How closely, if at all, can you test a battery for"newness"?

[Windmaker]

I have had some rather unpleasant experiences this year with supposedly "new" SLA batteries arriving either DOA or with considerably reduced capacity from their original state. The DOAs were for an electric wheelchair and the highly reduced capacity batteries came with a new (but year old 2014 model) electric mobility scooter that I purchased but had set idle in dealer inventory for a year or so and the batteries I'm guessing probably weren't recharged often or long enough to keep them in optimal condition. They only permitted about ten to twelve miles range per charge while they are advertised as getting up to 40 miles per charge (depending on varying conditions). I was sent a second set of "new" (4 x 12v-20ah) batteries for the scooter (under the warranty) and from a USA supplier, but unfortunately they also seem to be reduced in capacity due to again getting unusually limited miles per charge range (a little more, but only 13-15 miles).

My basic question is.....can a test or tests be done when batteries are received from a supplier that can accurately determine the actual status of the battery's current state as compared to it's original advertised capacity and strengths at time of manufacture? Or to put it another way, can you tell if an SLA battery has either been used or not properly maintained by the battery supplier and/or vehicle vendor after time of manufacture and it has lost some of it's original capacities? If such testing does exist, what is it or what would they be?

Thanks for looking.

P.S. - I took those warranty supplied batteries to an Advanced Auto Parts (chain) store for testing, but they ended up telling me that without a part # on the batteries, they wouldn''t know how to set up their testing device properly. For whatever reason apparently many/most Chinese made batteries aren't numbered. I then took them to a Pasco (Battery) retail store for testing and they told me all they could determine was whether the battery(s) had any faulty cells or not and the current voltage readings, but I took from that apparently they couldn't test to see if the batteries were, for instance, 1/2 used up or deteriorated.

 

[dilkes]

My understanding on SLA batteries is that the rated capacity in Ah is based on the “20-hour discharge rate”. For a 20Ah battery, that means it could deliver 1 amp for 20 hours. This is clearly not a realistic discharge rate for a mobility scooter – or any vehicle for that matter. Some battery suppliers will also show a table with the capacity at higher discharge rates. For an example, see:
http://www.power-sonic.com/images/powersonic/technical/1277751263_20100627-TechManual-Lo.pdf

This shows that at the “1-hr discharge rate”, the battery can deliver 12.4 amps, meaning the capacity at this rate is 12.4Ah. This 12.4 amp rate (or maybe a little less) is probably closer to what a mobility scooter might draw in normal operation.

As far as testing them goes, you can take a fully charged battery, connect a wattmeter in series to a resistive load and measure how many watts or Ah are used before the battery voltage gets too low. Depending on the wattmeter used, you may need a camera running to capture the values when it dies. In the old days, when I still used SLA, I have done this and managed to get a refund from the supplier for new batteries that didn’t come close to the specs.

Bottom line is that claims like “up to 40mi per charge” are likely based on some ideal conditions and perhaps at an unrealistic speed of 1 or 2 mph when the current drawn will be low.

 

[Voltron]

I don't have a picture, but when I had an SLA pack I used an inverter like you would use in your car for AC power, with a lamp and a old style clock with hands plugged into the inverter. You can hook it up, and turn it all on, and then it runs until it hits the low voltage cutoff, turning itself off. The clock then shows how many minutes it ran, without having to sit there and watch it. Great for comparing which SLA's are still putting out good capacity...

 

[Ykick]

Power meter would certainly be a good start and some sorta load. I use old heater elements from Toaster ovens, space heaters, etc.

I’d test IR (internal resistance) which can tell you a lot about how any battery will deliver a load. Or, accept a charge, for that matter.

It would be most useful to test IR of good similar batteries and then use that data for comparison to unknown batteries.

The way I do IR testing is to record resting voltage. Then apply a known load (through power meter) for about 10 seconds. Subtract 10s loaded voltage from the resting voltage. Divide that result by the current (Amps) and multiply by 1000 for m(mili)Ohm value.

For 5Ah RC Lipo bricks delivering 20-30A I like to see IR under 10mOhm. I’m ok with 15mOhm. Start getting bummed out and looking to replace by around 20mOhm.

I’ve got no idea what to expect from good fresh SLA in the size you’re dealing with but if you test and compare enough you’ll eventually have a good graph plot to be able to call bullshit on a suspected bad order from a supplier.

Back when I used SLA it was common to halve Ah capacity ratings. 12Ah you considered it lucky to deliver 6-7Ah.

