Generator Battery Going Dead

[ultramegabob]

I spoke with the battery factory (SBS)about testing the battery. They said to fully charge disconnected from gen. It should read about 13.7 volts and loose about .2 volts per day. That is exactly how it tested so I assumed the battery is good.

Most of the car parts stores around here will do a load test on a battery for free.

 

[zog]

Would not surprise me either. But I have a 2000 ford diesel truck with it's original batteries still starting every day.

Big difference, your truck batteries get deep cycled every day, these generator batteries just sit and sulfate for 3 years.

 

[hurk27]

Has it been removed from the generator at some point and stored on a cement floor for any length of time?QUOTE]

Many years ago, wet cell batteries had a rubberized case, and would absorb the lime from the concrete, lime is an alkaline which will neutralize the acid in the battery. it has been a long time since rubber has been used in the battery cases, so this is an old carried over story, not a myth as it was true at one time.

 

[zog]

Testing

Testing

Have not seen much for testing, besides a ICV test, which dosent tell much. Impedence testing will tell you true condition of your cell. SG would also be a good indicator of charge condition. Look at the EBITE system from megger, or hire a testing company to do it for you.

 

[hurk27]

Big difference, your truck batteries get deep cycled every day, these generator batteries just sit and sulfate for 3 years.

It's actually the fact that the truck battery has been kept at full float level for most of it's time that leads to longevity of a battery, deep cycling a battery will shorten it's life, as will leaving a battery sit around with not a full float charge on it. a good charger that maintains a full float without over charging will preserve the battery the best.

 

[mivey]

I don't know, but it is a good sized battery, 33 amp hours...

I was just curious as to the drain on the battery when the generator was just sitting. Was the 0.2 volts you mentioned with the battery disconnected or with the system idle?

Does the generator provide the re-charge when running?

 

[mivey]

It's actually the fact that the truck battery has been kept at full float level for most of it's time that leads to longevity of a battery, deep cycling a battery will shorten it's life...

That would be my thought. If you are deep cycling your truck batteries, you've got problems.

 

[mkgrady]

I was just curious as to the drain on the battery when the generator was just sitting. Was the 0.2 volts you mentioned with the battery disconnected or with the system idle?

Does the generator provide the re-charge when running?

The .2 volts drop per day is disconnected and sitting on a work bench after receiving a full charge. With the battery connected and the system idle it draws a small current. That small current drops the voltage to about 8 over a three week period. So I assume it is a few milliamps. The meter I had with me did not have a DC amp function.

The generator has two built-in chargers. One is a trickle charger that runs off constant AC. It is built into a large, expensive circuit board that monitors and controls the generator. This one seems to not be functioning. The second charger is from the engine itself, but of course this only runs once per week for 15 minutes during the exercise cycle. Not enough to keep the charge up.

 

[mivey]

The .2 volts drop per day is disconnected and sitting on a work bench after receiving a full charge. With the battery connected and the system idle it draws a small current. That small current drops the voltage to about 8 over a three week period. So I assume it is a few milliamps. The meter I had with me did not have a DC amp function.

The generator has two built-in chargers. One is a trickle charger that runs off constant AC. It is built into a large, expensive circuit board that monitors and controls the generator. This one seems to not be functioning. The second charger is from the engine itself, but of course this only runs once per week for 15 minutes during the exercise cycle. Not enough to keep the charge up.

It might be interesting to see the idle drain. Did you measure any charger output after you replaced the rectifier?

 

[mkgrady]

It might be interesting to see the idle drain. Did you measure any charger output after you replaced the rectifier?

I did not but it would have been zero output because the charging rectifier was from the engine not the trickle charger from house power. I did not know this when I installed it. If I had I would not have replaced it. I got some bad advice from tech support when they suggested I replace the rectifier. Today tech support suggested I replace the $300 circuit board. Instead I installed a seperate smart trickle charger

 

[brian john]

Has it been removed from the generator at some point and stored on a cement floor for any length of time?.

CEMENT HAS NO EFFECT ON BATTERIES. Self discharge as they sit on ANYTHING is detrimental.

In addition HEAT is more detrimental than cold in the overall life of a lead acid battery.

Not talking about freezing.

