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gcrank1
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# Posted: 8 Nov 2021 07:09pm
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Ya got a full plate, thats fer sure 
Maybe you can find a used std fridge locally to get you over the hump? Ask around
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bc thunder
Member
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# Posted: 12 Nov 2021 06:06am
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Can anyone please tell me how long my batteries should last @ 100watts till 50% soc
8 6volt deep cycle golf cart
230 ah each
2 strings in series and paralle
I can't figure it out.
Assuming full charge how long???
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gcrank1
Member
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# Posted: 12 Nov 2021 10:42am - Edited by: gcrank1
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Series wired bats combine the voltage, ah's stay the same. So for each quad of 6v bats you get 24v/230ah's.
For parallel wired the ah's double, the voltage stays the same. Pair 2 of those 'quad sets @ 24v' together the voltage stays 24v and the ah's go up to 460.
50% MAX draw down (=50% soc) is back to the 230ah's.
That 230ah's @ 24v is 5,520watts (amp x volts = watts) so lets round down to 5500w.
At 100w constant draw that should go about 55hrs or effectively 2 days and a bit.
Then, you have to put all those amps back into the batteries. It takes more amps back in to recharge; just the way it is. You take out 5500w you have to put back about 6000.
If your 'charger' (solar, hydro, wind, grid it doesnt matter) is a max 50w output (compared to your 100w drawdown) it will take twice ++ as long to recharge as it did to discharge.
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bc thunder
Member
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# Posted: 12 Nov 2021 10:49am
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Thanks for showing the math GC.
I'm getting 3.5 hrs.....
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gcrank1
Member
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# Posted: 12 Nov 2021 10:57am
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Well, 5500w available divided by 3.5 hrs is 1500+ watts use, not 100.
Without re-reading the whole thread, have you done an 'energy audit'; ie, listed and added up ALL your devices energy use?
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bc thunder
Member
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# Posted: 12 Nov 2021 03:43pm
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Now that I don't have a fridge anymore, I run about 100watts..........
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bc thunder
Member
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# Posted: 12 Nov 2021 03:44pm
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....for about 3 hrs.....
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ICC
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# Posted: 12 Nov 2021 06:16pm
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Quoting: bc thunder ....for about 3 hrs.....
How are you determining the cut off point? By voltage or by hydrometer?
Same questions as to how do you know the "battery is full"? If you are going by the charger indicating the batteries are full have you taken a hydrometer reading of each cell just to check or prove it is correct?
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gcrank1
Member
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# Posted: 12 Nov 2021 06:16pm
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That would indicate your bat-bank has to be compromised, waayyy compromised. At 100w/24v is 4.16 draw per hour over 3 hrs. is only 12.5amps.
You are sure that 12.5a draw is taking the bat-bank down to the 50% soc?
How did you determine that soc?
How do you know it is correct?
If all your batteries are good they aint hardly charging.
If 1 or more have gone bad it/they are pulling the good bats down to the 'least common denominator'.
Since your system is 24v and you have to work with 4x6v bats it is a bit harder to sort than a 12v set up.
You must split the parallel 2 quad sets and use only one quad made up of the best 4 6v bats you have for further trouble-shooting/testing.
Pull all the wires off the batteries carefully!
Are they full of water?
Can you hydrometer test the cells?
Voltmeter check each battery, do you have 4 that read pretty high for 6v bats (that will not be just '6v').
Take the best 4 and get them Each (Not ganged together) on an automotive charger until each is Fully Charged. Once that set is done get the other bats on the charger to see if they recover while you work with set one.
Then wire them up in series for your 24v (now only 115ahs to 50% soc) and test use with a confirmed steady amps draw for x calc hours to your 50%.
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bc thunder
Member
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# Posted: 12 Nov 2021 07:05pm
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Having a hard time getting a hydrometer, on order, should get it next week. All my readings are coming from a volt meter at the moment. Put them on charge for 7 hrs wiyh the generator and they lasted 3 hrs till about 60%. All readings off the inverter for now.
I have already isolated one string, and am planning on charging 4 batteries tomorrow just like you have suggested GC. and will follow that up with the other 4.