 

[Jon NCal]

When you do your capacity test, realize that the capacity is measured to a certain end voltage like 10.5 volts per battery, or 42V for 4. Because if you go lower, you may damage the battery.

Jon

 

[Windmaker]

My understanding on SLA batteries is that the rated capacity in Ah is based on the “20-hour discharge rate”. For a 20Ah battery, that means it could deliver 1 amp for 20 hours. This is clearly not a realistic discharge rate for a mobility scooter – or any vehicle for that matter. Some battery suppliers will also show a table with the capacity at higher discharge rates. For an example, see:
http://www.power-sonic.com/images/powersonic/technical/1277751263_20100627-TechManual-Lo.pdf

This shows that at the “1-hr discharge rate”, the battery can deliver 12.4 amps, meaning the capacity at this rate is 12.4Ah. This 12.4 amp rate (or maybe a little less) is probably closer to what a mobility scooter might draw in normal operation.

As far as testing them goes, you can take a fully charged battery, connect a wattmeter in series to a resistive load and measure how many watts or Ah are used before the battery voltage gets too low. Depending on the wattmeter used, you may need a camera running to capture the values when it dies. In the old days, when I still used SLA, I have done this and managed to get a refund from the supplier for new batteries that didn’t come close to the specs.

Bottom line is that claims like “up to 40mi per charge” are likely based on some ideal conditions and perhaps at an unrealistic speed of 1 or 2 mph when the current drawn will be low.

I had another similar mobility scooter before this one and I was getting a max range of over 20-23 miles with it. It had a 500w motor and the wheels were a bit bigger in diameter. My current scooter has a larger 750w motor. I suppose both of these factors may be contributing to the reduced range.....how much?..... I of course don't have a clue.

As for your testing suggestion....sounds like a kosher idea to me but I'd have to either purchase a watt meter or find a friend who has one. As for the testing practicalities, what would you consider to be a "resistive load", approximately how long would this testing take, and how low is "too Low" (when do you know it's time to stop the testing)?

 

[Windmaker]

I don't have a picture, but when I had an SLA pack I used an inverter like you would use in your car for AC power, with a lamp and a old style clock with hands plugged into the inverter. You can hook it up, and turn it all on, and then it runs until it hits the low voltage cutoff, turning itself off. The clock then shows how many minutes it ran, without having to sit there and watch it. Great for comparing which SLA's are still putting out good capacity...

Thanks, but I sure have some homework to do to better understand some basics in electricity.

 

[Windmaker]

When you do your capacity test, realize that the capacity is measured to a certain end voltage like 10.5 volts per battery, or 42V for 4. Because if you go lower, you may damage the battery.

Jon

Thanks for your reply Jon, but as I replied to another post, I need to some basic homework in electricity....or find someone who already has the knowledge and the testing equipment.

 

[dilkes]

As for your testing suggestion....sounds like a kosher idea to me but I'd have to either purchase a watt meter or find a friend who has one. As for the testing practicalities, what would you consider to be a "resistive load", approximately how long would this testing take, and how low is "too Low" (when do you know it's time to stop the testing)?

Link to cheap wattmeter at http://www.ebay.ca/itm/RC-Boat-Heli-Watt-Meter-Digital-LCD-Display-DC-Battery-Power-Analyzer-60V-100A-/111577487407?hash=item19fa89582f

A resistive load would be a heater, kettle, etc. hooked up directly or any AC appliance if you happen to have a 12V to 120/240V inverter on hand.

How long? depends on the load. If drawing 10 amps, probably 1 to 1.5hrs if the battery is good.

Sorry - no magic that I know of.

 

[Voltron]

That's the point of my method... one of these...
, ($30ish) a thrift store lamp ($2), and an alarm clock with hands ($3), you hook it to a 12v SLA brick, and it runs for about 25 or 30 minutes. It has a built in low voltage cutoff, no math, and no needing to be there when it cuts off, as the clock records the run time. It doesn't get much simpler. It makes it VERY easy to get a pack of similar capacity bricks, and to weed out a bad one. Otherwise, you will end up with (for example ) a 36v pack with one charging to 15v or more, while another stays low at say 13v, slowly killing both in the process. It's also handy for sucking some of the charge of the high one while charging the pack and letting the low ones catch up.

 

[Voltron]

P.S....it also makes it easy to see from distance when its done, as the lamp goes out, and its easy to add more load with a higher wattage bulb or a second lamp if you want to test it at higher discharge levels. After getting some nice balanced ones, I was pleasantly surprised how many cycles those poor bricks went thru despite my high amp draw and crushing discharge levels I put them thru.