Battery Load Tester

cork_ie

Joined Oct 8, 2011
428
I have worked for 36 year as an auto & marine electrician my take on testing lead acid batteries is
1) A battery has to be suitable for the application it is used for .
A battery that "Fails" in one instance eg cold weather starting in diesel engine may be perfectly serviceable in another less demanding situation.

I am absolutely against "High discharge" load testing.
Using these testers draws more or less the same current irrespective of battery size until voltage drops down. It will often FAIL a small light car battery , which is still perfectly serviceable and tell you a heavy diesel truck battery is OK when it isn't.

I have used Modern Digital EIS testers and to be honest am not really impressed. I had a demonstration from a tool company and the battery they told me was perfect died 2 days later.

I find on vehicle testing is best. This is how I do it

1) Ensure battery starts off at 12.5V or more

2) Turn on head lights, blower fan and heated rear screen for about 3 minutes, allow voltage to drop to just below 12V. Voltage, should drop by a maximum of 0.1V every 5 seconds after that, any more and the reserve capacity is insufficient.

3) Finally , pull fuel pump fuse or in some way disable starting and operate starter motor for 10 seconds. Anything below 10.0 Volt is a fail. This is your CCA test.
If in doubt retest vehicle when fully cold.

Finally always observe for swollen battery cases, gassing from cells etc. they are always a sign of impending failure.
 

THE_RB

Joined Feb 11, 2008
5,438
It's great to hear the voice of experience.

And don't forget another good technique; Once you start noticing slow cranking or any battery symptoms (that are not fixed by cleaning and tightening the terminals) just buy a new battery.

They don't cost that much and need replacing every couple years anyway.
 

crutschow

Joined Mar 14, 2008
34,281
Okay I give up. Apparently whatever I have been telling my students and what I have known to be true for 30 some odd years, is just nonsense. Let's go with the light bulbs and wires hanging all over the place because that sounds a lot safer than a carbon pile load tester with a true history and impeccable track record. Did I mention the fact that you can buy one of these for under a hundred bucks and it is safe to use? I think the OP has long left the building and gone off to buy himself some coiled wire to build himself a load tester. I hope he doesn't get hurt. I think I read that he was going to show other people how to use his method as well. Awesome. I love this forum because there are a lot of intelligent people on it, but this one has me baffled. There are tried and true method of testing batteries. Safe and sound. Why can't we just accept that and leave it alone? And just for the record, that would be one hell of a bank of 1157 bulbs to produce enough current draw to bring down a 1000 CCA battery. You could light up Central Park with that.
Testy, testy. :rolleyes: No one has said that there's anything wrong with the carbon pile load. But I also don't see anything wrong with the lamp approach. It can be built safely without wires "hanging all over the place" and since it's only 12V, where is the danger with that? Certainly it would take a lot of 1157 bulbs but there are 12V, 100W halogen bulbs that would allow a reasonable number of bulbs for the desired load, possibly cheaper than the carbon pile.

So I apologize if we seemed to marginalize (or ignore) your solution (which is certainly tried and true). But this is a forum of ideas and that's what we are discussing. :)
 

Thread Starter

Chalma

Joined May 19, 2013
54
Didn't mean to offend anyone. I actually took vacation and had no intention of doing anything remotely related to work. I didn't fully explain my reasoning I'm doing it this way with the light because as previous posters pointed out I have an excellent visual for a test technician. Not only am I getting my requirements out of the way BUT I'm doing it at a fraction of the cost vs the filament. I know some of you said the pre-made testers would suffice, but I've seen it with my own eyes (also a good lecture from my father) using one on a battery and pointing out that it was good (after which my father showed me to clean the battery etc....). Not only, but the lightbulbs will alert the user that they need to be unplugged etc. I don't know about you guys but the company likes to get 'temp' workers, and these guys are not interested in electronics or doing things right for that matter. The fact that I can just make a fixture and they can see it's good is much better than having them see if the filamants are heating up AND checking it with an AMP meter. I didn't mean to invoke anger in anyone, and the fact that there are people on both sides of the fence means to me that there IS room for discussion and the mod/admin shouldn't delete this thread. Thanks again all.
 

bwilliams60

Joined Nov 18, 2012
1,442
Testy, testy. :rolleyes: No one has said that there's anything wrong with the carbon pile load. But I also don't see anything wrong with the lamp approach. It can be built safely without wires "hanging all over the place" and since it's only 12V, where is the danger with that? Certainly it would take a lot of 1157 bulbs but there are 12V, 100W halogen bulbs that would allow a reasonable number of bulbs for the desired load, possibly cheaper than the carbon pile.