I'm only using the honda now (god bless honda), as I know longer trust the batteries, or the inverter. The high watts usage the inverer was giving off right before the fridge blew up, is now doing the exact same thing with my starlink. If that goes up in flame; $600 and a 4 month wait for another.
If by next week I don't have this sorted, I'm done with my current set-up (I don't have the knowlegde nor the patience for this), I'll break down and start over with fresh solar equiptment, or (and this is how I'm leaning) I'll get another bessed honda and turn my back on solar forever. If your not good with solar don't buy it, their is noone to help you, like if your car breaks down. Your on your owe. I have learned so much, mostly from you guys (thanks), but the canyon is vast. IF something goes wrong along the way, maybe I can fix it. But I feel over welmed like I had to forge the steel to build it, stretch the copper stands to connect it, and invent dc current to run it. Nothing has gone right since I bought it.
Fingers crossed for tomorrow, it's a new day
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travellerw
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# Posted: 12 Nov 2021 07:23pm
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Quoting: bc thunder If your not good with solar don't buy it, their is noone to help you, like if your car breaks down. Your on your owe. I have learned so much, mostly from you guys (thanks), but the canyon is vast. IF something goes wrong along the way, maybe I can fix it.
I'm really sorry to hear that.. but I promise.. You are the exception and not the rule. There are GREAT companies out there that will help you. Hell, many of them if you just buy their equipment (Masterolt, Victron, ect, they have forums where they will help for free).
There are also some fantastic forums out there with really great info. I agree the guys here are great too, but this is not the focus of this forum. The solar of off-grid forums are chocked full of info..
Anyway.. keep us updated here and we will do our best to help. If you plan to start over, we can make some great suggestions. I have probably built 20 systems for people and can offer some good insights (like the battery monitor, its a must).
P.S. One piece of advice. DO NOT get sold on LiFePO4. You are not a good candidate for it at this point. You NEED to get a good FLA system and operate it for a few years. Then maybe.
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travellerw
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# Posted: 12 Nov 2021 07:25pm
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P.S. May I ask why you went 24V? Watts are watts, but 24V systems are usually built for high draw users.
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bc thunder
Member
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# Posted: 12 Nov 2021 07:44pm
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Thanks, I can use all the help I can get........
I liked the AIO units for their simplicity, but the 12v unit is a little bit limited in terms of solar array, and the 48v unit would probly kill me dead. So I split the difference with the 24v
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travellerw
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# Posted: 12 Nov 2021 08:38pm - Edited by: travellerw
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Quoting: bc thunder Thanks, I can use all the help I can get........ I liked the AIO units for their simplicity, but the 12v unit is a little bit limited in terms of solar array, and the 48v unit would probly kill me dead. So I split the difference with the 24v
LOL.. Nah.. I had my strings configured in 80V.. One time I was laying on my back rewiring a string in a locker. I didn't bother to unhook the panels (I was going to be quick and careful). I gotta say 80V DC is spicy and made me hit my head.. but the funniest part was after the first zap, I went back and got zapped like 40 seconds later.. Rewiring was on hold till the next day.. LOL..
If you are thinking of starting over, 12V is easier and cheaper. Unless you are drawing 1500W or more, 12v works fine!
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gcrank1
Member
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# Posted: 12 Nov 2021 08:39pm - Edited by: gcrank1
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Do not depend upon the inverter 'read out' for battery monitoring, especially if it is a model that needs to be set for a known soc bat-bank to establish its parameters for its read out to be sorta accurate.
Sounds like you have hand held voltmeter?; it doesnt have to be a 'pro' model but not a bargain model either.
Solar is a 'system' (even if an aio which is just bundled for you). Each 'component' has to do its job and that is the only job it does.
The array
The scc
The bat-bank
The inverter
The wiring, fuses/cir.bkrs/etc
Advantage to a component system, you can change out/upgrade the components
But! The components have to play friendly with each other. Not all do, this is not an industry with total cross-compatability.
Throwing out the whole deal to start over without isolating the problem will likely only result in needless expense and a new set of issues.
Problem solving is an orderly approach with a start point and progression through the system.
Dont let this beat you, others have done this and you can too.
Fwiw, when I started I knew (or thought I did) a few things about solar. I had played around with a 'starter kit, lol. I had a good background in old school motorcycle and car electrics and some small RV/camper experience. For 12vdc electrics that helped a LOT. Btw, knowing what I do now Id start with 24v like you did.
