Battery fluid levels?

[311Hemi]

So, I am usually really good about maintenance on everything I buy but somehow I never checked the fluid level in the batteries of the boat I bought last year (first boat, never done it before). I checked them last night and found that the two trolling motor deep cycles were about 1/2" low but still above the plates. The starting battery fluid level was lower and was just even with the top of the plates, yet exposing the top just a little. It also looked a little frozen, but that may have just been a little fluid on the top of the plate that I was seeing. I do plug them in and charge them once a month with the on-board charger.

I am curious if I could have damaged or decrease the life of any of these batteries to the point that I may need to look at replacing or testing them before open water is here?

If so, is there a way to test them with a multimeter?

[Macgyver55]

The main thing is that the water is/was above the plates. If it was they should be ok. Fill them to the proper level before charging with distilled water. Testing needs to be done on a fully charged battery.

A multi-tester will tell little about battery condition, mainly just its voltage. A load test is a better indicator of battery condition.

[BobT]

McGyver quite right.

[Whoaru99]

I leave my OB charger plugged in most of the time, year 'round. Last set of batteries lasted 8 years and they were just plain old Stowaways, nothing fancy.

In addition to being sure the battery fluid is not low, you want to be sure they're not overfull. Don't want that nasty stuff coming out of the battery.