Recommendations for initial charging regimen?

Rossman · December 2014

Hello again all,

As previously mentioned I have an XW6048 running off a 48V battery bank, which consists of 24 Rolls S-1860's, which are 2V, 1445Ah batteries.

Due to some delays and now the current weather I will be unable to get my solar arrays functioning before spring (probably

), but I can't have my batteries just sitting around that long unattended, so I want to fire up the XW6048 with my generator just to keep the batteries in good shape. I have the XW wired up with it's power distribution panel and have wired a 30A, 250V power inlet box to feed in my Honda EU7000.

Just looking for some recommendations on how I can best maintain the bank until I get my array up and running. Some Rolls PDFs I found say I should perform an "initial charge", which seems obvious, and they list Absorb/Float/Equalize voltages that I should use (57.6V / 52.56V / 61.92 - 64.08V respectively). At some point I will need to actually start pulling power from the system, but we have no issue running the generator as much as is necessary to get through this. Should my initial charge be an "equalize"?

I do have a good hydrometer and digital multimeter and will be sure to take initial readings and start a spreadsheet to record the data as I understand this is helpful in the event any of the batteries ever fail (warranty purposes).

Thanks kindly in advance!
mark

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Also, this may be a really dumb question, but will the XW6048 itself charge the batteries or do I also need to wire in my SCC??

Cariboocoot · December 2014

Re: Recommendations for initial charging regimen?

The XW6048 has a built-in AC powered charger. If it has a source of AC on AC1 or AC2 it can charge the batteries. The source has to be 240 VAC and of sufficient current capacity to run the charger at the programmed levels, and the charger has to be programmed correctly for the batteries. This is why you need their system control panel.

Your initial charge needs to bring the batteries up to full SG and the same on all cells. This means you keep adjusting the parameters until you get there. That may take a while because that battery bank is huge. It will suck the full capacity of the XW and the gen if it is depleted much.

Your Absorb Voltage setting of 57.6 is much too low even if the maker recommended it. You should start at 59.2 and see if it needs to be raised from there. Absorb time should be set to its maximum and then watch the current level to see where it plateaus. The amount of time it takes to get there (from the start of Absorb) rounded up would be your maximum Absorb time.

Float Voltage is largely irrelevant as you don't want to keep a generator running to maintain Float.

You should only do a EQ if there is a cell variance of 0.010 or more or if you can't get all cell SG's up to the desired level. Usually increasing Absorb time and/or Voltage will achieve that goal though.

If possible, take this opportunity to cycle the batteries a few times.

What you really don't want is for the batteries to sit below 75% SOC for more than one day.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Thanks Cariboocoot! I do have the SCP hooked up so I can make configuration setting changes, no problem (as long as I can find them

). I will endeavour to set the Absorb voltage to 59.2V as you suggest, and just run the gennie for a full 6hrs, and see where that leaves me, does that sound a good starting point?

I have some 120VAC shop lights, 500W and 1000W respectively, would these be a good thing to use to cycle the batteries?

Our Honda EU7000 can deliver 5500W (240VAC @ 22.9A) continuously which, if I've done the math correctly, is about 114.5A @ 48VDC. The Rolls site tells me at this charge rate it would take about 5.28hrs to recharge the batteries from 50% DoD. This is good because our EU7000 will only run for about 6.6hrs at that power level before it exhausts it's fuel supply. At some point we will be implementing an external fuel tank to give us a longer run time in times of great need.

EDIT: We also have an EU2000 generator but as it only outputs 120VAC I don't think I can use it for much without additional hardware

Unfortunate, because we do have an extended fuel tank for that one.

Thanks again!
mark

Cariboocoot · December 2014

Re: Recommendations for initial charging regimen?

You'd have to leave those 1500 Watts of lights burning for about ten hours to do something close to a 25% DOD on that battery bank. You might want to up the load if you can.

By all means start with a 6 hour charge, and watch it to see what happens. Beginning SG, current levels, Voltage achieved, ending SG, and overnight rest Voltage. You want to see how it all performs and what changes as you repeat the procedure.

Blackcherry04 · December 2014

Re: Recommendations for initial charging regimen?

I find it helpful to number the batteries with a marker and start out with a log after you do the initial charge and record the voltage and SG level of each. That way you have a constant that you can use as a point to return. It will take a lot of cycles before they reach full capacity, until they do the SG's, capacity and ending amps will be all over the place. The way the plates fully form is not uniform from cell to cell. My Rolls took a whole summer of 50% cycles to get consistent. I did a bunch of EQ's starting out chasing numbers, looking back they were a waste of time and stress on the batteries because they would change up and down every cycle until the plates formed.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Cariboocoot wrote: »

You'd have to leave those 1500 Watts of lights burning for about ten hours to do something close to a 25% DOD on that battery bank. You might want to up the load if you can.

