It depends on how much you want to spend. You want to get a tester that checks the battery under load. There are all sorts of selections for 12V battery load testers from $40 all the way up $200. I have an old hand held Snap-On load tester, but by now those are prohibitively priced. Harbor Freight as a couple and there are a bunch on Amazon, so look at reviews for quality issues. And if you have a wet cell battery with removable caps that allow you to refill the water/electrolyte, a battery hydrometer will tell you the electrolyte specific gravity and state of charge for each cell and quickly give you a heads up on a bad cell and a soon to fail battery. Those are inexpensive to purchase.

If your battery is a sealed maintenance free version or an AGM battery, load testing is your only option since resting voltage alone will not tell you if the battery has internal issues. But the best thing you can do is maintenance, by keeping the battery connections clean and tight. If the battery is older, then testing will help you keep ahead of an inconvenient failure if you begin to notice cold starting problems or cold sluggish cranking.

 

Do they make a battery Test / Charger in one device? The cost may be similar? As technology evolves it seems like one should exist but unsure if it would meet your needs.

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Not sure if this would be an option for you and not sure how accurate they are but most auto parts places can check your battery for free.

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Never seen one. I've seen a tester/booster combo, but a not charger included with an actual load tester. He'd do well to purchase a small battery maintainer/charger unit like the Ctek MXS 5.0 that can handle regular flooded and AGM batteries and a separate battery load tester for under a hundred bucks when he wants to test the health of his battery.

 

Maybe just get a ScanGauge and youll get used to keeping an eye on it.

If you start to see a lot of fluctuation in voltage (like the alternator is doing all the work) under load, then might be a decent time to replace the battery.

 

There are two main types of automotive 'battery testers':

1. A true load tester. These contain a large resistor (just a large carbon or nichrome heating element) and a voltmeter and usually an ammeter. This type of tester actually applies a high current load to the battery, simulating the high current draw from a starter motor, and measures the voltage drop over 15 seconds. This is a more or more or less realistic simulation of actual starter motor function. These are rugged 'old school' technology, no microprocessors, LCD displays, or delicate electronic components.

2. The more 'modern', much smaller hand-held all-digital testers that requires that you input the type of battery (wet cell, AGM, etc.) and the battery's AH capacity or CCA rating. The tester provides a digital display of battery voltage, then measures the battery's internal resistance in milliohms and then 'calculates' the battery's potential remaining CCA delivery capability, and usually displays if the battery is 'GOOD' or 'REPLACE'. This type of battery doesn't apply any real load to the battery. Some YT vids are available showing comparison testing of multiple brands of this type of tester, and the results of the vids I watched were somewhat inconsistent. The internal resistance and remaining CCA capability measurements were similar, but the final 'GOOD or 'REPLACE' assessments were variable.

Personally, I think I'd go with the larger and more cumbersome resistive load tester that actually applies a high current load to the battery. I think they provide more accurate indication of a battery's ability to drive a starter motor, and should last longer than an inexpensive imported little digital tester.

 

There are two main types of automotive 'battery testers':

1. A true load tester. These contain a large resistor (actually just a large carbon or nichrome heating element) and a voltmeter and usually an ammeter. This type of tester actually applies a high current load to the battery, simulating the high current draw from a starter motor, and measures the voltage drop over 15 seconds. This is a more or more or less realistic simulation of actual starter motor function. These are rugged 'old school' technology, no microprocessors, LCD displays, or delicate electronic components.

2. The more 'modern', much smaller hand-held all-digital testers that requires that you input the type of battery and the battery's AH capacity or CCA rating. The tester provide a digital display of battery voltage, then measures the battery's internal resistance (in milliohms) and then 'calculates' the battery's potential remaining CCA delivery capability, and usually assesses if the battery is 'GOOD' or 'REPLACE'. This type of battery doesn't apply any real load to the battery. Some YT vids are available that showing comparison testing of multiple brands of this type of tester, and the results of the vids I watched were somewhat inconsistent. The internal resistance and remaining CCA capability measurements were similar, but the final 'GOOD or 'REPLACE' assessments were variable.

Personally, I think I'd go with the larger and more cumbersome resistive load tester that actually applies a high current load to the battery. I think they provide more accurate indication of a battery's ability to drive a starter motor, and should last longer than an inexpensive imported little digital tester.

Thanks for providing this great explanation. Much appreciated.