 

[Cold Fusion]

Zog -
You usually have pretty good answers - but this one
quote=zog;1082553]---SG would also be a good indicator of charge condition. ---[/quote] Tough to do with sealed cells.

quote=zog;1082553]--- Look at the EBITE system from megger, or hire a testing company to do it for you.[/quote] Hire a testing company for a $50 battery?? Are you sure this is a good idea?:roll::-?

cf

 

[brian john]

Zog -
You usually have pretty good answers - but this one
quote=zog;1082553]---SG would also be a good indicator of charge condition. ---

Tough to do with sealed cells.

quote=zog;1082553]--- Look at the EBITE system from megger, or hire a testing company to do it for you.[/quote] Hire a testing company for a $50 battery?? Are you sure this is a good idea?:roll::-?

cf[/QUOTE]

Checking SG, voltage, charging amps, and utilizing a portable resisteve load bank ( Small portable hand held)

AS for testing generator batteries I have several contracts and other no contract calls every year to test generator batteries.

When you have millions a minute resting on a multiple engine start, batteries are WORTH MAINTENANCE.

Batteries, fuel and with newer units the bloody electronics number one two and three starting issues.

 

[Cold Fusion]

Hire a testing company for a $50 battery?? Are you sure this is a good idea?:roll::-?

cf

AS for testing generator batteries I have several contracts and other no contract calls every year to test generator batteries.

When you have millions a minute resting on a multiple engine start, batteries are WORTH MAINTENANCE.---.

I installed this Briggs & Stratton 10KW generator 3 years ago at a residence. I have been doing the yearly maintenance ever since

Brian -
You also usually have pretty interesting posts. However, "millions/minute?? Considering the first post, the subject is not about a quartz oven for silicon fabrication it's a .... :smile::smile:

cf

 

[Cold Fusion]

---When you have millions a minute resting on a multiple engine start, batteries are WORTH MAINTENANCE. ----

I've never worked on a "millions/minute" process. Hummmm - Just thinking about the economics of the design:

Interesting they would depend on starting a gen to keep the losses down. If they are waiting on a black start a gen, that's a 30second down time to get it running and on line. That's a million dollars. More for the second one - have to sync it.

Almost seems like they would have on-line spinning reserve or an inverter backup.

I suspect one would check the utility statistics. Say the utility averages only one 5 minute outage per year, spinning reserve would be way too costly, but an inverter wouldn't be. Say 5MW for 15 minutes - 1.25MWH. Now that would be a battery bank - and yes it would need maintenance

cf

 

[Doug S.]

Testing the battery

Testing the battery

The trickle charger may be the problem, but with a bad battery it doesn't really mater much. As we all know having multiple variables makes for a moving target. I'd nail this one down.

A 40w 12v bulb ( Available at a local big box), makes a decent tester.

IIRC you mentioned this was a 55ah battery, in theory it should be able to run a 40w bulb for 16 hours.
(3 1/3 amps into 55ah is approx 16.5 hours right? It's been a while so correct me if I'm wrong)

I wouldn't suggest seeing if the light stays on for 16 hours, but connect it for a few minutes. If the voltage dips below 10v after a minute or two you probably got a weak cell. If it dips a few volts immediately you've got a bad cell.

OR you could just take to an auto parts store, and let them load test it...
SO what I'm trying to say is a no load test is bunk.

Can anyone re-charge my weak recollection of load testing a battery? The simple formula for batteries I just can't seem to remember. I'm pretty sure there are a few bad cells up there so retention seems to be an issue for me.

Doug S.

 

[techntrek]

The trickle charger may be the problem, but with a bad battery it doesn't really mater much. As we all know having multiple variables makes for a moving target. I'd nail this one down.

A 40w 12v bulb ( Available at a local big box), makes a decent tester.

IIRC you mentioned this was a 55ah battery, in theory it should be able to run a 40w bulb for 16 hours.
(3 1/3 amps into 55ah is approx 16.5 hours right? It's been a while so correct me if I'm wrong)

I wouldn't suggest seeing if the light stays on for 16 hours, but connect it for a few minutes. If the voltage dips below 10v after a minute or two you probably got a weak cell. If it dips a few volts immediately you've got a bad cell.

OR you could just take to an auto parts store, and let them load test it...
SO what I'm trying to say is a no load test is bunk.

Can anyone re-charge my weak recollection of load testing a battery? The simple formula for batteries I just can't seem to remember. I'm pretty sure there are a few bad cells up there so retention seems to be an issue for me.

Doug S.

For a field test you need to remove the surface charge on the plates, so you need to use a large load (20% of amperage rating) for a few minutes. Since this is a sealed battery and the best option isn't available (checking the specific gravity of the electrolyte) just measure the voltage. There is a strong correlation between voltage and capacity with a lead acide battery. Measure the voltage under load, and the voltage after the load is off. There are charts you can find online that tell you the acceptable ranges but in general under load a 12V battery shouldn't ever drop below 10.5 volts.