Building Charger for Sanyo Eneloop (CY-EB60 / CY-PAA6)

[Moecycle]

Hi There,

I've managed to get my hands on a Japanese Sanyo Eneloop hybrid here in London. Used, and no idea if the battery works. Unfortunately it didn't come with a charger. Given that its Japanese, finding a charger locally is coming up dry. To add to that, the factory unit is 110V only, so I'll likely need to modify it myself anyways.

The exact model of the charger is CY-PAA6 (https://panasonic.jp/sanyo-cycle/p-db/CY-PAA6.html), which spec'd to output 2A @ 29.2V
The battery it is charging is a Li Ion Sanyo CY-EB60 - 25.2V 5.7 Ah. When I opened up the battery, it seems to be 21 18650's. Currently putting out 10V, so not 100% dead.

I'm planning on just buying an off-the-shelf 29.2V 2A charger, and throwing together a make-shift stand to sit this on to see if the battery will hold a charge. Here are some photos for reference.

Anyone have any thoughts on what the "T" and "S" ports are on this charger?

 

[vfr400]

If the voltage were truly 10v, that battery would be scrap. Where did you measure it? You need to measure it directly from the cell-pack, not on the battery teminals because the BMS is probably switched off, and what you're measuring is the charge leakage through the mosfets.

T and S could be temperature and switch or it could be a feed and return for a remote switch.

What are those two metal pads on the BMS next to the screws? Are they exposed when the thing is assembled? They look like fast charge pads. Can you measure the voltage between them?

Where do all those black wires go?

 

[Nealh]

As vfr has said 10v is scrap and well beyond recovery, to stand a chance of any recovery it needs to be around 20v.

 

[vfr400]

As vfr has said 10v is scrap and well beyond recovery, to stand a chance of any recovery it needs to be around 20v.

I don't think it is 10v, though. It's probably switched off.

 

[Moecycle]

I don't think it is 10v, though. It's probably switched off.

Thank you all so much for the prompt replies! I'll be posting more photos and measurements today after work.

You're correct, I was only measuring from the terminals of the batteries, before the BMS (just to see if there was any life in the cells at all). I'll re-measure with the fuse replaced & the full circuit.

Cheers

 

[vfr400]

Thank you all so much for the prompt replies! I'll be posting more photos and measurements today after work.

You're correct, I was only measuring from the terminals of the batteries, before the BMS (just to see if there was any life in the cells at all). I'll re-measure with the fuse replaced & the full circuit.

Cheers

Thata's not very clear. Terminals by definition are at the end. If you measured from the bottom of cell 1 to the top of cell 7 before the BMS and you got 10v, the battery is scrap. If you measured on the battery output terminals - the things that connect to the charger or bike - and got 10v, the BMS is probably switched off.

 

[Moecycle]

Thata's not very clear. Terminals by definition are at the end. If you measured from the bottom of cell 1 to the top of cell 7 before the BMS and you got 10v, the battery is scrap. If you measured on the battery output terminals - the things that connect to the charger or bike - and got 10v, the BMS is probably switched off.

Thanks vfr. Seems I'm out of luck, 11V no matter where I measure. Do you mind if I know how you calculated this? 20v @ 21 cells ~~ 1V/cell?

Given this, I'm likely going to replace the cells in this pack myself. I'm having a hell of a time opening it to begin with, hopefully I manage to get it open without complete destruction.

I've attached a number of more photos. If you or anyone else has any suggestions on how to:
1. dis-assemble, or,
2. how to charge when I finally get it back together,

I would be infinitely grateful.

HD album here: https://photos.app.goo.gl/PSdhRUNi3S3ji3xw8

 

[vfr400]

11.7 volts divided by 7 is 1.5V per cell. Thinking again, if it's balanced, it might be recoverable. Measure the voltage of each of the seven cell groups. You can do that by putting the black probe on the pad with a blue mark on it next to the screw, then probe each of the wires that come up at the edge that look like staples. the final one would be the other pad with a screw in it. The voltages will be cumulative, so you can calculate what the individual cells groups are.

 

[Moecycle]

11.7 volts divided by 7 is 1.5V per cell

Right - parallel cell groups. Thanks for the battery 101 lesson by the way

So, measurements are in:
1.6V - Group 1 ~ 1.6V
3.14V - Group 2 ~ 1.54V
4.65V - Group 3 ~ 1.51V
6.25V - Group 4 ~ 1.6V
7.91V - Group 5 ~ 1.66V
9.55V - Group 6 ~ 1.64V
11.22V - Group 7 ~ 1.67V

So, max difference of ~0.16V

 

[vfr400]

That will recover enough to work the bike, but there's no saying whether it's already worn out. You'll have to try it. I use a Gophert adjustable power supply for this sort of job because I can start off with a low charge rate, then gradually turn it up as the battery gets into the normal range. I think you'd be OK with a normal 1 to 2 amp 24v (29.4v) volt lithium charger. Connect it to those two pads with the screws, but you must keep an eye on the individual cell voltages to make sure that none go over 4.2v at the end of the charge. Charging like that will work under controlled conditions for testing, but you won't be able to use it as a set and forget system.

