Is it possible to have a "Smart Charger" so that when a battery is fully charged it switches off, we can't monitor our charging all the time because I guess most of us put the battery on charge at night, I use a timer to regulate the charge time but I was curious as to how critical the overcharge time is.
Overcharging
- Thread starter johnc461165
- Start date
Yes. but it seems to depend on the battery type and configuration. For example fatboytrig has a Schwimm Tailwind which has a Toshiba 24V 5Ah SCiB. However, this is quite unusual. Also, I wonder if he has to condition the battery, and if so, how does he leave it on for longer? ... umm .. I'll ask him tomorrow.
My battery is a Cytronex 36V 4 Ah NI-MH which is also a bit unusual. Typical charge time about 1:10 mins. If I use all the battery then it takes 1:30 mins. If when its charged and the green light comes on if I don't turn it off then it will continue to charge so there is the potential for overcharging. My understanding is that leaving it for an hour or two is not critical. Quite what would happen if I regularly overcharged it I don't know.
I suspect other members will offer up info on other battery types and configuration .... It might be an idea to restrict this thread to the battery type and configuration that most interests you otherwise this thread might get a bit confusing.
My battery is a Cytronex 36V 4 Ah NI-MH which is also a bit unusual. Typical charge time about 1:10 mins. If I use all the battery then it takes 1:30 mins. If when its charged and the green light comes on if I don't turn it off then it will continue to charge so there is the potential for overcharging. My understanding is that leaving it for an hour or two is not critical. Quite what would happen if I regularly overcharged it I don't know.
I suspect other members will offer up info on other battery types and configuration .... It might be an idea to restrict this thread to the battery type and configuration that most interests you otherwise this thread might get a bit confusing.
Yes, there are smart chargers like the ones available for SLA's. For our Li-ion batteries the BMS will cut the charge at the correct point.... Most chargers are CC/CV types so the charge will naturally taper off towards full battery capacity and these can be used on say Lipo packs without BMS as long as the voltage is set to match the pack and there is some form of balance mechanism in place otherwise an intelligent RC type controller can be used.
Many are like that already, I just plug mine in when I get home and unplug in the morning.
For WIWorth.
Out of interest on our new Freego Eagle Bikes (Lion 17.5 amphr) I monitored the charge on our first few charges.
My trusty Screwfix AC - 240 v ammeter showed a charge rate of 0.6 amps whilst the charge light was orange, then fell to 0.1 amps , then to zero amps whilst still orange.
About an hour later, the charger light changed to green, still showing zero amps.
As the charger seems to run at Zero amps whilst the charge light shows orange, then green, I would hazard a guess that leaving it on, probably would not overcharge battery.
Well not to a point where, you have to look at your watch, then leave the pub to go home to unplug the charger.
Rgds
Out of interest on our new Freego Eagle Bikes (Lion 17.5 amphr) I monitored the charge on our first few charges.
My trusty Screwfix AC - 240 v ammeter showed a charge rate of 0.6 amps whilst the charge light was orange, then fell to 0.1 amps , then to zero amps whilst still orange.
About an hour later, the charger light changed to green, still showing zero amps.
As the charger seems to run at Zero amps whilst the charge light shows orange, then green, I would hazard a guess that leaving it on, probably would not overcharge battery.
Well not to a point where, you have to look at your watch, then leave the pub to go home to unplug the charger.
Rgds
Its where you fully charge the battery and then use it as normal until its completely flat...then you fully charge it again. Thats a conditioning cycle and completely unnecessary with Li-ion batteries other than to reset any BMS fuel gauge that may be fitted (so the battery level LEDs read correctly).
My brother's Fast4ward has a Li-ion battery. Here are some parts of the user guide:
Fully recharge your battery as soon as possible
because a lithium ion battery left in a discharged
condition deteriorates much faster than a fully charged
battery.
NOTE: Prior to its first use, charge the battery supplied
with your Fast4ward RIDE for at least 12 hours.
NOTE: You may recharge the battery at any time,
regardless of its state of charge. As your battery ages,
it will gradually lose capacity. With proper care and
maintenance, your battery will retain up to 80% of its
capacity over at least 500 discharge/recharge cycles.
As capacity diminishes, you will notice a gradual drop
off in maximum range capability.
There is also a section on charging which says:
Before using for 1st time - 12 hours
First 3 charges - 12 hours
Normal charging - 4-6 hours
After every ten charges - 12 hours
CAUTION: Avoid leaving the battery charger ON and plugged
into your battery for more than 12 hours at a time. Once the
battery is fullycharged, turn OFF the charger and unplug it from
the pack.
So, according to this information you should charge the battery for 12 hours after every 10 charges regardless of whether the battery is fully discharged or not. So, this is not a conditioning charge to reset the BMS fuel gauge. So , umm, what is it?
D
Deleted member 4366
Guest
I wouldn't take any notice what anybody says about battery conditioning.
