Optima Sealed 6V Battery On Stock Generator System

[Guest kencary]

The previous owner of my 1951 Pontiac 8 installed a 3-cell optima redtop 6V battery. The battery has plenty of cranking amps, but I am concerned about using this on an old generator system.

Do any of you out there have an Optima on an old electrical system?

I use Optimas on my modern cars and I love them, but I have 2 main concerns with it in my '51.

1. Since this is a non-vented battery, I can't add water. These batteries are designed for hold a ceratain amount of pressure in a modern system with a well-controlled charge voltage, but these batteries will vent and dry out if charge voltage is too high.
   
2. Though the Optia has lots of cold cranking amps, it does not have much capacity. This is especially true of the 3-cell 6V battery. When I am idling with the lights on, my ammeter indicates a discharge. I am worried about how long the Optima can carry the car through such discharge cycles.
   

Any real experience that you can share would be very helpful.

Ken

[Guest Fitz]

Good question.

The only experience I have with battery outside car, is from electric lift truck. You can have all kind of battery for your lift truck, liquid cell to gel cell. Tubular, flat plate.

All those batteries require the right charger to go with. If you mix charger, you will have problem like overheat, sulfating, not enough charged etc.

I think about those optima battery would be the same. If they are constructed differently (other technology), they are probably built first for alternator (more common).

For me I would use the same thinking as the electric lift truck batteries, all batteries don't use the same kind of charger.

With generator, no optima for me, unless you have the approval of the battery manufacturer.

Fitz.

[DavidMc]

I have had 6v Optima batteries in 2 1920's Packards for about 6 years now and they are still OK. Both cars sit unused for months and the batteries usually have enough charge to start the car. I charge them with a self regulating charger when I think of it. Ideally I should have 2 of those chargers and leave them on at all times.

Initially I was charging them with an old style non-regulated charger and I had no way of knowing when they were charged and I overcharged one which bulged the top cover a little. It has been going fine for years since then.

The other problem is that if they run flat you cannot charge them with a light charger, they need to be put on a garage type charger with a high amperage for a few hours.

They seem to outlast the old lead acid batteries which goes at least some way to offsetting their high cost, about 2.5 tmes the cost of a convential battery here in Australia.

They are popular amongst the people I know with old cars and I have not heard any criticism.

David

[Guest simplyconnected]

I have no love or hate for the Optima. They ARE lead-acid batteries and they are rated in amps per hour (amp/hours). Further capability reveals cold cranking amps; the number of amps a new, fully charged battery can deliver at 0° Farenheit for 30 seconds, while maintaining a voltage of at least 3.6 volts, for a 6 volt battery.

Optima's are wrapped like a capacitor (in a coil) rather than having flat plates. That is why each cell is round, not square. Other than that, NO difference.

Wrapping in a spiral saves space, so they offer more amp/hours for the same size package than a conventional battery. The voltage IS IDENTICAL because the number of cells is the same. Two volts per cell applies to all lead/acid 6-volt and 12-volt batteries.

Optima's are 'maintenance free' which means they recycle condensed water. Are they vented? If they weren't, fast-charging and fast-discharging would make them explode. They're vented kinda like your radiator cap.

Your generator was made for a lead/acid battery. These batteries are no different. Discharging is a function of your charging system, not your battery. When your idle is too low, the battery still feeds your field, regardless of armature speed. When your generator output voltage drops below your battery voltage, that little red "GEN" light shines. That's why the light is on before you crank the engine.

Optima batteries work equally as well with an alternator or a generator. They just store power at the rate they are charged, up to their amp/hr rating (saturation). Of course, an alternator puts out more power at lower speeds, but that has nothing to do with the battery's capability to store.

If your car came with an 800-amp/hr battery, and someone replaced it with a 500-amp/hr, that's not the battery's fault. The numbers don't lie. Get a bigger capacity battery. - Dave

[Guest kencary]

I have no love or hate for the Optima. They ARE lead-acid batteries and they are rated in amps per hour (amp/hours). Further capability reveals cold cranking amps; the number of amps a new, fully charged battery can deliver at 0° Farenheit for 30 seconds, while maintaining a voltage of at least 3.6 volts, for a 6 volt battery.

Optima's are wrapped like a capacitor (in a coil) rather than having flat plates. That is why each cell is round, not square. Other than that, NO difference.

Wrapping in a spiral saves space, so they offer more amp/hours for the same size package than a conventional battery. The voltage IS IDENTICAL because the number of cells is the same. Two volts per cell applies to all lead/acid 6-volt and 12-volt batteries.

Optima's are 'maintenance free' which means they recycle condensed water. Are they vented? If they weren't, fast-charging and fast-discharging would make them explode. They're vented kinda like your radiator cap.

Your generator was made for a lead/acid battery. These batteries are no different. Discharging is a function of your charging system, not your battery. When your idle is too low, the battery still feeds your field, regardless of armature speed. When your generator output voltage drops below your battery voltage, that little red "GEN" light shines. That's why the light is on before you crank the engine.

Optima batteries work equally as well with an alternator or a generator. They just store power at the rate they are charged, up to their amp/hr rating (saturation). Of course, an alternator puts out more power at lower speeds, but that has nothing to do with the battery's capability to store.

