Optimate 6

[Bala]

Thanks for the explanation on testing IR, where did you get the 7.2 in your equation ? (12.6 - 7.2 volts)

Is that what the SSB DBT-4000 tester does, measure Impedence and IR?

[Sunking]

Thanks for the explanation on testing IR, where did you get the 7.2 in your equation ? (12.6 - 7.2 volts)

Is that what the SSB DBT-4000 tester does, measure Impedence and IR?

If you look at the definition of Cold Cranking Amps aka CCA for lead acid is defined as: the numbers of amps a battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain 1.2 volts per cell (7.2 volts for a 12 volt lead acid battery).

So 12.6 volts is the voltage of a rested fully charged battery, and 12.6 - 7.2 volts is the Delta or change in voltage we need to find Ri aka Internal Resistance. To zero in for accuracy the formula is OCV - 7.2 volts / CCA = Ri. I assume OCV was 12.6 volts of a fully charged and rested battery.

A Battery Test Set checks and records the OCV, applies a load of say 20 amps, and measures the voltage again. Then performs the Calculation OCV - Loaded Voltage / Test Current = Internal Resistance.

Battery Impedance is similarly measured using a calibrated AC Square Waveform of 1000 Hz. Pretty straight forward. They apply a known square wave AC voltage signal, and measure the Decay Time. Another method is a 1000 Hz Sine wave. Example apply a .1 Volt RMS AC 1000 Hz Sine Wave Signal and measure 20 amps of current you have .1 volts / 20 amps = .005 Ohms. Most use the Voltage/Current method.

Internal Resistance and AC Impedance are excellent indicators of a Battery State of Health. There are two challenges to overcome when using Ri and Impedance.

One is temperature because both Ri and Impedance change with temps. Resistance rises with temp. No big deal to over come, just make the measurements when the batteries are at or around room temps. It i snot critical.

Second is a Reference point. In other words what is a good reading and bad reading? Answer is pretty simple, Baseline and experience. From Experience you are smart enough to remember what the Resistance should be on a new battery or Baseline. You know a new 1000 CCA battery should be around .005 Ohms, and when you measure .02 Ohms you know instinctively to toss that POS in the recycle bin.

Here is the bottom line and what you need to know. All but 1 battery problems show up as Internal Resistance rising.

So when you first use a Load Test, if Ri is too high, the battery cannot pass the Load Test assuming you used a good heavy Load Current like 50 to 100 Amps. Additionally using a high Load Test Current also makes the Ri test more accurate.

[Sunking]

Is that what the SSB DBT-4000 tester does, measure Impedence and IR?

Yes they just call it something different.

Conductance = 1 / Impedance. Conductance is the INVERSE of Ohm's call MHO's. They measure the AC Impedance and Invert it or divided into 1. So .005 Ohm's becomes 200 Mho's or vice versa 200 Mho's becomes .005 Ohm's. They do that to confuse the Russians & Chi-Coms. It uses the 1000 Hz AC Signal.

The Internal Resistance is hidden in the CCA Test Result which makes life even easier on the High School kid you hired to do grunt work. If he is testing a 1000 AH battery (.005 Ohms / 200 mho's) and it test CCA = 100 amps (.05 Ohms/20 mho's), he knows what pile to toss it in.

[Bala]

Thanks again for info, I will look into it more when i have more time but it is good to have an idea what the tester is testing. I doubt my cheap auto parts store multimeter is really accurate enough to measure such low ohms but I will do a comparison on new and old batteries.

I watched the Snap on charger today, In calcium mode it does a 16.3V Bulk, then 14.7V until the battery is full to 100% on its gauge, not sure what its parameter for 100% is.

The manual mode on the charger does 16.3 V bulk then 14.2V for maximum 120 minutes.

So for the moment I am running batteries on the auto calcium mode until full, then manual mode for 120 minutes.

I only want to put very good batteries back into service so I figure if they dont test well after that then they are not worth worrying about.

I am then letting them rest overnight before my test cycle of V check must be minimum 12.6, then CCA load test on the Hurst carbon pile load tester, then use the SSB electronic tester.

Today a battery was pulled from the pile to get put into service, i intervened and tested it,

It V reading was 12.38 ( Which told me it was not good), it failed the CCA load test dismally, below 10V @ 500cca and falling fast for a 775cca battery, but the SSB tester said it was 101%.

Instead of the truck getting this one extra odd battery it got 4 new ones.

most break downs on the road cost the company around $600, so I probably just saved that today.

[Sunking]

Hey Bala going to tel you a few secrets I know and have memorized. It is one of the tricks I use to about instantly know what a battery can do.

The hardest most Grueling, Telling test you can put on a battery. If there is any weakness will show up Immediately. We have already discussed it, but I stopped short. The good ole Battery Load Test. Now for the Trick or secret is to use 100 AMP Load. From that test alone you find the two most Important Numbers you want to know. Internal Resistance and Cranking Amps as both are the same characteristic, and give you a rough approximation of battery capacity.

Most good Electric Auto/Truck mechanics already use the principle, but may not fully understand what a 100 AMP load tells them. The test is simple, you apply a 100 amp load and read the battery voltage after 6 to 10 seconds. That is it and all there is to it. The Voltage tells you exactly what you want to know. All you need is a Table or the Scale calibrated on the Meter made to do the test.This is how your Snap-On Tester works to read CCA.

9.8 Volts = 200 CA = .014 Ohms
10.0 Volts = 400 CA = .0065 Ohms
10.4 Volts = 600 CA = .0037 Ohms
10.8 Volts = 800 CA = .00225 Ohms
11.2 Volts = 1000 CA = .0014 Ohms



So how much does such a Meter Cost? As little or as much as you want from $20 to $3000. All the same size, about the size of a DMM. You can buy one from Harbor Fright for $22, same Schmacher BT-100 on Amazon for $24, or a Midtronics PBT-100 for $140. I know you have sen these guys before.

[Bala]

I have a snap on charger and a durst tester.

I tried your suggestion, I put a 100 amp load of for 10 seconds and the result buy your voltage/CCA chart was that my 775cca rated battery was good for 1000cca.

So something is not right there. I have no idea of the calibration of the Amp meter on the durst tester.

I am happy with my test procedure. I load them up to their CCA on the Durst tester and use the digital V meter on the SSB tester to monitor V drop.

A good battery will hold around 10V at rated CCA and then recover to 12.6+V very quickly,

The not so good batteries do not hold the voltage as well and recover slowly to get back above 12.6V

the ones that I am totally happy with I mark as good, the others I mark as workshop use only.

[Sunking]

I tried your suggestion, I put a 100 amp load of for 10 seconds and the result buy your voltage/CCA chart was that my 775cca rated battery was good for 1000cca.

So how is that a problem?

Allow me to remind you CCA = Cold Cranking Amps, meaning the test is done when the Battery temp is 32 degrees. So did you stick the battery in a freezer over night? Of course not, the battery was quite a bit warmeer than 32 degrees right? It will test higher when warmer if it is good. The battery Internal Resistance goes lower as the temp goes up.

[Bala]

Ambient temp here would be about 30 Celsius. Perhaps that is why some if the good quality batteries test at 150% on the ssb tester. The standard ssb batteries only ever test at maximum 110%

[Sunking]

Perhaps that is why some if the good quality batteries test at 150% on the ssb tester.

Not PERHAPS, that is the reason.

It is like this; BCI and SAE developed the 100 AMP Load Test standard decades ago to make life easier on mechanics with a GO No-Go result