Help - I dropped my battery charger!

[vne165]

Hi ES folks,
Long time, no post.
Just looking for help from the collective wisdom here. In a moment of stupidity last night, I dropped my battery charger and it's dead. Pulled it apart, nothing obviously wrong, sadly I didn't have a meter handy to check the mains fuse on the board.
The bike is my commuter and I need to get another charger fast.

Problem is, my memory fails me and I can't remember whether I have a 48V or 52V pack. I know it's 16AH or thereabouts. It's an older (Em3 EV triangle battery pack and MAC motor, circa 2014, still in great condition after all these years).

What is throwing me is that I read a fully charged voltage of ~56.6V on the cycle analyst readout. As mentioned I didn;t have a meter handy to measure the actual pack voltage, will do over the weekend.

If it's a 48V pack, it should be 54V 100% SOC, if a 52V pack fully charged should be 58V.
The questions:
1. Do I buy a 52V or 48V charger?
2. Will I damage a 52V battery if I use a 48V until Em3 get's me a new one?

Thanks so much for any assistance
Vne

 

[amberwolf]

Just looking for help from the collective wisdom here. In a moment of stupidity last night, I dropped my battery charger and it's dead. Pulled it apart, nothing obviously wrong, sadly I didn't have a meter handy to check the mains fuse on the board.

Usually this causes a cracked PCB where the heaviest things are (caps, transformer). Sometimes it is just cracked solder on those heavy parts.

Sometimes there is a fuse holder as part of or near the AC inlet socket (in addition to or instead of a board-mounted fuse), and the fuse may have dislodged. Removing and reinserting it usually fixes such problems.

If it has a fan, and the fan is unable to spin, if the fan has three wires from it to the board, the charger may refuse to operate if it does not detect the fan spinning for any reason. If the fan is mechanically damaged so it can't start, or unplugged, it could cause what you see. (a two wire fan doesn't have an RPM signal so wouldn't cause this)

Problem is, my memory fails me and I can't remember whether I have a 48V or 52V pack.
<snip>
What is throwing me is that I read a fully charged voltage of ~56.6V on the cycle analyst readout.

That's higher than a 48v pack should ever be (56.6v / 13s = 4.35v), so if it is a 48v pack it would be overcharged at that level. Logically that points to a 14s (52v) pack vs a 13s (48v).

What is the CA's LVC and other battery info set to?
https://ebikes.ca/product-info/grin-products/cycle-analyst-3.html#CA3.1SetupMenu
In the Battery Setup Menu

[ Batt->Vlt Cutoff ]

If it's a 48V pack, it should be 54V 100% SOC, if a 52V pack fully charged should be 58V.

Assuming it is balanced, yes. If it is not balanced, a charger will stop (because the BMS turns the input off) at the point the first cell fills up to full, so the total votlage could be much lower than designed.

To test this without opening the pack, then once you have the correct charger you can leave it on the charger at least overnight, and see if it improves total full voltage. If it does, but doesn't reach normal full, leave it on the charger longer until it does. If it never reaches normal full, something is wrong and should be diagnosed.

2. Will I damage a 52V battery if I use a 48V until Em3 get's me a new one?

No. It just won't provide full capacity (something over half full). Whether that's enough to get you as far as you need, I don't know. (also depends on whether the cells are all balanced or not--the worse the imbalance, the less actual capacity you have available).

 

[vne165]

Thanks Amberwolf,
appreciate your assistance. I've since found the purchase order back from 2014 and discover it's a 50V 16.5 AH Samsung 18650 pack, which came with a 58.8V 5A Charger - the one I stupidly dropped. So that makes sense, it's 14S6P.

Thanks for the pointers for repairing the charger - there was a tiny internal flash when it hit the ground. But nothing stands out as blown, smelly or leaking. There was no smoke released.

I'll check the fan and also the little glass fuse - maybe the flash was it blowing?

 

[vne165]

Edited- it's a 52V pack (Em3 have explained they used to specify by the nominal voltage in 2014 (50V), but have since reverted to the industry standard of calling it a 52V pack.

