Battery Capacity Testing in the Real World

[Lake-Effect]

Originally Posted by lonesoldier0408

Don't expect those financial advantages to be passed on after the word, "Boat," falls from your lips.

We're watching golf-cart technology very closely

[hellosailor]

Maine, have you tried any of the newer cheaper capacity load testers? And compared their numbers to actual discharge load tests?

I would expect them to be "good enough" for most purposes, no? And fairly cheap these days, for "recreational" size batteries.

[Cheechako]

So..... what does this test actually do for you? I mean... if you do it in the middle of Timbuktu.... will it do anything other than make you stop worrying or make you worry more?

[Maine Sail]

Originally Posted by Cheechako

So..... what does this test actually do for you? I mean... if you do it in the middle of Timbuktu.... will it do anything other than make you stop worrying or make you worry more?

It could help slow the demise if you know what the current actual capacity is and you are not cycling it like it was the as new rating.....

Lets say you start out with a 100Ah battery and used 50% of it. That is okay. But now in year two it has only 90Ah's of capacity but you still cycle 50% of the as new capacity. You are now cycling to 40% SOC with each cycle. The third year you are down to 80Ah's and still doing 50% of as new and you are now taking the bank to 30% SOC with each cycle, by year four they are toast....

[srdumstorf]

Cheap testers sell for about 50-60 bucks. The tester has a carbon pile stack
which are round disc made out of carbon. The disc have a hole in the center, a shaft passes thru the disc and out of the front of the case. A voltmeter and ammeter are mounted above or along side the knob. A positive cable is connected to one end of these independent disc and the negative cable on the disc furthest away. The pos and neg cables have a clamp on the opposite end which you attach to the batteries pos and neg post. As you rotate the knob clockwise these carbon disc, that start loose, get clamped together,the tighter you rotate the knob the more clamping force is applied to the disc, basically shorting the pos and neg battery post together. The voltmeter, which is reading your battery voltage should be at around 13-14 volts prior to testing, as pressure is applied with the knob the ammeter begins to read the current. This Load should be applied until 1/2 of there rated CCA is reached, at this point the voltmeter should stay above 9 Volts on a good battery. A different tester works about the same but uses heating elements instead of a carbon pile. Batt has to be charged as much as possible prior to testing & will drain a bit. If you have lead acid batts, a good battery hydrometer & measure the specific gravity of the electrolyte in each cell. Most boat batts are destroyed by the batt charger overcharging, even at a trickle or maintenance charge.

[conachair]

Originally Posted by srdumstorf

Cheap testers sell for about 50-60 bucks. The tester has a carbon pile stack
which are round disc made out of carbon. The disc have a hole in the center, a shaft passes thru the disc and out of the front of the case. A voltmeter and ammeter are mounted above or along side the knob. A positive cable is connected to one end of these independent disc and the negative cable on the disc furthest away.

Sounds a victorian
You can't get a lot of microprocessor and sensors off Ebay for 60 bucks


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[srdumstorf]

The carbon pile testers do not pull the battery down to 50% of the capacity, 50% of the rated cold cranking amps is the applied load, for 10 secs. If within this time period the batt voltage falls to 9 volts it's a bad battery. Your applying less of a load than the starting motor does. Don't like that spend $350.00 with Snap-On-tools for an electronic batt tester. They've had the technology for years & you don't have to be an electronics genius to build one or operate.

[Maine Sail]

Originally Posted by hellosailor

Maine, have you tried any of the newer cheaper capacity load testers? And compared their numbers to actual discharge load tests?

I would expect them to be "good enough" for most purposes, no? And fairly cheap these days, for "recreational" size batteries.

I bought a Harbor Freight "electronic" model and it is a complete and utter joke when compared to the Midtronics or my now discontinued Argus.

I also own one of their 500A carbon pile testers and for what it needs to do works okay as long as you don't rely on the voltmeter on the unit or that it can draw what it claims to draw, it does not.

