Working to figure out what I don't know.

vtmaps

Re: Working to figure out what I don't know.

Denman wrote: »

My partner has given me the kind head-nod to upsize our panels/charge controller to match our battery bank.

I like the alternative plans better. If you can manage with one string of batteries, then do so. I would go to great lengths to avoid parallel batteries.

Denman wrote: »

I'm going to have to bite the bullet and start doing that specific gravity reading thing. I know, I know, I should have been doing it all along but I avoid it like the plague.

And when you do start measuring SG, that's when the aggravation really begins. I believe the aggravation goes as the cube of the number of battery strings. Don't forget that you will also need to monitor current through each string. When you start noticing SG or current differences between the two strings... then you will know real aggravation... rotating batteries, equalizing individual batteries or strings, and reading all the helpful and conflicting advise on the forums.

My point is avoid parallel batteries if you can. It is enough to deal with the problems of one string of batteries.

BB. wrote: »

Very roughly, a 2x larger battery bank will last 2.2x longer

I think that depends on how the battery bank is configured. If you get to a 2x larger battery bank by putting two 1x batteries in parallel, you lose some longevity because of the parallel configuration.

--vtMaps

Denman

Re: Working to figure out what I don't know.

I have ordered a nice course on building solar arrays It's clear to me that there are a number of right answers to most questions and I'm becoming increasingly frustrated with being unable to find a clear direction to go to solve this problem. I'm going to sit with my current setup taking readings every half hour throughout the day so I at least have some hard info to work with.

The local expert with an electrical outfit in my town was the one that told me not to mix old and new panels. He also said he doesn't care for Outback charge controllers as they're more difficult to set up and avoid over charging the battery bank. Do yall find this to be true ?

For the last week I've done a morning bulk charge with my generator. When Imeave for work the panel on my magnum inverter says its moved to absorb charge. I then shut down the generator and let the outback FM60 take over, when it wakes up as it's still dark for an hour or so when I leave home. Am I correctly following the advice here for getting a full charge on the batteries given that I need to upgrade my panel wattage? I have set the outback controller for a 4 hour absorb time period.

I'm feeling pretty beleaguered at this point, every time I think I know which way I'm going I find out more I didn't know. Good thing we always win because we never quit

gww1

Re: Working to figure out what I don't know.

He also said he doesn't care for Outback charge controllers as they're more difficult to set up

Being able to set it up is the key. You wouldn't want something that you can not customize to you spicific batteries and your other equipment.

Did this electrition happen to mention the wonder controller he liked better?
gww

Cariboocoot

Re: Working to figure out what I don't know.

Denman wrote: »

The local expert with an electrical outfit in my town was the one that told me not to mix old and new panels. He also said he doesn't care for Outback charge controllers as they're more difficult to set up and avoid over charging the battery bank. Do yall find this to be true ?

Nope. Not at all.

For the last week I've done a morning bulk charge with my generator. When Imeave for work the panel on my magnum inverter says its moved to absorb charge. I then shut down the generator and let the outback FM60 take over, when it wakes up as it's still dark for an hour or so when I leave home. Am I correctly following the advice here for getting a full charge on the batteries given that I need to upgrade my panel wattage? I have set the outback controller for a 4 hour absorb time period.

The pre-dawn gen charging will shorten the time the Outback is in Bulk and thus in Absorb as well. It is the best way to get the batteries fully charged without expanding the array size.

I'm feeling pretty beleaguered at this point, every time I think I know which way I'm going I find out more I didn't know. Good thing we always win because we never quit

I completely understand. This stuff is complicated and complex; anyone who says otherwise is either ignorant or a liar or both.

gww1

Re: Working to figure out what I don't know.

On the 4 hour absorb. I like it but some day when you have all day you might sit and watch when it goes into absorb and the amps going to the battery start dropping. watch till they get tothe lowest level that they go to and stay there for 30 minutes. Time how long that takes and that will probly be close to a good absorb period. I very seldom have enough sun during this time of year to get a full four hour absorb unless I start with a pretty full battery.
gww

Denman

Re: Working to figure out what I don't know.

The electrician says he prefers Xantrex. I've been working construction a long time and I've seen lots of folks like him that have a preference that's really only his preferrence without much real fact to back it up. He did come with a good reputation from other electricians I run into. That said, I just wanted to bounce his ideas off you folks. I've gotten quite good direction here.

My plan is to reconfigure my panel array wattage to give my 700ah battery bank a decent full charge without having to constantly run the generator. I can go to 3KW in panels for the max on my current FM60 controller. Monitoring the panel readouts tomorrow for the full day should help me figure out a good estimate for useage. My historic metering on the FM60 lists average daily wattage at around 4800 watts total.

I wonder if it wouldn't be better to treat this as a new system? Design what I should have installed and then change whatever I need to in order to bring it up to that?

westbranch

Re: Working to figure out what I don't know.

I wonder if it wouldn't be better to treat this as a new system? Design what I should have installed and then change whatever I need to in order to bring it up to that?

