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Won’t start? How to know if you need a new battery

Alright so today on Repairs101 I’m going to talk to you about what you need to know about how to determine whether or not the battery in your car or your boat or whatever needs to be replaced. I’ll show you the tools the mechanics and the other pros use in order to make that determination for you. And I’ll show you how to use them yourself.

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This episode of Repairs101 was made possible by Princess Auto. If you saw my last episode you saw this cool camera mount I found at Princess Auto. I went back and I found this great flexi monopod clamp and a Gorilla style mini tripod. I’ll tell you: I got so much use out of these things just shooting the video you’re watching right now that I’m going to go back and get a couple more.

First things first

OK the first thing you want to do is determine the age of your battery. Hopefully someone completed the “Date Installed” decal on yours. I’m pretty sure this battery is original so like my car it’s eleven years old. Which may be all you need to know to convince you to replace it. Next look at the condition of the battery and the cables attached. A swollen case is the sign of a sulfated battery. Neutralize spilled battery acid with baking soda and water.

OK you’ve got to get yourself a Digital Multi-Meter if you don’t already have one.

Can it be boosted?

Now a lot of people will go ahead and just try to jump any dead battery they come across. But that would be a mistake. Attempting to charge or boost a dead battery may result in the battery exploding.

The next test to perform is the Voltage Drop Test across the battery terminals under load of the starter. Anything less than ten volts is a fail. Now if you have more than ten volts you can try and jump it with another vehicle or a spare battery or a booster pack. Just remember the ground goes on last and comes off first. Do not allow the positive lead to ground against the car. Maybe make sure everybody stands back so they don’t get sprayed with acid if the battery pops when you throw the key. OK? If it boosted easily and you’re reading fourteen volts or more then you can drive it. But just don’t stall it because you may need another boost. Some batteries are maintenance free and have no serviceable parts. If you try to open one of them you’ll probably find it very difficult to close it again. On the other hand some batteries are user friendly and all you have to do is pry off some caps to access the electrolyte.


So I snapped together my new scaffold and set it up beside my neighbor’s boat so I could safely haul out his starter battery and two six volt golf cart batteries. So I used my hydrometer to check the specific gravity of the electrolyte in every cell.

Load testing

OK the last test is a load test done with a carbon pile load tester. You want to apply half the cold cranking amps or three times the amp-hour rating for fifteen seconds. Without seeing it drop below nine point nine volts.

These are six volt deep cycle Golf Cart Batteries. But I use this pigtail I made to chain them together to make a twelve volt battery. And that way I can charge them together at the same time.

Ok if you do decide to replace your battery – once you’ve figured out what size and power rating you want – check out Princess Auto, they will probably have what you’re looking for charged and ready to put into service. Alright make sure the new battery is secure in its home without being too tight before attaching the positive leads first and the negative or ground /black leads last. Action. Alright thanks for watching and don’t forget to subscribe and if you found today’s video informative – please, hit that thumbs up button.

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