Alternator Charging

[Kettlewell]

You'd be surprised, a lot of marine electronics are fine up to 15.5 volts or more. Some can handle up to 32 volts!

[goboatingnow]

Originally Posted by wolfaroo

I'm not trying to be a PIA, honestly! But please check this info... His alternator reg IS working!

Nearly all modern automotive-type alternators output a FIXED 14.4v. Some output 14.8v. Some older type output at 13.8v, but this is often considered too conservative and will reduce the battery capacity. Whilst charging, the voltage across the terminals will increase. Initially the difference between the terminal voltage & alternator voltage will allow current to flow into the batteries. As the terminal voltage increases, the voltage difference lessens and just a trickle charge flows to keep the batteries topped up.

In order for the trickle charge to overcome the battery resistance and flow from the alternator to the battery it is recommended that the charging voltage be at least 20% higher than the battery (12v + 20% = 14.4v). This will not damage your battery. Many solar/wind regulators will output at 14.4v-14.8v too.

OP - 14.6v is within normal levels and will remain fixed while your engine is running and will not destroy your batteries.

YES an external step charger/reg is much better for charging/managing DOMESTIC batteries in the long term - NB during absorbtion stage of charging voltage may be as high as 15.5v.

Obviously there is another debate about how much longer your batteries will last with ext reg v int reg, BUT a standard alternator will do just fine for most requirements.

Finally, long-term battery deterioration as a result of using a standard alt reg is generally the result of REGULARLY supplying too much current too quickly during the early phase of charging very FLAT batteries, not from continuing to apply a constant voltage after the batteries are fully charged.

I hope this clears a few things up.

I'm sorry so much of this quote is electrical nonsense.

Firstly there isn't a difference between alternator and battery terminal voltage. They are connected together hence no voltage difference. Current flows into a battery for different electrical reasons. ( see various pieces on battery chemistry and battery resistance. )

Secondly there's no 20 % rule for trickle charging.

Thirdly 14.4 is allmost the max voltage and is very close to the gassing point. 14.8 is certainly Above it and anything greater will cause significant and excessive gassing and loss of the electrolyte.

Modern car regulators are not designed for battery charging they are designed to provide all the cars electrical power when running. The output around 14v I've never seen 15v car regs ( see gassing)

Once you stay at 1/20 C or less you can regulary put high currents into battery banks. Float voltages should be typically 13.5 to 13.8 and no higher. Batteries will be damaged by the continuous application of much higher voltages.

All chargers of any capacity should sense battery temperature.

Dave

[donradcliffe]

I agree, Wolfaroo should go back to battery school. His advice will damage your batteries unless you are operating in very cold climates. Charging at over 14.1 volts will kill gel batteries in a couple of hours, and over 14.4 will destroy maintenance-free batteries in less than 24 hrs.

Why did the OP replace a sophisticated external regulator with an internal regulator in the first place?

[Maine Sail]

Originally Posted by goboatingnow

I'm sorry so much of this quote is electrical nonsense.

Originally Posted by goboatingnow

IModern car regulators are not designed for battery charging they are designed to provide all the cars electrical power when running. The output around 14v

Does this make more electrical nonsense...

I have a dumb one on our boat that puts out 14.4v and three cars that all put out 14.4v. Worked on a Yanmar alt yesterday that was putting out 14.3-14.4V. The current crop of alts on Universal/Westerbeke engines also put out 14.2-14.4.

Many older alts put out under 14v and they will chronically undercharge your batts but if you have one that can do 14.4v it can do a fine job of recharging a battery but you will not have any temp compensation.

Dumb regulators basically do two things, 1- full field the alt when not at the voltage limit 2- Limit voltage when they have reached the voltage set point. Smart or dumb regulator on the same alternator both set to the same absorption voltage will charge at nearly identical times. Done this test on my own boat and replicated it in my shop. A failed Balmar reg forced me to re-install the "dumb" reglator and when I began noticing zero performance difference I began investigating it further.