 

Thank you very much for everyone's input.

Couple thoughts/comments:

• at the risk of putting myself out there as totally ignorant, a lot of these terms and explanations are going over my head
• the Ctek MXS 5.0 looks interesting, but I don't need the charging feature as this gets driven a couple times per week
• I can research " under load" , but what does that mean and how do I make that happen to test it?
• can a handheld Amazon for HF model ( like Kaiju mentioned) that's the $40 range atg least give some heads up on if I need to get the battery checked further?
• I recently took someone's car to Autozone and they used a handheld to determine the battery was done. What "type" of unit was that?
• EDIT: my battery is NOT a maint free one,( I can lift off the caps and access the cells) .
• my mechanic is not super close, so just looking for something basic that will at least give me a heads-up to upcoming battery failure so I can be proactive.

Thanks for not flaming me on this and being patient with me! If I go with Amazon or HF hand held load tester I'd just like to know it is somewhat useful.

I'm gonna owe all you guys a detail on your FJ for all the help you're been giving me!

 

Since you own a sealed battery, skip the hydrometer. I own a resistive load tester and that's probably what Autozone used. It contains large resistors housed in a vented housing attached to large gauge wires and clamps with an indicator gauge on front, which is used to put an actual load on a battery. Kind of like turning on all your vehicle's accessories at once, but with a calibrated load for testing purposes. They do heat up and get quite warm during the test. This tool is the most accurate way to catch a battery that's close to failing since a bad cell, internal short or plate sulfation will show with a severe voltage drop and poor current output once the load is put on the battery. They look like this:

Amazon.com: Schumacher Electric 2-in-1, Battery Load Tester and Voltmeter, BT-100 - 100 Amp, Easy-to-read and Accurate, Heavy-duty Clamps, Durable Steel Case, 1 Unit - Black : Automotive

Buy Schumacher Electric 2-in-1, Battery Load Tester and Voltmeter, BT-100 - 100 Amp, Easy-to-read and Accurate, Heavy-duty Clamps, Durable Steel Case, 1 Unit - Black: Battery Testers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

OK, the ignorance continues. I thought this had a sealed battery as that is what I've had on all my other vehicles for years. Just went out and checked and I can pull off the caps to reveal the cells.

Still recommend same type of tester?

 

I can attest to Schumacher products … I’ve had my charger for decades, which also performs what I would assume is just a basic test prior to charging, it also has a jumpstart feature that works well.

 

That's an expensive investment, but well worth it. I have both an Odyssey AGM battery and the voltage booster. If you want something a little cheaper, go with a Diehard AGM battery from Advance Auto. I have one in my other car (Odyssey doesn't make the size for it) and it's working great so far. I'd avoid Optima's offerings however. Their failure rate is high. There's also XS Power's offerings that are high quality, but not cheap.

 

If price is an issue, look at Advance Auto and Diehard Platinum AGM batteries. They're still not cheap, but they're well made in South Korea. I also bought this voltage booster. It has 2 settings, the "Hi" setting is good for the extreme cold. Use the lower setting is for the normal and hot months.

Voltage Booster PRO "Texas Slim" (4th Gen 4Runner, FJ Cruiser, GX470)

VoltageBoosterPRO is a user adjustable, plug and play, diode modification with an inline fuse so that you can increase your alternator voltage to optimize your AGM battery charging.

voltageboosterpro.com

 

Wow.... I sure learned a lot today from the Professors at The University of FJ Cruiser Forums.. Thanks everyone!

 

I have a simple Bluetooth sender on both my batteries that provides voltage, cranking power, temperature, and a charging check. It's not as good as a tester in showing the condition of it, but it's better for preventing damaging the battery.
If cranking voltage is low, mostly trough extreme low temps where I live, I know I'm not even going to crank it without a second power source hooked up.
I can keep an eye on the second battery that I use for winching and as a backup for powering my cabin ( in mid winter when there is no solar), and turn on charging if needed.

It's a cheap solution that I bought of a Chinese website, and I'm very happy with it. I don't need more info than this, if the battery does not recover to full voltage you know it's done.

 

thanks for your post. Never heard of these.. I'll have to check them out.

 

Those still only report voltage. Plus, Bluetooth does draw a small amount of power to communicate with any receiver. Not enough to drain a good battery, but if the battery was marginal to begin with, it might drain it dead if left sitting for awhile.