I think all in, I've got 2000W of shop lights I could fire up (in increments of 500W). I have a small electric heater here as well that probably is about another 1500W if I crank it up!

If I've read all the posts correctly, I should start with the 6hr run, see where the batteries end up, and then either another 6hr run if not 100%, or start loading them if 100%? If the latter, run down to 50% and then start up the gennie again, rinse and repeat? At what point, or how will I know, when the plates are "fully formed"? The SG & cell voltage numbers will just all start evening out?

Thanks all so much for the kind advice, it really is appreciated! It's an exciting time, getting all this kit set up!

Cariboocoot · December 2014

Re: Recommendations for initial charging regimen?

Yep; charge 'em up. If they don't get fully charged, charge 'em again. If extending the charge time doesn't do it, turn the Voltage up a bit.

When they do get charged fully, draw them down again. Repeat the procedure and see what happens. What should happen is longer run time and shorter charge time compared to the initial results.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Great! Thanks so much! I assume full is considered 2.096V per battery with each battery having an SG of 1.290? Did I get that right?

It's looking like it may be a merry christmas after all!

Cariboocoot · December 2014

Re: Recommendations for initial charging regimen?

Rossman wrote: »

Great! Thanks so much! I assume full is considered 2.096V per battery with each battery having an SG of 1.290? Did I get that right?

Depends on what the manufacturer says full is. 1.290 is a rather high SG for most batteries. Usually they're about 1.265-1.275.

Blackcherry04 · December 2014

Re: Recommendations for initial charging regimen?

Since your only have a Generator to charge, I'd pick a ending Voltage for your discharge. Say 48 + volts depending on the load would be a good spot around 50% dod. When you reach it from house loads or a dummy load then start a full recharge. The Inverter will run it's full 3 stage charge. It will go to Float at 2 % the amps hrs capacity you set in the SCP / Combox. You can play with the amount of time you let the absorb run and once it get close to the 2% then shut it down and do a discharge cycle, if it takes all night to discharge, no big deal. As you do this you'll start to see more capacity and the temperature of the batteries will go up and that will help on capacity. All cycles do not have to be at the 50% level. The idea is to get good consistent cycles.

The sticker on the front of a Rolls / Surrette battery will tell the strength of the electrolyte, if not call.

Vic · December 2014

Re: Recommendations for initial charging regimen?

Rossman wrote: »

Great! Thanks so much! I assume full is considered 2.096V per battery with each battery having an SG of 1.290?

Actually, NO.

Surrette's Target SG is 1.265. The Capacity charts are for electrolyte at 1.280, BUT, that is a bit of specmanship that all battery mfgs use.

AND, technically, the real Capacity of these batteries is 5% less than the chart states, because of this lower ACTUAL SG.

FWIW Good Luck with the new system, it seems very capable. Vic

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Thanks again guys, target SG of 1.265 sounds good, and that's what's in the Rolls specs (actually 1.255 - 1.275 is listed as 100%) now that I've re-read them.

I hope to get the last couple wires run today to finish connecting my generator and I'll give this all a whirl. I've no doubt I will be reporting back with the progress and probably more questions!

FWIW Good Luck with the new system, it seems very capable

Thanks Vic, I hope this is a capable enough system, there was a little guesswork with regards to the designing/sizing, but I think we got it close to right.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Ok, I have everything wired up in what I believe is the correct way. I fired up the inverter and used the SCP to set the Absorb, Eq, and Float voltages as discussed. I set the Absorb time to it's maximum value. I had a question, there is a setting for "bulk" voltage - should this be the same as absorb? it was set to 57.6V

The only settings I can't seem to find, are the settings to limit the current pulled from the generator? Any advice as to where these are to be found??

Thanks,
mark

Cariboocoot · December 2014

Re: Recommendations for initial charging regimen?

Rossman wrote: »

I had a question, there is a setting for "bulk" voltage - should this be the same as absorb?

I think this is the same trouble another poster (cummins90) has. It seems if the two numbers are the same the charger flips in to Absorb as soon as 'Bulk Voltage' is reached because they are the same number. Dumb way to design a charger, but that's Xantrex for you.

I would suggest setting a difference of around 0.4 Volts between the two (Absorb higher).

There's definitely a setting for max input current somewhere. Max charge current is a percentage of this. Not sure where these numbers are located in the menus though.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Ok, I will set the bulk down a notch.

I found the current limiter, you just set the breaker size for AC2 and it will cap the draw that way.

I fired everything up and it all "seemed" to be working, after about 30 secs the generator inputs were qualified and the charging started. the only thing that seemed odd to me is that it was saying it was drawing -3500W or so from the genny? Not sure, why it would be negative??? Concerning, so I shut everything down until I get a response about that here.

Thank you!

Vic · December 2014

Re: Recommendations for initial charging regimen?

