MK date codes

[desert dweller]

OK, thanks!

[Burgerman]

For e.g today, 76Ah MOVE gel battery, I didnt go far. Estimate 15 to 20Ah to be returned.
So that means it doesent need quite as many hours at CV. And I am not getting up tomorrow for various reasons. So no rush. So its 25C in my room.

I dropped the "standard" voltage that I use at 20C from its 28.2 to 28V As the battery is warmer having just used it. I also increased the termination current from 0.3A to 0.4A. So it shortens the usual 8 to 10 hour CV time. And chose a float voltage that will complete the charge without stressing the battery during tomorrow. So I set 27.0V and 10 hours float. It will be perfectly charged when I need it on sunday.

Pretty good guess, so far its returned 17.13Ah. And has been 7 hours charging - starting at 12A and has just dropped to 0.4A and so the 27V float began..

[desert dweller]

Damn, your expertise is impressive. Makes me realize how much more I have to learn. Slowly but (hopefully) surely . . .

Thanks again for all of your help. Hope you're having a great day!

[Burgerman]

Theres nothing clever about it really!

Look at the other way around.
A battery can be stored - even charged and last almost indefinitely if its sat on a float voltage that is JUST high enough that it ends up completely charged eventually... Maybe 2 weeks. That tends to be around 13.3 to 13.35V. That will make your battery age as slowly as humany posible. And once it IS full, and it must be! Then only a few mA will need to flow all day every day to couteract its natural "self discharge. Maybe 3mA or 6mA. Not enough to cause any electrical corrosion or electrolyte loss and it stays full, so no sulfation.
You dont even need or want a charger to do this. ANY power supply that gives the correct voltage, like a wall wart that happens to be 13.3V to 13.4V will do that. Plug it in, indefinitely and just forget about it! Thats all it takes. But its no use to us, we need to charge in 8 hours!

Now, in something like a solar array, where we use the power at night and want to get back from maybe 30 to 50% discharged to as full as poss, with the longest service life possible. We use say 13.8V. Thats a high float. That will rapidly put back 90% of the charge, and may take another 16 hours to achieve the last 10 percent. But at least once every vew days it will end up completely full. And so still keep sulfation at bay. But now we are charging at a little higher voltage. So some overcharge happens. Especially in summer when nobody is home. So thats the best compromise where a complete charge done RAPIDLY isnt needed.

Then theres us. Traction use. Cyclic use. Some days heavy discharge levels. And we only have overnight to recharge! Also shift workers, overnight charging of floor cleaning machines, etc. This one shift charge time is refered to as CYCLIC charging.
So in this scenario we need a higher and more damaging voltage in order to force that last 10% in during the short overnight period we have available.

So on AGMs this is around 14.4 to 14.7V depending on actual brand/etc. And on GEL batteries its between 13.8 and 14.1. Its lower because gel is damaged by gassing. It makes voids, and it causes shrinkage of the gel. And thats not good! So gels are more critical to get right. If you do then they last longer! If not they dont.

Now consider this: When charing at the 13.3V long term float voltage, there IS no termination time or point needed. You just leave it turned on. Because the charge current drops to almost zero when this battery voltage matches the charger voltage at 101% full. Eventually...
So when we charge at a higher voltage to speed this all up, it is now much harder to determine when to stop. Lets say you are charging at 14.4V. Thats over a volt higher than the natural full voltage of the AGM battery.
So we have to manually or electronically tell it when to stop. To avoid any overcharge. Because with a 1V extra charger voltage the current will still flow in even when full. But thats why it speeds up the last part of the charging!

So at when to end charge, and at what point is it "full"?
Well it "depends"... Here we go again.
Every battery seems to be different. We know that after 8 hours at this elevated voltage it SHOULD be full. And we know that the current will drop to some low level. But that current varies depending on type, age, temperature, discharge state, previous history etc.
So it requires a little care and fine tuning.
So:
- if the current has STOPPED FALLING at all, over a 1 hour solid period, STOP. Go to float. Or lower (slow down) the charge voltage.
- if the current falls below approx 0.3A per*** 100Ah STOP and go to float.
- if the CV time (the time it has sat at its choosen voltage) for 8 hours STOP and go to float.
- if current begins to RISE again at any point during this 8 hours STOP.

***If it never wants to get low enough to that 0.3A termination point, then we increase it so that it trips at approx the 8 hour point when charging a deeply discharged battery. A lightly discharged one may ot take 8 hours.

It isnt a problem to set it to say 1A transition to float or whatever you wish as thats safe! It will end with around 98% charge if you do that. Then the float stage which is at a lower voltage will top that missing 2% up. But take a long while to do so. Depending on float voltage used. To avoid sulfation a 100% full battery must be achieved at least weekly.

In other words trying to speed up the charge to one useable in cyclic overnight conditions is where it gets more compicated to get right.

[desert dweller]

That was very interesting. I got lost starting here but the rest was really interesting.

- if the current has STOPPED FALLING at all, over a 1 hour solid period, STOP. Go to float. Or lower (slow down) the charge voltage.
- if the current falls below approx 0.3A per*** 100Ah STOP and go to float.
- if the CV time (the time it has sat at its choosen voltage) for 8 hours STOP and go to float.
- if current begins to RISE again at any point during this 8 hours STOP.

Unless I get the money to buy a ZXD and the time to learn how to use it, I'll have to keep using my mobility charger. The recommended cycle voltage for my batteries is 14.4 to 15V and for float it's 13.5 to 13.8. There's no design temperature or coefficients specified.

