I have boat lights that run off a 12v battery and i need to be able to tell how much battery life is left?

Question

I need to be able to just look over at the gauge and tell that the battery is 75% charged 50% and 25%, etc. This gauge will be in my boat. sorry for so many of these questions.

Answer 1

We use a Xantrex. It can be set up based on the batteries amps. It lets you know when you approach 50% of charge. You should NEVER bring your batteries lower than that. There are many makers on the markets. Make sure that it can be programmed for your needs. Most will be able to tell you Amps being used, Amp Hours, and Volts. If you are using batteries that need water added to them make sure that you follow a maintenance schedule. A good book to get is called the "The 12volt Bible for Boaters". by Miner Brotherton. I don't know what type of boat you have but this should help.

Answer 2

Well, you can actually buy a quantum charge meter, but they are a bit pricy. Your best bet is to buy a cheap DVM from Harbor Freight Tools (they sell them for $2.99 at times and I buy them by the dozen when they're on sale).

You will need to experiment a bit to make your own 'charge chart' by fully charging the battery and taking a reading, then run a 12 vold light for, say, half an hour and taking another reading and then continue doing this until the battery is pretty much dead. You can than take your readings and draw a pretty accurate graph of battery charge for your particular installation.

Answer 3

I will tell you the battery gages are a lot like gas gages. They show full for a long time then all of a sudden start dropping.

What I finally did to solve my problem in my boat was to put in another 12 volt battery and a switch so I can select either one. That way is I run the first one dead I have a backup.

Answer 4

get a volt meter and install it in the boats dash or where ever you need it

Answer 5

Ditto to Natives' answer.

Answer 6

You need an AMPERE-metre