Actually spent an entire Saturday at a buddies alternator repair shop throwing alt after alt on the 30k test machine and running up the load. Plugged Balmar and Heat Interface regs into one alt and compared them to the dumb reg again same amp outputs. Most every alt I tested put out between 14.2-14.6, though most were about 14.3-14.4. When loaded up every alt produced the rated amperage no matter that they had "dumb" regulators.. Full field is full field whether applied to the alt from smart reg or a dumb one.

Millions of trucks, tractors, industrial equipment and cars run dumb regulators every day of the week. My wife's 2003 Pilot has its original battery with 140k on it. It charges at 14.4 volts all day every day. That is 8 years o dumb charging and 140k miles.. Our boat is an even better story....

[wolfaroo]

Originally Posted by goboatingnow

I'm sorry so much of this quote is electrical nonsense.

Firstly there isn't a difference between alternator and battery terminal voltage. They are connected together hence no voltage difference. Current flows into a battery for different electrical reasons. ( see various pieces on battery chemistry and battery resistance. )

Secondly there's no 20 % rule for trickle charging.

Thirdly 14.4 is allmost the max voltage and is very close to the gassing point. 14.8 is certainly Above it and anything greater will cause significant and excessive gassing and loss of the electrolyte.

Modern car regulators are not designed for battery charging they are designed to provide all the cars electrical power when running. The output around 14v I've never seen 15v car regs ( see gassing)

Once you stay at 1/20 C or less you can regulary put high currents into battery banks. Float voltages should be typically 13.5 to 13.8 and no higher. Batteries will be damaged by the continuous application of much higher voltages.

All chargers of any capacity should sense battery temperature.

Dave

ok i will go back to battery school - the lynch mob hath arrived!

I may be wrong - I'm not the oracle [yet] but I was taught the info stated above by a family friend who imports new and refurbishes old 12v lead acid batteries for a living and has done for years and years. We call him Mr Battery!!! haha.

And if I am wrong then surely car batteries would be failing up and down the country all day long? In fact, why on earth would car manufacturers use the current crop of alternators at all if they were so harmful (and why hasn't anyone designed a new less damaging one?).

BTW a little gassing is healthy for your battery.

Anyway, I will now happily return to battery school and will report back here with my findings.

...And I thought 12v would be such a black & white, scientific, mathematical topic!...

[wolfaroo]

Originally Posted by goboatingnow

I'm sorry so much of this quote is electrical nonsense.

Firstly there isn't a difference between alternator and battery terminal voltage.
Dave

Battery school stated:
"the alternator needs to generate a larger voltage than the battery's rated voltage to overcome the internal resistance of the battery. The current needed to recharge the battery would not flow at all if the car alternator output voltage was the same as the battery. Therefore there is a voltage difference between the two"

Sources: How Does An Alternator Work - Charging System Alternator - Alternators Defined
and www.carbasics.co.uk,

[conachair]

Originally Posted by wolfaroo

After switching off the engine, isolate the battery and wait for >3 hours before reading battery volts, to avoid higher readings caused by surface charge. This should give you an accurate battery state. Depending on battery type & temp etc, expect a reading of between 12.8v - 14.1v.

You might find you need to wait a lot longer than that....

Measuring A Lead Acid Battery State of Charge Photo Gallery by Compass Marine at pbase.com

Not really practical on a boat.

[wolfaroo]

Originally Posted by goboatingnow

Thirdly 14.4 is allmost the max voltage and is very close to the gassing point. 14.8 is certainly Above it and anything greater will cause significant and excessive gassing and loss of the electrolyte.
Dave

"the absorbtion voltage is typically around 14.2 to 15.5 volts"

"Charging at 15.5 volts will give you a 100% charge with Lead-Acid batteries"

"flooded batteries MUST bubble (gas) somewhat to ensure a full charge, and to mix the electrolyte"

sources: Deep Cycle Battery FAQ
and The 12volt Side of Life (Part 1)

