Water Usage

plongson

Given some time now (about 6 months or so) I getting a bit of a trend on my water usage. It looks like I'm adding about 6 quarts about every 6 weeks on 16 (ea) L-16 Surrettes. What say you? Too much? About right? I'm in Southern Utah and the humidity is low mostly, but temps can swing widely. I'm set at 59vdc and 4hrs. absorb. The dang system is working so good, I don't want to mess with success...LOL

Paul

waynefromnscanada

Re: Water Usage

plongson wrote: »

my water usage. It looks like I'm adding about 6 quarts about every 6 weeks on 16 (ea) L-16 Surrettes. Paul

Hey Paul, the "(ea)" has me a bit confused. Does that mean that each (ea) L-16 is drinking a quart per week? or is it a quart a week for the total of the 16 batteries?
If it's a quart a week per battery - - that's HUGE in my opinion. My L-16's take much less than a quart each every 3 months and have been doing so for 10 years..

plongson

Re: Water Usage

Na, take out the (ea). that was just habit. It is 6 qts TOTAL for 16 batteries in 6 weeks. AND...I check all the time, but only need to add just a bit to bring them up, that is the total amount.

The Magnum battery monitor hits 100% every day by no later than 1400 (usually noon this time of year) and then the system adds about +20amp/hrs before the sun gets low. I'm wondering if I can crank back on the absorb time and save on water/battery abuse.

waynefromnscanada

Re: Water Usage

Oh, OK. So for comparison, each of my L 16 batteries use roughly 0.25 quarts of water per 6 weeks. Your's use roughly 0.375 quarts during that same 6 weeks.
I'll leave it to others to comment on that. Perhaps you're batteries are being more heavily used than mine, which only see 5 to 10% discharge per day.

Vic

Re: Water Usage

Hi Paul,

Well, if you are maintaining SGs to 1.265ish, and it has seemed that you are, then your charge parameters must be set correctly. You must cycle your bank to 80% SOC, or a bit lower daily (?). The deeper the discharge, the more water use, due to the required longer Asorb.

Guess that you are using an average of about one gallon per month for this system. That is about 1.25 US oz per cell per day. Seems perhaps a bit high, but if your batteries are not being overcharged, and you are not EQing excessively, then this must be what is required by the system.

Do you have an idea of the average electrolyte temp over a longish period of time, say in the past 6 week interval ... yea, know that this can be difficult ... some inverters and so on do read out the present temp.

IIRc Surrette recommends 58.8 as the mean Asorb voltage for solar-based systems. Somewhere in the Surrette bulletins that have read, there was a ref to approximate water useage. It seemed astonishingly high to me, but had guessed that they were assuming discharges to 50% SOC and daily recharge. This deep discharge requires a L O N G Asorb, and much water use. From my distant memory, the typ water use was stated as 100 ml per cell per 100 AH of 20-hr capacity per recharge cycle. This of course simply cannot be correct, as one would need to constantly attend the batts for every cycle (well, almost). Even this amount per month would seem high to me -- a 1000 AH bank needing basically one US Quart per month ... Will try to find a ref from Surrette.

Vic

Cariboocoot

Re: Water Usage

Watch the charge current to the batteries during Absorb. If it's spending the last hour basically sitting at the same Amps then that's an hour of Absorb time you may not need.

plongson

Re: Water Usage

Hey All,
Lately, as the days are longer and the weather is warmer, the SOC has been about 90% in the morning when we get up, so we're using 10% overnight. The SG when checked in the afternoon toward the end of float is pretty good and around 1.255 at the worst cell or two and 1.275 on about three cells the rest fall somewhere in the middle. Like I said I'm at 59vdc and 4 hours absorb. Electrolight temp over time...couldn't say, I'll have to ponder that one.

I'm playing with the auto EQ settings on the midnite, but I don't think it has even done one yet, so I don't think that is what's going on. I'll bet I can back off a bit on the both the time and vdc settings now the bank is in good shape.

I've heard climate makes a big difference too, hot dry weather vs soggy/cold...I'd like to get consumption down to about a gallon or so in 8 to 10 weeks. Is that realistic with my SOC usage?

vtmaps

Re: Water Usage

Vic wrote: »

you are using an average of about one gallon per month for this system. That is about 1.25 US oz per cell per day. Seems perhaps a bit high,

1 gallon per month divided by 48 cells = 0.0208 gallons per month per cell = 0.000693 gallons per day per cell = 0.0887 ounces per day per cell

Paul, I'm not sure if your water consumption is excessive. Do you have a remote temp sensor for the classic? If not, that may explain some things. As batteries get warmer they will tend to gas more if the charging voltage is not reduced (by temperature compensation).

--vtMaps

plongson

Re: Water Usage

Yes, there is a remote sensor. One from Midnite that stick on the side of the battery case and a sensor from Magnum that is mounted on the neg. terminal (which I don't understand how it works, it's not in contact with the battery...)

vtmaps

Re: Water Usage

plongson wrote: »

Yes, there is a remote sensor. One from Midnite that stick on the side of the battery case and a sensor from Magnum that is mounted on the neg. terminal (which I don't understand how it works, it's not in contact with the battery...)

