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Charging LiFePO4 Batteries

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Jim Brown-10

Charging LiFePO4 Batteries

This is what I got from Kevin. We also spoke on the phone.

On the phone, Kevin clarified that as long as the charger was "proper"
for LiFePO4 chemistry and charge current was safely limited, an LiFePO4
battery will NOT be damaged if charged during discharge. His only
concern was that the battery might not reach full charge simply because
more current was being drawn than was being supplied by the charger.

SO -- the bottom line is that LiFePO4 batteries ARE suitable for use as
the main power source in a station where a charger is always connected
as long as the charger has the proper charging characteristics for the
LiFePO4 in use. In general, battery life is maximized if the maximum
charging current is no greater than the 4-10 hour discharge current. For
example, a 10A charger is sold by Bioenno with their 40 - 100Ah
batteries. Higher charging currents reduce battery life.

Kevin also said that they have taken our concerns seriously with respect
to RFI from chargers, and that they have begun working on sourcing
chargers that are RF quiet. He noted that it typically takes 3-6 months
to find potential candidates, evaluate them, and get them in inventory.
I've volunteered to evaluate them in my station for noise.

Bioenno also works with Powerwerx, so they are generally aware of
connector issues. He said that they are using the larger connector as
standard because some of their customers need the larger connector with
the higher current rating. The grey SB50 connectors used in the ham
world are rated for 50A.

73, Jim K9YC

On Tue,7/12/2016 11:39 AM, Kevin Zanjani wrote:

> Hi Jim,
> I needed to clarify my response. Maybe it's easier to explain over
> the phone. My number is 714-336-2953
>
> The batteries with the bundled chargers, use constant current,
> followed by constant voltage to charge the batteries. Generally, with
> these chargers, if the battery is loaded while the charger is
> attempting to charge the battery (under a high load condition), then
> the battery may not be able to achieve a full charge as its loaded
> under a high load condition (it would certainly charge). If the load
> is fairly low amperage, that is less than the charge current, then yes
> the battery can take the full charge.
>
> With the PWR gate, you can certainly charge and discharge the battery,
> because there is a separate power supply that can provide a large
> enough charge current to the battery, while also supplying power to
> the radio from that supply . So in that setup, it is perfectly fine.
>
> So it depends on the charge current available to charge battery versus
> the load power to ensure the battery takes a full charge.
>
> -Kevin
>
> On Tue, Jul 12, 2016 at 10:52 AM, Jim Brown
> <[hidden email] <mailto:[hidden email]>> wrote:
>
> Kevin,
>
> I've been using the battery for about a week. Some correspondence
> you had with Wes Stewart concerns me greatly -- in effect, it
> negates the use of the battery in my station. I bit of background.
> Most ham gear is designed to run from a DC source in the range of
> 12-14V, and its performance is best near the top of that range.
> For many years, I've used flooded lead acid cells that are
> float-charged as the primary power source for the 12V equipment in
> my station, but had to accept the fact that for most of their
> discharge, they are at 12V or less. The primary reason for going
> to LiFePO4 chemistry is the discharge curve, with most of the
> battery's capacity above 12.5V.
>
> I am a contester. Typical contest operation for me is with two
> radios, each drawing about 1.5A in receive mode and between 10-20A
> in transmit mode, depending on the contest. Only one radio is
> transmitting at a time. The 10A contests are 36 hour events, the
> 20A contests are 10 hours long. It doesn't take much arithmetic to
> realize that a 100Ah battery must be charged during operation to
> handle the load.
>
> Your response to Wes seemed to indicate that LiFePO4 batteries
> cannot be charged during use -- that is, that they must go through
> a discharge cycle. I can find no technical references online for
> this statement, so I'd like to know the basis of your advice to
> Wes. Can you point me to technical references for this?
>
> Some other comments now that I've been using the battery in my
> station for several days. The PowerGate controller seems to work
> fine -- IF the power supply is set to a high enough terminal
> voltage to provide 10A charge current.
>
> The 4A charger you provided for my 20Ah battery pack works fine,
> but generates significant levels of RF noise. I can suppress that
> noise somewhat, but not well enough, by winding multiple turns of
> both AC and DC cables through ferrite cores to form common mode
> chokes. I've seen comments online from other users of your
> chargers indicating that they are too noisy to use in a radio
> environment. As I told you last week, it is important that you
> find chargers that produce far less RF noise. This is also
> critical for the pro audio market, especially for video production
> work.
>
> The Power Pole connector for charging is well chosen; the larger
> connector for the load is not. Ham applications have standardized
> on the smaller Anderson SB50 series for use with power sources.
> It's no problem for a technical user to replace the larger
> connector that you ship with, but it's added cost and time. And,
> of course, the technician must mount only one conductor at a time,
> inserting it in the connector shell, so that there is no
> possibility of shorting the battery in the process.
>

