Specific gravity of a cell on main battery bank appears to be....water.

softdown · August 2015

How in the world does this happen? The battery, of course, shows significantly lower voltage than the healthier batteries.

I have been working the battery bank very hard....charging my recently bought used forklift battery. Readings on the charge controller are "funny". Did a bulk with the genset. The CC seemed to think that was enough? Went straight to absorb then to float. Despite the batteries only being 83% charged? But thats a different problem.

My understanding is that a battery with a dead cell does a great deal more harm than good. Measuring 12.8 volts under float. Others are generally about 14 volts.

I am new to specific gravity measurements. Spending time on the board shows specific gravity measurements to be the "Holy Grail" in solar batteries.

Vic · August 2015

[QUOTE=softdown;n347921

]How in the world does this happen? ...

... I have been working the battery bank very hard....charging my recently bought used forklift battery. Readings on the charge controller are "funny". Did a bulk with the genset. The CC seemed to think that was enough? Went straight to absorb then to float. Despite the batteries only being 83% charged? But thats a different problem ...

.[/QUOTE]

Believe that you have answered your own question.

The existing main battery bank probably has reduced Capacity. During a discharge, the weakest cell/s can become FULLY-discharged. When a cell is brought to, or close to 0.0 volts this is usually DEATH to that cell.

If the discharge of the battery continues beyond one or more cells being taken to 0 volts, that/those cells will actually start being charged backwards -- reverse polarity. If going to 0 volts did not kill the cell/s, then being reverse charged almost certainly will.

Have been biting my tongue, avoiding mentioning that resurrecting a battery that has been abused (your forklift battery), you really need Grid power, and a/some very capable battery chargers.

It is not clear where the 83% SOC "data" comes from, but, probably this is some device that reads battery voltage, or similar. You need to rely, primarily, on your SG measurements, on EACH CELL of your batteries, for accurate SOC readings, until you know how to interpret voltage readings on the batteries.

When doing deeper discharges, if is really essential, to measure the voltages of each battery, and HALT the discharge when the voltage of any battery begins to fall rapidly -- this is a sign that that battery is nearing about 20% SOC (or lower), and a FULL RECHARGE is really an emergency condition, for the health of your main battery.

Perhaps, a bit late, now. FWIW< Vic

westbranch · August 2015

go back to the seller and see if he has other banks that are beyond recovery and check the remainng cells for a good one if possible

softdown · August 2015

That have not fallen below a 63% state of charge during my admittedly jerry rigged forklift battery charging. That would not phase a healthy battery.

I live in a very sunny mountain desert. The panels normally finish bulking the batteries in about an hour. They have the ability to charge my forklift battery....which is up from 22.2 volts to 23.8 volts. Certainly good for the forklift battery which is potentially worth multiples more than my eight 8Ds.

On a somewhat positive note, none of the forklift cells are reading: water. They are around .110 which is to be expected in their still low charging state.

Sure...it would be great to have grid power and a forklift battery charger. Almost all of the food that I eat expired awhile ago. So it was 90% off. Thats the kind of budget I have. The local towns do not seem top offer forklift rejuvenation services.

When, and if, I get the forklift battery to 25 volts....then it can wait a couple months for solar panels and a controller to maintain it. May be the best that I can do.

I ran a couple little 12 volt solar systems for a couple years. Read four books during the winter. I believe it would take several years of off-grid solar living to have good experience with even half of the challenges awaiting the solar enthusiast.

Batteries alone...sometimes we do what we have to do.

Vic · August 2015

softdown wrote: »

That (they?) have not fallen below a 63% state of charge during my admittedly jerry rigged forklift battery charging. That would not phase a healthy battery.

.... The panels normally finish bulking the batteries in about an hour. They have the ability to charge my forklift battery....which is up from 22.2 volts to 23.8 volts ...

On a somewhat positive note, none of the forklift cells are reading: water. They are around .110 which is to be expected in their still low charging state.

Sure...it would be great to have grid power and a forklift battery charger. Almost all of the food that I eat expired awhile ago. So it was 90% off. Thats the kind of budget I have. The local towns do not seem top offer forklift rejuvenation services.

When, and if, I get the forklift battery to 25 volts....then it can wait a couple months for solar panels and a controller to maintain it. May be the best that I can do.

... sometimes we do what we have to do.

Battery voltage is not a good indication of the SOC of a battery, particularly one that is not healthy.

The noted percentages are probably some unknown device's guess about the SOC of the battery (?). Even a good battery Monitor cannot know the health of each cell. In a tired battery with unknown past perhaps, (your main bank, for example) the voltage might indicate something, there can be low cells, and very low cells. This can show up as a somewhat lower terminal voltage, but, still, voltage is not a good indication of SOC, until one knows a lot about that particular battery's health, and this voltage needs to be temperature compensated.

