and down I have 6 golf cart batts 6V each serire paralleled together for 12V 660 A/h pulled 2 sets off for just 220 A/h and they are keeping thier charge.

Maybe t
You are frugal with electricity and thd the bank has a long time to recharge during the week. Your friend used a lot more power and now your batts are havjng trouble f
Recovering.

5% is not enough for me . With the price of panels at less then a buck a watt I like 10%
It's nice to have the extra power to EQ .

Good luck Thom

Ps The help here is outstanding .

vtmaps

Re: Maybe my battery bank is ruined - seeking advice

Bloom wrote: »

seven marine batteries I picked up on a closeout deal.

If any of your batteries can be recovered, you should attempt your recovery on one battery at a time. Putting the batteries in parallel means that one bad battery could take all the current meant for the other six batteries. That could be dangerous... boil dry one battery and trigger a thermal runaway.

Whatever you do for your next battery bank, do NOT assemble more than 2 parallel strings. One string is optimal. Seven strings, which you have, indicates that you are a danger to your batteries.
Good discussion about that here: http://forum.solar-electric.com/showthread.php?14674

--vtMaps

Cariboocoot

Re: Maybe my battery bank is ruined - seeking advice

The equipment you have isn't very good even if it were working. Chances of batteries recovering: near nil.

Flog the stuff and start over.

Bloom

Re: Maybe my battery bank is ruined - seeking advice

8n-bob wrote: »

Also from what I have learned here a bout solar charging

For minimum charge you need to have 5% charge current of the amp hour rating of your batt bank. So

You have 700 A/h of batt
700×.05=35 amps of charge

Now h
HF panels 180 watts ÷ 24 volts =7.5 amps
Thats if operating at 100% the best my panels give, and I have the same setup 4HF series/parallel to 24v, give 4.75a in bright direct sun maybe 5amps a few days in the summer.

I thought my batts were bad also just going down and down I have 6 golf cart batts 6V each serire paralleled together for 12V 660 A/h pulled 2 sets off for just 220 A/h and they are keeping thier charge.

Maybe t
You are frugal with electricity and thd the bank has a long time to recharge during the week. Your friend used a lot more power and now your batts are havjng trouble f
Recovering.

Thank you so much for your response! The computations and information are very valuable. Your experience is very similar to mine except I am using crap components. I am still learning. Your response made me very happy to finally understand the problem! You gave me good sound advice. I guess ya gotta sift through the chafe anywhere...

In my search to find some answers to this problem, I found http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/ - SUPERIOR! It deals with RV but a person learning on a small solar project, can use the information also. I'm glad I found it.

Thanks again for your help!

All the Best! Bloom

Bloom

Re: Maybe my battery bank is ruined - seeking advice

vtmaps wrote: »

If any of your batteries can be recovered, you should attempt your recovery on one battery at a time. Putting the batteries in parallel means that one bad battery could take all the current meant for the other six batteries. That could be dangerous... boil dry one battery and trigger a thermal runaway.

Whatever you do for your next battery bank, do NOT assemble more than 2 parallel strings. One string is optimal. Seven strings, which you have, indicates that you are a danger to your batteries.
Good discussion about that here: http://forum.solar-electric.com/showthread.php?14674

--vtMaps

Thanks for battery advice and the link. I appreciate the time you took to give me that information.

Did it make you feel good to add the personal remark that I am a danger to my batteries or was that just to add insult to injury?

BB.

Re: Maybe my battery bank is ruined - seeking advice

vtMaps was just trying to add emphasis--Not that you are a danger to your batteries--But the batteries are a danger to your family and home. There are a fair amount of very bad things that can happen with batteries--Short circuits, "boiling" electrolyte and exposing the plates, hydrogen gas explosions, battery thermal run-away during charging, sulfiric acid mists that ruin wiring+electronics+anything stored near by, etc...

We are all pretty used to the dangers of 20 gallons of gasoline in the car.... As long as it is in a sealed metal container, it is "relatively" safe.

A golf cart sized battery has about the energy equivalent of a 1/2 cup or 1 cup of gasoline in it... And if there are "problems" (internal battery shorts, short circuits in the battery wiring and no fuses/breakers, etc.)--The batteries can just take on a life of their own and start burning/cause an explosion, etc.... And there is no easy way to stop it once it starts.

We are very concern with safety on the forum. Lead Acid battery banks can output hundreds to tens of thousands of amperes into a dead short--Most of us do not have day to day experiences with these types of failures.

Since the battery banks are the core of a home power system--Many folks have the batteries inside their home, in a basement, attached lean-to, etc... We just want to make sure that whatever people do--They have understanding and protect against unreasonable risks.

Posting on the internet misses body language, tone of voice, etc... Sometimes we do try for some humor--and that does not always go well. Everyone here is watching out for mistakes/dangerous situations and we want to address those first. Clearly.

-Bill

vtmaps

Re: Maybe my battery bank is ruined - seeking advice

Bloom wrote: »

Did it make you feel good to add the personal remark that I am a danger to my batteries or was that just to add insult to injury?

It wasn't meant to injure or insult. It was meant to get your attention with a strong statement.

Bloom wrote: »

Thanks for battery advice and the link. I appreciate the time you took to give me that information.

It was all meant in that spirit. --vtMaps

Bloom

Re: Maybe my battery bank is ruined - seeking advice

I am a veteran of the electrical generation industry. While I didn't work with batteries and small dc systems, I did work with equipment generating electricity for large industrial and residential use. Working in a power plant has made all too familiar with electricity and the disturbing fatal accidents it can cause. Part of my specific duties included duties in the rooms housing the huge battery banks for our battery backup dc generators.

I've read some other forum discussions under "fuses" where large battery banks of twelve or more batteries were connected in various configurations. I found http://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A and plan on using these on all my batteries that I include in my small system. 8n-bob was so kind to include the calculations for helping me figure out how many batteries can be charged based on array size. Luckily I knew enough to store my batteries in a separate enclosure with correct ventilation outside of my cabin.

Thanks again for the responses.
Bloom

icarus

Re: Maybe my battery bank is ruined - seeking advice

All battery calcs. Start with the loads. Determining the loads, determines the size of the battery bank,which in turn dictates the size of the PV and the inverter.

Do a calc estimating your total daily loads, both total Wh, and peak, and then work backwards. Any other plan is simply "ready, fire, aim!", trying to put square pegs in round holes.

Tony

BB.

Re: Maybe my battery bank is ruined - seeking advice

Bloom,

We don't really know anyone's particular level of experience--We try to keep everyone safe. Sometimes it may seem repetitive or too basic at times. And sometimes it is.

-Bill

westbranch

Re: Maybe my battery bank is ruined - seeking advice

I just thought about one aspect of the battery demise you suffered.
A MidNite BCM would probably work well for you if and when you have others use your cabin...http://www.midnitesolar.com/pdfs/MNBCM12.13a.pdf

hth

Bloom

Re: Maybe my battery bank is ruined - seeking advice

westbranch wrote: »

I just thought about one aspect of the battery demise you suffered.
A MidNite BCM would probably work well for you if and when you have others use your cabin...http://www.midnitesolar.com/pdfs/MNBCM12.13a.pdf

hth

SUPER! Thanks so much.
Bloom