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Cobra PR3850WX will not recharge batteries

I have a pair of Cobra PR3850WX handhelds that will not recharge batteries when placed in charger, nor will the led on charger light up. Checked charger with volt meter and it showed 12v, also placed a discharged 9v battery across charger contacts, the led light came on and battery showed a gain in charge from 2v to 7v in about 2 min. Can you help?


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Re: Cobra PR3850WX will not recharge batteries

There is a contact in the upper left hand corner of the batt compartment.This has to touch the metal of the last batt.If your batts have paper around them scrape it off where it contacts that contact point.

Posted on Nov 18, 2008

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Re: Cobra PR3850WX will not recharge batteries

I have had this issue before. The contacts on your radio may not making sufficient contact. I would clean them thoroughly, maybe rub them with something abrasive (fine sand paper) Is there any measurable charge in the battery's?

Posted on Nov 15, 2007

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Charge time cobra 235 recharge batteries

Hi! I've got a different cobra model and I find it ridiculous, but there is no indication when the batteries are fully charged... Either use external charger for your batteries or just leave it plugged in overnight- that would ensure full charge (it does in my case, I've checked batteries with multimeter)

Sep 23, 2014 | Cobra Two-Way Radios

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Cobra Micro Talk PR4750WX.New rechargable batteries will not charge in provided charging cradle.

The original Sanik batteries have a negative side with about ten mm of metal showing on the side. Trim the plastic off your new batteries to match and the cradle charges again.

Dec 11, 2012 | Cobra 22 CHANNEL 2-WAY RADIOS

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Hi, I have a pair of PR 385 hand helds, could anybody tell me if any other battery packs from any other model Cobra fit my radios. I,ve searched and can't find a specific pack for the 385. If you

I realize this is a bit late, but I have to comment. When I viewed this page there were two responses to the original query (one that I also have).
It is terribly painful to have had to read them because they are both so sincere in their desire to help and so clueless in their response. The original poster asked about replacement batteries for the Cobra PR385 2-way radio. Both respondents posted about a DIFFERENT model. The first I can understand the mixup, he posted about the PR3850wx, If you don't mind the extra 0wx at the end then it is all fine. The second posted about the LI 7200 wx??? What??
Please, we all want help, but check your information before you post your response. The Cobra PR385 radios use the FA_NICD battery pack at 4.8v and 300mAh.
I did just find a source for batteries if anyone is in need:

I have not tried either of these shops but will be ordering shortly.

Oct 14, 2012 | Cobra Electronics microTALK® PR 3850 WX ...

1 Answer

Where can I get a new set of rechargable batteries for my cobra microtalk cxt275

The Cobra CXT275 radios can operate on any type of battery (Alkaline, Ni-Cad, NiHM). Each radio uses 4 AAA batteries. Only special rechargeable batteries can be recharged in the actual radio (see below)
If I remember correctly, they come from the factory with NiHM batteries rated at 300mAH. "mAH" stands for milli-Amphere-Hour and it represents the storage capacity of the battery. (The larger the mAH, the longer run time of the battery)

