Elecraft

KX2/KX3 DC Charging

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K9MA

KX2/KX3 DC Charging

One solution to charging the Li-Ion batteries from a 12 V DC source is
to use a small inverter. One I've found which works well is the Samlex
PST-120-12. It's a small "pure sine wave" inverter, rated 120 W, costing
about $120. It seems to work just fine with the KXBC2 charger, and
should work just as well with the KXBC3. I would use only a "pure sine
wave" inverter, as the square wave from a "modified sine wave" inverter
is likely to cause the charger to malfunction.

Needless to say, I have no connection with the vendor, other than as a
customer. I've had good luck with other Samlex products.

73,

Scott K9MA

--
Scott K9MA

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Dennis Moore

Re: KX2/KX3 DC Charging

So you're taking your 12v source (let's say it's 13.8v), adding an
inverter to make 120v, then plugging in a charger to bring it back down
to 13.8v.

I'm fairly new to the KX3 game, but it seems like I must be missing
something here.

73, Dennis NJ6G

On 11/16/2018 09:58, K9MA wrote:

> One solution to charging the Li-Ion batteries from a 12 V DC source is
> to use a small inverter. One I've found which works well is the Samlex
> PST-120-12. It's a small "pure sine wave" inverter, rated 120 W,
> costing about $120. It seems to work just fine with the KXBC2 charger,
> and should work just as well with the KXBC3. I would use only a "pure
> sine wave" inverter, as the square wave from a "modified sine wave"
> inverter is likely to cause the charger to malfunction.
>
> Needless to say, I have no connection with the vendor, other than as a
> customer. I've had good luck with other Samlex products.
>
> 73,
>
> Scott K9MA
>

K9MA

Re: KX2/KX3 DC Charging

Hi Dennis,

You're missing the charge controller. Li-Ion batteries are very fussy
about the way they are charged. While it would be more efficient to run
the charger directly on 12 Volts, such a charger for the Elecraft
batteries is not available, as far as I know. Even if it were, it would
probably cost more than the inverter. The inverter, of course, also has
other uses.

Elecraft also makes it very clear that their batteries shouldn't be
charged with any other charger, and there are good reasons for that.

73,
Scott K9MA

On 11/16/2018 12:15, Dennis Moore wrote:

> So you're taking your 12v source (let's say it's 13.8v), adding an
> inverter to make 120v, then plugging in a charger to bring it back
> down to 13.8v.
>
> I'm fairly new to the KX3 game, but it seems like I must be missing
> something here.
>
> 73, Dennis NJ6G
>
>
> On 11/16/2018 09:58, K9MA wrote:
>> One solution to charging the Li-Ion batteries from a 12 V DC source
>> is to use a small inverter. One I've found which works well is the
>> Samlex PST-120-12. It's a small "pure sine wave" inverter, rated 120
>> W, costing about $120. It seems to work just fine with the KXBC2
>> charger, and should work just as well with the KXBC3. I would use
>> only a "pure sine wave" inverter, as the square wave from a "modified
>> sine wave" inverter is likely to cause the charger to malfunction.
>>
>> Needless to say, I have no connection with the vendor, other than as
>> a customer. I've had good luck with other Samlex products.
>>
>> 73,
>>
>> Scott K9MA
>>
>
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--
Scott K9MA

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Dennis Moore

Re: KX2/KX3 DC Charging

Thanks Scott. Makes sense.

Dennis NJ6G

On 11/16/2018 10:47, K9MA wrote:

> Hi Dennis,
>
> You're missing the charge controller. Li-Ion batteries are very fussy
> about the way they are charged. While it would be more efficient to
> run the charger directly on 12 Volts, such a charger for the Elecraft
> batteries is not available, as far as I know. Even if it were, it
> would probably cost more than the inverter. The inverter, of course,
> also has other uses.
>
> Elecraft also makes it very clear that their batteries shouldn't be
> charged with any other charger, and there are good reasons for that.
>
> 73,
> Scott K9MA
>
>
> On 11/16/2018 12:15, Dennis Moore wrote:
>> So you're taking your 12v source (let's say it's 13.8v), adding an
>> inverter to make 120v, then plugging in a charger to bring it back
>> down to 13.8v.
>>
>> I'm fairly new to the KX3 game, but it seems like I must be missing
>> something here.
>>
>> 73, Dennis NJ6G

Todd

Re: KX2/KX3 DC Charging

In reply to this post by K9MA

There's not a whole lot of info out there, as well as not many making DC
- DC chargers that will work on LiPo or LiFePO4's.
I went down this road a couple months back looking for something to run
my KX2 mobile out in the boonies and still be
able to charge without use of a geny. I stumbled upon an outfit out of
VKland that seems to fit the bill.