I think you have at least one failed battery in your bunch, maybe even 1 in each quad. Think of what happens in a multi-cell flashlight when one battery goes bad. Dim light and not for long until it rests a bit, but each use keeps depleting it until its out.
You only need one quad of 4 good, fully charged bats to run. Get that satisfactory while charging the others, then if they each recover make quad 2 and disconnect quad 1, trial run and prove quad 2. If it works parallel them again.
Worst case might be, while you get the solar sorted, is you run off quad 1 while charging quad 2, maybe at a friends? with a heavy duty charger, and swap them out as needed.
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bc thunder
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# Posted: 12 Nov 2021 09:09pm
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Thanks for the encouragement guys, I know you're right. I'm just plenty discouraged right now......
I'll start with those batteries tomorrow and see. I could use even a small win right now!
Trav your luckier than me, I'm an excellant conductor of eclectricity lol
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Steve_S
Member
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# Posted: 13 Nov 2021 07:18am
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You are feeling disheartened and stressed as a result. This IS an unusual situation the way things worked out for you but it's not the end.
As previously mentioned, THIS is not really a Solar Support forum, that's why we have places like https://diysolarforum.com/index.php where we write up & document a lot of various things to help folks out.
The world IS changing quite fast and 2022 will bring more forward than many realize. Prices will be changing significantly on many things - including batteries (going down as more localized production increases). PS: We have several factories for Lithium Batteries in the works in Canada but all low key more or less till things get a little closer.
I'd suggest you sit down and think things through, do a bit more research @ DIYSolarForum for example to get a better handle on the details. Plan out your "intended" Big System for when you are in residence, and then consider the "Foundation" components to build on top of as the base. Once the solid foundation of the system is in place, then you can expand it and grow it as needs increase. This can be budgeted to happen over time.
I've mentioned this before just not sure if in this thread... Generally it is strongly suggested to not use more than 250A Draw from a battery bank.
12V@250A=3000W, 25A@120VAC / 17.5A@240VAC
24V@250A=6000W, 50A@120V/25A@240V
48V@250A=12,000W, 100A@120V/50A@240V
Excluding Surge Potential and without Efficiency Correction *Inverter efficiencies can range from 80% (Value Grade) to 96% Tier-1.
Stackables apply differently.
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bc thunder
Member
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# Posted: 13 Nov 2021 07:58am - Edited by: bc thunder
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While I only have a volt meter at the moment, all four disconnected batteries are full (over 6.3) before going on the charger, and coming off at around 6.38
I'm still not convinced it's the batteries, but will try these 4 to see if they last more than 1.5 hrs.
Last night the 4 hooked to the system now, were full reading ave 6.4 This morning they lasted 1.5 hrs and read 6.05 I then turn on the generator and 15 min later they read full????
All readings off the volt meter at the batteries.
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bc thunder
Member
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# Posted: 13 Nov 2021 07:58am - Edited by: bc thunder
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Sorry, they are not full 15 mins later, it has now been one hr, they currently sit around 6.25
And I must be cursed, my charger just quit working, it is older but still lol
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bc thunder
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# Posted: 13 Nov 2021 08:26am
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Draining quikely, and charging quikely. Is there anyway the inverter or anything else could be causing this, or do we still like this batteries as our nummber one suspect?
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FishHog
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# Posted: 13 Nov 2021 08:29am
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I haven't been following this thread BC, but based on your last few posts sure sounds like failing batteries to me.
They will charge up but not pass a load test and drain quickly. That is typical for old lead acid batteries.
If possible take one out to an automotive shop as ask them to load test them. But if it were me having seen the same thing many times in the past, I wouldn't even bother with that step. Sounds like time for new batteries.
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bc thunder
Member
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# Posted: 13 Nov 2021 08:29am
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The AIO is still at the default 60a charge.
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bc thunder
Member
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# Posted: 13 Nov 2021 08:31am
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Thanks Fish, that's a real solid practical idea. I love it......
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gcrank1
Member
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# Posted: 13 Nov 2021 11:37am - Edited by: gcrank1
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Fwiw, Im not confident about anything that aio is saying.
