Battery Tester?

[stueveone]

Hey all,
What are some good battery testers out there? For, 12V 50A batts? Anyone ever use the Battery Tender brand tester PST-100?

[leitmotif]

What are you testing for??
State of charge - use a hydrometer (if lead acid wet cell)
Capacity - do a 4 hour test discharge.

Look up Battery University on the Web for info on other types of batteries and how to test them.
Read manufacturer literature on the battery.

Dan Bentler

[aviken]

I don't use battery testers like these, and I have read that they are not very accurate...I would also point out that this is for motorcycle batteries, and only measures up to 30ah capacity. I was thinking this is for EVs...but now I'm thinking it could be for batteries in an electric bike or something....

Dan is the man when it comes to electronics, I'm sure his suggestions are sound. If you are testing a large number of mystery batteries and you are only trying to find out if there is life left in them, and you don't have time to fully charge & do a 4 hour discharge test, this might be useful. Correct me if I'm wrong Dan...

[leitmotif]

Hey all,
What are some good battery testers out there? For, 12V 50A batts? Anyone ever use the Battery Tender brand tester PST-100?

So I looked it up at
http://www.remybattery.com/Products/Battert-Tender-PST-100-Tester-(021-0001)__026-0001.aspx

The specs such as they are are listed at the end.
It is rated at 30 AH and you say 50 amp.  I assume you mean 50 AH so your battery is larger than the unit is rated for.

The other thing that makes me leery is they do not say what the battery construction is ie wet cell, gel cell, sealed lead acid, etc etc.

Now in all the years I have worked with batteries I do not understand their statement
"Works on Discharged Batteries"
What do I need this thing for?? I know the battery is discharged.  Think I would charge it up and see what it can do.

For now I am going to restrict this to lead acid wet cells since I am most familiar with them.
In essence to test a battery (when fully charged) you put a load on it and see how long it lasts before any one cell goes below a minimum voltage value.  I have run test discharges on a submarine battery and several station batteries (126 cell and a 63 cell) in a Nuc power plant.  We ran a 4 hour test discharge measured the current at set intervals (15 minute) and checked each cell voltage.  When the lowest cell voltage was at 1.51 V we stopped the discharge.

This unit does basically the same thing - I THINK -- based on limited factory info.  Just does it quicker and more convenient.
Would I buy one - NO WAY.  I will stick with the tried and true methodology, a known and controllable resistor bank, a Fluke VOM, current shunt and a hydrometer.

For a quick and dirty you can use two or three headlights and check the voltage on the battery posts.  If it drops real fast you have a problem (sulfated, depleted, warped plates etc etc).  If it drops say a volt but over 5 or 10 minutes then it is probably OK and may be worth using but under very short range conditions until you know it can be trusted over longer time frames.

Now I know a hydrometer will not work on sealed lead acid.  Nor is it worth a dang on any other sealed battery construction.
I also know that "jumping gravities" on a freshly charged battery is a hot nasty job and a royal PITA.  Took about an hour and we were crawling around on insulated decking mounted 6" or so above the cells.

For Nicads, the lithium types, etc I am not sure how to handle the test discharges - for one thing I would read the factory manual.  I gotta get around to studying these and get more knowledgable.

Thanks for the complement by the way.  I am not THE MAN on electronics - power generation, distribution, motor control -- well maybe.
Dan Bentler



PST-100 Battery Tender Tester

This Battery Tender Battery Tester will test ALL 12 Volt Batteries ranging from 2.3 to 30 Ah and 10 to 500 CCA!  If you have any questions regarding the Battery Tender Battery Tester feel free to email our Sales Department at: sales@remybattery.com!


--------------------------------------------------------------------------------

Features:
• Tests 12 Volt Batteries
    • 2.3 to 30 Ah
    • 10 to 500 CCA
• Voltmeter Range: 8 Volts to 19 Volts
• Short Circuit Protection
• Works on Discharged Batteries
• Spark Proof

Dimensions:
• Length: 7.5"
• Width: 3.75"
• Depth: 1.5"

[stueveone]

Hey thanks guys! So, for a 12V 50AH bat, how much load should I subject it to? Is there a general percentage depending or will 3 car headlights work?
Could you explain a little more about a "controllable resistor bank, a Fluke VOM, current shunt"?