When using a Fluke clamp on the wire and a fluke for voltage on the bank it works okay....

I have not been able to determine if the "electronic model" could be used in an A to A situation on the same battery using baseline when new and broken in vs. 1 year, 2 years etc. on the same battery. I think in an A to A comparison when getting a baseline it could work but I would really need to figure out what "dead" is on it because it is not using any sort of industry standard level of analysis that I can see...

One thing it does to is drift quite a bit. One reading will yield X and the next XXX even on the same battery. It is not consistent at all. The Midtronics & Argus analyzers are very consistent.

I suspect it could be used to track changes but what those changes mean would need some figuring.....

[hellosailor]

Carbon pile testers? No, that's the old technology. Still being made but not what I meant by new testers.

Amazon.com: SOLAR BA7 100-1200 CCA Electronic Battery and System Tester: Automotive

Typical of the inexpensive new (electronic, not carbon pile) testers. Of course your local battery distributor will say it isn't the same as his $1500 electronic tester, but then again, it ain't $1500 either.

Maine-
Horror Fright. Not my idea of a paradigm of anything except "cheap" or "disposable". I picked up one of their free DVMs one day, to have a "won't cry when it is stolen" one for the car. Checked it against my voltage calibrator and my only complaint is that the display should read "YES/NO" instead of having all those confusing numbers on it. Once calibrated...it seems to hold though.

[conachair]

Originally Posted by hellosailor

Carbon pile testers? No, that's the old technology. Still being made but not what I meant by new testers.

Amazon.com: SOLAR BA7 100-1200 CCA Electronic Battery and System Tester: Automotive

Typical of the inexpensive new (electronic, not carbon pile) testers. Of course your local battery distributor will say it isn't the same as his $1500 electronic tester, but then again, it ain't $1500 either.
.

Aren't those things useless for testing Ah capacity?

[hellosailor]

I would have thought that the percent or original cranking amperage (CCA) could translate fairly well into percent of AH remaining, for deep cycle batteries.

But if not...surely there's something in the "under a grand" price range? Or the $40 carbon pile testers have some use? Given all the variables with "capacity" they wouldn't have to be anywhere near dead accurate to still be useful.

[conachair]

Originally Posted by hellosailor

I would have thought that the percent or original cranking amperage (CCA) could translate fairly well into percent of AH remaining, for deep cycle batteries.

But if not...surely there's something in the "under a grand" price range? Or the $40 carbon pile testers have some use? Given all the variables with "capacity" they wouldn't have to be anywhere near dead accurate to still be useful.

A quick Google says no...
http://batteryuniversity.com/learn/a...d_cranking_amp

" The DC load method has the advantage of detecting batteries with a partially shorted cell (low specific gravity) but the device cannot estimate battery capacity."

The thread was started asking about making an inexpensive data logging microcontroller based tester. Shouldn't be that difficult, I'm itching to have a play but several thousand miles from the boat

Sim card adaptors can be had cheaply for an arduino board ad well, so shouldn't be too hard to text your boat and get it to text you back with battery voltage and temp or something useful

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[Lake-Effect]

Originally Posted by conachair

Sim card adaptors can be had cheaply for an arduino board ad well, so shouldn't be too hard to text your boat and get it to text you back with battery voltage and temp or something useful

Or if you use a Raspberry Pi and your marina has wifi, the Pi could wake up and email you periodically.

[conachair]

Originally Posted by Lake-Effect

Or if you use a Raspberry Pi and your marina has wifi, the Pi could wake up and email you periodically.

I suspect the majority of people who can afford to keep their boats in marinas might not be quite so obsessed with self reliance

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[conachair]

Update, finally got to play, early days but didn't take long at all to get an arduino logging voltage data, image is of 75 seconds as solar panels and other bits get turned on and off, logging once per second.
Now just waiting for several temperature sensors and a couple of current sensors to turn up from eBay. Plus a smaller arduino copy board, which was £10.00.