 

[amberwolf]

Thanks for the pointers for repairing the charger - there was a tiny internal flash when it hit the ground. But nothing stands out as blown, smelly or leaking. There was no smoke released.

I'll check the fan and also the little glass fuse - maybe the flash was it blowing?

That is possible, but so is an arc across a high current connection as the solder joint or PCB cracked.

A blown fuse often leaves stuff spattered on the inside of the glass or plastic, if it is a clear enough housing to see a flash thru you can usually see this. Or you can usually see the gap in the fuse element inside.

I've since found the purchase order back from 2014 and discover it's a 50V 16.5 AH Samsung 18650 pack, which came with a 58.8V 5A Charger - the one I stupidly dropped. So that makes sense, it's 14S6P.

That means that if you only get 56.6v as a full-charge voltage, and the charger was working correctly before, there is something wrong (cells aged and capacity lost unevenly among them) with the pack causing an imbalance--not surprising for a nearly 9-year-old pack.

 

[mattek]

That's higher than a 48v pack should ever be (56.6v / 13s = 4.35v), so if it is a 48v pack it would be overcharged at that level. Logically that points to a 14s (52v) pack vs a 13s (48v).


Assuming it is balanced, yes. If it is not balanced, a charger will stop (because the BMS turns the input off) at the point the first cell fills up to full, so the total voltage could be much lower than designed.

To test this without opening the pack, then once you have the correct charger you can leave it on the charger at least overnight, and see if it improves total full voltage. If it does, but doesn't reach normal full, leave it on the charger longer until it does. If it never reaches normal full, something is wrong and should be diagnosed.

Hi Amberwolf. I realize this is not my thread, and that you are currently helping me in my own thread, but this is exactly what's happening to me right now.

My 48v pack is reading 56.6v on my mutlimeter. Should I plug it into my original charger that came with the scooter and let it sit overnight as you suggested here to see it it levels out?

 

[amberwolf]

If it's already overcharged, plugging it into *any* charger is probably a bad idea. If it's higher voltage than the other charger puts out, then in the unlikley event that the charger is not designed correctly it could damage the charger. If it's the same voltage as whatever charger is connected, at best it will do nothing, at worst it will continue the charge process (albeit slowly) as usually the battery will self-discharge a bit over time even under normal circumstances.


The quoted suggestion in your post is not to correct the overcharge. It's about balancing an unbalanced pack that *isnt* charged to full.

The discussion about overcharge in this thread was deducing that it is not an overcharged pack without opening the pack and measuring the cells directly.



Your issue is separate, where you have actually verified by direct measurement that your cells are too high a voltage.

I would guess from your statement about an "original charger" that that charger was a lower voltage than the one you used on the battery last?

A "48v" pack that is 13s should charge to around 55v (13 x 4.2v =54.6v). Some packs that are actually 14s (14 x 4.2v = 58.8v) are called 48v, but are really "52v", since the voltage is the average or nominal battery voltage.

To fix the problem, if there is one, you'd need to discharge it by running the scooter with it, or some other load. This doesn't fix any damage the battery cells may have already experienced, so if you start having problems with the battery that you didn't before, it may be caused by this.

If yours is at 56.6v, it is not likely that it would damage the scooter by plugging it in, but we don't have any specifications on what the scooter's system can handle, so there's no guarantees on that. Some systems will have an operating limit (HVC) where they will turn on but won't run if it's too high a voltage. If it doesn't have that and runs you can simply ride it to discharge the battery.

If you don't want to risk the scooter or it wont' run because it's too high, you could connect something like a resistive heater, or old-fashioned mechanical-control toaster oven, individual spiral ceramic stove element, etc., to the output. If the load you want to try has an electronic display, it probably can't be used this way, but if it's mechanical switches, it'll probalby work (if it has a fan in it, the fan probably wont' work on the DC voltage, and if the item relies on the fan it could be damaged by this, but probably not).


It's also possible the BMS in the battery won't allow it to operate because of the problem, but if you're able to read a voltage *above* normal (rather than well below) on the output then that's probably not the case. If it is, you'd have to open it up to do any discharging, and do that until the BMS then allowed the pack to work again.

