Higher Voltage: Fool Your Alternator?

My experience: If you totally discharge an automotive starting battery (by doing the D.S. thing of leaving the lights on, for example) even though it appears to take a recharge, you might as well replace it! If you dont, you will be replacing it within six months, anyway.
 
Hi again,

Yes i agree. I always check my lights now and of course take voltage readings as soon as i get into the house. If the lights are on, the battery will discharge much much faster so i'll know right away because i'll see the voltage readings going down fast.
 
This is what I know.

  • Anything more than 14.2 will boil electrolyte faster and produce H2 outgassing. 14.6 will be quite audible from outgassing The rate rapidly increases above 14.5. and 15V is very risky long term without ventilation.
  • Temperature makes a big difference with over voltage and one can expect a battery to last 1 year in Arizona to 10 years if properly maintained checked for cell balance and fluid level while regulated 14~14.2 and well-sized for application.
  • Most will last 5 yrs and they have cut plate thickness to save costs on cheaper batteries which causes much variation in experiences.
  • If H2 concentration in surrounding air exceeds 5% it has reached the threshold for easy ignition or the lower explosive limit (LEL) ( risk increase with concentration level.)
  • Higher temperatures and Charge voltage will indeed increase battery capacity and lower ESR which raises CCA, both at the expense of rapid aging.
  • Desulphation works well for cars in hot climates or infrequently used. It also works well for $10k motive power applications. It doesn't fix warped plates or antimony contamination. We used to make the Solartech product and I verifed the effects of 20ns pulses with S.G , ESR and CCA . It only used < 5Watts of power when the alternator was running but 10A peak trigger the lead sulphate crystals to breakdown like ultrasound on kidney stones and it really pissed off truck drivers how it interfered with AM reception between cities... but it works to prevent and also restores.
  • AS plate thickness is reduced ESR tolerances increase which the only cause for cell mismatch when new @1%. This increases with erosion and causes wider tolerances and ultimate failure in a series string of 6 cells
  • Aging is also accelerated significantly by permanent chemistry changes if fully discharged and worse again if overcharged
  • you can fool your alternator and make your battery work overtime, if you dont mind replacing it more often, due to one bad cell mismatch being accelerated or you can stick to conventional wisdom and make your battery more reliable.
 
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This is what I know too.

Batteries are some of the hardest things to understand. I have stuffed up car batteries and tractor batteries by taking them into Deep Discharge...they don't like that. Take them there once and they are never the same again.

No matter what you do thereafter with charging etc...they will not be 100% after that.

I have a little PP3 project that is ongoing. Rechargeable PP3's. One of the most vulnerable things to look after in use and when charging.
So far so good. Project initiated 2009....to date no Battery losses. Batteries worn out and Capacity lost yes...after many hundreds of cycles.

I just thought I should say that.

Regards,
tvtech
 


Hi there,

Thanks much for your input here too.

So you are saying that you believe that 14.6v would be pushing it then?
I will check into this again soon with simple experiment: charge the battery using 14.6 volts and see what happens. What i think happens is it charges fairly quick with a decent current level and then the current goes way down. Last time i did this was a few months ago but back then the power supply i was using had a voltage adjustment problem where it would change by itself due to bad pots, but they have been replaced now. It made it hard to do any real careful experiments.

The friends car charges at 14.55v but mine doesnt want to go over about 14.0 volts, maybe 14.1 volts sometimes. I found that if the battery is older it has higher series resistance, so if it charged at say 14.0 volts when new it wont charge very well at 14.0 volts when older, or at least it will take a LOT longer to charge up to a decent level. If i drive the car a short distance it barely charges, but a longer distance and it charges better (although still not as well as i would like). I noticed this because the voltage drops faster with no load when the charging time is reduced. In fact with only a little charging time it will drop back down to the same low level it was before the charge in only 24 hours, while with a longer charge time it will hold that voltage up higher for a much much longer time even though the battery is old now. It's unfortunate that i cant say what the higher voltage charge level was because of the faulty power supply, but i will be able to repeat that experiment soon. Whatever it was though it must have been 14.3v or higher because the resting voltage was up around 12.6v for the first time in a long time, and stayed there until used again.
 
MrAl said:
...So you are saying that you believe that 14.6v would be pushing it then?...
Click to expand...
Tony seems to have missed that battery makers reformulated the plates of starting batteries by adding Calcium in about the 1990s. If you went and measured a bunch of new cars at the dealer's lot, you would find that they will show between 14.5 and 14.7V.
 

Hi,

That's what i was beginning to think too based on your posts, what else i read on the web, and the measurements of the other car.
I have seen readings as low as 12.1v on a battery resting which would be low, but that was a casual reading which may have been fudged just to show the meter for sale. The sites that seem more reliable always have 12.6v, and the battery charging with 14.6 or something like that.

We also need a good timeline on the addition of calcium because i am finding articles that say that this could have been as far back as 1935 which means that cars 1970 and older should surely have the 'new' battery type and thus the slightly higher voltage.

Maybe Tony can add to this a little more.
 
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Yes I agree with most of what has been said in this thread based on experience also .
Mostly never flatten a car battery. Its like the guts come out and hard as you push back in it just will not go back in. It stays as a surface charge only , there is no inner force ever again no matter what you try.
Two interesting things though , I have been messing about with aluminium sulphate solution (pickling solution in the states) and using it in batteries instead of sulphuric acid .