A short while back didnt you say these bats were only 8wks old or was it 8mo?
Most 'inexpensive' bats have a 1yr return guarantee; if yours do, take them back (maybe 2-4 at a time?). I believe most places will load test them on site before doing the 'exchange'. I might not mention 'solar' in the conversation, they are golf cart bats which I think is typically even harder cycling than solar but saying solar might 'give them an out'.
Btw, are all the bat cells full of water?
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bc thunder
Member
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# Posted: 13 Nov 2021 02:47pm
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just got back all are good under load.
I also found a hyrometer, cant remember best time to test??
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Brettny
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# Posted: 13 Nov 2021 05:15pm
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Quoting: travellerw Not sure how your panels are configured (parallel or series), but that makes a big difference with Epever controllers. They have so many bugs in the MPPT tracking that series connections are literally unusable. Frankly, my advice would be to throw that controller in the bush. They really are poor and probably the reason you are seeing low numbers. .. EDIT - Looking at your numbers on the MT-50, you are hooked up Parallel. Those are very poor numbers for even an Epever. Wondering how much cable between the panels and controller and what size!
Loosing 4% is alot? I have about 15ft of 12ga wire hooked to the pannels in parallel.
At the moment this is only a temp setup and I plan on adding 4 more pannels. At that point I'm going to add another of the same charge controller. I cant see scrapping a $200 charge controller to maybe gain 2% or even 3% effencency. No matter how much you spend on a victron your still only going to produce what the pannels can.
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travellerw
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# Posted: 13 Nov 2021 07:53pm
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Quoting: Brettny At the moment this is only a temp setup and I plan on adding 4 more pannels. At that point I'm going to add another of the same charge controller. I cant see scrapping a $200 charge controller to maybe gain 2% or even 3% effencency. No matter how much you spend on a victron your still only going to produce what the pannels can.
Good luck.. I hope it works out for you.. I have scrapped so many dead Epever controllers (2 for me, many for customers). Bridge rectifiers gone dead short. They last OK if you keep them away from their rated values. For me, I just gave up futzing with them. If it works for you, great! As long as they haven't blown up and are working for your scenario, keep using them.
There is a video from a fella in Australia that shows one of the big bugs with Epevers firmware (from like 2014). I can't seem to find it but will keep looking. That bug still exists today in their current products (and offshoots like Renogy). If I can find the video, you can actually do his test a verify the bug (essentially they fall down in cloudy conditions).
I suggested Victron as they are well priced with great performance/warranty/support. There are other great brands too. Mastervolt, Midnite, ect.. but they are all more money.
P.S. my monthly numbers between Epever and Victron were not %4.. More like %30 more harvested power over a month.. I have blog posts detailing it. Of course I'm one case and one scenario that was highly variable since we lived full time on our solar.
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bc thunder
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# Posted: 13 Nov 2021 08:02pm
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yes 8 weeks old (approx)
water levels good
Took 4 in and they load tested at 6.4
Hydrometer backs up the load test
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gcrank1
Member
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# Posted: 13 Nov 2021 08:43pm - Edited by: gcrank1
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Then hooked up they should give you 115ah's usable to 50%soc. That is, if that is what they really have and the rating wasnt hype.
Hook the quad up only, can you configure the scc or aio, whatever to take that bank as the 100% benchmark for its internal calc?
If not, so be it.
Then, if I were you....
I'd derate that 115ah's to 100 to be conservative; thats 50ah's to 50%soc.
Hook up a steady draw of, say, 5amps and run it 20hrs (=100ah) while checking the voltage with the handheld every couple hours and noting (yes, writing down) what is happening. Also note what your read-out is saying to see if it correlates.
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bc thunder
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# Posted: 13 Nov 2021 08:57pm
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I have alreadyhooked back up both strings, and ran it for 3hrs till the AIO read 24v
Then I cheacked the bank with both load meter, and hydrometer. Both were still close to 6.3
I then ran the generator for 10 mins, turned it off, and the AIO read 25.5
I ran with that for 1.5 hrs, the AIO read 24, and the bank was at about 6.2
AT that point I was done for the night, and turned on the generator, and watched the hockey game lol
I'll take a longer look tomorrow........
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