Measuring EACH CELL's SG with a Hydrometer IS a good indication of a battery's SOC.

A one-hour Bulk period is not any indication of much, other than the time it took to Bulk that battery, given the amount of sun, PV power, Absorb voltage setting, etc that was available. Sulfated batteries usually "charge" quickly.

For your forklift battery, suggest that you measure the SG of each cell, and use SG measurements to determine when charging is done, rather than using battery voltage. When the lift battery is essentially charged (if possible), then, you can proceed to EQing. During EQ you will want to watch the battery temperature, and SGs.

Am not sure that my Hydrometers go down to 1.110 SG ... that indicates a very LOW SOC -- for batteries with target SGs of 1.265 1.110 SG is below 0% SOC:

http://support.rollsbattery.com/supp...ecific-gravity

Most forklift batts use a electrolyte of at least 1.280, probably higher, so, the SGs in the above link are a bit lower than noted.

We all do wish you well. The prime reason that I avoided posting anything in this thread,, previously, was that it can be a bit difficult to be very positive about the situation, and know that most of us do not like adverse comments, and so on ... Wish you the very best luck, Vic

softdown · August 2015

Learning a lot about forklift batteries. Still thinking this will all work out. One couldn't expect good S.G. readings at this stage of the game. Maybe in a week or so.

Does anyone make a nice S.G. log book for solar users?

Vic · August 2015

You may not really need an official battery Log Book.

Have been using bound "Composition Books" for some time. These used to be available in Drug Stores. If you cannot fine one of those, there are other real bound note books.

Spiral bound notebooks are a distant second, as, in time, the spiral wire gets dinged up, and turning pages becomes difficult, and ultimately, the historic pages can fall out.

Have recently seen other, real bound books, with plastic covers vs the cardboard covers of the previous types.

This is a good time of year to look for such books, as it is still Back-to-School time in many chain-stores. Snagging a few now, should serve you for years to come.
Vic

softdown · August 2015

It costs plenty to have forklift batteries rejuvenated by a specialist. Was not able to nail down a price....but it is plenty. I wonder what magic they may perform? Other than equalizing and de-sulfating.

waynefromnscanada · August 2015

softdown wrote: »

One couldn't expect good S.G. readings at this stage of the game. Maybe in a week or so.

Does anyone make a nice S.G. log book for solar users?

Sorry to have to tell you, but discovering a battery that for all intents and purposes is DEAD, not knowing how long it's been that way, and not expecting to get it recharged for another week or so, you won't be needing an SG log book, you'll need a new battery. It's very likely your battery is ruined and beyond recovery and no amount of "magic" will bring it back.
I wish you and your battery well, but I fear this has been a very expensive learning curve.

softdown · August 2015

The internet is a wonderful place for those who may like to rain on parades. A 1652 pound battery for $375 costs me nothing more than gasoline and wear and tear on the car. A 24 volt forklift battery showing 22.2 volts isn't necessarily "DEAD". Now it has 23.8 volts. I'm reasonably confident that a few more days of charging will get it to 25 volts.

This thread is about my 48 volt bank. Not my forklift battery.

waynefromnscanada wrote: »

Sorry to have to tell you, but discovering a battery that for all intents and purposes is DEAD, not knowing how long it's been that way, and not expecting to get it recharged for another week or so, you won't be needing an SG log book, you'll need a new battery. It's very likely your battery is ruined and beyond recovery and no amount of "magic" will bring it back.
I wish you and your battery well, but I fear this has been a very expensive learning curve.

Thom · August 2015

It is if u destroy your 48v bank trying to revive a 24v battery . Won't u b 24v short of a full bank ? Charging that size battery with auto chargers is like bringing a knife to a gun fight. I hope u can get the life battery working .

Thom

Thom

softdown · August 2015

Running a couple 8 amp 12 volt chargers should not "destroy" the battery bank. The genset was the primary source of power for the brief runs with the larger charger.

Batteries go bad. Perhaps especially when they are now four years old. 8D's are not reknowned solar batteries. Much of the reason that I continued searching for another solar battery bank. A trusted friend swore the 8Ds were about as good as his Rolls batteries. Thats why I tried them. I also knew I would likely kill my first bank. I think most people do.

The solar industry is badly in need of ground breaking new battery technology. A lot of off grid people just use a genset for power. Still strong arguments for doing that.

waynefromnscanada · August 2015

softdown wrote: »

The internet is a wonderful place for those who may like to rain on parades.

I don't like people "raining on parades" either.
That said, my post was intended as a reality check, not a rainstorm, and I was being as gentle as possible under the circumstances.
I wish you luck with your batteries.

Specific gravity of a cell on main battery bank appears to be....water.

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