Following up - As part of our monthly generator PM, we checked battery specific gravity, water level, charger errors/voltage and current, generator control panel errors, fuel day tank level, engine oil level. If I remember correctly, the PM was assigned to both mechanic and plant electrician.
Data Center managers demand 100% uptime, so generator starter batteries are not a place where you might look to save on your maintenance budget.
Questions:
1) What size are your generators? What voltage?
2) Are they all sync'ed in parallel?
3) Are your starting batteries 6 or 12 volt? Deep cycle or standard duty?
4) You said 4 starting batteries. Are they wired in series or parallel/series combination?
5) Do you ever run the generators with a load (load bank or switched online with a data center load)?
Our company demanded 100% uptime, but the installation had issues from the get-go. We improved our uptime as we resolved the issues one at a time, gradually increasing our uptime rate. The manufacturing plant had UPSes to handle the power outage to generator. We also found several UPS sync settings there were fine while running on the grid, but largely incompatible while running on generators.
It's a challenging environment where the application demands 100% uptime, but resolving downtime issues requires testing under real-time conditions. The two are in direct conflict with one another. We were required to notify the IT group and anyone else who might be affected by a shutdown, so they could get the supported load in a safe state, just in case testing brought forth the intermittent flaw we were working to resolve.
I might even have a job plan somewhere. More later.
------------------------------
Jeff Wahl
Maintenance Manager, CMMS
Loveland CO
------------------------------
Original Message:
Sent: 12-12-2019 03:25 PM
From: Jeff Wahl
Subject: Diesel generator starter batteries life
Hey there Lee - I was on-call 24/7 for years with one of my previous employers, both as Lead Maintenance and Troubleshooting Electrician and then Electrical System Engineer. We were in the business of injectable drug manufacturing, a business heavily regulated by the FDA. We had up to 10 diesel generators in back-up power service. Depending on which building the generators were backing up, the 2 MW generators ran in parallel or or stand-alone. They also backed up data centers as well as instrumentation, PLCs and critical electrical loads. I learned many lessons during my tenure there.
Now I work in the Arctic Science Program for the National Science Foundation. The sites we support are off-the-grid, and the generators are rated for Primary Power (as opposed to Stand-by Power). Primary Power Generators vs. Stand-by Power Generators in-and-of-themselves are their own learned lesson.
I have a meeting coming up, but will check back later to expand on those two subjects.
Best regards,
------------------------------
Jeff Wahl
Maintenance Manager, CMMS
Loveland CO
Original Message:
Sent: 12-12-2019 08:43 AM
From: Lee McClish
Subject: Diesel generator starter batteries life
Thank you very much Terry. FYI, we run the generators monthly for about 20 minutes till up to operating temp. Then annually load them and test for about an hour. So not run much, which some log only around 15 hours/year. This doesn't help extend the battery's life.
------------------------------
Lee McClish
Manager, Maintenance and Reliability
Raging Wire
Ashburn VA
Original Message:
Sent: 12-12-2019 08:08 AM
From: Terry Taylor
Subject: Diesel generator starter batteries life
Hi Lee,
Through the many years in mining we fought several battles with batteries on our mobile mining equipment. From that experience, here is what I would suggest
1. Make sure you are buying the best batteries you can buy for your application. This in one place you do not want to go cheap.
2. If using lead-acid batteries you definitely want to be checking the water level and checking specific gravity. BTW - 1.265 at 80F is the specific gravity you are looking for in a fully charged battery. Follow the safety rules when doing this!
NOTE: You might want to consider going to maintenance free batteries. We made the switch to Group 31 maintenance free batteries and it was very successful but our application was continuous use.
3. Not sure what the "running the generators 30 hours annually" actually means but you want to be sure to exercise your generators on a routine schedule for several reasons. Certainly one of those reasons is to make sure your batteries have a sufficient charge to start the engine.
4. If the batteries have a low specific gravity and/or they will not start the engine, put an automatic charger on the individual battery(s) as needed. Recheck specific gravity after charging and replace if it's not up to spec. You can also apply a load cell to the batteries as a secondary check before condemning a battery.
5. Lots of opinions about water in batteries. You can use distilled water but tap water works as well. The one thing you absolutely do not want to use is de-ionized water. That is the kiss of death in a battery.
6. Lastly, I would recommend that you create a battery charging station. This can be very simple but it is very important when you are depending on having good batteries at all times. If you have a battery charging station, if you suspect a bad battery, simply retrieve a battery you know is good from your battery charging station, swap it out with the suspect battery and your generator is good to go. Take the suspect battery to your battery charging station, rerun your tests, attempt to charge it and then condemn it at that point.
Hope this helps!
------------------------------
Terry Taylor
Senior Consultant
IDCON INC
Raleigh NC
t.taylor@idcon.com
Original Message:
Sent: 12-06-2019 09:08 AM
From: Lee McClish
Subject: Diesel generator starter batteries life
We are a Data Center and have over a hundred Diesel generators. Each has 4 starter batteries. Cummins recommends replacing every 2-3 years. One thought is just do it as the cost of these batteries is small compared to potential downtime. But there is a back up set. With running the generators up to maybe 30 hours annually, these batteries should last longer. There should be savings to be had. Does anyone take specific gravities or use a battery meter to check cold cranking amps or another method to determine when the batteries should be replaced? They are lead acid type. Same concept for many applications - forklifts, trucks, vans, etc.
------------------------------
Lee McClish
Manager, Maintenance and Reliability
Raging Wire/NTT
Ashburn VA
------------------------------