0
\$\begingroup\$

I have a DAB radio which has a 7.4 V 2000 mAh LiPo battery which recently stopped holding its charge.

I purchased a replacement battery, 7.4 V but 3000 mAh. The old battery had a single 3 wire connector which I have removed from the board and with a multi-meter confirmed a 7.4 V reading.

The replacement battery has an additional 2 wire connector which I believe is for balancing, I think the terms is correct? I've installed the new battery but it is not holding the charge despite it being a new battery.

the red/back 2 wire connector is currently not connected

[red/back 2 wire connector is currently not connected]

Presumably the 3000 mAh is not significant, doesn't this just mean the battery should hold its charge for longer?

Does the additional 2 wire connector need to be plugged somewhere, in which case I've likely ordered a battery which is not compatible?

Just wondering what other factors might be at play, can I test the battery itself as perhaps that is at fault, despite being 'new'?

EDIT - Additional Info

The DAB radio in question is an Azatom Multiplex D2.

The mainboard:

enter image description here

The actual battery:

enter image description here

Unfortunately I don't have the old battery, it looked almost indentical, down to the blue plastic wrap and the print type, however as mentioned if only had the single JST connector.

Item purchased:

https://www.aliexpress.com/item/1005002559967860.html?spm=a2g0o.order_list.order_list_main.65.19a218021wLFND

I didn't intentionally cheap-out on the battery, I was not aware they are Li-Po type, I simply searched for the battery rating and came across the above item and purchased as it looked to be compatible given it similar appearance.

\$\endgroup\$
4
  • \$\begingroup\$ Could be temp sensor. You need to disassemble the old battery without damaging the actual cells to tell for sure. Measure with your multimeter? If 0 V, switch to resistance and report back. \$\endgroup\$
    – winny
    Commented Apr 23, 2023 at 9:12
  • 2
    \$\begingroup\$ If old battery does not hold charge (when installed in the device, I suppose) and new battery doesn’t either, that would seem to point to something other than the battery. \$\endgroup\$
    – jcaron
    Commented Apr 23, 2023 at 11:49
  • \$\begingroup\$ WHERE did you buy the battery (links please!)? What is the model of the radio? Do you have pictures of the radio PCB where the battery is connected? If you want answers, you need to provide all the details. \$\endgroup\$ Commented Apr 23, 2023 at 12:02
  • \$\begingroup\$ additional info added as requested \$\endgroup\$
    – Alan A
    Commented Apr 28, 2023 at 15:24

1 Answer 1

1
\$\begingroup\$

This looks like a fairly common type of LiPo battery pack for RC vehicles. The three-wire (JST-XH type) connector is actually the balancing connector and the two wire "T-type" or "Deans" connector is for (high current) charging and discharging.

The balancing connector is only suitable for low currents.

Your 2S LiPo pack might have a built in BMS that does not allow high charging currents through its balancing connector, which could explain why it does not seem to hold a charge. By connecting the red and black wires from the high current connector to the balancing connector you might be able to get this to work. But make sure you are very careful as LiPo packs can be dangerous when shorted or charged/discharged incorrectly.

The other possibility is that your new LiPo pack just isn't a very high quality one.

If you provide a link to a datasheet or a product description, we might be able to help you further.

This site explains how these plugs are connected to the battery cells (remember yours is a 2S battery pack).

\$\endgroup\$
5
  • \$\begingroup\$ I agree that no-name-brand junk batteries are garbage. I always buy name-brand Li-PO batteries that work perfectly from my local hobby store, not online from China. 20-06-26 might be that it expired or was made on June 26, 2020. \$\endgroup\$
    – Audioguru
    Commented Apr 23, 2023 at 16:01
  • \$\begingroup\$ See the description for additional info, although the battery might be low quality grade I'd at least expect to get some limited usage out of it, albeit with poor performance. Seems odd that it would not hold charge for a single cycle. \$\endgroup\$
    – Alan A
    Commented Apr 28, 2023 at 11:15
  • \$\begingroup\$ @AlanA When given a battery, the thicker wires are always for the load. Simple as that. You have to actually verify that the battery is being charged by the device it's in before condemning the battery. For all we know, the device is broken. \$\endgroup\$ Commented Apr 28, 2023 at 14:39
  • \$\begingroup\$ @Kubahasn'tforgottenMonica my post says I used a multi-meter to verify that 7.4v is read where the battery plug to the board \$\endgroup\$
    – Alan A
    Commented Apr 28, 2023 at 15:30
  • \$\begingroup\$ 7.4V is the storage voltage and selling voltage of the 2-cells lithium battery that is almost not charged. Your 'new battery is over 3 years old and it might not work. A new 2-cells battery must be properly charged to 8.4V for it to work. \$\endgroup\$
    – Audioguru
    Commented Oct 7, 2023 at 17:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.