Load testing batteries.

[Ahmad Daze]

Hi all.
Newbie question..
What is the best way to load test a battery? I have 3 x 12v 7ah. I am going to focus the charging and conditioning to one of the batteries, using the other 2 as primary's. Not at the same time, just so I can keep the primary constant, these will be chrged with a regular charger.
I'm aware that to start with I'll probably be putting in more juice than getting out.
I've read of people connecting LED's or resistors over the terminals to load test the battery? Could someone clarify please, don't want to damage (or explode) these new batteries.
Also could I hook up an inverter and simply power my equipment making better use of the energy gained to do the load test? I'm thinking of leaving a small guitar amp on or mixing desk as a constant load.

Thank you in advance for any insight offered.

Ahmad

[ben_says]

I am also interested in veterans comments for best load testing methods, both in what to measure and notate.

[vallentin]

Ahmad, ben_says
You MUST use a C20 rate of discharge. No matter the battery capacity size. C20 rules.
The maximum current you can draw without hurting the battery over a period of 20 hours.
For your 7Ah batteries use a 350mA load (7000mAh/20 hours).
A 4W car lamp for example. Or a 35 ohm resistor. But I guess you can make use of the light over the 20 hours of load testing.
No matter what, stop your discharge test when your battery goes down to 12,2V.

Years ago, I did my 20 runs test using a simple webcam and a program called Nircmd to take snapshots of my multimeter during the load test - every 10 minutes.
After that I watched every picture, take notes (on paper) of the voltage and chart the charge/discharge curves in an excel file.
As a load I used a 220V CFL and an auto inverter. I think it was 18W.
As it happens, the current draw was 360mA. Yes, I had the same batteries you have now. I still have them. 8 years since I got them, plus 4 years in service in an UPS, but they behave like new ones. With a difference: their end of charge is 16.10V.
The program tells your computer to do a loop with an another program (your camera snapshot software) and name every picture you shot with date/time of the day. Easy!
I have to dig thru my old laptop for that particular excel file I used to chart everything and upload it somewhere for you and the exact nircmd command.
This way, you can see if your conditioning improves, or not.
You can use my (kind of) empiric method (I had to see with my own eyes how things are rolling) or devise your own method.
But never forget about the C20 discharge rate and 12.2V minimum discharge voltage. Here's why:

And read these: How Lead Acid Batteries Work and Bedini-The Battery Bible
One more thing. Keep your run batteries separate and charge them conventionally.
With an SSG you cannot rotate batteries (different kinds of energy) unless you use a cap pulser.
The thing is, you must be able to charge at least 2-4 batteries at the expense of only one. Not the other way you're doing now.
Concerning the use of an inverter, the answer is YES. You can use it. But measure how much current it draws first. You need 350mA max. How many watts is your mixing desk? Don't expect wonders out of this small battery.
Regards,
Valentin

[vallentin]

Lee on Battery Maintenance (he considered lead-acid batteries as alive like the family dog).

1. They need exercise; it's good for them. You get the longest life when they are worked to about 50% of their capacity at moderate loads.
After they have been loafing for weeks, you will notice a distinct improvement just from giving them moderate exercise.

2. But don't work'em till they drop! If you drive an EV until it barely moves, the batteries are having a near-death experience!
This is outright batterycide, and a leading cause of early death.

3. They need to be be fed regularly (charged). Feed as soon as possible after a workout; they don't like to sit around starving after use.
Batteries left sitting for days in an undercharged state develop a condition called sulfation.

4. Don't overfeed, or they get fat and have cumulative health problems and so die early. Chronic overcharging is a major cause of early death.

5. Don't underfeed, or they can starve to death. Chronic underfeeding also leads to a weak sickly battery and an early death.

6. Batteries can sit unused for months (hibernate) without needing to be fed. You don't need to put them on a trickle charger; just be sure to feed them occasionally so they stay near full charge.