Many feel that the magnum way is superior. The battery terminal is a metal 'probe' sticking into the interior of the battery. Its temperature reflects the temperature inside the battery. The classic probe sticks on the outside of a plastic battery case, so it is a bit insulated from what's going on inside of the battery.

--vtMaps

Vic

Re: Water Usage

OH,

Thanks vt for fixing my math ... so much for doing this stuff in my head.

For 10% of capacity discharge, I have been surprised that you have required 59 V Vasorb for four hours. But, your SGs seem to say that you are recharging your bank well. However, the ideal time to measure SGs to make certain that the Asorb voltage and time are just right, is at the beginning of Float. And the best time to determine if the Float voltage is correct is at the very end of Float. The Float voltage should be set so that you just maintain the desired SG.

I would be nice to know how many AH are returned to the batts during Asorb, let's say, but without a Battery Monitor, this number is elusive.

Regarding the BTS type and placement, opinions do differ. Personally, I like to place the sensor midway down the battery case, all on a single battery in the center of the pack. All of the BTSes are then insulated under a chunk of styrofoam sheet, about 1.5" thick. This styro has been hogged out to allow the it to lay flat on the batt case. This styro is taped or strapped to the battery. This allows the temp of the sensors to be much less affected by the ambient temp, and more accurately reflect the electrolyte temps. Some say that placing BTSes on battery terminals causes errors (probably small) when battery currents are high. These things will never be perfect, but any approach is a huge improvment over having no BTS at all. Personally, I prefer the plastic encased BTS over the metal battery terminal type. Have seen an MS metal probe type BTS fault to ground. This is not common, but just one more possible failure mode.

And, Paul, if you could borrow a neighbor's Hydrometer, it might be good to confirm your SG readings. Some NAPA auto parts stores do have glass Hydrometers. Always good to have a second vote on SG, and a backup. Vic

plongson

Re: Water Usage

Hey Vic,

Well, I must admit, the current absorb setting is what I put in back in November when it was winter, and when I was having problems getting the SG's up. Now with longer days and it looking like my SG problems are behind me, I really do need to modify the absorb and float settings. It's probably why I'm seeing this water usage up from the dead of winter. 6 months is still a pretty lousy trend, but i gotta' go with what i got...LOL

I see your point about checking SG at the end of absorb, and setting float to a desired SG. I'm gonn'a do that next time i check them.

I do have a battery monitor, a Magnum BMK that I rely on for the SOC. It's mounted remotely in the kitchen and very easy to watch. I believe I calibrated it correctly after talking to Magnum and this 800ah system goes to 100% by about 1300, then by the time the sun gets low it reads usually +20ah. This is why I'm thinking I should set the transition from absorb to float...when it hits 100%, or when the SG hits 1.265+\-.

That +20 ah seems funky though because it will rip through it in no time and when it hits 100% it slows down and acts pretty normal. Not sure I really trust that plus (+) reading...

I also like your idea of insulating the BTS to rule out ambient interference.

As for hydrometers, right now I have 3 of them! LOL, One was a cheepo that I didn't trust, bought another one on-line and found out the cheepo was pretty accurate. Then ordered a part for the good one and received an entire hydrometer instead...(a shipping error). It's never been out of the box yet.

Any-hoo...THANKS for all the input, I'm going to change the absorb settings slightly and see if I can reduce this charge time. It'll be in small increments though, this ship doesn't steer too fast...HA-HA

Paul

Vic

Re: Water Usage

Ok Paul,

In was not certain that your Magnum montior was a full Bat Mon, good that it is.

Some day will look at the manual for your monitor. Am not certain what the +20 etc means ... perhaps this is the integrated additional AH that have been placed in the batteries in Float, or perhaps it is the result of the inefficencies of charging batteries (?).

Great that you have three Hydros. That is what we have here ... an additional opinion is always good to have avail if needed.

And, yes, believe that Asorb and Float charge settings should be changed in small steps, and monitor results over a number of days to see the resluts. Largish battery banks respond a bit slowly, so large changes can result in tail chasing. Of course if something is really wrong, then a large step and monitoring the result is good.

Sounds like you are on top of things.

BTW, did find a ref in Surrette Bulletin #507 to water useage: While, to me, it is written ambigously it states that, " When a battery uses water in excess of 30-60 ml per cell per 40 hours of operation the regulator is set too high. The ideal voltage setting for a regulator may be defined as that setting which will keep the battery at or near full charge with a minimum use of water".

It is mu ASUMPTION that the 40 hours of regulator operation may well be a total of 40 hours spent in Asorb (?). If this is what they are saying, then guess that would be 10 days with your present 4 hr Asorb. Dunno.
This is a bit different than my typical operation, which is: Recharge fully every day if at all possible, with the exception of intentional bank cycling. ...
Back to work. GL, Vic

mike95490

Re: Water Usage

(reposted here on water thread)

7 Month update. 800AH NiFe battery bank

Cells were not quite yet down to the FILL---- indicator line, but each took about 1/2 gallon of distilled, to top them off.

Bank seemed fine, but not under any heavy load yet. I've set the absorb time back again, to reduce gassing, we'll see how it goes.

Their size is roughly a bit larger than L-16's :

Attachment not found.