The Charger supplied with mu secondhand 36v Sakura E bike shows the state of the batteries during charging namely:- Red - 0%, Orange - 80% and Green - 100%. My question is " Does the charger automatically shut down when it shows Green or will it carry on charging until I switch it off". If anyone knows the answer, I'd be much obliged.

 

The only manufacturers mark on the charger is the number G4M20211-2347-E-16

When the battery is at the same voltage as the charger (fully charged), no current can flow. Assuming that your battery's management pcb has a balancing function, this is where it happens, so don't always be too quick to switch off the charger. Occasionally, you should leave it on for a bit after you see the green light.

When the battery is at the same voltage as the charger (fully charged), no current can flow. Assuming that your battery's management pcb has a balancing function, this is where it happens, so don't always be too quick to switch off the charger. Occasionally, you should leave it on for a bit after you see the green light.

Many thanks D8VEH. The trouble is I have no idea if my battery has a " Balancing function", so really I am no wiser. I do know however, that you should not leave a 12 volt lead acid battery on continuous charge as it will eventually damage it and therefore I am still hoping that someone can recognise my battery from the description I have given and can tell me if it has what you call a Balancing Function.

You cannot tell whether your BMS balances without dismantling the battery. Most batteries have it, but not all.

 

The main point is that you don't have to panic about switching off your charger. If your BMS doesn't have the balancing function, then everything will be dormant: No current will flow and no harm can be done. If your BMS does have balancing, then a tiny bit of current flows, but no harm can be done, only good.

You cannot tell whether your BMS balances without dismantling the battery. Most batteries have it, but not all.

 

The main point is that you don't have to panic about switching off your charger. If your BMS doesn't have the balancing function, then everything will be dormant: No current will flow and no harm can be done. If your BMS does have balancing, then a tiny bit of current flows, but no harm can be done, only good.

Again, many thanks for your reply. However, I am still a little confused because I have read articles specifically about charging lead acid batteries and they all agreed that leaving a battery on continuous charge between use, will shorten its life over time. From what you are saying, it seems there is no point in having a charger that switches itself off on the basis that no charge will flow anyway, once fully charged, so why do manufacturers bother to make batteries that switch off ? I am not trying to be argumentative, it is simply that I am getting conflicting information about charging lead acid batteries and all I want to know is whether to leave mine on charge overnight or to switch it off when the green light appears. And of course, it would be nice to know if my charger has or has not the shut down facility.

Sorry, are you saying that you have SLA batteries? If so, disregard everything I said before and switch off your charger as soon as it goes green. I was referring to lithium batteries.

Sorry, are you saying that you have SLA batteries? If so, disregard everything I said before and switch off your charger as soon as it goes green. I was referring to lithium batteries.

My apologies, I should have mentioned my batteries are Lead acid in my original query but I am grateful to you for taking the time and trouble to reply.

 

All I need now is to know if anyone can confirm if my charger switches off or not because at my age, I worry that I may forget it is on charge and if it does not switch off automatically, I will have to invest in a timed plug socket to be on the safe side.

We have three bikes with SLA battery's two sakura and a powabyke,all of them state somewhere do not leave the battery's on charge for extended periods what extended means i have no idea and with this technology being so outdated i doubt i could find out.

I have never left them on charge overnight but often for an extra couple of hours with no detriment,sorry it doesn't answer your question but its all i have

We have three bikes with SLA battery's two sakura and a powabyke,all of them state somewhere do not leave the battery's on charge for extended periods what extended means i have no idea and with this technology being so outdated i doubt i could find out.

I have never left them on charge overnight but often for an extra couple of hours with no detriment,sorry it doesn't answer your question but its all i have

Many thanks Electric Mike. Until I find out if my charger has or does not have, a cut off facility, I think I shall do as you do and allow say an hour after the green light appears and then switch it off.

 

I must say I can never understand why original bike users leave you with a charger but not the instruction manual. Still, that's the way it is I suppose.

Bernie,are you enjoying the Sakura.

Bernie,are you enjoying the Sakura.

Does your charger mention anything about a 'float voltage' and if so, what is it listed as?

Edited August 11, 201411 yr by danielrlee

Yes I am, although I have only just started getting used to riding a bike again, let alone an electric one. The last time I got on a cycle was over 70 years ago, so you can guess what fun I had learning to ride the Sakura. I thought first of all it was too heavy (40 kilos) but I have gradually got used to it and have bought it mainly to get me to and from my Golf Club. I am getting rid of my car and going back to basics but only time will tell over the Winter whether I manage it or not.

