Reention Dorado 17ah 48v charger led goes green always

[Mansour]

Reention Dorado 17ah 48v charger led goes green always:
I am new here, and looking for experties. After reading some forum the first diagnostic was the fuse. I open the battery case and unfortunatly, in my Dorado reention 48v 17ah is no fuse. I went to the next mess during open the case and pull up the cells. I found two free cables and don't know where should be connected?

Next question: I ordered a BMS 13s 48v 35a and replaced it with original BMS 13s 48v 45a unfortunatly, the result is the same the charger will not charge the battry and the green led switches on as soon as I push in AC.

When I measure the charger or discharger both have same voltage currently 46v. As soon as I push the charger in AC and measure the charger the multimeter showes 54v.

I would welcome any advice would rescue the battery. Thank in Advance

 

[tomjasz]

Some chargers can't be checked with a multimeter, as there is communication between the battery, BMS, and controller.

I'd try another charger.

That said what is the voltage out from the charger.

 

[tomjasz]

BTW endless_sphere may be a better resource. If you use Facebook there are some good battery groups there.

 

[Mansour]

Some chargers can't be checked with a multimeter, as there is communication between the battery, BMS, and controller.

I'd try another charger.

That said what is the voltage out from the charger.

Thanks tomjasz, I did not measure on Chrager device, I meausred on the BMS pin (C-, Ch-)

 

[tomjasz]

I did not measure on Chrager device

Try it and see what you get.

 

[Mansour]

Try it and see what you get.

With charger I measured 54v and replaced it with a lab energy supplier (set to 54v) again I measured 54v with Multimeter

 

[Mansour]

Any other idea, e.g. exchange the BMS?

 

[harryS]

When a battery doesn't charge, it's because the BMS will not let it. Your second BMS woun't let it charge either. Did you look for the cause? Unplug the balance cable and walk a voltmeter up each pair of pins and record the cell voltages. If any are at 4,2V, the BMS deems the battery at full charge. Green LED on charger. If any are too low, like 2.8V, the BMS calls that a hazard, and will refuse to charge. Still a green LED on charger.

I had a little balance problem recently with a battery. One of the cells was at 3.6V*, and the rest were fully charged at 4.2V. The BMS, not being a balamce BMS, was unable to correct it. I charged it alone, with a 4.2V supply. Now it's good.

*If it had been at 2.5V, I would have written off the pack. You get too low, the electrolyte forms metallic threads that will give you an internal short circuit. Potential fire right there.

 

[Bitmugger]

I am repairing a Dorado battery myself at the moment similar symptoms. Doesn't charge (light stays green) but does discharge properly. I have a new BMS coming for mine and via other batteries and chargers I've eliminated the obvious (fuses, bad chargers, bad connectors). I can say I have 2 wires inside mine that go no where but have factory shrink over the tips so they were never connected. When my BMS arrives Tuesday I'll open my Dorado again to start getting serious about repairing it. I'll keep you apprised and if you want to compare any notes or have me try things on my battery hit me up.

One suspicion I have about mine is that one cell group might have a bad cell and is under voltage and therefore so far out of balance the BMS isn't accepting a charge. I'll be checking each group to see if things are in balance as a first step on mine. This is what seems to happen over time to my Makita and Ryobi cordless tool packs, will discharge, won't recharge. If so I'll be chasing down a few replacement cells but will struggle to weld them as I don't have a battery spot welder nor does anyone I know locally. Might be time to invest in a $30-$40 cheapy battery welder but as I am not really looking to build battery packs from scratch I'd rather avoid a purchase, solder is an option I suppose.

 

[harryS]

My first battery scuffle came with a pack that wouldm't charge. I verified all the voltages were in spec, and they were safe. There was no reason the BMS shouldn't have allowed charge. So I replaced it. As I completed the change, I found one reason why it wouldn't charge. Broken wire on the charge port, Ahh, bummer.

 

[Bitmugger]

My first battery scuffle came with a pack that wouldm't charge. I verified all the voltages were in spec, and they were safe. There was no reason the BMS shouldn't have allowed charge. So I replaced it. As I completed the change, I found one reason why it wouldn't charge. Broken wire on the charge port, Ahh, bummer.

