Is my cheap controller damaging my forklift battery at 30 volts?

softdown · November 2015

I bought a used 24 volt forklift battery that had been sitting around for ~ a year. The voltage reading was 22.2 volts. So some degree of sulfidization had likely taken place.

De-sulfating was attempted and difficult due to the sheer size of the battery. I managed to kill a $120 de-sulfator that clearly was not up to this task.

The best way to charge this battery was to connect a couple extra 24 volt panels. I used two 190 watt Grape Solar panels rated at ~5.5 amps/each.

The battery is temporarily in a marginal location. My 12,000 pound forklift got stuck and almost clobbered my building. So the battery will sit until I am able to enlist some help. My help is currently very busy replacing customers solar batteries. But should free up time in a "few weeks".

In the meantime, I am "sacrificing" a very cheap Chinese "MPPT" controller to charge it. "Sacrificing" because the controller sits in a black battery box for element protection and was getting pretty warm when the weather was warmer. Purchased a simple Morningstar controller that will be used when I am able to get the battery to a good location....close to the building where the charge controller and inverter will be.

Here may be the problem. Every morning I hear the electrolytes simmering a little bit and the battery is being charged at 30 volts. With only two 190 watt panels to service it, my guess is this:
1) The amperage is likely too low to damage a 1650 pound battery.
2) This may serve to equalize the battery some and this is clearly highly desirable.

The Morningstar will service this battery when I am able to move the battery closer to the building that the Morningstar will be located in. A Cotek pure sine wave inverter will then supply power to my chest freezer. This freezer is my second largest consumer of power. I likely will add four panels and then also supply power to my refrigerator.

TLDR: Are two 190 watt panels supplying 30 "Bulk " volts going to damage my 1650 pound forklift battery? Just playing it safe....

Vic · November 2015

Believe that this battery has exposed terminals for each cell. If this is the case, why not measure, and record the voltage of each cell.

Also, you could measure and record the SG of each cell. There may only be a few cells that are gassing.

Believe that you would be quite lucky if you were able to EQ the battery with only about 10-ish amps of current from the two PVs. AND, being in CO, the battery is probably COLD, which means that the required Vabs and Veq would be well above 30 V. Temperature has a large effect on charge voltage, at --5mv/cell/C.

EDIT: ... generally, a current source that is 1% of 20-hour Capacity can be used on Flooded batteries, even without a CC, with little worry about damaging a battery. One would need to keep an eye on the water levels. If this current source is from PVs, then there is further protection of the battery due to the periodic nature of PV output.

And, BTW, SG measurements need to be temperature-compensated, when temperatures are relatively far removed from the Standard Reference temperature of 77 - 80 F.

You have not noted the 20-Hr C of this battery, but it is probably in the range of about 1000 - 1200 Ah (guessing), so 1% would be in the range of about 10-ish amps. Some Traction batteries are not rated at 20 hours, but this can often be inferred from the other ratings<.

Good Luck, Vic

softdown · November 2015

Thanks.....each cell is currently reading between 2.43 volts and 2.47 volts. Exceptions being the cells that are connected to the charge controller reading at 2.50 to 2.53 volts. Looking pretty good.

I am unable to find an Ah rating on the steel case.

Vic · November 2015

Of course, SGs are the Gold Standard of SOC.

It IS good that the

Just LOST a long post, the above is what remains in 'My Drafts'.

The bottom line is, good that spread in cell voltage is not large.

Assuming that you measure 30 V terminal voltage, and let's say that the battery is 0C, this equates to about 1.5 V increase in terminal voltage, at negative 5 mV/cell per degree C away from a 25 C reference temp. So you ARE still in Bulk.

Some horrible bug that kills Auto-Save and blows up a post, IMO, FWIW, Vic

softdown · November 2015

That is maddening. Used to happen to me all the time when putting together anything of length.

I might surmise that the system pretty well remains in bulk for much of the usable charge period. The batteries were still simmering a bit five hours after the sun rose.

As I remember, the battery reads ~29 volts even after the panels are no longer charging. Seems high....but it is a slightly different battery than most. My meter may also read a little bit high of course. Depends on the state of the battery I think. Though my other meter gives similar readings.

Vic · November 2015

Yea, There was a Link to GB battery Battery Selector ...

In that list there was a 1652 Lb battery, with a 20-Hr Capacity of 1340 Ah, IIRC. Forget if you mentioned the manufacturer, in your earlier posts on this battery.

Here is the Link to the list of Standard Products:

http://gbindustrialbattery.com/Forklift_Battery_Sizes_and_Specifications_Zone15.html

Posting this before I blow up the Post again ... Vic

softdown · November 2015

Thanks...it is indeed 1652 pounds. The sticker on the steel case is for Industrial Battery Service in Denver. They have a website....industrialbatteryservice.com. They currently sell: GNB batteries which are made by Exide.

I do not know if GNB and GB Industrial are the same outfits.

EDIT: Apparently they are the same company. http://gnbbattery.com/

I've been in a funk since being robbed of at least ~ 120 pounds of silver. Probably by my brother who is a government locksmith. He knows where I am and what I have....I mean had. The family black sheep. That was my nest egg that would have allowed the comfortable completion of my shop....plus a lot more. That is why I don't concentrate, or do much, so well at times.

Vic · November 2015

soft..,

GB is Giant Battery. GNB is a part of Exide, now. I haf previously thought that GNB was Globe National Battery, but DO notice that Globe Battery is a part or name for a Johnson Controls company ... difficult to keep up.

Sorry to hear of the theft of the Silver. 120 Oz. would have been quite a loss, in my book ... 120 pounds would be a serious loss. Sure do hate thieves, even petty ones.

Good Luck, Vic

softdown · November 2015

http://gnbbattery.com/

If you click on the link...you will see a truck that is painted with a Giant Battery Co. sign. I believe they are the same. There are only 3-4 battery manufacturers around the US. Johnson Controls moved to Mexico. Then you have East Penn and Exide and Deka I think.

At 5pm MST.....battery reads 26.4 volts. That seems pretty good really. Probably be ~25 volts at 6am with a temperature of ~10F?

EDIT: Reading is 25.6 volts at 8F.

EDIT: East Penn is the manufacturer for both MK and Deka http://www.batterystuff.com/all-products-by-brand/east-penn-deka-mk/

Is my cheap controller damaging my forklift battery at 30 volts?

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