 

With regard to the Sakura, as long as the batteries last and my knees don't give way, I am very happy with it. By the way, the only concern I have is the location of the battery L & N connections at the bottom of the battery case where they sit in the frame and connect to the motor wiring circut. When it rains, have you ever experienced water forming in the bottom tray and affecting the electrics, as it seems an obvious water trap to me. I have not been out in the wet yet, so don't know if I am worrying over nothing but perhaps you can enlighten me.

 

Regards

Bernie

Does your charged mention anything about a 'float voltage' and if so, what is it listed as?

No, it has no indication on it whatsoever, other than the code number quoted in my original post. However, I am absolutely sure, I have seen an identical one to mine on Ebay but can't find it any longer. As mentioned, it just has the number and the three colour codes on it but I have a feeling it was advertised as a Powerbyke charger. That's all I know.

The only way to tell is to measure the voltage of the battery, while it is connected to the charger once the charge cycle is complete. SLA's can be safely held at a standby voltage by a charger with the capability to do so.

Yes I am, although I have only just started getting used to riding a bike again, let alone an electric one. The last time I got on a cycle was over 70 years ago, so you can guess what fun I had learning to ride the Sakura. I thought first of all it was too heavy (40 kilos) but I have gradually got used to it and have bought it mainly to get me to and from my Golf Club. I am getting rid of my car and going back to basics but only time will tell over the Winter whether I manage it or not.

 

With regard to the Sakura, as long as the batteries last and my knees don't give way, I am very happy with it. By the way, the only concern I have is the location of the battery L & N connections at the bottom of the battery case where they sit in the frame and connect to the motor wiring circut. When it rains, have you ever experienced water forming in the bottom tray and affecting the electrics, as it seems an obvious water trap to me. I have not been out in the wet yet, so don't know if I am worrying over nothing but perhaps you can enlighten me.

 

Regards

Bernie

 

Cant help with the water situation as our sakuras are different.

The only way to tell is to measure the voltage of the battery, while it is connected to the charger once the charge cycle is complete. SLA's can be safely held at a standby voltage by a charger with the capability to do so.

 

I'm sorry but I don't quite understand your reply. I can certainly measure the voltage at the end of the charge cycle and frequently do but what does that tell me in so far as knowing if my charger has switched off. Or are you saying I could measure the current when the green light appears and whilst the battery is still connected. That would probably tell me if the charger has stopped charging or whether it continues a trickle charge. As I don't want to get any shocks while I'm doing this, can you confirm that that is what you had in mind, as I regret that I don't understand your second sentence.

.... I don't want to get any shocks while I'm doing this....

 

36v is extremely unlikely to do you any harm. Because the battery is isolated from Earth, you would have to grasp both positive and negative terminals at the same time. If you did this there is a theoretical chance of a dangerous level of current passing through you, but in practice, you won't even feel it.

 

I guess the biggest danger is from burns caused by shorted battery, but this is pretty low risk/consequence.

I'm sorry but I don't quite understand your reply. I can certainly measure the voltage at the end of the charge cycle and frequently do but what does that tell me in so far as knowing if my charger has switched off. Or are you saying I could measure the current when the green light appears and whilst the battery is still connected. That would probably tell me if the charger has stopped charging or whether it continues a trickle charge. As I don't want to get any shocks while I'm doing this, can you confirm that that is what you had in mind, as I regret that I don't understand your second sentence.

No, I mean voltage. Measuring current will tell us something, but it won't tell us if the battery is being charged or held at an incorrect voltage. Also, measuring voltage is usually easier since the circuit doesn't have to be 'broken' as when measuring current inline. As long as you don't go probing inside the charger, the risk is minimal. As Mike said, the biggest risk would be if you were to accidentally short the battery.

 

Having had time to think about this, I would be surprised if it wasn't safe to leave the charger connected for longer periods of time. If the charger has the logic built in to tell you the charge is complete, it would seem silly to not also have the charger cut the current at this point. This isn't a given though - often many a corner is cut to save a few pence at manufacturing.

 

To test, you will need to find a way of connecting a multimeter or wattmeter while the battery is charging. If you wish to do so, I will provide further information.

No, I mean voltage. Measuring current will tell us something, but it won't tell us if the battery is being charged or held at an incorrect voltage. Also, measuring voltage is usually easier since the circuit doesn't have to be 'broken' as when measuring current inline. As long as you don't go probing inside the charger, the risk is minimal. As Mike said, the biggest risk would be if you were to accidentally short the battery.

 

Having had time to think about this, I would be surprised if it wasn't safe to leave the charger connected for longer periods of time. If the charger has the logic built in to tell you the charge is complete, it would seem silly to not also have the charger cut the current at this point. This isn't a given though - often many a corner is cut to save a few pence at manufacturing.

 

To test, you will need to find a way of connecting a multimeter or wattmeter while the battery is charging. If you wish to do so, I will provide further information.