new battery for the generator

[vavet]

We have a 6 year old Generac 22kw whole house generator. I noticed the yellow light was illuminated on the side panel while i was mowing the grass over the weekend. The control panel indicated "low battery". I checked with my DVOM - 8.6 volts. Dropped it off at a auto parts store last night. They tested and said it was good, but needed to be charged. That seemed weird, but i left it with them to charge. They called me an hour or so later to say it tested negative.
I stopped in this morning to buy a new one. $120 later, I have a new battery that I'll install this evening when I get home. Don't want to get caught with a no-start generator when a big storm rolls through.

 

[65ranchero]

Have you checked that the trickle charger on the gen. is working?

 

[kelpaso1]

Like to know how they can test a half charged battery and say it's good?

 

[nadogail]

My 13 horse generator uses a $40 lawn tractor battery for starting. I bought the battery from O'Reilley auto parts.

 

[vavet]

Have you checked that the trickle charger on the gen. is working?

Good point. I'll fire up the generator this evening and make it's putting out. Thanks.

Like to know how they can test a half charged battery and say it's good?

I was wondering that myself, but they connected it to their magic box. Can't argue with the magic box!

My 13 horse generator uses a $40 lawn tractor battery for starting. I bought the battery from O'Reilley auto parts.

I was tempted...believe me, I was tempted. The generator manual calls for minimum of 500 CCA. None of the lawn mower batteries had that capacity.

 

[65ranchero]

Do you have a Interstate Battery near you ? They have "blems" that can be purchased for less money than retail
You may have to provide a old battery or pay a core charge.
I used to have one near enough to me but now have consolidated and moved 1.5 hrs. away.
how big of a engine? 500 CCA is pretty big for a small engine
Walmart is my go to now for batteries or Costco when I had a membership

 

[65ranchero]

Good point. I'll fire up the generator this evening and make it's putting out. Thanks.

There is most likely 2 charging circuits Standby and running .
The stand by is for when the unit sits not running so it can keep a constant current trickle charge to keep the battery in top shape.

 

[vavet]

There is most likely 2 charging circuits Standby and running .
The stand by is for when the unit sits not running so it can keep a constant current trickle charge to keep the battery in top shape.

Not sure I'm following....are you saying when the unit it not running, there's a constant trickle from the utility power through the generator, rectified to DC, and into the battery? I did not know that. I assumed one of the reasons it "exercises" weekly was to keep the battery fully charged.
The outgoing battery was 6 years old. I think that's a pretty decent life for a wet-cell battery.

 

[Bert_]

They have a trickle charger. The control panel is powered up all the time and will drain a battery in a week or less without the charger.

 

[mike93lx]

I bet it needs nowhere near 500 CCA, but they spec that to create headroom, as the application can be critical.

 

[Shiftless]

Like to know how they can test a half charged battery and say it's good?

Right!
Also, I thought that those whole house generators do an automatic weekly test run. 8.6 volts no load reading on a 12 volt lead acid battery is basically 100% discharged.
Better check the system.

 

[honcho]

We have a 6 year old Generac 22kw whole house generator. I noticed the yellow light was illuminated on the side panel while i was mowing the grass over the weekend. The control panel indicated "low battery". I checked with my DVOM - 8.6 volts. Dropped it off at a auto parts store last night. They tested and said it was good, but needed to be charged. That seemed weird, but i left it with them to charge. They called me an hour or so later to say it tested negative.
I stopped in this morning to buy a new one. $120 later, I have a new battery that I'll install this evening when I get home. Don't want to get caught with a no-start generator when a big storm rolls through.

6 year old lead acid battery? Totally due for replacement even if it tested good. Regular tests and proactive maintenance is the only way to make sure your equipment works when you need it.

 

[dcg9381]

Like to know how they can test a half charged battery and say it's good?

they can't.. They had to charge it for him then load test it.

I think generac recommends battery replacement every 24-36 months. 6 years is a darn good run on lead acid battery that sits out in the heat/cold. I believe mine has a "check battery" deal on the schedule.

Yes, these have a trickle charge circuit. Mine is setup to exercise weekly, I assume that they eventually fail enough so that the generator won't start, you'll get an error indicating such.

 

[65ranchero]

I agree with 6 years is about replacement time , however the weekly test cycle of 20 min. is not long enough to charge the battery to top capacity. Longer charging is needed especially in the cold months. So maintainer circuit is a good add-on
I also have a battery warmer option that sit under the battery

 

[dscheidt]

Like to know how they can test a half charged battery and say it's good?