[leitmotif]

Hmmmm I see a need for a basic electricity class and a basic instrumentation class.
OK OK now taht I R electician ,,,,,,
I must remember I did not know once upon a time (back when ships were made of wood and manned by men of iron)

Lessee where to start
OK there is Ohms law which says that for a potential (voltage) with a resistor across it a current will flow.
So rounding off a bit House is 100 volt, lite bulb is 100 ohm.  When I connect bulb on 100 volt line I get 1 amp.
Now then power equals current x voltage so I am drawing 100 watt.
The voltage drop across teh lite is 100 volt ie I x R

If take a very low resistance say 0.001 ohm and stick it in the above circuit in series with lite,
the volt drop at 1 amp will be 0.001 volt.
This is basically a shunt.  So shunts are a high current capable resistor (I have seen 5,000 amp) used to measure current.  They are rated in ampacity and output voltage SO for exampl a 500 amp shunt with a 50 mV output.

A Fluke VOM is a Volt Ohm Meter.  An average one will measure AC and DC volts and millivolts (mV); amps (up to 10) milliamp (mA), resistance.  This will cost around $150 - I recommend it highly -- my first got stolen but it survived geting kicked around dropped off a truck, dropped in a washing machine (of course it was full of water), my second has not been that abused.  Do not waste your time with anything at Home Depot.  See Grainger for one. 

A simple controllable resistor bank could be 3 lites in parallel.  If matched and draw 100 watt each;
with one on the bank draws 100 W,
two on 200 watt,
3 300 watt. 

I picked lite bulbs because everyone knows about them.  For a 50 Ah battery unless they were very large (aircraft landing lites) they are too small for a real battery test unless you wanted to test for oh heck I dont know uhh 72 hour curve??.  If you wanted to do a 4 hour test then current draw would be 12.5 amp -- maybe I was closer than I thought using headlights - not bad for just throwing a dart at the wall.

Dan Bentler

[aviken]

Thanks Dan.

You are right, there are some of who keep reading about ohms law, and all the basic stuff...but then get tripped up and wonder what the heck does it all mean!

[leitmotif]

Well you can read and study and do the sample problems all you want.
BUT when you have a VOM out there and you want to know if a cable has continuity it comes in real handy to know and understand Ohm law.  So working with it and teaching it tend to make you remember it and better yet understand it.

Dan

[aviken]

Agreed Dan.

I am a visual person, and I remember by doing. It's that "a picture is worth a thousand words" thing I guess.
In fact I have a Trace charge controller / inverter I bought about 2 years ago with some Golf Cart batteries...which have since sat and gone dead...I often wonder if I could bring them back to life, or if I should give them away, etc. I have a true rms voltmeter, nothing to fancy, but a real one none the less. One of these days I'll try to get it all working or something. I had read the manual but got all caught up on the grounding of it. Something about bonding the ground to the neurtal if hooked to a generator, or grounding it at the box or with a separate ground. I tried hookin' it up once...couldn't get it to work...but I didnt try too hard...I was afraid I'd fry something....

Heres a pic of my batteries (4 x 6v)...I was wondering if I wired them in twos if I could charge them on my 12volt charger? I would like to see if I can get anything back out of these batteries...

Ken

[leitmotif]

Connect two in series.  I would only do two at first to minimize overloading charger.  If each battery is below 3 volt I would not hold my breath but you should have some idea if they will take a charge in two or three hours - if voltage drops from charge volt by half a volt right away BUT stays above where you started out you may be in luck.

After you get the first two up to about 13 14 volt add the other two.  If they have not been gassing you should be OK.  If they have been gassing do the connections outdoors or in VERY WELL ventilated area.  OR let first two "rest" and cool and charge second two - thinking on this is safer and preferable and the first two will have a chance to cool down.

WATER to the top of the cells ONLY.  The headspace above them WILL fill due to expansion from heat and gassing.
Your charger may have the option to do 6 volt also.

Dan

[StorminN]

aviken,

Those golf cart batteries of yours look pretty new. If they were not abused... ie., overcharged, shorted, swelled, etc. then you can probably recover them. What is their standing voltage right now?

I would second what leitmotif says, especially about not overfilling the cells... they just need enough liquid to cover the tops of the plates, no more... once they are charged, the level will come up. If you're going to add anything, just add distilled water, no acid! I would also add that if they were my batteries, I would charge them slowly... like 2A max and monitor their temperature. I don't agree with the popular auto parts store / service garage notion of "put 50A to completely dead batteries" to "wake them up". Yes, that boils the electrolyte and helps eliminate stratification, but IMHO, that's a good way to murder batteries.

