Dead charge port. Where to buy a BMS.

I have a very lightly used 13S 48V Dolphin pack from 2015. Less than 400 miles on the bike that it came with. I took it out yesterday and found it wouldn't take a charge after the ride. Tried two different chargers, which do work on my other 48V battery. Finally I took it up to a partial charge of 53.8V using the discharge port. Still drawing 1.0 amp when I terminated charging. Then opened it and checked the cell groups. No bad cells to inhibit charging. All in balance.

The BMS looks sturdy, with screw terminals for the power connections. Big heat sink on the discharge devices The board provides the interface to light the LED display commonly seen on Dolphins. I could just replace with a generic BMS, but then I would lose the 5LED voltage readout as well as the illuminated ON/Off switch. Anyone have a source for this kind of BMS?

For a work around, what's the risks with if I just rewire the charge connector to the discharge port? i Might not have over voltage protection? Balance won't work?

docw009 said:

I took it out yesterday and found it wouldn't take a charge after the ride. Tried two different chargers, which do work on my other 48V battery. Finally I took it up to a partial charge of 53.8V using the discharge port. Still drawing 1.0 amp when I terminated charging. Then opened it and checked the cell groups. No bad cells to inhibit charging. All in balance.

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But they may not have been balanced when it wouldn't take the charge initially, or they may have been so low overall with one or more overdischarged, that the BMS was trying to protect the battery. Not likely, but possible. Since it wasn't opened up to check the cell groups before recharging, you can't know what the original state was.


Does it charge thru the charge port after the initial charge thru the discharge port?

I could just replace with a generic BMS, but then I would lose the 5LED voltage readout as well as the illuminated ON/Off switch.

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Are those part of the BMS board itself? They aren't on the similar-cased batteries I've opened up.

If they are not part of the board, you don't lose the voltage readout, because you just solder the wires from it to the discharge port of the new BMS.

The on-off switch depends on how it works. If the switch is a momentary switch, then the new BMS would have to have an on/off switch function; there'd probably be pads for it on the board. The LED part you'd have to see how it's powered on teh original BMS, but most likely it runs off the 5v that the BMS chip runs on. If the new BMS doesnt' have that, you could still run the LED off pack voltage if you change the resistor.

If the new BMS doesn't have a switch pad to turn it on and off, you could use a non-momentary switch (push or toggle) of the same size (so it fits in the case) and wire it between the BMS's discharge FETs gate line and the BMS enable output (would have to cut a trace probably; there's a number of posts by Dnmun showing this).

For a work around, what's the risks with if I just rewire the charge connector to the discharge port? i Might not have over voltage protection? Balance won't work?

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You'd have no protection on charging at all. If anything is wrong, the BMS can't shut off the charger, so you could have a fire if the conditions to cause one occur.

Amberwolf, all the LED circuit must be on the BMS. I see a 10 wire cable to the LED board, with a wire to drive each one of the 5 LED's.

The battery was at 46 volts, and still running the bike, when I tried to recharge it. I'm pretty confident no cell groups were undervoltage, or it wouldn't have been useable.

Yes, I wondered about overcharge. That's why I kept an eye on it and terminated manually. Maybe it just needs a reset. Pull off the balance connector.

Nicely made electronics there. Hate to scrap it.

Yes, charging through the discharge port will bypass the over voltage protection. Not safe.

It's definitely worth a try to unplug the BMS and reconnect it to see if you can reset it. Discharging from the charge port might also do something.

Another thing to check is look for a temp sensor and make sure the wiring is good. Most boards will disable discharge as well as charge if the temp goes too high.

It would be hard to find that exact model of BMS. A generic one would work but not have the level meter. You could use a separate voltmeter or amp-hour meter. They make really inexpensive battery meters these days.


$9.00usd

Specifications:
Model: BW-LY6
Backlight color: Green/Blue(Optional)
Operating voltage: 8-63V
Operating current: <5mA
Working temperature: 0 ~ 40°C
Display area: 43 x 11mm
Dimensions: 57.5 x 20 x 16.5mm(L x W x H)

How to adjust model:
Press and hold the key on the back when turn off, then power on. Tester displays the present specification, then click key to adjust, select correct specification you need, then turn off and power on.

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Probably explains all those hoverboard battery fires. I bought a few from alarmhookup on ebay and they don't hook up the charge port on the BMS.

Ordered the parts to replace it. 30A BMS with on/off switch. New USB module to replace the existing and also power the switch's LED. Tiny 60V LCD display to show voltage. Now to wait 5 weeks. Thought about using it w/o an on/off switch, but don't want to fry the connector sliding pack onto bike.

LOL. I left the battery outside as a precaution and it rained. The Dolphin is not bad for water resistance. The whole case has a tongue/grove fit.