My question is prompted by the fact that I just had my electric scooter batteries replaced, but I assume it applies to any sealed lead-acid batteries.
With everything brand-new I am supposed to be able to go about 20 miles on a single charge on my electric scooter (“supposed to” because I have never actually tried to go anywhere approaching that distance). I noticed a couple of weeks ago that my charge meter was beginning to drop after around 12 blocks (no idea the mileage - a mile or two?) and it slowed down a bit. If winter wasn’t coming I would have been stubborn and waited a while longer and just stayed closer to home; it was still quite functional. However, Old Man Winter is coming and I use it year round, so I thought I should get the situation dealt with now rather than finding myself dead in the water at -20C (OK - dead in the ice :D).
The guy at the store said that yes, the batteries were getting weak. HOW did he confirm that? They are sealed lead-acid batteries, and I was keeping them charged as best I could, meaning that my charge meter was showing pretty well maximum when he got the scooter. Did he have to put a load across the batteries for an hour or two to see what happened, or is there a quick way to test sealed batteries to see whether they are getting wimpy?
Most likely, with the symptoms you describe, a weak battery will be the culprit more often than not, since that is the most likely failure point in a battery-powered system. Also, just because your scooter thinks the batteries are fully charged doesn’t mean that they have their original capacity, just as a D-cell will show the same voltage as a tiny button cell but have far more capacity; the state-of-charge of lead-acid batteries is usually measured by terminal voltage.
FWIW, “sealed” just means that the battery is just that, just as an alkaline, NiMH or Li-ion battery is “sealed”; they are otherwise basically identical to non-sealed batteries (although there are some disadvantages, longer recharge time and shorter life (especially if overcharged, as they have a pressure-relief vent and water will be lost), and much more expensive, but they can be mounted upside-down if you wish).
I understand what you are saying, but why did the charge meter on my scooter initially read pretty close to maximum and then only taper off after quite a few blocks, and (given that my own meter was reading close to maximum), how did the store determine that my batteries were poor?
the voltage is measured and then a load is connected, then monitoring the voltage and current for a bit will show about the condition of the battery.
often simple indications of battery on the device only show the voltage which can be high and the battery deteriorated. i have a battery screwdriver that has a battery that after charging will spin the drill fast and illuminate its light brightly for about 10 screws (new was supposed to be a couple hundred).
A standard test for lead-acid batteries is a load test, where a calibrated load is applied for a specified number of seconds. The battery voltage will drop during this test. A good battery’s voltage will not drop below a specified level; if the voltage goes below the spec the battery is weak.
The rest voltage only indicates if the battery is fully charged. A weak battery, fully charged, will show the same rest voltage as a good battery, but the weak battery can’t hold and deliver as much power as a good one. The reduction in power and drop in the charge meter you observed are consistent with a weak battery. Most likely the scooter’s charge meter is a voltmeter, and in driving it you were applying a sort of rough load test that showed the batteries to be running out of power (because they were weak) when the meter reading went down prematurely.
Another possible method:
Step 1: the store had batteries to sell.
Step 2: you suspected the batteries, thus indicating you would willingly spend money on new ones, if they said yours were poor.
Step 3: profit!
I.E., that the store just said they were poor to get you to buy new ones. (Actually, your symptoms did indicate dying batteries. But such sales techniques are not unheard of for repair mechanics.)
How old we’re your batters that were replaced?
You say you should have gotten much more out of said battery’s but didn’t.
Well did you recharge your scooter often or just like once a week?
Battery’s need to be charged at all times, if left for days in a discharged state will cause damage and shorten the life.
Also, a charging unit can be faulty.
I use two different kinds of battery testers. One is a analog load tester. It will put aprox 100 amp load on the battery for about 10 sec. (it is auto on some and manual on mine and I believe it’s 10 sec.)
The anolog meter will start to drop and the cranking amp will dictate how much of a voltage drop will be allowable for a battery.
The other tested is what I call our intelectual tester. It is programmed to the battery amperage and then a few tests are preformed. After they are done and one can see the voltage during these tests and will know what is coming next, but the tester will ask questions about the ambient temp and if the battery has been charged previous to test and then give a good battery or bad battery message.
This is the best test as the load test I call the red neck tester will look good and the same battery can be tested on the electronic (intellectual) tester and be called a bad battery and the battery is brought in because there is a problem most times.
And a test of the battery will confirm a bad battery is bad but not always confirm a battery as good. One of the real tests is after a questionable battery is tested and it passes the test, if left to sit 2-3 days and retested you will a lot of times find it will then test bad and or low capacity.
Then there is the old specific gravity test. That test is a very good test to determin if one or more cells in the battery are weak. Of course lots of battery’s today are sealed so this test is not able to be done.
There are also capacitance testers that don’t put a load on the battery, and are quite accurate. Many car makers require this type of testing for warranty use on batteries.
Yes battery’s have a manufacture date code on them. This is to protect not only the customer but also the retailer. If a battery is old on the self it isn’t going to always give a good life to the customer and then the customer will not buy from that store again.
The barriers we sell are East Penn and a bad battery is a very rare thing. We have bad ones come in but they are old or the case is bulged indicating the battery froze.
It’s difficult to convince someone who just bought our battery two months ago that there battery froze and that it’s not the battery that was at fault.
Some of those old boats with the air suspension run battery’s down.
And by the way, if we get a bad battery returned we replace it on a por rated base but we do not get reimbursed for the new one. We mark our stock and of course only replace the ones we sell, being an independent store.
We also resell a core that isn’t completely bad. Some understand this and if they can get a month or two they are happy and I will buy a core personally for the hunting shack.
Like GaryT said, a load test is a standard way to test a rechargeable battery. Like any rechargeable cell, as a lead-acid batt ages, capacity loss is the most noticeable symptom. Usually due to a build-up of sulfate on the plates.
Thanks everybody for your comments. It gives me a much better idea what is going on. It’s rather difficult more me to get at my batteries to check dates or anything like that (I could probably do it, but it would be “interesting” trying since I’m paraplegic). I was unhappy about my last batteries only lasting a year, but I am prepared to give the store to benefit of the doubt ONCE. I’ve had scooters for many years, so I have a good idea what to expect out of batteries. We shall see…