New Forklift Battery

I got delivery of a 48V forklift battery 5 weeks ago (Sunlight 750Ah (C5)). I also got a single 2V cell, just in case I need to replace one of the cells in the 48V battery.

It came from a company that deal with forklifts. They know nothing about solar charging, etc.

When it arrived the voltage reading was 49.7V. I didn’t check the sg readings.

4 weeks later (just last week) I got a reading of 49.6V (indicating a 75% charge). The sg readings were low around 1.200 (suggesting a charge of 60%). The Voc didn’t match the sg readings.

I checked the single cell. It gave a Voc of 2.12V (equivalent to 50.9V for a full set of 24 cells) but to my surprise there was no electrolyte. Upon further investigation I found that there was just acid at the bottom of the cell.

My assumption is this. The forklift company gets supplied with batteries that have the acid in the bottom. When they sell them on they add deionised water. Thus the s.g readings are from the top of the battery and they are going to be lower than one would normally want. Is this a correct assumption?



Now my main question is this. What do I do next? I plan on connecting the battery to the inverter/charger before the end of the week. I already used a small power supply (about 5 Amps for 4 or 5 hours) and brought the Voc up to 50.1V (which surprised me). Do I just connect the battery to the inverter/charger, allow the charger to do its daily charge or should I do something else? I have about 6kW of panels but at this time of year it can be end and miss with the weather.



Also, the battery is outside, under a canopy. Because of its size I couldn’t get it into the shed. The canopy is closed on 3 sides and I plan on closing the open side. Its on the north of the house. It will hardly go above 20 celsius in summer and below freezing in winter. Should I put insulation around the battery?

I’d pause for a minute. Lots of folks here with lead acid experience. Do you have the manual?

No! No manual. The company I got the battery from only do forklift talk. They are a reputable company. I have asked questions about bulk voltage, etc. but they don't know any thing on that front.

Feenster said:

4 weeks later (just last week) I got a reading of 49.6V (indicating a 75% charge). The sg readings were low around 1.200 (suggesting a charge of 60%). The Voc didn’t match the sg readings.

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1.200 is when damage starts to happen. IMHO, charge immediately.

Feenster said:

I checked the single cell. It gave a Voc of 2.12V (equivalent to 50.9V for a full set of 24 cells) but to my surprise there was no electrolyte. Upon further investigation I found that there was just acid at the bottom of the cell.

My assumption is this. The forklift company gets supplied with batteries that have the acid in the bottom. When they sell them on they add deionised water.

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I would not assume that. It is possible that it's accurate. If you can find documentation for activating or commissioning a cell, I could believe it. However, I don't know the long term implications of allowing extremely concentrated acid to sit in the battery.

Feenster said:

Thus the s.g readings are from the top of the battery and they are going to be lower than one would normally want. Is this a correct assumption?

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There is some stratification of the electrolyte, but proper SG measurements eliminate that: Suck, expel, suck, expel, suck, read SG value, expel.

Feenster said:

Now my main question is this. What do I do next? I plan on connecting the battery to the inverter/charger before the end of the week. I already used a small power supply (about 5 Amps for 4 or 5 hours) and brought the Voc up to 50.1V (which surprised me).

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Get SG to 1.265 or higher as quickly as possible and by whatever method is available.

Feenster said:

Also, the battery is outside, under a canopy. Because of its size I couldn’t get it into the shed. The canopy is closed on 3 sides and I plan on closing the open side. Its on the north of the house. It will hardly go above 20 celsius in summer and below freezing in winter. Should I put insulation around the battery?

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The less the temperature swings, the better. Insulation will help. Make sure your charging system has temperature compensation enabled.

You need to find the manufacturer of your battery and obtain:

Charge current
Temperature compensation value
Absorption voltage
Absorption duration
Tail current
Specific gravity at full charge.
Equalization voltage
Equalization criteria
WTF do you do with this spare cell?

