When to charge the acid battery properly?

borko444 · Sep 15, 2019

So I should not exceed the manufacturer's prescribed max 3A.
And aim for every 25 charge cycles to measure each battery and if there is a gap to charge them separately with a 12V charger.
Can you tell me what is the battery gap?
As you can see in my post above, only one battery goes away. 5 batteries for 12.07V and one is 12.04V
Is this a big gap?

Voltron · Sep 15, 2019

You should be checking the spread when the 72v bulk charger cuts off at full.

borko444 · Sep 16, 2019

Now the last battery is charged and then I'll put them in a group to charge at 72 volts

Voltron · Sep 16, 2019

You're doing it backwards... You should bulk charge the series at 72v, checking to see if any are going over 14.5 during the final stages.... Then even them out with the 12v charger.

borko444 · Sep 16, 2019

Anyway, I've already leveled them all with a 12 volt charger.
Now I connected the batteries in parallel and let them straighten. then i will measure them all individually.

Voltron · Sep 16, 2019

Now you won't be able to tell if one or more are going to high voltage during bulk charging, unless you check them all again after the next time they've been run down.

borko444 · Sep 16, 2019

I connected them to 72 volts, but the charger turned on for 1 minute and stopped because they were fully charged. Either way, I will pull cables from each battery to control and level them without having to remove them from the motor. I'll put it in perspective. I have now put them in parallel so that the charger can keep them charged, and when my parts arrive I will connect them and put them back in their place.

Voltron · Sep 16, 2019

:thumb:

999zip999 · Sep 16, 2019

The problem with balancing just one 12v battery is they have 6 cells and unless you can check each cell you can't tell how balance one 12v is. In the old days you used a hydrometer and checked the gravity of ea h cell or all six cells in one 12 volt battery that would tell you the difference , but these were flooded SLA batteries. So unless if you can put a tap wire in each cell to check the voltage of each cell of 6 cells in one 12 volt battery you would never know how balanced it really is. Or after draining battery blank you could check each 12v battery voltage. No recommended as sla look to be always fully charged for long life.
So just charge with 72v charger. What is your charger set to voltage ?

borko444 · Sep 16, 2019

That's what I meant.
Each battery has 6 cells.
After disconnecting it from the 72-volt ignition and having less voltage than the others, it is probably due to a failure in one of the cells and after balancing with 12 volts charger I don't think it made the difference, because if one cell is damaged in the battery balancing will affect him.

borko444 · Sep 19, 2019

I dropped the cable to each battery and waited for the sockets to arrive.
So I will be able to measure the batteries, test and charge them to flatten them.

999zip999 · Sep 19, 2019

Ok now you should write down and keep notes and see what happens over time.

borko444 · Sep 19, 2019

That's exactly how it will be documented and in 2 3 months I'll upload all the notes here

Voltron · Sep 19, 2019

You cannot balance the individual sections of the 12v sealed batteries. That's not what the 12v charger is for. It's for bringing the 12v units that are under voltage up by the time the 72v bulk charger cuts off.
Maybe I missed it, but have you checked the voltage spread right after normal discharge and full bulk charge to see what the voltage spread was at "full"?

Voltron · Sep 19, 2019

And are the ends of your new balance wires (the blue and brown ones?) covered? Even if cut off flush they could get sparky...

Another reassembly thing is making sure the power wires are contacting the battery terminal directly... No washers or the balance wires in between the main current path.

Voltron · Sep 19, 2019

That kind of evening out the cells in a sealed unit is usually called equalizing instead of balancing, just so we're talking about the same thing.

borko444 · Sep 19, 2019

Voltron said:
72v bulk charger cuts off.

Voltron said:
And are the ends of your new balance wires (the blue and brown ones?) covered? Even if cut off flush they could get sparky...

Another reassembly thing is making sure the power wires are contacting the battery terminal directly... No washers or the balance wires in between the main current path.

borko444 · Sep 19, 2019

In this case, I used one cable socket for each additional cable for each battery socket.
There is no sparky between the sockets.
First to the battery socket is the main cable. Second is the 12-volt cable and the bolt at the top.
My question is is it possible to get a weak connection between 72V?
As I said before, the main cable is directly to the battery.
Look at the picture.

borko444 · Sep 20, 2019

You can already see everything finished.

also look at the clip with the first measurement of each battery.

[youtube]https://www.youtube.com/watch?v=T5vhNyX2RN8&feature=em-uploademail[/youtube]

Voltron · Sep 20, 2019

That all seems great.

Voltron · Sep 20, 2019

Just maybe go back in a week and make sure all the terminal fasteners are all nice and tight on the main power wires. And I have had times where those screw terminal blocks that you're using for the balance wires let the wire slip out after the copper strands got compressed. Hot glue them too? Fuses? The bouncing around from rough city traffic wiggles that stuff around a surprising amount.

Voltron · Sep 20, 2019

And having messed with some packs where the spread at cutoff was as bad as 16.2v to 11.0 with the rest all over the middle.... That video was pure satisfaction.

borko444 · Sep 20, 2019

Now after 19 km.
The battery is 77 volts.
Batteries average 12.83 Volts.
Check out the video.

[youtube]https://www.youtube.com/watch?v=z5l998v24Ao[/youtube]

Voltron · Sep 20, 2019

:thumb:

The key is after some more cycles, like a couple of weeks or a month, monitor it as it gets to bulk charge cut off to see if any are going over 14.5v-ish, or self discharging really fast... That's two things that get a battery real hot.

major · Sep 20, 2019

borko444 said:
Now after 19 km.
The battery is 77 volts.
Batteries average 12.83 Volts.
Check out the video.

[youtube]https://www.youtube.com/watch?v=z5l998v24Ao[/youtube]

Nice job dude. Like it. Easy to measure. Easy to equalize charge when needed. Good luck.

major

When to charge the acid battery properly?

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