YES and yes all based on your consumption and then fine tuned by your recent real life experience....

Denman

Re: Working to figure out what I don't know.

I'm all set. (as if). I took a sampling of SG readings and they were a pretty constant 1.23 (ish). Checking my Rolls Surrette link to their battery site it should be in the 1.65 category since I bulk charged this morning before I left the house and they were down to about 7 amps input to the batteries (still on an absorb cycle).

Tomorrow? I'll follow the manufacturers guidelines on a serious equalize charge with my generator doing the input starting before sun up. I'll remove my water saver caps, take an initial SG reading, turn on a manual absorb cycle, then monitor both SG and temperature making sure I don't exceed 125 degrees on a center section battery cell and keep an eye on the SG making sure it makes it up to 1.65 (ish). Supposedly that'll get me a good restart on this and then I can get to seriously upsizing my array.

Repair then replace as necessary. Just like powerlines right?

BB.

Re: Working to figure out what I don't know.

I think you have some typos in your specific gravity numbers:

http://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/

Attachment not found.

Roughly, you should be in the range of 1.16x to 1.27x specific gravity for flooded cell lead acid batteries.

-Bill

Denman

Re: Working to figure out what I don't know.

That helps thanks, Definitely a typo. I went back to the Rolls site and they list 1.265 +/- 0.005 as the number to shoot for. Guess I shouldn't start on that celebratory tequila while I'm doing my figures.

Denman

Re: Working to figure out what I don't know.

Working on a battery equalization cycle today. Got up, got the woman off to work, took specific gravity readings on all cells in all batteries (48 cells). Picked 2 as samples. Did bulk charge on bank, doing absorb charge on bank now. Will then start the equalization charge. Got a blower fan from a wood stove cut into the battery box to exhaust the hydrogen. (will get a good explosion proof exhaust fan in a couple weeks). Started the equalization charge at 9:50 AM. 1.23/1.225 SG respectively on sample cells. Rolls-Surrette says to run EQ charge until sample cells read 1.26 then charge for 3 more hours. We'll see if it comes up or not. That SG is where I started when the voltage on the bank was 49.2.

I'm taking volt/temp/amp readings every 15 minutes and will do SG every half hour for a while. Sitting in my battery building reading up on all the manuals to see what I might have missed the first time around

Denman

Re: Working to figure out what I don't know.

Almost 3 hours and not much change in the SG readings. I set my equalize voltage at the recommended 64v level for my 48v parallel bank of Rolls-Surrettes. I'll let it go to 6 hours looking for a rise. I'm still hanging at my original reading of around 1.23 SG. Once cell has come up about 0.005. Perhaps it's just time to let these batteries last as long as they're gonna go and get a nice new bank to treat right .

westbranch

Re: Working to figure out what I don't know.

Don't recall if you posted their age?
From what I have read here Rolls have a need for long absorb times.

BB.

Re: Working to figure out what I don't know.

Ate they fizzing much?

-Bill

Denman

Re: Working to figure out what I don't know.

They're fizzing pretty good. I'm seeing the cells becoming equal and a very small (to me) change of 0.0025 so far after the two (of 48) cells that I'm using as a sample. The good news is no dead cells.

From earlier help from yall I've started bulk charging in the morning with my generator and then going to a 4 hour absorb. The bulk that I did this morning took 45 minutes starting at 55 amps and dropping down from there. The batteries are just shy of 2 years old and we've determined that my array is too small to properly charge them (hence the generator while I figure out a panel upgrade). So I'm quite sure my ignorance has caused some damage, I'm doing this really long equalize charge to see if I can bring them back any. I'm using a pretty good hydrometer to check with so I'm thinking I just need to go longer?

Oh and when this part of the saga is over I'll move to a smaller than my current 700 ah paralleled battery bank to a single string that's adequate to charge up with the approximately 3KW in panels I plan to go to. I went to 3 websites with off-grid system sizing calculators and with my historic useage (4 years) they are suggesting a battery bank in the 420 ah range. Funny thing is they're suggesting only 1 KW in panels to support it. I'm not buying that line for nothin!

Thanks again for the input and help. You guys rock.

Denman

Re: Working to figure out what I don't know.

As I'm checking several other cells in the banks it looks like some are improving more quickly than others. At some parts of the string I'm up to 1.25 on the SG. I suppose that means there is hope!

Denman

Re: Working to figure out what I don't know.

Up to 1.245 I aint quittin

Denman

Re: Working to figure out what I don't know.

Started at 7:30 AM yesterday. Did a bulk charge, that took 40 minutes at 50 amps from the generator. Then did an hour of absorb charge, then started the Equalization charge at about 9:30 AM. Shut it down at 7:30 PM as the battery temps were getting high (120 degrees). Finished up with my test cells between 1.245 and 1.25 . I ran the generator on float charge for 3 hours before shutting that down. This morning the FM 60 charge controller said "Charged" when I got up around 8 AM. I'm not done refurbing this 2 year old bank of rolls surrettes, but that is a vast improvement. I did take readings on all cells and will go back and read them today after the temps have gone down on the batteries. Still at 104 F this morning. During this week I'll go in and R&R the battery connections. I'll pull them off, wire brush and put them back with some nice oxide inhibitor on 'em. It seems like that's probably a good maintenance thing to do.