Lead acid batteries left uncharged will self-discharge and develop lead sulfate on the plates, which diminishes the batteries' capacity. You can try wiring them in 12V pairs and charging them, and like Dan said, see how they react. If you're lucky, they will take a charge and you're OK... but what you probably really need is a desulfator... Google "desulfator" and check out the Yahoo groups and such that discuss them.

Desulfators are basically a little electronic box that you connect to your batteries. The theory is, the box has a circuit that generates pulses that resonate within the battery and "break up" the lead sulfate on the plates. Like anything else, there are good pulsers and bad ones. Some commercial models are complete scam rip-offs, just a box with a circuit that makes a light flash, put a 'scope on them, and you'll see that they don't even output a pulse. Other commercial ones do pulse, but don't put out much power, so they might be OK for maintenance of good batteries, but they're not much good for recovering sulfated batteries.

The simple home-made pulsers (desulfators) are usually based around a 555 timer circuit, you can find plans for these online, or buy a kit for about $60, or a completed unit for about $120. They are usually 1W in power and will recover about 2lbs of lead a day... so, for example... if your golf cart batteries are 60lbs each and you wire two in series (for 12V) for pulsing, that's 120lbs of lead, at ~2lbs a day, that's about 60 days to recover two completely dead batteries (less for batteries not so bad off to begin with)

A step up from the 555 pulsers are the pulsers based around a STAMP circuit... these are about 2W in power, and can include other circuits like dedendriting circuits and such. Last time I checked, the STAMP pulsers cost about $250 complete and will recover about 4lbs of lead a day... so 30 days for two of your golf cart batteries wired in series.

The cream of the crop of pulsers are the CIP pulsers (which are 120VAC powered), they are expensive and powerful... like $850 complete, and 50W in power and they will recover 20+lbs of lead per day, so two of your golf cart batteries would take maybe six days.

Both the 555 pulsers and STAMP pulsers are usually powered by the DC of the batteries themselves... so they require that you have a small, 1A or 2A NON AUTOMATIC trickle charger connected to the batteries while they are being pulsed. The trouble is, finding a NON automatic charger these days. Yard sales and eBay seem to be the best bet... find the old, metal case motorcycle battery chargers, and they will work. If you have really dead or big batteries (like the L-16's I had that read 0.2V) even the newer small, non-automatic chargers will trip off on an internal circuit breaker. The old chargers work better. The new AUTOMATIC chargers don't work at all, they get fooled by the pulsing and turn off or error out.

Finally, there are plenty of people that don't understand how these pulsers can work and therefore don't believe that they work. When you encounter this, ask them if they've actually tried one... I  assure you they haven't, they're just guessing... and most of these people have a vested interest... like they SELL batteries... of course they don't want pulsers to work, because you'll never buy batteries from them again. I'm here to tell you they work. I have a home-made STAMP pulser I bought... I've recovered 12V car batteries, big Trojan L-16's, and I recently loaned my pulser to a friend that has an EV with fifteen Trojan 8V batteries (T-890's?) in it. Those batteries have 5,000 miles on them and three of the batteries were getting down on voltage, weaker than the rest of the pack. My friend has since pulsed them individually, a weekend at a time with the STAMP pulser, and those three batteries now consistently show higher voltages than the rest of the pack.

P.S. - None of the pulsers will do any good with a battery that has a truly bad cell... an internal short, something where the battery has been physically abused... overheated, swelled, etc. Of course the pulsers work better (and quicker) on marginal batteries... those with a standing voltage of 10.5V or better for a 12V battery (or 5.25V or better for a 6V battery), than they do on really dead batteries.

P.S.2 - I've wired a few of those Trace inverters and charge controllers (I have a SW5548 and a C40 in my basement), if you need some help, let me know...

I hope this helps,
-Norm.

[leitmotif]

I am not sure about this pulsing to knock off sulfate.  THis seems to be a mechanical operation and in essence will lead to quicker battery depletion.  In a normal charge the voltage is raised high enough Temp Volt Gassing (ie TVG) (or in an equalization even higher) to give enough potential to drive the chemical equation backwards recharging the battery and removing most of sulfate.

Take a volt reading on each battery and let me know.  A dirty trick with automotive batteries where the inter cell connections are buried is to put a paper clip on each test lead and dip one lead into a cell and the other in the adjacent cell.  Does not matter if you get + or - readings on a digital meter just do all the same.  Now if one reading is opposite polarity then that cell is reversed and you may as well scrap the battery.  If you go from the post into the electrolyte on the first cell you will get about 1/2 cell voltage.

