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Thanks for the battery video. Who can explain the following information that I’ve verified several times using a laboratory quality Fluke VOM?
I bought a new motorcycle battery by mail order and it was a modern VRLA battery. Valve Regulated Lead Acid battery, which is sealed maintenance free. I opened the box and my new battery with no load gave a voltage of 12.89 V. Great. Nicely charged as delivered. But I put it on my small 4 amp charger anyway, and the ammeter on the charger started near 3 A, but within a minute fell to less than 1 A. Which I consider normal behavior. Then with the charger in place, and pushing in less than 1 A, I took a voltage across the battery and was shocked to see 16.6 V. No typo, 16.6 V. I quickly took off the charger and measured the voltage across the charger with no load, which was 14.7 V.
And I repeated all the above two more times for verification.
How can the voltage across the charger when connected to the VRLA battery be 16.6 V when my charger only puts out 14.7 V at no load?
With a non VRLA battery, and the charger connected I see a hair less than 14.7 V, which is just what I expect.
So I took the VRLA battery out of my Accord, and same thing as the motorcycle battery, 16.6 V while charging.
What am I missing here guys? Where is that 16.6 V coming from? My charger doesn’t put out 16.6 V.
[quote=”Rereonehundred” post=129986]Thanks for the battery video. Who can explain the following information that I’ve verified several times using a laboratory quality Fluke VOM?
I bought a new motorcycle battery by mail order and it was a modern VRLA battery. Valve Regulated Lead Acid battery, which is sealed maintenance free. I opened the box and my new battery with no load gave a voltage of 12.89 V. Great. Nicely charged as delivered. But I put it on my small 4 amp charger anyway, and the ammeter on the charged started near 3 A, but within a minute fell to less than 1 A. Which I consider normal behavior. Then with the charger in place, and pushing in less than 1 A, I took a voltage across the battery and was shocked to see 16.6 V. No typo, 16.6 V. I quickly took off the charger and measured the voltage across the charger with no load, which was 14.7 V.
And I repeated all the above two more times for verification.
How can the voltage across the charger when connected to the VRLA battery be 16.6 V when my charger only puts out 14.7 V at no load.
With a non VRLA battery, and the charger connected I see a hair less than 14.7 V, which is just what I expect.
So I took the VRLA battery out of my Accord, and same thing as the motorcycle battery, 16.6 V while charging.
What am I missing here guys? Where is that 16.6 V coming from? My charger doesn’t put out 16.6 V.[/quote]
Likely because you don’t take voltage readings with a charger connected. If you want to check the battery, remove it from the charger and check it. The charger is designed to put voltage in, therefore it needs to be above the surface voltage of the battery in order to do that. That is likely the reason for the readings you got.
Solid video.
[quote=”Rereonehundred” post=129986]What am I missing here guys? Where is that 16.6 V coming from? My charger doesn’t put out 16.6 V.[/quote]
There are a variety of charging routines for lead acid batteries. Your charger may use a method that tries to maintain a constant current during the charging process, and the voltage is allowed to float (just a guess).
As the battery reaches its full capacity, it takes more energy to “squeeze” those last electrons back into the electrode plates, so the charger has to increase the applied voltage to maintain a constant charging current. I imagine the effort and finesse required to close the junk drawer as more stuff is added to it.
Your battery is new, and the specific gravity should be on the high end of scale. This is one of the reasons why the open circuit voltage is higher for a new battery compared to an older one. This also means that a higher voltage is required to charge a new vs an older battery. This might explain why you’re seeing 16.6V instead of 14.7V.
[quote=”Hanneman” post=130057]Solid video.
[quote=”Rereonehundred” post=129986]What am I missing here guys? Where is that 16.6 V coming from? My charger doesn’t put out 16.6 V.[/quote]
There are a variety of charging routines for lead acid batteries. Your charger may use a method that tries to maintain a constant current during the charging process, and the voltage is allowed to float (just a guess).
As the battery reaches its full capacity, it takes more energy to “squeeze” those last electrons back into the electrode plates, so the charger has to increase the applied voltage to maintain a constant charging current. I imagine the effort and finesse required to close the junk drawer as more stuff is added to it.
Your battery is new, and the specific gravity should be on the high end of scale. This is one of the reasons why the open circuit voltage is higher for a new battery compared to an older one. This also means that a higher voltage is required to charge a new vs an older battery. This might explain why you’re seeing 16.6V instead of 14.7V.[/quote]
I don’t really know, but I think my charger is a simple voltage device, and the current falls as the battery charges.
My open circuit charger gives 14.7 V, but when I put it on a VRLA battery it climbs to 16.6 V. More normally, when I put it on a conventional lead acid battery the charger’s output drops to about 13.7 V.
When Eric loaded his Fairmont battery the battery’s voltage dropped from 12.6 to 10.3 V. When I put any load on my charger (battery or bulb) it’s voltage output drops. Which I think is normal for any power source.
So why, when my load is a VRLA battery, does the charger’s (or battery’s) output go to 16.6 V? I sure don’t know.
Maybe some other’s can give it a try too and share the findings.
Nice Video & Good tips on battery maintenance! Good basic things to do periodically to keep everything operating well! Thanks!
A few related items….
I use to get corrosion on the battery terminals after a few years. Way back when (don’t ask…) the shops, when installing a battery, would spray some kind of sticky material (color of automatic transmission fluid) on the terminals to prevent corrosion. I see the point that too much of that could get down in between the terminal and the lug and create a problem.