If I go by what's recommended for the other AGMs I looked at, design temp would be 25C, bulk coefficient .05, and float coefficient .03.

So based on a 26.7 daytime temp, the max temp-adjusted bulk voltage would be 14.92 and the max temp-adjusted float voltage would be 13.75, if I calculated correctly.

My mobility charger puts out 29.4V bulk and 27.4 float. From what you said, I gather that while it's within the temperature-adjusted specs for my batteries, it's higher and more damaging than ideal but unfortunately necessary in order to be able to use my scooter daily.

Thanks again for your help and all of the info.

[Burgerman]

Unless I get the money to buy a ZXD and the time to learn how to use it, I'll have to keep using my mobility charger. The recommended cycle voltage for my batteries is 14.4 to 15V and for float it's 13.5 to 13.8. There's no design temperature or coefficients specified.

Thats not the tech data the manfacturer has thats a maximum wide limits that they dare to let people use. Why wide? Because they are selling batteries to thousands of ignorant batery users that already have generic chargers. So...

They sell more batteries if they say 14.4 to 15 volt. But they dont tell you when to stop, which is AT LEAST as onportant, or how long to leave it on float at that very high wide float voltage either. People dont want to know! That data is a sell sheet. Not a tech data sheet.

Let me show you what MK say about charging their battery.
They say in cyclic use to use 13.8V to 14.1V (MAX!) and so they really mean 13.95V in their tech data sheet. They say that anything above 14.1 voids warranty. Yet their own "sell sheet" says 14.1 to 14.6V.

So, they tell you you can charge 0.65V too high on the sell sheet.

And they are correct. You CAN. And it charges just fine... But they dont tell you that it COSTS you 60% of the cycle life.
But remember that they really meant 13.95V @ 20C in the tech data.

Then in the tech sheets they tell the truth about what that 14.6 less 13.95V = 0.65V too high actually does!

[ex-Gooserider]

Back when I was first starting to learn about power chairs several years back I had MANY different people tell me that Interstate batteries were pretty much crap... Essentially they were targeting the low end market and the assumption that it was less expensive to replace batteries occasionally under warranty than to make a high quality battery...

IIRC one of their big customers / sales routes is AAA, as one of the member benefits that they will come install a 'discount price' battery w/o mentioning that it is only a short-term rated (24 month?) item that will need to be replaced regularly...

ex-Gooserider

[Burgerman]

hats called a "work creation scheme". It means your car will fail, and you will keep on renewing membership...

I knew a plumber once that used to visit many places with his advertising stickers. And business cards. He used to put them all around the public loos, etc. And on tanks in roof spaces. Then used to stab the float on those auto valves called ball valves here with his dart below the water line. He played darts... So every pub the team visited. Civic buildings, cinemas, etc.

He says the float gradually fills with water over a few months and sinks... And then the phone rings. Another easy job £££. He called that a job creation scheme.

In the US oil changes on cars are pushed as being important. They get to charge you for oil, filter, and labour every few weeks. Here the very same cars have double or tripple the oil change intervals in the manuals. Only in america is that a big business.

Take my van. In the UK/Europe its oil change is every 12k miles. What is it for the same vehicle in the US ? Likely it will be half that.

[LROBBINS]

But the oil and filter in the U.S. cost about 1/10th of what they cost here in Italy.

[Burgerman]

But you signed up to the soviet style EU socialist green superstate so everything costs a fortune esp oil. Fuel, and vehicles.

And just like you, we have that same mentality here.

Even though our lefty green globalist polititicians (both the so called conservatives, and the labour party in our 2 party system are both the same here) eventually removed us from the EU, in name only. And even though the public for 30 years have repeatedly voted FOR reduced EU, reduced tax, reduced foreign givaways, reduced imported goods, reduced legal and illegal migration, and reduced smaller governments, and to dump all the globalist nonsense. They have lied, and ignored everything. Every 4 years we get to vote again. Same result. Two cheeks of the same backside.

So now after the brexit fiasco where they refused to do it, and even now have not actually done it, people here are desperate. We dumped the "conservatives" with an absolutely total decimation of votes as punishment. Now, that allowed the "other" party in... They are even worse.

Fortunately we now have the massive rise in just a few years of REFORM. Who promise to do everything that we have been desperate for for the last 30 years hat the other elites simply refused to do. .
They went from a nothing party, with a handfull of votes to beating all the other big 2 over a couple of years. They are now about 10% above the labour and conservatives in the poles. Basically we will e finally getting in a party that will do brexit properly, small government, law and order, ban all the woke garbage, protect free speech, dump a mountain of legisplation, and dump net zero totally. And deport illegal migrants and reduce migrant to zero. One in, one out.

So finally expect a trump style recovery in 4 years.
We are an island of coal oil and gas floating in a sea of it! And not using any of it. Buying energy at 5x the cost of the US energy in order to build "wind" and solar" the so called unreliables. 500% energy costs over the USA. For no reason. Destroys business and the countries economy. Same with migrants.

[Burgerman]

https://www.walmart.com/ip/Mobil-1-FS-E ... hbdg=L1200

Here I can get mobil 1, 0-40 at half the price. Filters still the same cost.


And on amazon same oil is exactly the same 51 UK £ in Amazon italy as the amazon UK.

So yes oil is half the price in the USA. In some cases. But I can likely get it cheaper if I dont look at amazon too!

Now, thats because they do not tax everything to death in the US and because drill baby drill. Drives oil prices down.