For my battery I was really hoping it was something simple like that. Not the case though, tried to fuses and checked the wires, in my case I was sure it wasn't a loose wire or fuse though as when I plug in the charger the BMS shuts down entirely for a few minutes before coming back to life, but still checked them anyway

Hey @Mansour, did you check both fuses? There's one in each end. One for discharging (the top fuse) and a smaller 5A one for charging on the bottom.

 

[tomjasz]

I just got a banggood welder to check out for fun. I’ll report back after a brief trial.

 

[Mansour]

@Bitmugger, Yes, basicly I opened the battery to find a fuse unfortunatly I found no fuse there, and asked the people, obviously this kind of battery (Dorado reention 48v 17.5 ah) has no fuse. That is why I dicided to change/replace the BMS

 

[Mansour]

@Bitmugger : Before I changed the BMS last week I messured the voltage of battery at all, it showed 46.800v, then I tried to replace the BMS connector as your picture cable by cable, it does not worked. I measured the cable as you mentioned today. I does not seem good. I think i demaged the battery, because I could measure till 8. cable round abot 30v. But from 8. cable I have 0v now. You mentioned that you are able to charge the cells. How did you do it? I have an ab energie supplier, I aske me how should looks the connection and voltage.

 

[Bitmugger]

To charge just one group of cells you need to think of your 48v battery pack as a group of 13 small 4.2v batteries wired in series. The balance lines all come from the interconnection point of each of the 13 groups. You can simply send 4.2v down the correct pair of balance wires to charge a single group. BUT the balance lines can't handle massive current so keep the current low. I will literally just use a small 18650 charger I have and run some leads to the group and let it sit until the charger says it's good (if the cells charge).

 

[harryS]

DId you check your balance voltages? You said you changed the BMS, so you must have pulled off your balance connector. For a 48V battery, 13 red wres and one black. The latter is at the most negative termial. The others go to each positive terminal of the series groups.

.
Then measure each pair of leads on the balance connector to see the inividual volrage of each group. Write them down. Some people stick in a pair of pins to make it easier to probe the leads. Just be careful theu don't cross and short out. You want each pair (a) between 4.2 and 3.0 volts and (b) be within a .10-.20 volts of each other. This is how most folks judge the healt of your battery and decide whether it is worth further work. If any are at zero, that could be a bad wire connection.

 

[Mansour]

@Bitmugger and @harryS many thanks for your contribution: I walked with a voltmeter up each pair of pins and record the cell voltages as follow: the neighbor pair has 3,9v as avarage. Pin 1-2 3,9v...6-7 3,9v 7-8 0v 8-93,9v 8-10 7,8v ...10-11 3,9v and 1-13 0v. it seems to be any demage between pin 7-8. However I checked the connection it seems to be fine as in picture below. There is only one connection point between both block and it seems to be okay. Any idea how could I repair it?

 

[harryS]

Your data says all the balance wires are connected, because you can read 6-7 as 3,9V, and 8-11 as 7.9V, but no voltage between 1-13. There's a broken connection between the middle cell groups. I think that's a show stopper. Better to be safe and get a new one.

I doubt you can fix that properly unless you had access to a battery spot welder. Someone would have to take the cells apart where the break is, and attach a new strip of nickel. It probably happened where the strip gets folded to connect one layer to the next.

Then again, maybe your battery has individual cell fuses on each cell, and those blew. Again, you need the right tools/expertise to fix.

 

[Bitmugger]

@harryS. Your logic is sound but what doesn't track is that if a cell group is fully disconnected and reading zero then your batteries should no longer be 13s but more like two separate 7s and 6s packs, I am unsure how @Mansour got 46v from the battery originally. Maybe that group kinda makes connection once in a while, just enough to be tricky. 54v I can understand as that was with the charger connected but to get 46v you'd need all the groups connected in a 13s configuration. @Mansour says pins 1-13 read 0v so that certainly backs up the idea of a break in the series groups.

 

[john peck]

Maybe it´s just a magic battery that´s always fully charged?