With a conductance tester. The normal failure for lead acid batteries is build up of corrosion or sulphur on the plates, or shedding the lead from the plates. that reduces the conductance of the plates, and by measuring the impedence of the battery, you can get a good idea about the state of the battery health, independent of the state of charge, though the accuracy is better with a charged battery. It works very well, but it requires telling the tester the right parameters for the battery. If you tell the tester it's a 200CCA battery and it's really 500 CCA, it will give poor results. Some of the testers are also not good. Better testers measure the internal resistance, instead of, or in addition to conduction, but the principal is the same. (but the trend is opposite: internal resistance goes towards infinity as the battery fails).

It wouldn't surprise me to learn the clerk did the first test wrong, and after the battery charged, a real load test was done, or the conductance test was redone by someone who put the right numbers in.

 

[kelpaso1]

Hmm. good info. But testing a battery right after charging is not going to give accurate results. Need to let it sit for at least a day after charging before testing. These "smart electronic testers" are a gimmick to me. A good old carbon pile tester will show what's actually happening when a battery is "loaded" with 300-400 amps.

 

[mm08822]

Once the battery voltage drops below 12.1 vdc, it triggers the "low battery" warning.

From the service manual:
BATTERY CHARGER
The charger operates at one of three battery charging voltage levels depending on ambient temperature.
• 13.5 VDC at High Temperature
• 14.1 VDC at Normal Temperature
• 14.6 VDC at Low Temperature
The battery charger is powered from a 120 VAC Load connection through a fuse (F3) in the transfer switch. This 120 VAC source
must be connected to the Generator in order to operate the charger.

During a Utility failure, the charger will momentarily be turned off until the Generator is connected to the Load. During normal
operation, the battery charger supplies all the power to the controller; the Generator battery is not used to supply power.
The battery charger will begin its charge cycle when battery voltage drops below approximately 12.6V. The charger provides
current directly to the battery dependent on temperature, and the battery is charged at the appropriate voltage level for 18 hours.
At the end of the 18 hour charge period battery charge current is measured when the Generator is off. If battery charge current at
the end of the 18 hour charge time is greater than a pre-set level, or the battery open-circuit voltage is less than approximately 12.5V,
an “Inspect Battery” (Nexus) or “Charger Warning” (Evolution) warning is raised. If the engine cranks during the 18 hour charge
period, then the 18 hour charge timer is restarted.

At the end of the 18 hour charge period the charger does one of two things. If the temperature is less than approximately 40 ºF
the battery is continuously charged at a voltage of 14.1V (i.e. the charge voltage is changed from 14.6V to 14.1V after 18 hours). If
the temperature is above approximately 40 ºF then the charger will stop charging the battery after 18 hours.
The battery has a similar role as that found in an automobile application. It sits doing nothing until it either self-discharges below
12.6V or an engine crank occurs (i.e. such as occurs during the weekly exercise cycle). If either condition occurs the battery charge
will begin its 18 hour charge cycle.

Every generator annual PM that I do, each battery gets electrolyte gravity checked and the battery load tested.
I have seen some fail just after 2 years and know many that are going 6-7-8 yrs.
Some companies change them out at 3 yrs w/o ever checking anything.
I am comfortable at 5 yrs with testing annually.

Those that have been early failures were each sitting on heating pads!

 

[AP514]

I am sure there is an "Electrical Diagram" for your generator. it will show if there is a trickle charge circuit.

 

[justsam]

I would look into replacing the lead/acid/AGM with a lithium phosphate chemistry.

 

[Davefr]

For a whole house generator I'd use an Optima yellow top battery. I've never had one last less then 13 years. I'd also recommend a lithium jump pack to have on hand.

 

[mike93lx]

For a whole house generator I'd use an Optima yellow top battery. I've never had one last less then 13 years. I'd also recommend a lithium jump pack to have on hand.

Modern yellow tops are not the same as the old ones. New ones are generally regarded as ****, plus that isn't the right application for a deep cycle.

 

[mjeff87]

I replaced the battery in my 20K unit at 8 years. It was still fully charged/functioning, but I figured it was probably a good idea to put a new one in, all things considered LOL. I still have the old one in the garage.

OP, did you replace yours yet? If it's anything like mine, it will seem physically impossible to get the old battery out and the new one in with the way the cabinet is designed. There's one little angled bracket you can take off, and then gently pry the outside cabinet away and you can wiggle it through. Trust me, it will even though it seems it won't (assuming you purchased the same series/size replacement).

 

[vavet]

I replaced the battery in my 20K unit at 8 years. It was still fully charged/functioning, but I figured it was probably a good idea to put a new one in, all things considered LOL. I still have the old one in the garage.

OP, did you replace yours yet? If it's anything like mine, it will seem physically impossible to get the old battery out and the new one in with the way the cabinet is designed. There's one little angled bracket you can take off, and then gently pry the outside cabinet away and you can wiggle it through. Trust me, it will even though it seems it won't (assuming you purchased the same series/size replacement).

Yes, I replaced it with a 526R size battery I got from Autozone...the same size that came out. I didn't have any issue with it going in or out.