You have 2 options: A or B
Option A) Buy a set of Nickel-Metal Hydride AAA rechargeable batteries and a external battery charger. When the batteries die, pop them out of the radio, and charge them in the external charger. When they are recharged, pop them back in the radio.
Option B) If you want the ability to charge the batteries in the radio, using the "drop-in charger" then you will need modify the batteries so they can charge in the radio.
Follow these steps: You must be somewhat electrically inclined to do this...Note: By doing this you are going to void the warranty of the radio and new batteries that you just purchased.
1) Buy a set of Nickel-Metal Hydride AAA rechargeable batteries. You can probably find some rated at 600 mAH (this will extend the run time)
2) Looking at the back of the radio with the cover removed, there are 4 slots for batteries.
3) Looking at the battery slot on the far right, you should notice 2 contacts for the negative contact. The one on the bottom, is the contact for the radio to receive power from the battery. The one on the side (about 1/8" inch up from the bottom contact), is the contact for the charger to recharge the battery.
4) You will need to modify 1 battery for each radio. Somehow you need to bridge the bottom contact with the side recharge contact.
5) (look at the negative end of the cobra factory batteries and this should help you realize what you need to do) depending on the manufacturer of the new rechargeable batteries, you may be able to use an X-acto knife and remove 1/4" of the plastic wrapper from the bottom of the battery on the negative end. This should reveal the metal shell of the battery that can mate with the radio's side recharge contact.
If it does not, you need to find another way to have it mate with the bottom contact. You might be able to use some Aluminium Foil to bridge the bottom contact with the side recharge contact. Be sure the Aluminium Foil does not touch the positive contact of the battery to the left! You could have an electrical short!
6) Insert the Modified Battery into the right slot.
7) Insert the other 3 new batteries into the other slots. These do not have to be modified. Only the right most battery needs to be modified.
8) Drop the radio in the charger for the batteries to charge. The red LED on the charge base should come on. If it does not, then the side recharge contact is not making a good connection with the negative battery terminal.
9) If the red LED comes on, then the modification works. Let the batteries charge for 24 hours for their first initial charge.
10) When the batteries die after radio use, then charge them for about 12 - 16 hours in the drop-in charger. Do not let the radios sit in the charger for long periods of time. That can destroy the batteries. Take the radios out of the charger when the allotted time has passed.
11) If you hardly ever use your radios you will want to drop them in the charger for about 8 hours every 3 months. This will keep the batteries fresh without damaging them.
I hope this helps, Thomas (Electrical Engineer)

Feb 22, 2012 | Cobra Two-Way Radios

2 Answers

What battery is needed for Cobra Model #PR3850?

just have to wrap a bit of tin foil over the bottom of one battery and use normal nimh rechargeables. The Cobra's have a seperate circuit that must be made to differentiate between normal AA and rechargeables. The OEM battery has an exposed metal ring on the bottom of the battery. If a normal AA is put it and allowed to attempt to charge, it will start a fire. If you look, there is one contact at the negative end of one battyery that must be made for it to allow to charge in the base. You could scrape away the plastic, but a wrap of tin foil did the trick for me.

Oct 26, 2011 | Cobra Electronics microTALK® PR 3850 WX ...

2 Answers

Cobra pr 3850wx bought new NiMh 800mAh 1.2v rechargable batteries now the base charger lights won't come on when i put the radios in it

  • A Cobra 3850wx Radio requires 4x600mAh NiMH 1.2V AAA Part # GA-3ANH rechargeable batteries.
  • Not just any AAA rechargeable battery will charge in the unit.
  • All will work in the radio but not all will charge inside the radio. It has to be a specific battery.
  • This is an example of what you need. GA-3ANH batteries which will charge inside your radio.
Regards, Tony

May 22, 2011 | Cobra Microtalk 100 FRS Walkie Talkie...

1 Answer

I lost my manual. Can I download a basic guide for free? Cathie

Yes, Cobra has the user manual for the PR3850WX available for download HERE

Oct 13, 2010 | Cobra Electronics microTALK® PR 3850 WX ...

2 Answers

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Sounds like the radio was subjected to electrostatic discharge. If you have your manual, and it describes a way to do a "master reset" on the radio, follow the instructions. This usually involves pushing down on one key while turning the radio on. Otherwise you have to find a licensed dealer for factory service, as there is no way to repair the radio yourself. The use of surface mount technology still confuses many Techs unless they have been to a company's two or three week seminars.

Jul 23, 2009 | Cobra Two-Way Radios

1 Answer

Microtalks won't charge

I have the Cobra Microtalk 4100 FRS radios with charging base. After changing the batteries with new nimh rechargables the charge light would not illuminate and the unit would not charge. I noticed the original batteries had a metal band around one end. This band makes a small connection inside the battery compartment on the first battery. Seems to be a cheap way to ensure you dont try to recharge the unit with non-rechargable batteries installed. I rapped a small piece of tinfoil around one end of the first battery in the new set then popped it back in and now they will charge correctly again. Dont try this with non-rechargable batteries! I would recomend buying original replacement batteries.

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