7. They need fresh, clean water occasionally. Sealed batteries have a built-in watering system, but flooded batteries do not. Be sure to check water levels, and fill with distilled water as needed (dirty tap water poisons them!)

8. They need to be kept at reasonable temperatures, that you would find comfortable. Not too hot, and not too cold. Lead-acid batteries are
"cold-blooded", so the lower the temperature, the slower they get. Likewise, they can't "sweat", so high temperatures cook 'em to death.

9. Batteries can't talk. They won't whine when they're hungry, or cry when you hurt them. You have to check their state of health with instruments, like voltmeters ammeters and hydrometers.

10. There are different "breeds" of batteries, each with its own good and bad points. Slow plodding workhorse are flooded, but long lived.
Racehorse AGMs that are fast and powerful, but short lived. Using the wrong breed of battery for the application, or unrealistic expectations leads to disappointing results.

11. And some is just the "luck of the draw". For no obvious reason, identical batteries in the same vehicle will have some die young, and some seem to live forever.

The usual reason you see used EVs that say "needs batteries" is because the previous owner treated the batteries cruelly. Whether by ignorance
or laziness, some or all of the above guidelines were violated. But batteries are replaceable, and it usually means you can get the EV
"cheap".
But such problems can be cured. A little detective work to fix the problems, and then some tender loving care will go a long way toward
getting the longest life possible on the next set of batteries.

More here: Lee's Wiser Moments

[Ahmad Daze]

Thanks for that Vallentin. Really useful info there. The battery bible is just what I needed to get a few things straight. Need a little time to digest it though.. I realise that the batteries I am going to need for powing audio equipment will need to be alot larger than these little 7ah's. But hey they're as good a starting point as any to understanding what is going on!
With some preliminary runs done so far I've stopped charging at 15.4v. They seemed like they would just keep going..! Is there a good cut off point when charging?.. will ask the bible..
Thanks again for the info
Ahmad

[vallentin]

Here's how my charge chart looked like:

After your battery will be conditioned, you can go to 16-16,2V and stop there. At the top of the bell or close to it.
That's why it is important to chart what you're doing. I did. John B did and does.
Depending on your SSG, the end result may differ. So chart your charge and see where you stop (set a programmable timer after that to do it for you). The bible won't tell you where to stop unless you do the chart.
To me, it looks like after the maximum voltage is attained, kind of an overspill effect appears.
Like pouring water under pressure into a glass and then when it reaches the top, it overspills. Stop the water flow and you'll end up with less water in your glass. Or battery, in this case (if your machine is bigger than the battery needs to).
Try it. With a glass of water.
Resting the battery for more time or less time affects directly the voltage reading at the end of the charge/discharge cycle. Resting is very important if you want to keep track of your data. correctly.
Again, to closely monitor the charge & discharge process and to keep track of it, I hooked a webcam to my laptop and using a command line tool (nircmd), I managed to take snapshots of the screen monitor the way I wanted.
And then chart everything. Charge and discharge.
The command line is:
nircmd.exe loop 600 300000 savescreenshot d:\batterytest\charge_~$currdate.MM_dd_yyyy$-~$currtime.HH_mm_ss$.png
Meaning 600 snapshots every 5 minutes, wich is more than you need. Replace 300000 with 600000 you'll take pictures every 10 minutes.
The end result (every resulting picture) looked like this:

PM your email address to send you the modified COP calculator and see for yourself what I did and how.
Regards,
Valentin

P.S. My old SSG description: 7 litzed coils (6x0.8mm,1x0.5mm) x 90meters, BD243C transistors with neon bulbs, 19V/2,27A A/C adapter, 192 ohm swetspot on base transistors, 419mA current draw.