My rules for batteries:
1 Charge up your bike til full
2 Use the bike
3 Charge it til full when you get home
4 Use the bike
5 Repeat for a long and enjoyable and worry-free ebike experience
Anything else is just intellectual masturbation and will have little effect on battery life.
Some batteries which have internal fuel gauges and diagnostics need to be fully discharged to set the fuel gauge. Don't confuse this with the little LED battery charge level indicator lights found on most cheap batteries.
My rules for batteries:
1 Charge up your bike til full
2 Use the bike
3 Charge it til full when you get home
4 Use the bike
5 Repeat for a long and enjoyable and worry-free ebike experience
Anything else is just intellectual masturbation and will have little effect on battery life.
Some batteries which have internal fuel gauges and diagnostics need to be fully discharged to set the fuel gauge. Don't confuse this with the little LED battery charge level indicator lights found on most cheap batteries.
Seeing as the charger is not switchable between fast and slow charges leaving it on for 12 hours is going to have a negligable effect. It seems to be a hangover that gets put into instructions because it's the done thing.
I might be wrong about the charger not being switchable but I doubt it.
I leave it plugged in for a while. It says on the charger to leave it on for an hour after the green light comes on.
I've noticed that if I unplug it as soon as the light goes green, the battery will measure 41.7v, whereas it can reach 41.9v if left plugged in.
I use a power monitor when charging it, and it still takes power up to 3 hours after the green light comes on sometimes.
When the green light comes on after charging, the charger is pulling about 14 watts from the mains, which drops gradually. Charger switched on without battery attached uses about 4.5 watts. So I wait until it drops from 14w to less than 5w before unplugging everything.
The whole process on my HP 4a 36v charger seems like this:
180w: When charger is switched on..
200w: a few minutes later, this is the peak draw, the more discharged the battery is, the longer it stays at these high watts, then it starts reducing.
110w: At this point, it can drop to 104 then it goes to the next stage.
42w: It stays at this level until the battery is nearly completely charged, then starts dropping to 14w then the green light comes on as mentioned earlier.
I've noticed that if I unplug it as soon as the light goes green, the battery will measure 41.7v, whereas it can reach 41.9v if left plugged in.
I use a power monitor when charging it, and it still takes power up to 3 hours after the green light comes on sometimes.
When the green light comes on after charging, the charger is pulling about 14 watts from the mains, which drops gradually. Charger switched on without battery attached uses about 4.5 watts. So I wait until it drops from 14w to less than 5w before unplugging everything.
The whole process on my HP 4a 36v charger seems like this:
180w: When charger is switched on..
200w: a few minutes later, this is the peak draw, the more discharged the battery is, the longer it stays at these high watts, then it starts reducing.
110w: At this point, it can drop to 104 then it goes to the next stage.
42w: It stays at this level until the battery is nearly completely charged, then starts dropping to 14w then the green light comes on as mentioned earlier.
Hmmm, Interesting.
I didn't realise the charge current varied so much during a full charge cycle. I quite often take opportunist top up charges when out and about.
Suppose I've ridden a while and the charge is half used up. If I then place it on charge for approx 45 minutes, will it charge at a higher rate because its just started or will it know the battery is still half full. Is it just the voltage available at the battery that regulates the charging current applied?
I fully expect that's a silly question, but I'm a bit dim with anything electrical! I'm just wondering that, whereas a full charge from empty takes 6 hours, will a 1 hour charge fill up the battery by 1/6th of a full charge, or will it be more because the rate of charge is higher at first??
I didn't realise the charge current varied so much during a full charge cycle. I quite often take opportunist top up charges when out and about.
Suppose I've ridden a while and the charge is half used up. If I then place it on charge for approx 45 minutes, will it charge at a higher rate because its just started or will it know the battery is still half full. Is it just the voltage available at the battery that regulates the charging current applied?
I fully expect that's a silly question, but I'm a bit dim with anything electrical! I'm just wondering that, whereas a full charge from empty takes 6 hours, will a 1 hour charge fill up the battery by 1/6th of a full charge, or will it be more because the rate of charge is higher at first??
D
Deleted member 4366
Guest
You can charge it whenever you want. Just wait for the green light and then it's best to unplug it, but won't do any harm if you leave it on green for a few hours - or even overnight if you want. There's always a risk that something goes wrong - like the cat decides to sleep on the charger because it's nice and warm, causing it to overheat and burn outt, so don't leave it on green when you don't have to.
Eaglerider;128328 Suppose I've ridden a while and the charge is half used up. If I then place it on charge for approx 45 minutes said:
The rate of charge is higher when the battery charge is low, the cell input resistance being lower then. Towards the end of charge as the battery fills, the rise in the cell input resistance slows the charge rate. In addition, with our lithium batteries the internal management spends time towards the end of charge equalising the cell content, during which time some cells may not be receiving anything. That makes the late stage overall charge rate even lower.
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