 

[Nealh]

The recovery is worth it for an experiment on how to charge and try to recover cells, I expect if you can get them to a reasonable level the battery will likely sag vey badly. For Li all spec sheets have a min V level of about 2.5v per cell. Just be very careful charging and initially use very low current and do so in a safe place where damage can't cause much harm.
WHAT EVER YOU DO DON'T LEAVE THEM UNATTENDED DURING CHARGING.
If they do charge leave them overnight or for 24hrs to see what happens to the volatge.

 

[Moecycle]

The recovery is worth it for an experiment on how to charge and try to recover cells

Thanks Nealh and vfr. Ordering in some components and follow up when I have some results.

You have been very helpful, very glad to participate in this community.

 

[Nealh]

If the voltage can be raised then as mentioned before leave the battery to stand for 24hrs to see if the voltage drops, if it does by quite a lot then they are toast. But as mentioned before don't trust them and leave unattended during any charge process.

For charging one will have to bypass the BMS to charge the pack, the BMS won't allow charging as the cell groups are well below the min of 2.8 - 3v per cell group.

 

[Moecycle]

Hi Folks,

Short update here, parts came in and I've given it a charge. I decided to remove the BMS in the off chance everything went terribly wrong and it fried. I've charged the cells at 29.4V 2A for 1hr. Very happy to see consistent voltage across the parallel groups throughout the charge cycle.

Also happy to see what one would expect from a Li-Ion charging V curve. Very rapidly from 1.6V -> 2.5V (~5 minutes), more consistent from 2.5V -> 3.6V (15 minutes). After 3.6V, it definitely slowed quite a bit.

Charged for 1 Hour total and reached 3.75V.

10 minutes after charging, battery is at 25.4V the cells groups are sitting at:
C1: 3.66
C2: 3.66
C3: 3.66
C4: 3.66
C5: 3.66
C6: 3.66
C7: 3.66

I'll follow up tomorrow evening to see if they held the charge at all. If that goes well, I'll try to charge for 12+ hours on the weekend outside. My goal here is to get this battery to a point where I can test the rest of the bike. I'm likely going to swap in new 18650's after I figure out what else this bike needs.

 

[Nealh]

That's good news and all nicely balanced as well, the real test for them will be on a discharge cycle. Now the cells are above 3v and balanced, the BMS can be reconnected as it will now work as it should do.

 

[Moecycle]

This morning the battery remained at 25.4V, so at least it's holding a charge overnight.

I reconnected the BMS, but unfortunately that didn't go well. It has a button with 4 lights which "should" show the charge level, but the button doesn't seem to be doing anything.

Furthermore, when I tried connecting the charger directly to the anode/cathode of the battery after the BMS was installed, I didn't see any voltage change across the cells and the light on the charger was flashing red (usually solid red when charging). I turned it off after that.

On the output of the BMS, the voltage from from the main terminals is only 170mV. As expected, when I plug it into the bike (which only has ports -,Y,+), no response at all. Here is a diagram of the voltage drops across the terminals now.



I'm wondering if I can attempt to charge it through the BMS? I'm quite perplexed by the terminals.

Thoughts on if I can connect a 29.4V charger to any of these terminals?

 

[vfr400]

S and T could be for a remote switch. I have a Panasonic battery that works like that. You need to trace where the connections go to on the bike side.

 

[Moecycle]

S and T could be for a remote switch. I have a Panasonic battery that works like that. You need to trace where the connections go to on the bike side.

Thanks for the input. The charger is the only device with the S and T ports, so I may have to import one from Japan to figure this out. The bike only has + , Y, - (photo below). I'll open up the bike this weekend to see if I can get any clues.

I'm beginning to fear the issues with the battery are more severe and the BMS is junk as well.

I'm slightly tempted to just build a new regular 25V battery and see if I can get this bike moving.

 

[Moecycle]

Hi There, had some time to spend on this during the Christmas break.

I've come to the conclusion there is something wrong with the current BMS. While the battery has ample charge (26v), the output of the +/- of the is never 26V, and the LED light indicators show no sign of life.

I decided to re-wire the terminals of the battery to directly connect the anode+cathode to the outputs, and see how the bike would react.

The good news is that the bike shows signs of life. Unfortunately, no power going to the motor yet. Here is a short video:

New video by Moe Adham

photos.app.goo.gl

The flashing indicator lights on appear to be an error code related to the "connector" according to the Sanyo Enloop Manual. This seems rather expected as I left the middle connector (Yellow, unknown BMS output) blank.


At this point, I'm not really certain what to do next. I would like to debug what that yellow battery connector is for, and if I can somehow emulate/replicate it.

I opened up the rest of the bike, and its unfortunately it didn't reveal many interesting info.

*If anyone happens to have any idea what the non-power terminals on Sanyo/Panasonic batteries are for, would really appreciate it!*

More photos for reference:

 

[Moecycle]

Just a short update here. I've tried supplying that 3'rd control connector anywhere from 2.8->28v. No difference in terms of response from the Bike.

Seems the electronics are complex enough that you can't really operate this bike without at least an original BMS.

I'm going to try to source a new battery from Japan. If that proves too complex, I'll likely try to just swap out the controller itself and see how much of the original electronics I can salvage (hopefully the 250w motor).