Testing for a Smart Charger

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
How can I tell whether a charger is a "smart" charger?
Is there something I can do with a volt meter/ammeter to indicate if the charger is cutting off the current or going into trickle charge mode when the battery is fully charged?
Thank you.
 

Eximo

Titan
Ambassador
Depends on the battery chemistry.

By design pretty much all Lithium chargers have to be smart to detect the so called knee in the charging curve. Charging beyond that point will result in thermal runaway and a fire.

Lead Acid can be dumb, but it is rare these days. Most will have a full manual mode though that you can get in trouble with, but is sometimes necessary to get a dead battery recognizable to a charging circuit as good. I would say your easiest test there would be voltage. If it charges at 15V and then ramps down toward ~13 when the battery is charged it will switch to a trickle mode. I suppose you could set up an Ammeter, but it would have to be a pretty high rated one to handle 12V charging currents

Older NiCAD and NiMH are dumb chargers I believe. Not 100% sure. They just have a target voltage controlled by a simple transistor circuit. Newer ones, not sure, been a while since I bought any.
 

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
Thanks.
It is a 36V Li Ion battery from my father's electric mobility scooter
.
The charger says 42V 1.8 A.

If I put a capable digital ammeter in series with the charging circuit, should the amperage drop if it is a "smart" charger when the battery is fully charged?
The indicator light on the charger goes from red while charging to green when the battery is full. It is also green when the charger is plugged into the wall but not into the battery.

The manufacturer is telling me that despite the $119 cost of the charger and $900 cost of the battery, the charger is not smart and should not be kept plugged into the battery for an extended period of time (say overnight) when it is fully charged.


Seems very strange to me.
 

Eximo

Titan
Ambassador
Lithium batteries don't really discharge on their own, so in some sense unplugging it is best. But it is likely to have a parasitic drain coming from the scooter itself, and it could be offset by leaving the charger plugged in. I don't believe the manufacturer in this case.

Either the brains of the operation is in the charger, or the scooter has a simple battery management system. Measuring the current would be a pretty surefire way to see if it slows down.

Do you happen to know if the batteries are Li-Ion or LiFePO4? If you can see and count the cells, there should be 15/16 LiFePO or about 12 for Lithium Ion. LiFePO are less power dense, but far safer.

Does the charger look like this:

https://www.amazon.com/Wyness-Battery-Charger-100-240V-Electric/dp/B01MZAAZJG

Inside the brick is going to be a transformer, a big capacitor, a regulating IC for the charging, and its accompanying components. $17.99 for above seems pretty cheap, but the bill of materials in bulk is probably about half that. I see a few slightly cheaper as well. I can see this working fairly well if the safety circuits are in the battery pack.
 

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
I don't think there is any parasitic drain in the scooter.

The batteries are Li-Ion. I can't count the cells without ripping it open.

The battery cord end is an RCA. Center positive.

Here it is...

https://ebikeling.com/products/36v-ebike-li-ion-battery-charger

They do say...

Do not leave the battery on the charger for long periods like several days or more.

So I would think that overnight once in a while is OK. Still testing it with my multimeter.

Edit: I just finished testing and when the light on the charger turns green signalling fully charged, the current drops from 2A to 2ma.
So it looks like it is smart after all to some extent.
 
Last edited:

Eximo

Titan
Ambassador
I wonder if that is just an abundance of caution to avoid lawsuits or clinging to older battery types.

The times I've heard people talk about or ask about battery memory problems with Lithium...
 

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
Could be.

Li-Ion batteries should not have a problem with memory.

I can leave my laptop attached to it's charger indefinitely.
I have ear pods that can be left attached to its charger.
I have a Samsung smartphone that can remain attached to its charger overnight with no ill effects.
My cordless phone sits in its cradle when not being used, charging as necessary.
I have a RayOVac AA/AAA battery charger that I use to charge my Lithium Ion batteries that cost $30 and it is a smart charger.
I have a Canadian Tire 12V battery booster that weighs 5 pounds and I can leave it plugged in at all times and it will stop charging when full.
I also have a 20V Li-Ion battery pack for my cordless dril that I keep plugged in in my workshop.
I also have a 20V battery pack for my Black&Decker weed wacker and leaf blower that I keep plugged in all the time in the garage (except when it's cold - but then it won't let it charge when it's too cold)

That $900 battery cost $350 last year so maybe they are having production problems or are taking advantage of Covid.
 
and then what? You did not finish your sentence.
Yes I did finish don’t leave it on the charger or else you’ll wear out your battery

Leaving your smart phone on the charger overnight it’s stupid to because it wears out your battery and you can easily check with your battery status after several months of doing that your battery status will deteriorate
 

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
Yes I did finish don’t leave it on the charger or else you’ll wear out your battery

Leaving your smart phone on the charger overnight it’s stupid to because it wears out your battery and you can easily check with your battery status after several months of doing that your battery status will deteriorate
I'm amazed at how people don't read. I specifically said it was for my father's scooter, not a smart phone. People are just lazy I guess.