Rossman,

I do not have an XW inverter/charger, but in the older Xantrex inverters, there was a Charger or Battery Charge menu, and in that menu, there were settings for Ac input Amps, and for battery charger AC Amps (all at probably 240 VAC amps, in your case).

Your inverter may have similar menus, but the terminology may be different ... there were some posts here regarding "Circuit Breakers" in the context of limiting currents, in some menus. Will Look later. Vic

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Vic wrote: »

Rossman,

I do not have an XW inverter/charger, but in the older Xantrex inverters, there was a Charger or Battery Charge menu, and in that menu, there were settings for Ac input Amps, and for battery charger AC Amps (all at probably 240 VAC amps, in your case).

Your inverter may have similar menus, but the terminology may be different ... there were some posts here regarding "Circuit Breakers" in the context of limiting currents, in some menus. Will Look later. Vic

Yeah you got it, you set the AC2 breaker size and it seems to pull about 80% of that value. In my case I just set it to 20A for now that appears to be sufficient, it's only trying to draw 14A or so from the gennie! Man this is super exciting! Woooo! Nothing says merry christmas like firing stuff up and it actually working as advertised!

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Man these batteries really gurgle up a storm under charge! I hadn't realized how vigorously they would bubble!

westbranch · December 2014

Re: Recommendations for initial charging regimen?

BTS in use? battery temp? Volts in? At rest voltage before and after charge? watch for excessive use which may indicate too high V or too long an Absorb.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Yeah, i have the battery temp sensor installed on the side of a cell about halfway along the bank (between two batteries). The batteries do not feel even slightly warm to the touch, they are in our utility room which has an average temp (right now) of around 5-10degrees C (i made sure to set the XW setting for the cooler battery temp). How long should I let the batteries rest for, after this initial 6hr charge, to take SG and/or voltage readings?

It's been about 2 1/2 hrs so far and the charging current keeps slowly dropping off...down to around 31A now (started ~50A).

Vic · December 2014

Re: Recommendations for initial charging regimen?

Rossman,

Forget if you have done the Commissioning EQ on this new bank, yet, but Surrette recommends one after a full charge.

Believe that you DO have the Surrette Battery Use Manual, which covers these things.

Contrary to what others might say, the Surrettes in use here do NOT need a particularly high Absorb voltage. About 58.0 is what is needed by these batteries. One reason that they do not need high-ish Vabs compared to Trojans, for example, is that the electrolyte SG is "only" 1.265 for the Surrettes, and the Trojans are 1.277 - 1.280 - my opinion. One member here had to use a very high Vabs early in breaking in a new bank, but, am not sure just where that Vabs settled out (blackcherry04).

Yep larger batteries do gurgle quite a lot in Absorb, and a battery in EQ, that does not need much of an EQ, really fizzes .

EDIT: BTW, the Surrettes here seen to need almost exactly 1% or 20-hour Capacity for Shunt End Amps to terminate Absorb, at 58 Vabs, nominal

Have fun with the new system. Vic

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Vic wrote: »

Rossman,

Forget if you have done the Commissioning EQ on this new bank, yet, but Surrette recommends one after a full charge.

Believe that you DO have the Surrette Battery Use Manual, which covers these things.

Contrary to what others might say, the Surrettes in use here do NOT need a particularly high Absorb voltage. About 58.0 is what is needed by these batteries. One reason that they do not need high-ish Vabs compared to Trojans, for example, is that the electrolyte SG is "only" 1.265 for the Surrettes, and the Trojans are 1.277 - 1.280 - my opinion. One member here had to use a very high Vabs early in breaking in a new bank, but, am not sure just where that Vabs settled out (blackcherry04).

Yep larger batteries do gurgle quite a lot in Absorb, and a battery in EQ, that does not need much of an EQ, really fizzes .

EDIT: BTW, the Surrettes here seen to need almost exactly 1% or 20-hour Capacity for Shunt End Amps to terminate Absorb, at 58 Vabs, nominal

Have fun with the new system. Vic

Vic, this is the first charge, I have not done a commissioning EQ as yet. The Surrette manual I have talks about an "initial charge" but does not explicitly say it should be an EQ charge...?

Should I stop the current charge and reduce the absorb voltage? Not sure, what I should do at this point. Right now the absorb is continuing, charging amps down to 26A. The BTS says the batteries are at 53 degrees Fahrenheit.

Not sure I fully understand your "edit"...?

Thank you again for all your help! Just trying to get through this and not wreck a brand new battery bank!

- mark

Vic · December 2014

Re: Recommendations for initial charging regimen?

Hi Rossman,

Why not continue the initial charge at 59.XX ... forget if it was 59.6, or what.

Had seen the high Vabs recommendation early in this Thread, but had felt that since this is a new bank, it did not really matter if it was a bit high.

