Off Grid battery backup system charging question.

[Zerk]

I guess they just talk different in CA. But where I work, we got guys that service batteries banks. Past tense would be they serviced. As in the batteries were serviced yesterday, clean fluid levels checked, specific gravity checked. If the fluid is low, they need service, or need to be serviced. English language is funny.

 

[Industrial Toys]

I need to replace a couple of batteries in my Electric Gator 48V. I am always getting almost new ( but different every time) batteries from a friend in the business, but I dare not use them. Quite a shame! So I am faced with buying eight new batteries I guess.

I am curious, if you have shorted cells in parallel connected batteries, what happens? When jumping a fully charged battery to a dead one, I never get the spark I would expect. Someday, I will use a DC clamp meter to see what is happening.

 

[ForestGrump]

I guess they just talk different in CA. But where I work, we got guys that service batteries banks. Past tense would be they serviced. As in the batteries were serviced yesterday, clean fluid levels checked, specific gravity checked. If the fluid is low, they need service, or need to be serviced. English language is funny.

Huh??

 

[ForestGrump]

I guess they just talk different in CA. But where I work, we got guys that service batteries banks. Past tense would be they serviced. As in the batteries were serviced yesterday, clean fluid levels checked, specific gravity checked. If the fluid is low, they need service, or need to be serviced. English language is funny.

We speak and write English a whole lot better too!

 

[Zerk]

I would be embarrassed to tell someone I lived in CA.

English? I thought you guys spoke spanish. Maybe the translation is the issue

 

[ForestGrump]

I would be embarrassed to tell someone I lived in CA.

English? I thought you guys spoke spanish. Maybe the translation is the issue

We would too!

 

[westcliffe01]

Depending on options available to power the charging, if individual banks have different size, age and condition batteries, I would try to charge each matched bank set separately. If you can afford multiple chargers, that would be the best. Just use isolation switches to keep each bank separated from the others when charging and in use if you only have a single charger.

 

[Tractor Seabee]

Too bad the OP hasn't provided a diagram of what he has, configuration, and what he is trying to accomplish. We are all stabbing in the dark which may not be too helpful.

Ron

 

[90cummins]

I've been away, thanks for the reply's.
All my batteries are Trojan deep cycle lead/acid batteries that require maintaince.
When I say (servicing) I'm implying maintaince, water level, specific gravity & individual at rest battery voltage checks.
My batteries (banks/groups) are the same type, ah rating and age.
Each bank is in series for 24 volts.
My inverter charger is a Xanterx XW4024 grid-tie, off-grid inverter/charger with temperature compensation and generator assist feature.
The charging capacity is 150 amps @ 24 volts and has 3 stages, Bulk, Absorb & Float.
The charge rate is programmable and I set it according to the battery type and ah rating that I'm charging.
Battery connections are made using 4/0 cable or buss bars & Anderson 2 pole connectors.
Too allow (servicing) I use a (Marine) Blue Sea 4 position 300 amp isolation switch.
Off = no connection to charger and battery banks are isolated from each other.
Position 1 = bank of T105's rated at 225ah's powers inverter.
Position 1&2 = connects L16RE-B bank (parallel) with T105 bank to power inverter combined ah rating is 595ah's.
Position 2 = bank of L16RE-B's rated at 370ah's powers inverter.
The 12 volt J185H-AC batteries that I'm trying to revive are being charged while isolated from the other groups.
I did Google this and didn't find an answer that's why I put it out for input.
My feeling was that the two groups would be seen as one when parallel at 596ah's but I wanted to check, no room for error here.
Hopefully this info helps I'm not good at diagrams.
Thanks 90cummins

 

[Larry Caldwell]

As long as you are doing a fairly slow charge, just hook the batteries in parallel and charge away. The smaller battery will reach full charge first, but will not overcharge because the larger battery is absorbing the charging current. There are other factors, like the internal resistance of the batteries, but you are not going to damage anything. For safety, monitor the electrolyte level. If one is overcharging, it will drink electrolyte. Do not charge or discharge them in series.

 

[Zerk]

I am going to go with what the manufactors recommend. Same size. Now if financially I didn't want to replace all the batteries, I may roll the dice.


Another thing is are float charging, constant charge, running of charger, or boost charging, periodically raising voltage. Not sure how these tenders work. We do both on battery banks, not sure the reason, Maybe just the thoughts at the time.

We have battery banks that last 25+ years. They don't get moved, constant temp, and charging. I think lack of movement may be a driving factor. But battery banks at home are not moving.

As mentioned earlier there are safety concerns with charging large banks of batteries. Do people take this into account at home?

 

[RNeumann]

What your Xantrex "sees" is voltage- this is what determines when it is charging, floating etc. It isn't the battery type. The Xantrex is asking for amp hour rating to determine the estimated time left at the current rate of discharge. The unit is asking battery type as different battery construction types (AGM, lead acid) take slightly different charge/float voltage. No battery charger changes rate of charge based on amper hour rating- that is always changing with battery condition.
The battery banks need to be properly isolated (your isolation switch ain't it- that's for sure) from each other. It would be interesting to see how you can keep them isolated and yet charge them as one.....not sure their is a practical solution to this.
My other concern is the thought of "reviving" batteries. If this was truly possible someone would be very rich and batteries would last a long long long time. Without a Midtronics tester you will have very little idea the actual state of the batteries.
Good luck. But based on what I've read so far things are far from optimal.