I've pretty much decided to purchase a new set of 12 panels, all 250 watts, using all my other set up as is. My flexmax 60 will handle that size array (3,000 watts) and it'll be a 1,020 watt improvement over my old set of panels which I'll use on another building a ways off on my property. When my current battery bank expires I'll replace it with something in the 500 ah range rather then the current 700 ah set. That should be a better fit for my usage and panel supply. Yall now have me eyeballing those fancy 1/2 ton forklift batteries.......

In any case.... this forum has been enormously valuable. I intend to keep interacting with it and good lord willing and the creek don't rise, I'll even be able to help someone else out here some fine day.

Vic

Re: Working to figure out what I don't know.

Hi Denaman,


Just a couple of things;

As you probably know, SG readings need to be Temperature Compensated, particularly if the battery temperature is not close to the nominal 77 F (25 C).
This compensation value is fairly small, but for hot or cold batteries it is good to pay attention to this. Recall that this compensation is about 3 points for each 10 degree F change from 25 C. If the battery is warmer than 25 C, subtract 3 SG points per 10 F above, and add for each 10 F below 25 C.

When doing a Corrective EQ, as you appear to be doing, this compensation is important.

Also, you have chosen several Pilot Cells to act as a fairly good indicator of the SOC of the bank, when you measure their SGs. It is often a good idea to choose the lowest SG cells for Pilots.

Good Luck bringing back your Surrettes. Vic

Denman

Re: Working to figure out what I don't know.

Thanks. The meter I was using claims to be a temperature controlled meter. I'm gonna check all the SG's again on Saturday to see if there's any improvement after having come back down to operating temp and after it's supposedly fully charged. I did choose the lowest SG cells (one in each of the parallel banks). It'll be interesting to see what's showing then. One fun thing, a guy down the road has had a set of Rolls Surrettes online for the last year. He's moved to those giant 1/2 ton forklift batteries and has his one year old bank of S-600's for sale. That would be the perfect size if they're still in good shape. I'm assuming that buying year old batteries is risky. Also assuming that the best way to lower the risk (if the price is right) is to test the SG on each and every cell in that bank? Any other tips?

BB.

Re: Working to figure out what I don't know.

If they have not been charged, at least, 24 hour every 30 days, or kept on float charge--After 1 year of no charge--They are probably just scrap lead.

If they show >75% state of charge with a hydrometer (each cell)--They might have been taken care of.

-Bill

Denman

Re: Working to figure out what I don't know.

In order to figure out and properly size my system I'm borrowing the recorder we use at work to graph and total my complete daily usage for a week. Then I'll design a proper system around that and replace/upgrade etc anything that doesn't properly fit into a correct design. Am also going to change the angle on my roof panels as they were a bit low for my latitude. Man, by the time I'm done with this I'll perhaps know a thing or two.

gww1

Re: Working to figure out what I don't know.

I did that once using my electric bill and it was going to cost $90,000 to cover my needs with grid tie and no battery so I just bought what I could afford. Now I need to adjust my loads down to what I have. I know, a bit backwards.
gww

Denman

Re: Working to figure out what I don't know.

I figure since I'm already out here and off the grid it'll give me a good idea about the feasibility of building the system to support my currently conservative needs. Already have the LED bulbs, timer on the well pump, low low wattage TV, use laptops and not desktop computers, propane fridge..... It can't hurt to try

gww1

Re: Working to figure out what I don't know.

Like I mentioned in my pm to you, You have already used the rolls battery for a bit, so you should be ahead of the game on figuring out your needs. I was just being a smart a-- when pointing out my own bacwards approch.
gww

Denman

Re: Working to figure out what I don't know.

I like it. I do need to figure out a direction pretty soon, my dear sweet partner is getting tired of my running options in her presence.

Alaska Man

Re: Working to figure out what I don't know.

Denman wrote: »

I figure since I'm already out here and off the grid it'll give me a good idea about the feasibility of building the system to support my currently conservative needs. Already have the LED bulbs, timer on the well pump, low low wattage TV, use laptops and not desktop computers, propane fridge..... It can't hurt to try

Sounds like you are more than halfway there.

Denman

Hey, this is fun. Generator went out. Now I get to get a new generator that'll be more fitted to our needs. The old one will get repaired and set at location #2 otherwise known as the redundant system to be used in case of equipment failure.

gww1

Wow, new batteries soon, new generator, This is getting fun isn't it?
Good luck
gww

Denman

It's a hoot! Thank goodness I can afford my somewhat slow learning curve. Don't forget a new set of panels. I've practically got that whole redundant system before I even get started.