Since then it seems like those red & green felt-like doughnuts have been placed on the lugs before the terminals have been placed. Am I correct in observing that those work well in keeping down the corrosion or with sealed batteries I’ve been sold a bill of goods? Seems like I have had those for years and the corrosion issue has been banished?
While we’re talking batteries – what about the “battery terminal disconnects?” If one is working on their car frequently do these make sense as an alternative to constantly pulling the terminal ends off? Is there a preferred style or brand?
Finally – Have seen some suggest that grounding is often an issue and thus it makes sense to replace the OEM wire with a lower gauge (thicker/beefier) cable? If so what gauge makes the most sense?
Thanks again for a great video on a topic just about anyone can do, but is important!
Great video. Lots to see there. Couple questions and feedback as well. Eric, you appear to do the same thing as I and use cheaper tools around batteries. I will not get my Snap-on stuff around acid. Thats what cheap tools are for. Where was the intro music with the organ riff ? I myself will not use bolt on battery terminal ends, they just fail sooner or later. Crimped on/Soldered on connections for batteries is the only way to go. One thing I think you should have addressed it the size of the battery vs the temperature vs CCAs. A low compression 300 ci motor will start with a fairly bad battery, where as a tight and fresh 454 cubic inch motor with higher compression and advanced timing will take much more amperage to turn over and requires a much healthier battery ( and this doesn’t show up with simple voltage testing.) It has been my experience that a car with a full carburetor bowl in good tune shouldn’t take more than a few cranks to get it running. If the engine sits for a day, or an hour, and takes 6 or 8 full cranks and hits on the battery further investigation should be done on the mechanical condition of the rest of the system. I consider a car fully tuned when it will start with no more than 2 hits on the starter, if not, and the battery is really pouring the coals to the starter, then something else is wrong. I started my oldsmobile 400 ci today after it sitting since thanksgiving, and after I filled the carb bowl with gas, a fully charged battery fired it after about 10 seconds. Before I even begin to crank, I make sure I can see fuel spraying out the accelerator pump.
I will not use the batteries amps cranking on the starter to fill a carburetor bowl with a mechanical fuel pump, its to hard on stuff
Eric, you missed or didn’t go into too much detail on sulfation. As far as charging, using a good quality desulfating battery charger can make the batter last significantly longer. If you are not going to be using your car for more than a couple of days, it should really be on a battery maintainer (desulfating battery charger). 
[quote=”Rereonehundred” post=129986]But I put it on my small 4 amp charger anyway, and the ammeter on the charger started near 3 A, but within a minute fell to less than 1 A. Which I consider normal behavior. Then with the charger in place, and pushing in less than 1 A, I took a voltage across the battery and was shocked to see 16.6 V. No typo, 16.6 V. I quickly took off the charger and measured the voltage across the charger with no load, which was 14.7 V[/quote]Ok – so for chargers, you want to be sure you are using one which is designed or has a mode for VRLA batteries (you didn’t mention which one you have – it will be either a gel cell or AGM – the former is common in smaller batteries, while the latter for larger) – while the basic electrochemistry is the same, the quantity of available electrolyte is different. Overcharging (going to voltages far beyond the normal charge voltage) results in gassing (water decomposition at the plates – basically making hydrogen and oxygen) – VRLA batteries have a valve to vent excess pressure, but can’t handle the water loss in the same way that a flooded battery can. Consider an AGM battery – you essentially have an acid starved system – there is pretty much just enough electrolyte to work – and it’s held in a nonwoven glass fiber fabric that separates the positive and negative plates – losing electrolyte results in improper acid concentration and availability and will degrade performance of the cell. (note – you always get some gassing when a battery is operating or being charged, and as long as there isn’t much, the VRLA battery can deal with it (they are recombinant batteries) – the normal gassing is why you don’t want an open flame around an operating battery – if it’s gassing, you can get a fire. Gassing is minor until you drop a cell in the battery, then it can be pretty significant because you are overdriving the remaining cells during charge – same thing that happens when you go to a real high voltage with any battery during charge)
VRLA batteries (AGM) are really nice in cars – you generally have a high surface area, so a high peak current delivering capability, and if the case is punctured (in an accident, etc.) they don’t leak or spill acid everywhere like a flooded battery.
Some comments on the video – surprised to see red wires being used for both positive and negative – I am sure that was what was available, and as long as you check the battery terminals before, say, giving someone a jump, there would never be an issue – but it’s sort of inviting trouble in the event someone jumps the car and doesn’t notice…
For checking the integrity of the terminals, I would suggest using the multimeter to measure the resistance of the connection from the terminal to the cable – you’ll only see a voltage if there is some resistance accompanied by a current drain of some sort (ohms law…) – interesting about the debris on the top of the terminal being conductive enough to allow you to measure a voltage! One thing – the discharge rate is going to be pretty minimal – you will be able to measure a voltage to the terminal if you have an even sort of ionically conductive path – you don’t have to pass current to get that. As soon as you try to pass current through the guck on the top of the battery, the IR drop through the guck will almost certainly consume any voltage you have available to support electrochemistry in the battery. (sort of the same thing as connecting the multimeter across the positive and negative terminals – the multimeter has a high impedance (resistance) in the same way the film on the surface of the battery does – but it lets you measure the voltage across all 6 cells without draining them (i.e., no real measureable current passes through the multimeter))
Checked my battery today, same exact one as in the video, and noticed a pretty significant surface drain right next to the cell caps. It was ranging from 5.2 to 8.4 volts depending on the spot. Took it apart and cleaned every inch of the surface with the usual baking soda/water solution. Hooked it back up and now I’m only getting a 4 volt drain in the same areas. Yay. Is there anything else I can try out to get rid of it?
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