 

[mattek]

If it's already overcharged, plugging it into *any* charger is probably a bad idea. If it's higher voltage than the other charger puts out, then in the unlikley event that the charger is not designed correctly it could damage the charger. If it's the same voltage as whatever charger is connected, at best it will do nothing, at worst it will continue the charge process (albeit slowly) as usually the battery will self-discharge a bit over time even under normal circumstances.


The quoted suggestion in your post is not to correct the overcharge. It's about balancing an unbalanced pack that *isnt* charged to full.

The discussion about overcharge in this thread was deducing that it is not an overcharged pack without opening the pack and measuring the cells directly.



Your issue is separate, where you have actually verified by direct measurement that your cells are too high a voltage.

I would guess from your statement about an "original charger" that that charger was a lower voltage than the one you used on the battery last?

A "48v" pack that is 13s should charge to around 55v (13 x 4.2v =54.6v). Some packs that are actually 14s (14 x 4.2v = 58.8v) are called 48v, but are really "52v", since the voltage is the average or nominal battery voltage.

To fix the problem, if there is one, you'd need to discharge it by running the scooter with it, or some other load. This doesn't fix any damage the battery cells may have already experienced, so if you start having problems with the battery that you didn't before, it may be caused by this.

If yours is at 56.6v, it is not likely that it would damage the scooter by plugging it in, but we don't have any specifications on what the scooter's system can handle, so there's no guarantees on that. Some systems will have an operating limit (HVC) where they will turn on but won't run if it's too high a voltage. If it doesn't have that and runs you can simply ride it to discharge the battery.

If you don't want to risk the scooter or it wont' run because it's too high, you could connect something like a resistive heater, or old-fashioned mechanical-control toaster oven, individual spiral ceramic stove element, etc., to the output. If the load you want to try has an electronic display, it probably can't be used this way, but if it's mechanical switches, it'll probalby work (if it has a fan in it, the fan probably wont' work on the DC voltage, and if the item relies on the fan it could be damaged by this, but probably not).


It's also possible the BMS in the battery won't allow it to operate because of the problem, but if you're able to read a voltage *above* normal (rather than well below) on the output then that's probably not the case. If it is, you'd have to open it up to do any discharging, and do that until the BMS then allowed the pack to work again.

I should clarify - my pack was reading 56.6 from the charging cables coming out of the battery pack

the output cable that goes to the controller reads 48v for a split second and then starts dropping very fast until its in the mV. if i wait an hour it will go back up to 48 but drop as soon as i make the connection with my multimeter again

All the while the charger cable still reads 56.6

However, after having the charger connected for about 9 hours the charger cable now reads 55.4v and each cell is reading 4.26v. So it's dropping to normal levels as if the charger is slowly regulating the pack.

 

[amberwolf]

What is happening is you are forcing current out of the battery into the charger electronics, potentially damaging the charger with unpredictable future consequences.

That's why I said it's a bad idea.

Hopefully nothing catches fire now or later.

 

[mattek]

What is happening is you are forcing current out of the battery into the charger electronics, potentially damaging the charger with unpredictable future consequences.

That's why I said it's a bad idea.

Hopefully nothing catches fire now or later.

even though the charger reads normal on my meter? Do chargers not have protection for that kind of thing?

 

[amberwolf]

They're designed to connect to batteries that are lower in voltage than they are, not to anything that is higher voltage than they are. So they don't have to have protections for this scenario.

They *could*, if they're well-engineered, but that's not very likely for most of them. Even those that were designed to have such protections may not have them installed by the manufacturer, because extra parts cost extra money.

Even if the charger appears to work it could still be damaged; so just like the overcharged cellls you won't know if there is a problem until something goes wrong. Unfortunately it's possible that something could be a fire; or it could just stop working, or something else could happen, or nothing may ever happen and it keeps working the rest of the time you use it. No way to know, and no way to give you a probability either. (also no good way to know if anything that does ever happen was caused by this, or just by a factory defect or design flaw).

But the best way to prevent problems is not to do things with the equipment it wasn't intended for, which is why I warned against it.