Surrette used to recommend a Commissioning Charge followed by an EQ, but some of these items do change over months/years.

IMO, I would do an EQ today or tomorrow, perhaps at the lower end of the recommended voltage range -- perhaps about 62 V (temp compensated), perhaps for one hour, and measure SGs afterward to see the cell balance.

Am sure that you are beginning to log the data, and believe that numbering each battery has been mentioned. Prefer a paper log book, that stays in the power room, but each person has their own style.

Regarding the " EDIT " , Just edited the post, soon after posting it, and that was just an attempt to not add an additional post -- trying to the keep the post count within reason ...

Flooded batteries are very robust and forgiving. Paying attention to them -- measuring SGs, checking and adding Distilled Water, EQing on occasion, etc, is all that they usually need. Hard to ruin them, the way that you are going at it.

These are my opinions. Have Fun, Vic

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Vic wrote: »

Regarding the " EDIT " , Just edited the post, soon after posting it, and that was just an attempt to not add an additional post -- trying to the keep the post count within reason ...

I understand the edit function

I wasn't sure if I understood the content of your edit. If i read it right you are saying when the absorb charge current gets down to 1% of 20hr cap it should be set to stop the absorb?? (ie. in my case set to stop absorb at around 14.5A??)

Vic wrote: »

These are my opinions. Have Fun, Vic

All opinions are welcome!

Thank you!

Vic · December 2014

Re: Recommendations for initial charging regimen?

Hi Mark,

Yes, the Ending Amps would NORMALLY be right in that range, at least for about a 58 Vabs, reasonable temperatures, and so on.

However, your batteries are very young. Do believe that looking for that plateau in actual battery current is the thing to look for. Once the rate-of-change in charge current is very small or essentially stops changing at all (there will always be some Jitter in the measured value), this is about what the battery needs/will take at that time. This value may well change with cycling of the bank.

Believe that you are using End Amps to terminate Aborb. Believe that this is the best method, as just using a timed Abs does not take into account the DOD of the bank in the previous discharge (and variable DOD needs a variable Abs time).

Vic

westbranch · December 2014

Re: Recommendations for initial charging regimen?

Hi Rossman, the rest time after charging is 3 or more hours, before taking an SG and Voltage reading.
I hope you have a record of SG per cell for future reference as this batteries age, this is essential data for a new bank.

Concur with all Vics' advice, he is a wealth of information on FLA batteries.

Rossman · December 2014

Re: Recommendations for initial charging regimen?

westbranch wrote: »

Hi Rossman, the rest time after charging is 3 or more hours, before taking an SG and Voltage reading.
I hope you have a record of SG per cell for future reference as this batteries age, this is essential data for a new bank.

Concur with all Vics' advice, he is a wealth of information on FLA batteries.

Thanks westbranch, yes, I have set up a spreadsheet to record battery voltages and sg's and other assorted details (generator run time, notes, etc). After my current charge cycle finishes I will let the batteries rest for 3 hrs and take the next set of measurements. I will report back when I do that.

I do note in the Surrette PDF they say the initial charge could take as much as 10 hours, so I may just leave the bank charging longer today (gennie seems to be running in eco-mode now that the charge current is lower) and let the batteries rest overnight, then take my measurements in the morning. Depending on how they look I will either charge them again, or apply a load and draw them down, as previously discussed.

Thanks so much for your insights, they are appreciated!

Vic · December 2014

Re: Recommendations for initial charging regimen?

westbranch wrote: »

Hi Rossman, the rest time after charging is 3 or more hours, before taking an SG and Voltage reading.

Hi Wb, YES, three hours should be a reasonable rest period for fairly accurate Rested voltage readings.

Not to argue, but have not ever felt that SG measurements taken at the end of Absorb to be inaccurate (and therefore seem to not really require a rest period), and for an off-grid system that is in use, resting is not an attractive option.

Realize that Mark's system is probably not required to run 24/7, and a real Rest could be possible, have not found rested SG readings necessary. Know that some have mentioned that SGs are more accurate after a rest.

And, of course, temperature compensation of voltage readings is very important, especially on higher voltage banks (at --5 mV/cell/C). Contrary Vic

Rossman · December 2014

Re: Recommendations for initial charging regimen?

Yeah, for now I do not need to run the system 24x7. I just need to make sure I don't ruin this brand new beautiful battery bank through neglect!

Rossman · December 2014

Re: Recommendations for initial charging regimen?

It's now around 6:30pm, system has been charging since about 11:30am (about seven hours). Charge current is down to 13A and the battery temps are up to 57F. Spot checked a couple cells SG they were around 1.255 or so, which seems not too shabby.

Think I will let it go another three hours to get to the 10hr mark recommended by Surrette, then shut it all down and let them rest till the morning, and take an official set of readings. Will post back to let you all know how it goes!

Ho ho ho!

Recommendations for initial charging regimen?

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