If your car came with an 800-amp/hr battery, and someone replaced it with a 500-amp/hr, that's not the battery's fault. The numbers don't lie. Get a bigger capacity battery. - Dave

You are partially right about the energy density of the spiral system. Yes they pack slightly more capacity per volume in each cell than a prismatic (flat plate battery) but because of the empty space between the wound cells, most Optimas have slightly LESS capacity in Ah than a flooded, flat plate battery that will fit in a given battery tray. What Optimas do have is a lower internal cell resistance which gives more cold cranking amps. They also have a lower self-discharge rate which makes than ideal for cars that sit in garages for al long time. An added advantage is that the tightly wound plates makes them less susceptable to shorts due to flakey plates. They also tend to survive deep discharge better.

An Optima is a type of VRLA or Valve Regulated Lead Acid Battery. This means that within reasonable charge conditions, the cells will not vent. This is similar to what people generically call "gel cells" (actually a trade name for another type of VRLA battery.

The above vent system is what raised my concern.

I contacted Optima tech support and they verified that these batteries WILL in fact vent and dry up if the charge voltage is too high. That being said, I checked my charge voltage with a DVM and it is well below the max given by Optima.

You would be wise to check your charging voltage with a meter before using an Optima.

Here is the reply Optima sent me:

Hello Ken

An Optima RedTop battery can be discharged to 0% state of charge and recharged successfully about 80 times. Dimming lights would indicate discharge as you mentioned but it should be a fairly shallow discharge. This will shorten the life of the battery but not as significantly as if it were deeply discharged. To avoid this you may want to consider installing a 2nd battery. Wiring a 2nd 6V will double your reserve capacity which will give you more run time and will discharge each battery less than the one by itself. Also, assuming this isn't a "daily driver", I'd recommend keeping it on a float charger/battery maintainer when it's stored to ensure when you do drive you are starting with a fully charged battery.

Voltage of a fully charged Optima 6V is 6.4V. Your charging system voltage should range between 6.85 and 7.35.

I don't have any application notes specific to those older cars, however, I can say I know many people with them.

Thank you,

Amanda

Optima Customer Service

Despite this information, I wanted to hear from actual users and based on what DavicMC posted above, I feel confident that I am OK here.

Ken

Edited December 13, 2009 by kencary (see edit history)

[Guest simplyconnected]

I AM an optima user.

What is your question? Is it about max charging voltage? If so, you never asked about that.

The support team affirmed that charging too fast, discharging too fast, or over charging, causes the plates to gass-off. ALL lead/acid batteries work that way. If the optima's venting rate is exceeded, the battery could dry up. I didn't hear a word about plate sponge, which is were the REAL action takes place.

Your generator probably outputs ~35-amps at full armature speed. Your regulator points simply open and close the Field current, allowing full armature/no armature current cycles, until the battery gets to ~7-8 volts (depending on regulator ambient temperature). Believe me, neither your generator nor your regulator care about what kind of battery they charge. (They could be NI-Cad, Ni-mh, Lithium Ion, or lead-acid batteries.)

...If your car came with an 800-amp/hr battery, and someone replaced it with a 500-amp/hr, that's not the battery's fault. The numbers don't lie. Get a bigger capacity battery. - Dave

The support team advised you to put two batteries in parallel. Isn't that the same as replacing with a higher amp/hour battery? It sure is.

The reason I'm not too hopped up on Optima is the cost. BTW, trucks use lots of batteries in parallel, but they are in MATCHED SETS. One shorted battery will bring the others down. Same goes with Optimas; if you put two together, they need to be the same age. - Dave

[Guest kencary]

I AM an optima user.

What is your question? Is it about max charging voltage? If so, you never asked about that.

The support team affirmed that charging too fast, discharging too fast, or over charging, causes the plates to gass-off. ALL lead/acid batteries work that way. If the optima's venting rate is exceeded, the battery could dry up. I didn't hear a word about plate sponge, which is were the REAL action takes place.

Your generator probably outputs ~35-amps at full armature speed. Your regulator points simply open and close the Field current, allowing full armature/no armature current cycles, until the battery gets to ~7-8 volts (depending on regulator ambient temperature). Believe me, neither your generator nor your regulator care about what kind of battery they charge. (They could be NI-Cad, Ni-mh, Lithium Ion, or lead-acid batteries.)

The support team advised you to put two batteries in parallel. Isn't that the same as replacing with a higher amp/hour battery? It sure is.

The reason I'm not too hopped up on Optima is the cost. BTW, trucks use lots of batteries in parallel, but they are in MATCHED SETS. One shorted battery will bring the others down. Same goes with Optimas; if you put two together, they need to be the same age. - Dave

Dave,

My question is very simple, and I don't think you looked at my orginal post.

The question is whether anyone can tell me if they have real world experience with the Optmia in an old 6V generator system.

I really don't need technical information as Optima provided that to me. If you wish to discuss battery chemistry and VRLA technology, feel free to PM me as I have spent 30 years in the battery/DC power industry, but this type of discussion would be boring to most people.

Over these many years of working with all kinds of battery technology, I have come to learn that there is a certain amount of Black art in batteries. It is for that reason that I ask actual users about their experience with these Optima batteries in old cars. Nothing beats experience and this forum is the best way to find it.

Ken