So I apologize if we seemed to marginalize (or ignore) your solution (which is certainly tried and true). But this is a forum of ideas and that's what we are discussing. :)
This has been an interesting discussion and one that I have certainly learned from. First of all, I am not testy, I would call it frustration. I have done this for 35 years+ and thousands of batteries later, seminars until my ears are bleeding from battery manufacturers such as Interstate, Delphi and East Penn and more, and not once have I ever heard of using lamps for a load tester. When I replied for the very first time, I laid out the exact procedure, which is an industry standard (and not 30 seconds) that has been used since early 1980's to answer a question on how to load test "large" batteries, quickly, efficiently and safely. I answered that. What I have learned from this is that people have many opinions including myself and what we throw out on the Internet can and will be used by people who are untrained. To those of us who know Ohm's Law and how current works, it makes sense. But I'm sure you can agree that it would take a lot of bulbs to pull down a 1000CCA battery in order to make a valid test. As the lamps heat up, resistance will increase and amperage will decrease. So how do you monitor what you are drawing from the battery? How long do you let the draw occur to say the battery is good or bad? I agree that we can use anything which will create a load, to load test batteries, but it won't be as accurate as a carbon pile load test. The second thing I learned from this is that doing things incorrectly and using inferior equipment is also acceptable in the workplace. In my world, I have no room for that. I try to have the best equipment and the proper procedures so that I can support my findings with concrete facts and I go to sleep at night, knowing that everything I did was safe for myself and my co-workers.
So I hope you all forgive me if I seem a little testy. I have been taught do "Do it right the first time" and use the proper equipment. If I'm playing around at home, that's different. That is how we learn. We make mistakes, we talk about them on forums and have a laugh about letting the smoke out.
In closing, I will say that I enjoy forums because we get to bounce different ideas off each other and learn from each other but when it comes to a persons safety and learning proper procedures, I am black and white to the core. I will not usually comment on this forum unless I know what I am talking about. There are far more intelligent people on here than me.
Cheers to all, no hard feelings, let's hear more.
 

crutschow

Joined Mar 14, 2008
34,281
......................... To those of us who know Ohm's Law and how current works, it makes sense. But I'm sure you can agree that it would take a lot of bulbs to pull down a 1000CCA battery in order to make a valid test. As the lamps heat up, resistance will increase and amperage will decrease. So how do you monitor what you are drawing from the battery? ....................
Well, if you used 100W bulbs, it would take 1 bulb for each 8.33A of current so the op can figure out from there as to whether it requires more bulbs than he wants to buy/wire for the amount of load current he needs.

The bulbs heat up in milliseconds, so I don't think the change in resistance is a big factor, unless you consider the momentary initial surge current a problem. I assume you monitor current with bulbs the same way you monitor it using a carbon pile. And how long you maintain the load would not change for the same current with bulbs or the carbon pile. Or am I missing something?
 

wayneh

Joined Sep 9, 2010
17,496
Proper testing must be done with a carbon pile load tester and you can get a cheap version of these for a couple hundred dollars.
Not to belabor this discussion, but I think that's the crux of it. I, for one, assumed the OP wasn't interested in spending a couple hundred dollars and was looking for a reasonable DIY alternative. That's just the sort of thing we see most often around here. If he prefers a more professional device and is willing to pay for it, then by all means he should pursue that.
 

bwilliams60

Joined Nov 18, 2012
1,442
Well, if you used 100W bulbs, it would take 1 bulb for each 8.33A of current so the op can figure out from there as to whether it requires more bulbs than he wants to buy/wire for the amount of load current he needs.

The bulbs heat up in milliseconds, so I don't think the change in resistance is a big factor, unless you consider the momentary initial surge current a problem. I assume you monitor current with bulbs the same way you monitor it using a carbon pile. And how long you maintain the load would not change for the same current with bulbs or the carbon pile. Or am I missing something?
You are assuming the OP knows all this and Ohm's Law as well. He also mentioned passing it on to his cohorts at work. I fully understand and agree with you on the logic behind it, don't get me wrong, I just don't think "most" people would know how to do this properly. I read a post on another forum where a person did this exact load test, documented it for an hour or so and then went to bed leaving the bulb to burn all night. Just saying....

Not to belabor this discussion, but I think that's the crux of it. I, for one, assumed the OP wasn't interested in spending a couple hundred dollars and was looking for a reasonable DIY alternative. That's just the sort of thing we see most often around here. If he prefers a more professional device and is willing to pay for it, then by all means he should pursue that.
As for spending money, the link that we gave him was for a carbon pile load tester for $49. Probably an off-shore knockoff but does the trick.

Look, all I am saying is, be safe, do the right thing using the right equipment and where a workplace is involved, comments on this forum should reflect safety first for their sake and ours. I don't feel that a noob should run out and get dryer heater coils or light bulbs and start messing with things they don't understand. As for people working at home and experimenting with electronics, that's up top them what they do. Hell, I could care less if they daisy chained 5,000 bananas together for a load, as long as they don't slip on the peels.
Anyways, I never intended to start a fire-storm and I apologize if I offended anybody here, not my intent. I am passionate about my trade and wish to teach people the fastest, most proper methods available to achieve good, accurate results. Enough said.
 

wayneh

Joined Sep 9, 2010
17,496
As for spending money, the link that we gave him was for a carbon pile load tester for $49. Probably an off-shore knockoff but does the trick.
I never saw the link. Did it get lost, or am I just blind?

Look, all I am saying is, be safe, do the right thing using the right equipment and where a workplace is involved, comments on this forum should reflect safety first for their sake and ours.
You won't find an argument with that, and even the pros around here appreciate learning from the experience of experts. One should always know what the state of the art is, before deciding to compromise down from that.

One thing that is always challenging around here is that a project that would be safe and easy for one person could be life-threatening to another, and we usually have only a hint or two about the poster's abilities. So we end up insulting a few people while, hopefully, saving a few from burnt fingers or worse.
 
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