Its been in 2 working batteries for more than 12 months and the batteries which were pretty well buggered when I changed fluid are now seemingly improving . Its on an LED night security lights setup , two 12 V lead acid car batteries in series to produce 24V for the 100 watt LED spotlights. 80V solar panel connected direct.About 1 amp at best.

Second is I had an E type Jag when they came out with the V12 in 1976. Mine was new but 6 cylinder and it had a lucas regulator in it which charged at 14 . 6 V and it regularly boiled the electrolyte and acid spilled out down the passenger side inside of the bonnet . i got it fixed and on sold the car but I was pretty pissed off at the time . Eats into the finish.
 
Hello,

Yes that is interesting. So my suspicion must have been right, that the batteries being made today are too different to be used in every car made today.

That's the fault of the battery industry then, who dont care because if people have problems with their batteries who benefits? THEM of course. They get to sell more batteries.

As far as the article, i have charged several batteries under more controlled conditions now (extremely well regulated and carefully set voltage and current monitoring) and have found that there is NO way that a battery is going to over heat when charged with a certain VOLTAGE. I emphasize 'voltage' here because heat does not come from voltage alone, it comes from the product of voltage and current. Therefore we can not specify a given voltage alone we must specify at least one other quantiy that allows us to calculate power, because power is what causes the heating effect.

What have i seen? At 14.4v i see less than 1 amp flow into the battery at that point That's less than 14 watts, and in a BIG package like an automobile battery the surface area of the battery and thin case would never let it get hot or even warm for that matter, and this is exactly what is observed: not even warm after charging for several hours under that condition.
If this was a small TO-5 transistor with metal case i would say 14 watts needs a heat sink. But for a big battery the surface area should be more than enough to dissipate the heat fast enough to keep it from getting hot, or even warm to the touch. That's exactly what i had observed with two types (and sizes) of automobile batteries. Once was smaller and one was bigger, but not one of them got hot or even warm to the touch.

Would it get hot with more current? I bet it would, but because of the internal characteristic of the battery it wont draw too much current at a mere 14.4 volts.
Do i have to pay attention to ambient temperature too? I would think so. If the battery got colder outside then it would draw more current at the same voltage, but that's a known issue too so the charging system should know about that, and it does, it brings the voltage down as the car heats up. The problem is, it starts out too low and then brings it down even lower. That's just plain stupid, unless you like to sell new batteries for profit...then it's money in your pocket doing something that could be called fraud.

From what i have seen in the past it appears that the batteries do charge a little, but because they dont charge up all the way they end up working at only about 1/3 to 1/2 of full capacity. This would make winter cold starts harder.
To observe this behavior, all that is needed is to catch the low point voltage level when the car is turned over in the winter time. When the battery is fully charged, the voltage will dip down to maybe 10 volts, but when the battery is not fully charged it can go down to 8v which is a lot lower for this type of battery.

I cant say here what i would say to the battery industry if i had the chance to say anything i wanted to.
 
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So, it really looks like the batteries should have a "customization module" attached to them. That way batteries could actually be matched to the charging system/
Or the OBDII scanner system (the expensive ones) have something else to do: set the float voltage.
There isn't much difference in the float voltages, but there is a major performance (i.e. lifetime) hit.
 
Hi,

Yes, or just an adjustable alternator. I considered modding my older car's alternator but got rid of the car first.

I dont know if any one remembers, but the very old 'generators' with separate 'regulator' was adjustable. Now they think they know too much for that or are just trying to force people to buy new batteries. As time goes on, things just keep getting dumber and dumber.

Future long range space travel? Yeah right, they cant even get a simple charging system to work right.
 
i've been browsing this thread, and was going to ask why the alternator voltage in cars seems to have crept up every so often, this answer makes sense. when i was young, the voltage listed in service manuals was 12.6V (recommended charging voltage was 2.1V/cell), and these days seems to be approaching 15 ( a charging voltage of 14.7 yields 2.45V/cell). it would make sense that it's related to improvements in battery chemistry.
 

I respect mike's opinion a lot... but i have regenerated batteries to 75% of AH ratings with that exact problem in an overnight fashion. Which then lasts another year or so. But I operate in a tropical environment so winter issues do not exist.
 
Correct charging Voltage for lead acid batteries is between 13.7 to 14.1 Volts.
Battery at rest is 12.6 Volts.
I have used lead acid batteries under those for 8 - 10 years in diesel vehicles with no issues at all.
And fit the largest battery which fits and good clean connections is a must.
 
RODALCO said:
Correct charging Voltage for lead acid batteries is between 13.7 to 14.1 Volts.
Click to expand...
Not really, or rather the charge voltage depends on usage and charge cycle stage.

For a permanent "Float" charge, where it's a backup type system and rarely loaded, around 13.8 is fine.

For a cyclic use where batteries are being run down then re-charged, the "ideal" correct initial charge voltage is near 15V.
After the charge current has dropped to a fairly low level, then the voltage can be reduced to 13.8 to maintain the battery condition.
(In all cases with a current limit appropriate to the battery ratings, to prevent excess charge current).

eg. https://www.chargetek.com/assets/threestage.jpg
Note the voltage reduction to float state.

As cars etc. are a semi-cyclic system they seem to use somewhere around 14.5 - 15V as a compromise.
 
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