How to read SLA battery label

Here comes the newb questions.

1. I'll try to answer it myself and hoping you guys can tell me if I'm right or wrong. My concern is that I have no clue when my battery is done charging. My understanding is that I can take a volt meter to it and when it reads 14.50-14.90v, then it's done, correct? My guess is that for this particular battery which reads:

Standby Use
Voltage Regulation 13.50-13.80V

Cycle Use
Voltage Regulation 14.50-14.90V



This means that at rest (standby), the 12v battery should read anywhere between 13.50-13.80v when fully charged?
This means that while while checking with a volt meter to the battery while it is being charged, that it should read between 14.50-14.90 when fully charged?

This nominal and actual stuff is confusing me. It's pretty clear for me with LiPo's. 3.7v nominal = 4.20v actual or 4.35v for LiHV's and storage charge is 3.8v and 3.85v respectively. But with SLA, there seems to be such a huge range. I did my own research before bothering you guys with this, but I kept seeing huge ranges of what a fully charged 12v battery really should be. Some sources say 14v while others say 14.1 and others, 12.6v which has me super confused. Can someone please shed some light on this and educate a newb?

2. And how far can I discharge a SLA before it becomes unhealthy for the battery? I've read not to go below 12.06v and definitely not 11.0v. Once it's at 10.90v it's toast and need replacement? But what is ideal for balance of objectivity of the battery while maintaining range?

The voltages vary by SLA battery type. IIRC, a starting battery has a significantly lower rest voltage than an AGM (absorbed glass matt), with a gel type falling between the two. Doesn't your charger have an auto shutoff, and switch to float mode, with a battery type switch? If not, and you need/want to keep using it, then get a cheap smart-type battery maintainer, and switch to that for the last part of charging. The battery in the photo appears to be a gel type, unless it is marked "AGM" - and maybe even if it is marked that way. I think that some companies are throwing in a few strands of fiberglass and then calling their batteries AGM...

kmxtornado said:

My understanding is that I can take a volt meter to it and when it reads 14.50-14.90v, then it's done, correct?

Click to expand...

proper stop-charge algorithm for lead

https://endless-sphere.com/forums/viewtopic.php?p=1606463#p1606463

> This nominal and actual stuff is confusing me.

Nominal voltage is ~50% SoC resting isolated.

Voltage alone is ballpark only, need to spec Absorb stage Hold Time, but preferably use endAmps as above.

Standby usage is UPS, kept on Float all the time, hardly ever drawn down.

Deep cycling for lead means to around 50% SoC unless in a crisis.

Each model battery has its data sheet, good mfg easily findable and have tech support on call to discuss

This is very much an over-generalisation.



The main deep cycling lead chemistries are AGM, FLA and GEL.

FLA is both cheaper and lasts longer, i.e. withstands abuse by noobs better.

_______
Some chemistries the 100% resting voltage is not far below the CV setpoint, others a lot.

For LFP for example 3.45Vpc is as high as you need to get to 100% Full

resting isolated result is 4.33-4.35Vpc

4S is nominal 12V.

For the other LI including LiPo, 4.10V is better for longevity, at rest does not drop so far. zcannot get 12V nominal.

LTO is way lower, 5S is 12V.

Thank you for the link. I'll read up on that.

Sorry you went through all that and I don't understand a single thing you said. You're going to have to talk to me like a 6 year old. I didn't really gather any of that. So bottom line, what reading should I get while charged and not on the charger for my 12v battery? Is my interpretation of the numbers written on the side correct?

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means. I'm guessing that means the voltage reading while it's not on the charger (standby use) and while it is on the charger (cycle use), but I could be completely wrong. I just don't understand the jargon.

kmxtornado said:

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means.

Click to expand...

Those are charging voltages for different battery applications. "Standby use" isn't relevant for an electric vehicle, if that's what the battery is for. "Initial current" is a limit for the rate of charging.

If the battery is for a vehicular application, then a lead acid battery is probably the worst choice available to you. What are you powering with it?

Use google to clarify terms, work through each statement one at a time.

If you are still stuck ask me a specific question, one at a time and I will try to clarify.

I very specifically addressed the UPS/standby vs deep cycling use cases, you are doing the latter not the former right?

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means. I'm guessing that means the voltage reading while it's not on the charger (standby use) and while it is on the charger (cycle use), but I could be completely wrong. I just don't understand the jargon.

Click to expand...

Unless the battery will be powering a UPS (uninterruptible power supply), just look at cycle use. In your case the best think you can do is to get a "smart" charger for your battery voltage. Problems solved, and they are cheap for lead-acid batteries.

Chalo said:

kmxtornado said:

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means.

Click to expand...

Those are charging voltages for different battery applications. "Standby use" isn't relevant for an electric vehicle, if that's what the battery is for. "Initial current" is a limit for the rate of charging.

If the battery is for a vehicular application, then a lead acid battery is probably the worst choice available to you. What are you powering with it?

Click to expand...

The scooter (see avatar) came with SLA batteries. I replaced it with LiFePo4 awhile ago since I had one for an electric bike conversion. Aftetr awhile, it went bad. Rather than spending another $350, I'm just sticking SLA's back in to get it running. I like the easier maintenance as well. I just needed to know what voltage to charge it to.

john61ct said:

Use google to clarify terms, work through each statement one at a time.

