We're having a boat surveyed. It has 2 4d AGM batteries with 400 Ah. The stickers indicate they are 5 years old (April 2015). What can a surveyor do to test the batteries or indicate the health of the batteries?
How to check out batteries
- Thread starter Scott T-Bird
- Start date
Scott, simple "truth": 5 years old, consider on figuring on replacement. You have no idea how the PO treated them. And 4Ds are heavy. No doubt you've read repeated suggestions to go to 6V golf carts. Even Grp 31s are lighter.
I had 2 4d lifeline agm batteries on my boat that were 8 years..... Still functioned well but at the end of their life primarily due to owner neglect. Did he/she plug the boat in every week? Try and find out a little of p/o habits.I switched to 4 6volt and am very happy so far.
As all have said a simple load test will tell a good story but not a complete one.
good luck
Greg
As all have said a simple load test will tell a good story but not a complete one.
good luck
Greg
The batteries are well into their middle age or later. When my boat was surveyed, all the surveyor did was power up the electrical system and checked the voltage. I doubt the surveyor will do much more than that. Plan on replacing the batteries sooner than later, especially AGMs as they don't like being in a PSOC for very long. You might ask the surveyor how he checks the batteries.
So, what kind of boat are you looking at?
So, what kind of boat are you looking at?
If he tries to tell you anything, regarding state of health for house batteries, with a "quick test", it's a mis-truth at best. A lot of surveyors think battery conductance testers are a reliable answer to battery state of health, but they are not..
https://marinehowto.com/are-battery-conductance-testers-worth-it/
Carbon Pile load testers test for cranking ability for starting batteries.
As others have said, at 5 years old, count on them as a replacement item.
I second Ken Cross recommendation of using an inexpensive load tester, given the age of the batteries. First check the analog needle readings against a know good battery (visual calibration). Second, charge the batteries to be tested and allow them to rest (no charge-no load)for 2 hours. Check them individually for voltage and flip the toggle switch to allow for load. Do the readings compare favorably with the known good battery or are the readings off? How do each of the batteries being tested compare to each other? Such tester will provide a "good enough" practical test to indicate if a battery is weak or bad. In my experience a battery that tests OK will be good for the next six months so re-test them every six months. A weak battery is just a good battery that will no longer hold its rated capacity, but as long as the remaining available capacity meets your needs then it is a good battery. If the test results for both batteries are not similar it means the weaker battery will bring the better battery down to its level and it also means it could cause charging problems, so if the readings vary widely I would replace both.