 

[Tractor Seabee]

Per Neumann, above stated reviving cells (batteries) is not really possible. I have seen minor sulphating be overcome but the capacity and life are compromised. There is a shocking process used that causes the sulphate to drop off the plates. In a clear case cell (all large individual cells have clear cases) you can see this happen and it piles up in the bottom of the case. Sulphating reduces the strength of the acid when it precipitate's on the lead plate. The Sulphur crystal part of the acid does dissolve back into the liquid acid. De-sulphating is probably not a good DYI effort.

Lots of luck, Ron

 

[CCWKen]

I have a 7KW UPS system that uses four drawers of motorcycle sized batteries. They're connected in series for 120vdc (+/-) and parallel for current support. If just one battery in the case is flaky, the console flashes an error and beeps. It takes me about an hour to find the errant battery and replace it. The charging system is smart enough to know there's a problem but not smart enough to tell me where. I suspect it monitors charge/battery factors in a narrow band and throws a warning if it goes out of bounds but its always been right. On average, I replace 1-2 batteries a year. And all the batteries have to be the same or it chokes on startup. If I hit the lottery, I may just replace them all and get 4-5 years of peace and quiet.

And yes, I'm a nervous wreck after poking around in a 120vdc cabinet.

 

[Zerk]

Curious what are you doing with this? Is it just a back up for your house, instead of a generator? Are you charging it with alternate energy an using it, or is it just back up?

 

[Tractor Seabee]

I have a 7KW UPS system that uses four drawers of motorcycle sized batteries. They're connected in series for 120vdc (+/-) and parallel for current support. If just one battery in the case is flaky, the console flashes an error and beeps. It takes me about an hour to find the errant battery and replace it. The charging system is smart enough to know there's a problem but not smart enough to tell me where. I suspect it monitors charge/battery factors in a narrow band and throws a warning if it goes out of bounds but its always been right. On average, I replace 1-2 batteries a year. And all the batteries have to be the same or it chokes on startup. If I hit the lottery, I may just replace them all and get 4-5 years of peace and quiet.

And yes, I'm a nervous wreck after poking around in a 120vdc cabinet.

I know what you mean non working around DC. I would much rather get it by AC not if I can help either. Just be careful and isolate live parts with a blanket and wear di-electric gloves. I have safely worked on up to 500V DC and 480 V AC by being careful and not going into live stuff except when absolutely that is the only choice. The most dangerous (scary) array is large banks of large single cells (a room full) for 250 and 500 DC power. The National Electrical Safety Code (NESC) does not allow working on live parts.

Be safe, Ron

 

[Industrial Toys]

Most xantrex chargers I have owned or worked on have a selection for the type of battery. Usually flooded, gell or glassmat

I hope everyone with battery banks has a high current limiting fuse or breaker at the battery. CRAZY not to.

Plus tape up your wrenches.

 

[scdeerslayer]

So is this 4 total batteries? If so I would just get a 4 bank marine charger.

 

[Zerk]

Most xantrex chargers I have owned or worked on have a selection for the type of battery. Usually flooded, gell or glassmat

I hope everyone with battery banks has a high current limiting fuse or breaker at the battery. CRAZY not to.

Plus tape up your wrenches.

Ya battery banks have fuse. I don't find working with 125 vdc that big of deal. 250 DC will melt alligator clips faster.

 

[90cummins]

What your Xantrex "sees" is voltage- this is what determines when it is charging, floating etc. It isn't the battery type. The Xantrex is asking for amp hour rating to determine the estimated time left at the current rate of discharge. The unit is asking battery type as different battery construction types (AGM, lead acid) take slightly different charge/float voltage. No battery charger changes rate of charge based on amper hour rating- that is always changing with battery condition.
The battery banks need to be properly isolated (your isolation switch ain't it- that's for sure) from each other. It would be interesting to see how you can keep them isolated and yet charge them as one.....not sure their is a practical solution to this.
My other concern is the thought of "reviving" batteries. If this was truly possible someone would be very rich and batteries would last a long long long time. Without a Midtronics tester you will have very little idea the actual state of the batteries.
Good luck. But based on what I've read so far things are far from optimal.

As I described my original 2 banks of batteries are isolated with a switch and has a 200 amp fuse in the circuit.
When charging/discharging the J185 batteries I de-energize the T105 bank and remove 1 bridge between the batteries then connect the J185's to the 24v charger using a 175a Anderson connector, then re-energize that bank only which charges the j185's.
I paid $50 for the complete machine with batteries.
I went to my local salvage yard and was told that the scrap price for each battery was approx. $25+- so I have nothing to lose here.
In addition I have stripped the machine of all relays and heavy cable including a 175a connector that is being used here.
This is a learning experience for me with nothing to lose, as I mentioned earlier I revived the T105's currently being used and they are at 80~90% capacity.
If these batteries are beyond saving I will put them aside as a core for when I need to buy new batteries.
This is all good information and appreciate the input.
90cummins