Company called REDARC:
https://www.redarc.com.au/battery-chargers/in-vehicle-chargers They
do have a US distributor now
from what I can tell. Their unit also has Solar input - which would be
a plus - and designed to handle the new
"smart alternators" that are common on newer vehicles...I didn't know a
thing about these newer alternators until
I found this site. This is a common deal in VK with all the
"overlanders". Dual batteries to run the fridge, radios, and
other camp assy's while in the "outback". Charge off of solar while
parked, 12vdc while in motion, to keep the LiFePO4's
(aux battery) charged.

I've used a goal zero inverter, and it works ok - if I don't use it and
any radio gear at the same time. ;-)

Todd KH2TJ

K9MA wrote:

k6dgw

Re: KX2/KX3 DC Charging

www.revolectrix.com

Fred ["Skip"] K6DGW

On 11/16/2018 2:40 PM, Todd wrote:

> There's not a whole lot of info out there, as well as not many making
> DC - DC chargers that will work on LiPo or LiFePO4's.
> I went down this road a couple months back looking for something to
> run my KX2 mobile out in the boonies and still be
> able to charge without use of a geny.   I stumbled upon an outfit out
> of VKland that seems to fit the bill.
>
> Company called REDARC:
> https://www.redarc.com.au/battery-chargers/in-vehicle-chargers They do
> have a US distributor now
> from what I can tell.   Their unit also has Solar input - which would
> be a plus - and designed to handle the new
> "smart alternators" that are common on newer vehicles...I didn't know
> a thing about these newer alternators until
> I found this site.   This is a common deal in VK with all the
> "overlanders". Dual batteries to run the fridge, radios, and
> other camp assy's while in the "outback". Charge off of solar while
> parked, 12vdc while in motion, to keep the LiFePO4's
> (aux battery) charged.
>
> I've used a goal zero inverter, and it works ok - if I don't use it
> and any radio gear at the same time.   ;-)
>
>
> Todd KH2TJ n

ktalbott

Re: KX2/KX3 DC Charging

In reply to this post by Todd

There are many inexpensive chargers available for the 3S1P battery pack
(12.6v charged, 11.1v nominal. The pack has charge controller PCB to prevent
over charge or under discharge. It does NOT provide the connector for
balancing the cells. I bet you have one of the 12.6V Li-ion chargers there
now. It probably looks like a 12.6V wall wart with an LED in it. Best DC-DC
charger option is RC plane equipment like iMax B6 at ~$29 (Amazon). The
more expensive ones also have AC input so you can use them anywhere. If you
aren't addicted to the shrink wrapped packs, inexpensive 3-cell 18650
battery holders are available on eBay that allow you to manage your cells
independently. BTW, you will probably need to change connectors to APP.
Ken ke4rg

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Todd
Sent: Friday, November 16, 2018 5:41 PM
To: K9MA <[hidden email]>
Cc: [hidden email]
Subject: Re: [Elecraft] KX2/KX3 DC Charging

There's not a whole lot of info out there, as well as not many making DC
- DC chargers that will work on LiPo or LiFePO4's.
I went down this road a couple months back looking for something to run my
KX2 mobile out in the boonies and still be
able to charge without use of a geny. I stumbled upon an outfit out of
VKland that seems to fit the bill.

Company called REDARC:
https://www.redarc.com.au/battery-chargers/in-vehicle-chargers They
do have a US distributor now
from what I can tell. Their unit also has Solar input - which would be
a plus - and designed to handle the new
"smart alternators" that are common on newer vehicles...I didn't know a
thing about these newer alternators until
I found this site. This is a common deal in VK with all the
"overlanders". Dual batteries to run the fridge, radios, and other camp
assy's while in the "outback". Charge off of solar while parked, 12vdc
while in motion, to keep the LiFePO4's (aux battery) charged.

I've used a goal zero inverter, and it works ok - if I don't use it and
any radio gear at the same time. ;-)

Todd KH2TJ

K9MA wrote:

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