[Rossmonty01]

another factor to take in to account is the length of cable to the battery and then to the electronic device. Sufficient to say around 15V charging the cable voltage drop would lower the volts to around 14.6 generally speaking.
My boat has a battery set close to the anchor winch and it has its own alternator and its set a 15.5 Volts and is 9 meters from the charger.
Each situation has to judged on it own. Automotive Alternators are designed to slow the charge after about 20 minutes reguardless of the voltage so other external regulating methods have to be used. A lot of lay people have experienced their own situation and its just not the same for each installation.
Rosso

[goboatingnow]

Originally Posted by wolfaroo

"the absorbtion voltage is typically around 14.2 to 15.5 volts"

"Charging at 15.5 volts will give you a 100% charge with Lead-Acid batteries"

"flooded batteries MUST bubble (gas) somewhat to ensure a full charge, and to mix the electrolyte"

sources: Deep Cycle Battery FAQ
and The 12volt Side of Life (Part 1)

This is nonsense at normal temperature the absorption voltage is approx 14.4 ie 2.4v per cell. It's nowhere near 15.5.

All battery manufacturers provide limits to the length of time absorption charging should take. They do not recommend that that voltage be impressed continuously.

Any sealed , VRLA or " maintenance free" types and especially GELs cannot be charged at the gassing point. As electrolyte and hence battery capacity will be lost permanently. With accessible cells a certain amount of gassing can be tolerated provided that regular watering takes place. It is not necessary to regularly stir the electrolyte to get 100%

Nobody charges normal temp lead acids at 15.5 volts nobody .

Car alternators provide 100% of the running power in your cars system charging the battery is secondary. Most car batteries are only lightly discharged as the AH for car starting is tiny.

Keep studying. ( ps what's a battery " reference voltage" , a SI version of terminal voltage maybe!!)

Dave

[wolfaroo]

Originally Posted by goboatingnow

This is nonsense... Nobody charges normal temp lead acids at 15.5 volts nobody
Dave

im here to learn so will happily accept your view on this. But why are there so many sources that mention 15.5v, including manufacturers? Can they all be wrong?

[four winds]

I have one of the typical Scheafer smart chargers for use on my cars and motorcycles.

When connected it first shows percent of charge and voltage, then one selects battery type and charge rate and it takes it from there. Stops on its own when 100% is reached.

I almost freaked the first time I noticed the display reading 16.7 volts during charging. This occurred for several minutes near the end of the charging process.

Actually I have two of these chargers and they both exhibited this behavior on a few different batteries, all of which are still good batteries. I just don't drive or ride enough anymore. (I have too many vehicles)

So there is at least one person who charges at this seemingly elevated voltage, for what it's worth.

Also, for some reason the "red line" on a typical car's in-dash voltmeter, if equipped, is at approximately 18 volts.

[DeepFrz]

im here to learn so will happily accept your view on this. But why are there so many sources that mention 15.5v, including manufacturers? Can they all be wrong?

Search back through all the chaff in the battery threads and look for posts by btrayfors and rick if you want to learn.

Also go to the Trojan web site. As far as I remember the 15.5 volts is for equalization, not regular charging.

[barnakiel]

Originally Posted by DeepFrz

Remember also that your electronics are connected to the batteries while they are charging. I don't think you want 15 volts and higher at your expensive plotters, radios, etc. even if it is cold.

Good point. I know some accept higher voltages without issues, but definitely one has to look up the specs and be sure!

b.

[Kettlewell]

14.4 volts is the normal maximum Bulk Charge voltage, whereas 15.5 volts is the maximum Absorption voltage for Interstate lead-acid deep cycle batteries. See this chart from Interstate batteries. So at least some batteries do recommend some charging up around the 15.5 volt range. My recommendation would be to go with the regimen recommended by the particular battery manufacturer. Just for example, a lot of GM cars came with alternators with a 14.8 volt set point to accommodate the lead-calcium no maintenance batteries the cars came equipped with that could also withstand the higher voltage. And, on the other side of the coin, most gell cells don't want to see more than about 14.1 or 14.2 volts to prevent gassing and electrolyte loss, which can't be replaced.