Plus...

I never said I wanted to leave it on the charger. Just overnight. Which smart phone is that not good for?
Please, in the future, read up-thread.
 
No I’m not lazy I read your whole post, just because you were saying that you can leave your phone on the charge and it doesn’t hurt the battery is what I was refuting it does hurt the battery and I’m sure the scooter battery will be damaged and deteriorated if you leave it on the charger too long especially since the manufacture has already told you not to do it. Why do you think they told you not to do it?! Because it’s harmful to the battery

And if you’re going to be the grammar police then people are going to be very willing to help you. go solve your own problems. Go leave your father scooter battery on the charger and see what happens

Smart chargers ruined batteries. The best way for the longevity of the battery is charged up to about 90% and use it down to about 30% and keep it between those two percentages
 

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
No I’m not lazy I read your whole post, just because you were saying that you can leave your phone on the charge and it doesn’t hurt the battery is what I was refuting it does hurt the battery and I’m sure the scooter battery will be damaged and deteriorated if you leave it on the charger too long especially since the manufacture has already told you not to do it. Why do you think they told you not to do it?! Because it’s harmful to the battery

And if you’re going to be the grammar police then people are going to be very willing to help you. go solve your own problems. Go leave your father scooter battery on the charger and see what happens

Smart chargers ruined batteries. The best way for the longevity of the battery is charged up to about 90% and use it down to about 30% and keep it between those two percentages
No you didn't.
I said "say overnight", nothing else when referring to the scooter battery. I did not ask for advice on smartphone batteries and I did not allude to leaving my smartphone plugged in indefinitely.

Grammar police? Who the hell said anything about grammar?
You said...

If the manufacturer tells you not to leave it on the charger and do not leave it on the charger

is incomplete because it gives me no advice on what to do, it just leaves the reader hanging.

No. You go away.
I've been in Tech Support for 25 years and have won numerous awards.
I need to take no lessons from you.
 

Zerk2012

Titan
Ambassador
36 volts would be 18 cells.
Hook a volt member to the battery/ batteries with the charger plugged in when it says it's fully charged the charger should cut off. With the charger in its off state look at the meter reading then unplug the charger and if their no volt drops then charger is doing nothing.

With most actual chargers it should be doing nothing but if left connected if the voltage drops to a certain level the charger should kick back on.

Their a difference in a battery tender and charger.
 
Reactions: gdmaclew

gdmaclew

Distinguished
May 20, 2008
1,472
32
19,490
99
36 volts would be 18 cells.
Hook a volt member to the battery/ batteries with the charger plugged in when it says it's fully charged the charger should cut off. With the charger in its off state look at the meter reading then unplug the charger and if their no volt drops then charger is doing nothing.

With most actual chargers it should be doing nothing but if left connected if the voltage drops to a certain level the charger should kick back on.

Their a difference in a battery tender and charger.
Thanks Zerk
 

Zerk2012

Titan
Ambassador
I have 2 actual "Battery Tender" units I use for my "summer car" and lawn tractor.
Are electric fork lifts as powerful as the propane powered ones?
Depends on the rating for the lift capacity their usually used in a warehouse setting.
In a enclosed building they don't require removing the fumes from the warehouse like a propane lift would.
 

Eximo

Titan
Ambassador
2 volt Lithium Ion? 3.7 volts is about the nominal for them. At least for typical cells you find in laptops, smartphones, etc. Common fully charged voltage is 4.2 x 12 = 50.2V
Lithium Iron Phosphate are the safer ones, they run about 3.2 volts.

2V for lead acid cells, but you don't often see cells. Usually 12V batteries. (Though you might be able to shed some light on forklifts for me. I have seen the really tall forklift batteries before, are they individual cells, or like 6V or something?

Not to sound arrogant, but I have been dealing with EVs since the early 2000s (We live in strange times where it has become mainstream) Lithium was pricey back in the day, so we made lead sleds. Speaking of which, I need to find my nearest Enersys supplier, want to pick up a new 12V deep-cycle for my sump pump.

Just spent the last few weeks trying to justify bringing in a company to manage our charging rates. We have electric buses, and some electric cars.

I drive around in a Ford Focus Electric. A shame Ford stopped making cars, though the new Mustang is half tempting.
 
Reactions: gdmaclew

ASK THE COMMUNITY