At the minimum get water over the tops of the cells and get them on charge.  The slower the better.
Watch the temperature - no more than 105 in any cell better yet 100.

It is awful hard to overcharge a lead acid battery you can only drive the chemistry backwards so far.  The major problem is overheating.  The one exception to this is when you are trying to desulfate one - takes a higher voltage and a long duration this is still sort of technically overcharging but that is what you gotta do to drive the sulfate ion back on the other side of the equation.  Watch your temps very carefully when you do this. 

Gonna take a few bucks to charge them before you know much.  But you have 2 to $300 worth of batteries there.
Oh yes after you get both seriesed batteries charge to around 14 volt let em cool and hook each set (two in series) in parallel and let em charge some more that will be about the best you can do to equalize all cells.

Dan

[aviken]

Thanks Dan & Norm,

This is great information!

So I went out to assess the damage...and the readings are very low. First I topped off (just covering the plates) cells with distilled water. Only 3 of the cells were already covered...the rest were all moist looking or a few were completely dry on top...I took readings on each battery separately, and they are about 1.3 to 1.8...one however, was showing only 0.34 volts. For the whole battery, not just one cell...I think that one is toast...but what the heck, I will try to see what I can do with them.

I put two in series, and put them on my auto-charger. It has a 2 amp, & 10 amp setting, with a 50 amp starting mode...I put it on 2 amps. It has 2 settings for type - I put it on low conventional low maintenance battery setting, as opposed to maintenance free deep cycle setting. They are pretty much deep cycle, but they are not sealed / maintenance free...so I picked the first one.

I don't have a "good" way to monitor battery temp...any advice on what I could get to do this (and inexpensively!) would be great.

Also, how long should I have the batteries on before I check them - see if they are taking any kind of a charge?

Why we are on the subject - I have a small trickle charger solar panel I use to keep some small 12 volt batteries topped off. I think it's only rated at about 1 amp...dont remember. My VOM shows it delivering 21-27 volts pretty regularily...my question is what function or test would I use to measure amp output? It's a small panel and I like to move it by hand to align see what different readings I get, and I was wondering how I could also measure the total output (not just volts, but amps, to get to total watts).

Thanks!

[leitmotif]

Also, how long should I have the batteries on before I check them - see if they are taking any kind of a charge?
QUESTION How much did voltage increase when you put them on charge??
I would check about 4 hours later then 8 after that.
To check temp use a glass thermomter (preferable)

Why we are on the subject - I have a small trickle charger solar panel I use to keep some small 12 volt batteries topped off. I think it's only rated at about 1 amp...dont remember. My VOM shows it delivering 21-27 volts pretty regularily...my question is what function or test would I use to measure amp output? It's a small panel and I like to move it by hand to align see what different readings I get, and I was wondering how I could also measure the total output (not just volts, but amps, to get to total watts).
REPLY  You can use the current function on VOM - if so equipped.  Generally this will go up to about 10 amp.  This will require hooking meter in series.  If you want to get near simultaneous current and voltage and not reconnect then you will need a shunt (about $25).  Be VERY careful when meking the connections and changing meter settings from volt to amps - you can depending on version blow the fuse inside - you will NOT find this at Home Depot - Grainger or Branom Inst - yes I know been there dun it.

Dan

[aviken]

QUESTION How much did voltage increase when you put them on charge??
ANSWER: If I remember correctly, the voltage showed 11.83...and was ticking upwards, a hundredth at a time....that was about 30 - 45 minutes ago. I just went out & checked again, it's now reading 12.4 (at the terminals, with the 2 amp charging in progress).

To use the glass thermometer, you mean just the ones with the mercury in side? Or do I need a specific kind, like one for candy / etc? I guess I would take the caps off and check the temp of each cell periodically, or just one cell per battery? Sorry for all the naive questions, but monitoring battery temperature, as much as I have been learning it is important, is something I've never done.

Ok, so my VOM is supposed to have a current setting, but I just don't know which one it is. It's from Home depot - the it's the Ideal 61-361 (http://www.mytoolstore.com/ideal/ide03-05.html)...by the process of elimination, I would guess that the dial should be set on ADC...but not sure exactly how to set up the probes...Ok, so if VDC is volts DC, then ADC would be Amps DC...Now it is becoming more clear...yeah, I'm a bright one....ok, seriously, so I have this solar panel, and I want to test the current....so how exactly would I do that again?

FYI, I'm thinking I only get 2 Amps...that's what the specs say...so if it's over that it'll knock the fuse out...but cool to know my vom has it atleast...