If you are still stuck ask me a specific question, one at a time and I will try to clarify.

I very specifically addressed the UPS/standby vs deep cycling use cases, you are doing the latter not the former right?

Click to expand...

Nevermind.

Doing more research and it looks like when fully charged, a 12v battery should read 2.30v - 2.45v per cell while it's being charged. With 6 cells in a 12v SLA, that would be 13.8v - 14.7.

Other sources say 14.1v which is pretty much in the middle. I guess I'll go with that.

LeftieBiker said:

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means. I'm guessing that means the voltage reading while it's not on the charger (standby use) and while it is on the charger (cycle use), but I could be completely wrong. I just don't understand the jargon.

Click to expand...

Unless the battery will be powering a UPS (uninterruptible power supply), just look at cycle use. In your case the best think you can do is to get a "smart" charger for your battery voltage. Problems solved, and they are cheap for lead-acid batteries.

Click to expand...

Yup, I've got one but it was for a different scooter. I just wanted to double check what the readings should be on my volt meter just to be certain my charger was doing what it was/is supposed to do. The light on the charger wasn't turning green, so I was a bit concerned after it had been several hours with no change in status, but it looks like I just had to give it another 20 minutes b/c it did eventually turn green.

At resting state it's measuring 12.93v.

Charger is a 1.8amp one. I'm charging a 9ah battery and from what I understand, I should be charging at 0.25C rate which I understand to mean 9x0.25 = 2.25amps, so I'm not exceeding that which is good. A bit slow, but it's what I have so I'll just use it I suppose.

Not something that can be just generalized if you want to get good lifespan.

Each model battery has its specific specs.

If you can't find the specific data sheet do not buy that battery.

For me, if there isn't quality tech support than I do not buy that brand.

The higher end of the range is better than lower, but voltage on its own is not enough, the current level that you use as your termination spec is just as important.

If you don't care to buy good quality and learn how to get good lifespan from it, then really it doesn't matter.

Chalo said:

kmxtornado said:

I guess what I'm asking is to confirm I understand correctly what "Standby Use" and "Cycle Use" means.

Click to expand...

Those are charging voltages for different battery applications. "Standby use" isn't relevant for an electric vehicle, if that's what the battery is for. "Initial current" is a limit for the rate of charging.

If the battery is for a vehicular application, then a lead acid battery is probably the worst choice available to you. What are you powering with it?

Click to expand...

I see. Okay, thanks for explaining that clearly. Much appreciated. Looks like I was way off on the definitions. Yes, the battery is for an electric scooter (the goofy clown looking thing in my avatar). Here's a closer look:



It came originally as a 24v system using (2) 12v batteries. I was happy to find that the (2) 12v 10ah SLA batteries can be replaced by (3) 12v 9ah SLA batteries as far as fitment in the battery bag it came with. So upped the voltage and sacrificed just 1ah. Totally worth it for the short ranges I ride this goofy little contraption.



I had overvolted it about 3 years ago with plenty of good help from members of this forum so it's now on 36v with replacement controller and throttle. I had powered it with a LiFePo4 battery back then which was just being repurposed from another project. It has since gone kaput. The build thread is in my signature as Mini Folding scooter. Just excited to revive it w/o spending too much money. It's not a commuter or anything. Just a toy to play around with or at best, acts as a solution for one of those "last mile" scenarios.

Took it for a spin with a friend of mine whom I let borrow an electric standup scooter. We swapped rides before and after lunch. Fun times.

john61ct said:

Not something that can be just generalized if you want to get good lifespan.

Each model battery has its specific specs.

If you can't find the specific data sheet do not buy that battery.

For me, if there isn't quality tech support than I do not buy that brand.

The higher end of the range is better than lower, but voltage on its own is not enough, the current level that you use as your termination spec is just as important.

If you don't care to buy good quality and learn how to get good lifespan from it, then really it doesn't matter.

Click to expand...

Yeah, it's just a toy. Not huge priority as I have a number of other hobbies I'm more focused on at the moment. I just wanted to revive an old toy as it's been sitting around and I remember how much fun I used to have riding it and wanted to do everything safely.

Thanks for taking the time to respond. I'm just not at all an expert in this and was a bit lost and was looking for some confirmation that I was at least going in the right direction.

I guess another way to calculate it is 2.4v per cell of a 6-cell SLA, so 2.4x6 = 14.4v. With 3 batteries, that's 3x14.4v so when it hits 43.2v, that's full.

Voltage is just one of the variables involve.

While charging, without the current and time element does not have much meaning wrt SoC%. So:

"when it hits 43.2V" it has only reached the CC to Cv transition, ended Bulk charging stage and about to start Absorption stage.

Depending on the C rate, the SoC at that point could be 75%, or it could bev95%

To get to 100% Full could require only another hour, or five more hours.

Once you have performed a charge cycle that **does** get to 100% as defined by trailing amps

let it sit 24hrs isolated

measure the **resting** voltage

You could then use that as your benchmark, dozens of different chargers (charging profiles) can be found to get to that same result.

But the most accurate is to just continue to use stop-charge based on endAmps.