If you have a battery label, might be able to glean some of the above.

You need to become your own battery expert, or you won't get what you paid for out of that battery.

You're going to need some serious current to keep this battery healthy something on the order of 80 - 100 amps. Do you have a forklift charger? Those tall cells need aggressive charging to stir up the electrolyte and prevent sulphation.

No, I don't have a forklift charger. Once I get them up and running I won't be cycling them too deep.

Feenster said:

No, I don't have a forklift charger. Once I get them up and running I won't be cycling them too deep.

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You still will need a high current charging source. If using solar you need a SCC at the upper end of the charge current range and enough solar panels to create the current. Without sufficient amperage your battery's electrolyte will stratify and you risk irreversible sulphation

littleharbor2 said:

Without sufficient amperage your battery's electrolyte will stratify and you risk irreversible sulphation

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Amperage or voltage? I thought you charge at 60V for equalization?

You can't get the thing to 60v on solar in a reasonable time frame without a high current charge source. And if you can't recharge in a reasonable time frame you are looking at sulfation issues.

The more current, the more bubbling aka mixing of the electrolyte which limits stratification which limits sulfation during partial soc.

Ok, never had that problem.

Forklift charging or solar charging should not matter. Should be pretty much the same. You can always do custom settings. I.e max charge amps, etc.

Single cell- from what I know, brand new cells, uncharged cells need a very specific charge sequence in order to prepare them for use. Very high current chargers, specific times, adding acid, water etc. The company should be able to get this info. It is important to do the setup correctly or the cell may not work. You have to add acid and water at specific times and charge in a specific way. I think they are shipped empty for safety reasons. I also got a forklift battery and the charge process was a problem for me. The supplier ended up doing it for me and shipping with lower water levels. They did the charging setup and I added that water later. Works fine.

It would be good to know if the distributor set up the battery and it is ready to go i.e. plug into a forklift ready to drive or if it still needs its initial acid, charging etc. before use.

You really need info from the battery supplier. Your battery may not have been "set up" yet. My guess is that you could damage it just by charging it when there is no electrolyte in the cell(s).

Here are some basic lead acid settings from SMA for the Sunny Island inverters. Once set up, I think it will be ok for most lead acid batteries. Again, you can customize it. Cold (freezing) temps are not good for lead acid batteries.

Feenster said:

My assumption is this. The forklift company gets supplied with batteries that have the acid in the bottom. When they sell them on they add deionised water. Thus the s.g readings are from the top of the battery and they are going to be lower than one would normally want. Is this a correct assumption?

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"The acid on the bottom"
Do you mean dry powder?
Are you sure?
I don't think empty batteries ever get filled with water.

I've received "dry charged" FLA batteries. I think that means manufactured, filled with acid, charged, drained out and dryed. They usually come with acid electrolyte which is to be added.

For maintenance I use distilled water, not deionized. Perhaps some of that is ultra-pure? But I know distilled is just H2O. That is to make up for water lost due to electrolysis, for a battery previously filled with acid and used.

Forklift charging or solar charging should not matter. Should be pretty much the same. You can always do custom settings. I.e max charge amps, etc.

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Yeah, but you're still limited to whatever your system can actually make. Like 6kw of solar, if it actually gave 6kw (it wont), would give maybe a bit over 100a into charging a 48v pack, if the charger was 100% efficient (it isn't), AND nothing else was on in the whole house!

I'm not saying this thing is unworkable, but i think what's being asked is whether to do a 'commissioning charge' or just hook it up and go. I suspect it does need something like a commissioning charge, and OP needs to know how to do it. It sounds like if he uses his house solar to do the commissioning charge he might need to be willing to 'not power the house' for about a whole (solar) day or maybe two, depending on the specifics. The system would be basically 100% dedicated to trying to bring up and 'equalize' those cells, which while they may be near equal in charge, probably still need it to get their electrolyte circulated around nicely since it was probably just dumped in and then left to sit.

