NovaKool gremlins - input DC voltage low

[km1125]

Source of the post

It's what we call the tester I linked to since it is simply a heating element that gets red hot just like a toaster when activated

Gotcha - I didn't see any link though. I'll Google it. Thanks!

It's funny. I didn't see the link or picture either, until I went back and tried to quote the post, then the link showed up.

The "toaster" test really is just something to put a known large load on the battery, then it just measures the voltage while the load is there. It's a good snapshot of what the battery can deliver but not an all-encompassing test. It doesn't really measure battery capacity or cranking capability, but guesses at those based on the loaded-down battery voltage. The battery does need to be fully charged (or nearly so) to get a decent reading. You also have to let it cool down between subsequent tests to get an accurate reading. They also only are intended for larger batteries, like car or boat batteries.

The digital battery testers actually measure the internal resistance of the battery. That's a better measurement of what's going on inside the battery and using that they can pretty accurately gauge the cranking amps and overall capacity. I have an older version of the Harbor Freight one and I've been (pleasantly) surprised at how good it's been at estimating battery condition. These do not need to 'cool down' between tests and the battery does not need to be fully charged to test, although it won't work if the battery is very depleted. These can be used on any size lead-acid battery, from big 4Ds down to small tractor or even the little batteries that go into the kid's electric jeep.

An example of the battery "toaster" testing device:

battery toaster.jpg

[KyleR]

Thanks for the clarification! Definitely inexpensive enough - plus I don't have to lug these batteries out and back to the boat to have them tested at an auto parts store! My back thanks you!!

[KyleR]

I wanted to follow-up on this thread to give an update on something I discovered. So many people chimed in with great suggestions and recommendations - some I was able to try, others I haven't gotten to yet. We are still making our way down the east coast towards the Florida Keys so projects sometimes get deferred - especially if you can make a safe and effective work-around!

Anyway, one of the comments someone made came to mind:

The other thing I wondered about is if perhaps some of your activities changed.

What I have come to realize is that the TEMPERATURE has changed! We started off in Wildwoods, NJ in November - pretty chilly! And it remained pretty cold most of the way down until we got to the Florida area. Even when we were at Jekyll Island, GA for Christmas we had temps in the 20's!! So guess what - we were running the generator for around 3-4 hours at least twice a day. Sometimes longer and more frequently! We love our heat!!

Anyway, once we got into a warmer climate we started running the generator just a short time - maybe 30mins to an hour a few times a day. Just enough to cook, make some coffee, charge our electronics, etc. But never any long sustained period.

So, right after my last post, that got me thinking maybe I should try running the generator like we had been doing - 3ish hours in the morning and the same at night. Lo and behold, our refrigerator is now operating like it was when we bought the boat. It's been going 10+ hours between battery charges and not cutting off once. And I'm sure it would go longer but we have been typically turning off the generator by 10pm and then up at least by 8am making coffee. So 10 hours is about all it sees on DC only.

For reference, when we were only partially running the generator the refrigerator wouldn't even last 6 hours without cutting itself off and thawing out! Basically it appears I was never running the generator long enough to get the house batteries fully charged.

Anyway, I'm sure there are other electrical gremlins that I need to go after to optimize my DC consumption, but for now, this "fix" is both effective and safe and lets us keep on cruising!!

Thanks again to all who contributed!!

[bud37]

So it seems that you were running the bank down and not allowing enough time to recharge the bank properly. Fyi it takes many more hours than you think to get a battery bank properly topped off....that is where the Victron bmv like devices come into play....

Really all your banks should be getting charged as you cruise along, so long as you choose the right battery switch selections. Engine alternators are some of the best ( efficient) battery chargers going.