[teej_seeker]

Here's how my charge chart looked like:
[ATTACH=CONFIG]1038[/ATTACH]
After your battery will be conditioned, you can go to 16-16,2V and stop there. At the top of the bell or close to it.
That's why it is important to chart what you're doing. I did. John B did and does.
Depending on your SSG, the end result may differ. So chart your charge and see where you stop (set a programmable timer after that to do it for you). The bible won't tell you where to stop unless you do the chart.
To me, it looks like after the maximum voltage is attained, kind of an overspill effect appears.
Like pouring water under pressure into a glass and then when it reaches the top, it overspills. Stop the water flow and you'll end up with less water in your glass. Or battery, in this case (if your machine is bigger than the battery needs to).
Try it. With a glass of water.
Resting the battery for more time or less time affects directly the voltage reading at the end of the charge/discharge cycle. Resting is very important if you want to keep track of your data. correctly.
Again, to closely monitor the charge & discharge process and to keep track of it, I hooked a webcam to my laptop and using a command line tool (nircmd), I managed to take snapshots of the screen monitor the way I wanted.
And then chart everything. Charge and discharge.
The command line is:
nircmd.exe loop 600 300000 savescreenshot d:\batterytest\charge_~$currdate.MM_dd_yyyy$-~$currtime.HH_mm_ss$.png
Meaning 600 snapshots every 5 minutes, wich is more than you need. Replace 300000 with 600000 you'll take pictures every 10 minutes.
The end result (every resulting picture) looked like this:
[ATTACH=CONFIG]1039[/ATTACH]
PM your email address to send you the modified COP calculator and see for yourself what I did and how.
Regards,
Valentin

P.S. My old SSG description: 7 litzed coils (6x0.8mm,1x0.5mm) x 90meters, BD243C transistors with neon bulbs, 19V/2,27A A/C adapter, 192 ohm swetspot on base transistors, 419mA current draw.

valentin,

what tool do you use to chart the batteries?

/teej_seeker

[vallentin]

Teej, like I said above, I take snapshots of my screen using a program called nircmd. Look at the last picture.
I'm using a cheap webcam to display my multimeter, I'm running a macro inside the excel file to do the time calculation and then I use the best tool: my hand.
Meaning that I write every voltage found in the pictures inside a column in the same excel and then graph it. The pictures are timed. 10 minutes apart.
I took the liberty to modify the classic COP calculator to suit my needs. If you want the excel file, just say so.
Valentin

valentin,
what tool do you use to chart the batteries?

/teej_seeker

[teej_seeker]

Teej, like I said above, I take snapshots of my screen using a program called nircmd. Look at the last picture.
I'm using a cheap webcam to display my multimeter, I'm running a macro inside the excel file to do the time calculation and then I use the best tool: my hand.
Meaning that I write every voltage found in the pictures inside a column in the same excel and then graph it. The pictures are timed. 10 minutes apart.
I took the liberty to modify the classic COP calculator to suit my needs. If you want the excel file, just say so.
Valentin

valentin,

apologies for not reading closely at what you had written.
the results are impressive and I would humbly like to request for a copy of the excel file.

[vallentin]

No need to apologize, teej.
There's too much information to digest at one time. And we are here to help each other.
The reason I did my tests this way: no funds to buy a proper data logger. So I had to improvise something cheap, put some elbow grease in, and get the same results.
PM your e-mail address to send you the file.
Regards,
Valentin

[Jon Christianson]

Vallentin,
Do you leave the probes on the charging battery all the time?

My understanding is you should not leave any measuring probes on the charging battery while it is running because it will effect the charging. (I believe this was stated in the old Yahoo Group)

Is this true or not?

Thanks, Jon C

[vallentin]

That's what they said.
I must have a pretty good meter then
It's working non-stop, for years, attached to the circuit and I have never seen any effect. With, or without it.
Though every wire is as short as possible in my circuit to reduce losses. And the wires that go to the battery are as thick as possible.

Vallentin,
Do you leave the probes on the charging battery all the time?

My understanding is you should not leave any measuring probes on the charging battery while it is running because it will effect the charging. (I believe this was stated in the old Yahoo Group)

Is this true or not?

Thanks, Jon C