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Can I overcharge the batteries in my KX3

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Jerry

Can I overcharge the batteries in my KX3

Hello,

I am about to take a month long trip to California and then back to Virginia
starting this Sunday. I am taking my KX3 along with some accessories so I
would like to know - is it possible to overcharge the NiCads or Enloops. I
have a system set up on my motorcycle that will provide 13.8vdc at 3 amps
clamped. for charging some 12 v sealed lead batteries and I am wondering if
I use this output voltage and set the timer to 8 hours on the KX3 charging
system, can I overcharge the batteries and ruin them or worse the internals
of the KX3?

Thank you.

Best regards,

Jerry, W1IE

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Matt Zilmer-3

Re: Can I overcharge the batteries in my KX3

The KX3's internal charger is intended to charge _NiMH_ batteries. Its
output is a constant 200 mA. At that current level, you are unlikely to
overcharge the AA cells, and all that will happen is that they'll stay
warm.

Theway I handle mobile ops with batteries is to run the charger in 4
hour durations, and periodically check the BT voltage on the DISPlay.
For NiMH, if the voltage is 10.8V or higher, I just disable the
charger. 10.8V is very close to 100%. Others recommend charging up to
11.1V, which is 100% for most formulations (e.g., Tenergy). Not sure
what Sanyo recommends for Eneloops. You might wan to read up on that.

Specifically for Eneloops - they hold their charge quite well, so there
is little need to top them off as youmotor alongunless you'redrawing
current from them all the time. If the 13.8V input is connected, it is
diode steered with the battery output and any current you draw will be
from the external power connection. In this arrangement, the highest
voltage wins.

73,

matt W6NIA

On 5/4/2017 3:38 PM, Jerry wrote:

> Hello,
>
>
>
> I am about to take a month long trip to California and then back to Virginia
> starting this Sunday. I am taking my KX3 along with some accessories so I
> would like to know - is it possible to overcharge the NiCads or Enloops. I
> have a system set up on my motorcycle that will provide 13.8vdc at 3 amps
> clamped. for charging some 12 v sealed lead batteries and I am wondering if
> I use this output voltage and set the timer to 8 hours on the KX3 charging
> system, can I overcharge the batteries and ruin them or worse the internals
> of the KX3?
>
>
>
> Thank you.
>
>
>
> Best regards,
>
>
>
> Jerry, W1IE
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Elecraft mailing list

Re: Can I overcharge the batteries in my KX3

In reply to this post by Jerry

First of all, forget the Nicads. The KX3 isn't really designed for Nicads, and they have a lot of problems such as excessive self discharge, and leakage. If you want rechargeable cells, use modern low self discharge (LSD) nickle-metal hydride (NiMH) cells. Eneloops are one example, and probably the most popular. The KX3 manual discusses the use of them in the Internal Batteries section. Usually LSD NiMH cells are sold in a charged condition. Once installed, they can sit in your radio for long periods losing very little of their charge. I have never seen a modern NiMH cell leak, unless they are discharged to less than 1.0 volts per cell. The KX3 prevents this with its adjustable battery warning and automatic shutdown.

Assuming you are using LSD NiMh cells of at least 2000mah in size. The KXBC3 charger is a 200ma - 250 ma (approx.) constant current charger which is about 0.1 times the capacity of the cells. That is a perfect constant current charge for 2000mah cells or larger. Cell manufacturers' guidelines for these cells state that is isn't likely that you will overcharge using this method but they suggest you not leave the charge on constantly like you would when using a trickle charger. (A trickle charge rate would be about 1/4th of the KXBC3 charge rate, if my memory is correct). Since the KXBC3 also monitors cell temperature, it complies with the manufacturers' recommendations. It will only charge while the cell temperature is within limits, and will suspend charging until the temperature returns to normal.

In reality, MiMH cells work best when charged somewhat longer than necessary. That allows the lowest charged cells to be brought up to a fully charged condition. They are self-leveling.

Mark
KE6BB

On Thursday, May 4, 2017 3:40 PM, Jerry <[hidden email]> wrote:

Hello,

I am about to take a month long trip to California and then back to Virginia
starting this Sunday. I am taking my KX3 along with some accessories so I
would like to know - is it possible to overcharge the NiCads or Enloops. I
have a system set up on my motorcycle that will provide 13.8vdc at 3 amps
clamped. for charging some 12 v sealed lead batteries and I am wondering if
I use this output voltage and set the timer to 8 hours on the KX3 charging
system, can I overcharge the batteries and ruin them or worse the internals
of the KX3?

Thank you.

Best regards,

Jerry, W1IE

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Bill K9YEQ

Re: Can I overcharge the batteries in my KX3

In reply to this post by Matt Zilmer-3

Matt, thank you for the refresher. I had forgotten the info you espoused even though I was an FT back in the KX3 earliest days!

72 & 73,
Bill
K9YEQ, FT'er for K2, KX1, KX3, KXPA100, KAT500, W2, etc.

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Matt Zilmer
Sent: Thursday, May 4, 2017 6:07 PM
To: [hidden email]
Subject: Re: [Elecraft] Can I overcharge the batteries in my KX3

The KX3's internal charger is intended to charge _NiMH_ batteries. Its output is a constant 200 mA. At that current level, you are unlikely to overcharge the AA cells, and all that will happen is that they'll stay warm.

Theway I handle mobile ops with batteries is to run the charger in 4 hour durations, and periodically check the BT voltage on the DISPlay.
For NiMH, if the voltage is 10.8V or higher, I just disable the charger. 10.8V is very close to 100%. Others recommend charging up to 11.1V, which is 100% for most formulations (e.g., Tenergy). Not sure what Sanyo recommends for Eneloops. You might wan to read up on that.

Specifically for Eneloops - they hold their charge quite well, so there is little need to top them off as youmotor alongunless you'redrawing current from them all the time. If the 13.8V input is connected, it is diode steered with the battery output and any current you draw will be from the external power connection. In this arrangement, the highest voltage wins.

73,

matt W6NIA

On 5/4/2017 3:38 PM, Jerry wrote:

> Hello,
>
>
>
> I am about to take a month long trip to California and then back to
> Virginia starting this Sunday. I am taking my KX3 along with some
> accessories so I would like to know - is it possible to overcharge the
> NiCads or Enloops. I have a system set up on my motorcycle that will
> provide 13.8vdc at 3 amps clamped. for charging some 12 v sealed lead
> batteries and I am wondering if I use this output voltage and set the
> timer to 8 hours on the KX3 charging system, can I overcharge the
> batteries and ruin them or worse the internals of the KX3?
>
>
>
> Thank you.
>
>
>
> Best regards,
>
>
>
> Jerry, W1IE
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html Message delivered to
> [hidden email]

--
"A delay is better than a disaster."
-- unknown

Matt Zilmer, W6NIA
[Shiraz]

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______________________________________________________________
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