I suspect the system can 'maintain' the batteries acceptably after 'commissioning' with the right equalization timers/settings in it, IF the actual consumers in the house are willing to work around it. Because it will take pretty much all that system can do, to equalize that pack, which means while it's happening you basically can't be trying to use the system for anything else. I believe that's what i'm supposed to get from what Littleharbor was saying, hopefully i'm not way off base on that.

Honestly, the Rolls Surrette youtube channel is a pretty good place to start if one had no idea and no way to get anything from the manufacturer. They talk a lot about FLA generalities in the training seminars on the YT channel.

Tips:
1. Get one of these. Great item, easy to use. Temperature compensated.
The glass tube ones stick and difficult to get a good reading and not temperature compensated.

2. Get a FLow Rite battery watering system. This battery can last 20 years and this will make watering easy. I've been doing it manually for the last 17 years and got a new Flow Rites system on the new battery. Makes it so easy. Cost a bit, but worth it considering you will have to add water for up to 20 years. Of course lithium can make lead obsolete way before then also.....

Vigo said:

You can't get the thing to 60v on solar in a reasonable time frame without a high current charge source. And if you can't recharge in a reasonable time frame you are looking at sulfation issues.

The more current, the more bubbling aka mixing of the electrolyte which limits stratification which limits sulfation during partial soc.

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What he said....
Wow! step out for a little while and this thread just about goes viral. lol

Hedges said:

For maintenance I use distilled water, not deionized. Perhaps some of that is ultra-pure? But I know distilled is just H2O. That is to make up for water lost due to electrolysis, for a battery previously filled with acid and used.

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Right. Distilled = no minerals. Only ever add real "distilled water."

WARNING. Walmart sells "Parents Choice Distilled Water." DO NOT USE THIS. The label does not say it, but the website says that they "add minerals" to the water. This "distilled water" contains Magnesium sulfate, potassium bicarbonate, and potassium chloride.

Accidentally bought some when they were out of the other "distilled water." AARGH.

littleharbor2 said:

What he said....
Wow! step out for a little while and this thread just about goes viral. lol

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Don't charge controllers have an "equalize" function built in (not that it matters for this case)?
My Sunny Island is set to equalize the battery every 6 months. Can be set from 7 days to 365 days.

Calvin98 said:

Single cell- from what I know, brand new cells, uncharged cells need a very specific charge sequence in order to prepare them for use. Very high current chargers, specific times, adding acid, water etc.

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I'm not too worried yet about the single cell - I will worry about that at a later stage if I ever have to use it.
As regards the 48V FLT battery all the supplier said was they recommend 48V/100A.

Hedges said:

"The acid on the bottom"

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No. I am not sure. I just assumed it to be the case. The single cell has to be turned well over to see that there is a liquid in it. The smell is of acid. I didn't check it any other way.

Having an equalization setting is one thing, but if it’s adjustable you still want to make sure that whatever the default values are are appropriate. They probably are, but i’d hate to put unnecessary wear/damage on a huge new battery because i didnt click through and look at a few numbers.

Also sounds like the supplier has no real info. Charging to only 48v would let the battery degrade very rapidly.. i’m guessing they probably meant ‘use 48v values’ which is vague but not patently bad advice. 100a is vague too (100a when?) but at least serves as corroborating evidence that you should at least be ABLE to get in that ballpark with your charge current, and if you can’t then you need to look at expanding that side of the system a bit to get the most practical use and lifespan from the battery. ?

IIRC my fla charge settings are bulk/absorption 56.4, float 54.0. But if you listen to Rolls Surrette on those training seminars they sound very comfortable when they recommend that you feel free to move that up or down according to what you observe on your SG readings. A high absorption voltage doesn’t really matter if you’re not able to finish absorption in a typical day anyway. In lieu of anything from the actual manufacturer, Rolls just say make sure they hit 100% SOC once every 2 weeks or so.