The Stovebolt Site Forums The Shop Area The Electrical Bay Battery charger question

My battery charger is 42 years old and since we have had several batteries die recently I did a test on it. The battery voltage is raised to 12.8 on the low setting and to 16.1 on the high setting. The battery doesn't boil or stink during the normal high rate charge time of 30 minutes. Could the high charge rate for that amount of time kill battery life? I know that rate would be bad for one held there for days at a time but don't know about a short interval. Anyone else ever put a volt meter on a battery during charging and if so what was the reading?

12.8 volts is actually low compared to what the alternator is putting out. most batteries are charged at about 13.4 - 13.8

Take the following with the appropriate grain of salt.

While tinkering with my 70 340 Duster this week I checked my factory shop manual on alternator output, it showed a charge voltage of over 15 volts at max output.

I've always believed a longer,lower voltage/amp charge was better for long battery life but I suspect in the real world charging a battery at 16 volts for 30 minutes that had the correct level of electrolyte ain't going to hurt anything. That voltage I do believe will boil the electrolyte if left too long, so I'd definitely check it before charging.

JMHO

RonR

I have known fellow classic car and truck owners who have charged up their batteries many times and at a quick charge due to them not checking their batteries until them wanting to go to the car show with it.. I never knew one of them people who said that their batteries did not last long because of fast chanrging,, but a couple have said that they make sure the room is well ventilated because of the off gasing that occurs from getting the battery hotter when charging faster.. I use a 2 amp slow charge and it takes avout 24-30 hours to charge the battery up.

I use HF battery tenders on anything that will be sitting a period of time.
About 6 bucks on sale each and have not had any issues yet.
Once the battery is 5 or so years old, it's time for a new one.
https://www.harborfreight.com/automatic-battery-float-charger-69955.html

Don

My last battery was an Optima and it lasted 13 years and they are sealed so no outgassing. I use a maintainer on them from time to time.

I've had really good "luck" with the batteries in my old vics. The "one year" el cheepo battery in my Binder was 9 years old when it quit taking a charge. The battery in my plymouth is now 5 years old, but it has a parasitic drain, so I keep a HF trickle charger on it most of the time, since it will kill the battery in about 2 days without it. I've forgot to hook it up at least a dozen times in the past 2 years, and the battery keeps on re-charging. ( since i have my garage space back, maybe I'll find time to figure out what is causing the drain ).


When the battery in my Jeep started to "fail", I bought a new one, and put the old one in my trailer to run the electric jack. I also keep it on a trickle charger, and it's been fine for over a year now.

Back on topic, maybe? I've always tried to use a charger with enough voltage settings to allow a slow charge in the 10-15 amp range, and a quick charge capability of 40 amps or a little more. The state of charge of the battery is entirely responsible for how much voltage is needed to achieve a particular charge rate. A very low battery will take a 30-40 amp charge at around 13 volts or a little more, while 14.5 volts or more will be needed to push 10 amps into a fully-charged battery. The more voltage settings the better, but I like chargers with at least 5 or 6 charge rate options. A "Starting Boost" rate of 100 amps is also a good thing to have available, but don't use it for battery charging.
Jerry

I have had the same charger for close to 40 years. Just a simple 10 amp charger with both 6 and 12 volt settings. Nothing fancy but it gets the job done. I use it on just about everything from car, rv and lawn tractor batteries.

John

I have half a dozen battery maintainers, two shoe box sized 6-10 amp 6 volt-12 volt chargers that are 30+ years old and one 4 level charger including 100 amp boost for the heavy work. Seldom use the big boy but it's nice to know it's there if needed. The higher charge rate on your charger will not hurt for short periods, just don't forget it's on there. My large charger instructions actually say if the battery is almost completely discharged put it on 100 amp boost for 2 minutes before reducing to a lower charging rate to bring it the rest of the way up.

Back when I was messing with impressionable young minds on a daily basis, we spent close to a week of classroom time on battery design, chemistry, charging, and maintenance. There's a lot going on inside a battery, chemically and physically, and it's really necessary to have a good understanding of what's happening to make an informed decision about how to go about bringing a battery to full charge and keeping it there. That's particularly true of one that doesn't get "cycled" regularly. On a vehicle that sits idle more than it gets driven, it's a good idea to partially discharge and then recharge the battery at least once a month. Turn the headlights on for an hour or so, then connect a low-rate charger overnight. That keeps the chemistry going, and prevents "sulfation" which will drastically reduce a battery's cranking capacity and ability to take a good charge.
Jerry

To answer your actual question:
If your charger is the type that controls the rate and shuts down automatically, then you are OK. "The battery voltage is raised"...I assume means that during charging, the battery reads 12.8V and 16.1V. This is normal but, charging at 16.1 for long periods is bad. 30 minutes is not long. That's why you need a charger that tapers down automatically as it senses amperage. A fully charged battery is 12.4-12.6 Volts. It sounds like your charger is operating normally. 16V is peak charging rate for most chargers and will "equalize" and stir up/knock off sulphation. But 16V for long periods is no good as you said. You did not say what the battery reads after charging with charger disconnected. 12.4-13.4 ?

The only effective way to monitor a battery's state of charge is to measure the specific gravity of the electrolyte. Voltage readings are nothing but a SWAG by people who don't understand much about battery functions. Sealed-top batteries with no way to monitor the acid concentration or add water are for people too lazy to test the gravity, so checking the open circuit terminal voltage is the only way to make a somewhat educated guess about what's going on. Depending on the strength of the acid when the battery was manufactured, a specific gravity between 1.250 and 1.265 is full charge. Continuing to force current into a battery once the gravity in all the cells stabilizes just evaporates water and overheats the cell groups.
Jerry

Yeah, but anyways, my answers have been graded by the entire Stovebolt staff as a "B" and yours an "H"...so who's smarter? Bingo!....me.

Noticed a coupon in the Sunday paper today where the floating charger/maintainer is $4.99 with coupon if anyone is interested.