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Clay Autery

Re: Charging LiFePO4 Batteries

Thanks Jim!!!

Here is what I take from that.... Say, you have a 100+ Ah battery and a
10 amp max charge current (limited) on the charger. (And assuming the
charger meets other requirements for CC/CV voltage during CC and the
desired Voltage during CV (trickle current cell balancing).

Assuming a K3s/P3 for instance with only the 100W internal PA...

During Transmit, the rig pulls anywhere up to about 15 amps or so on
peaks (my experience).
On receive, the rig is pulling well less than 1.5 amps...

So, on receive... MOST of the time, the charger will be charging the
battery.... and when at rest, even with the rig on say overnight (I
seldom do this), the battery will easily reach full charge and enter CV
cycle which is where the cell balancing happens.

On a contest where the TX duty cycle is much higher.... say 50+%, The
battery will be averaging somewhere around it's 10 Hr charge current in
power draw... So, for the duration of the contest (or high duty cycle
session) the battery will remain in the CC charge cycle.

At the conclusion of the high duty cycle use, the battery will continue
in CC until it is fully charged and thence to CV for maintenance/cell
balance...

I don't think there is going to be anything super tough about this one...

IF a commercial solution doesn't present, I will proceed on the path of
finding/building a linear supply that will provide at least the required
voltage and trim (if necessary) it with a well-designed linear regulator
circuit to the CC voltage required. Add a second linear regulator that
provides the CV voltage.... Then add a sense/feedback circuit that
monitors the battery for the event/events that signals the need to
switch from CC to CV or CV to CC...

Seems pretty doable... unless I am missing something...

73,

_____________________
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 7/12/2016 2:16 PM, Jim Brown wrote:

> This is what I got from Kevin. We also spoke on the phone.
>
> On the phone, Kevin clarified that as long as the charger was "proper"
> for LiFePO4 chemistry and charge current was safely limited, an
> LiFePO4 battery will NOT be damaged if charged during discharge. His
> only concern was that the battery might not reach full charge simply
> because more current was being drawn than was being supplied by the
> charger.
>
> SO -- the bottom line is that LiFePO4 batteries ARE suitable for use
> as the main power source in a station where a charger is always
> connected as long as the charger has the proper charging
> characteristics for the LiFePO4 in use. In general, battery life is
> maximized if the maximum charging current is no greater than the 4-10
> hour discharge current. For example, a 10A charger is sold by Bioenno
> with their 40 - 100Ah batteries. Higher charging currents reduce
> battery life.
>
> Kevin also said that they have taken our concerns seriously with
> respect to RFI from chargers, and that they have begun working on
> sourcing chargers that are RF quiet. He noted that it typically takes
> 3-6 months to find potential candidates, evaluate them, and get them
> in inventory. I've volunteered to evaluate them in my station for noise.
>
> Bioenno also works with Powerwerx, so they are generally aware of
> connector issues. He said that they are using the larger connector as
> standard because some of their customers need the larger connector
> with the higher current rating. The grey SB50 connectors used in the
> ham world are rated for 50A.
>
> 73, Jim K9YC

Wes Stewart-2

Re: Charging LiFePO4 Batteries

Despite your earlier response, allow me to offer a suggestion. I've written
about this too before but I'll summarize again. I used for a number of years a
HB analog charger on a 90 AH AGM battery to run most of my station. This was
built using an Astron 35M power supply for the raw DC, heatsink and series pass
transistors. The regulator board was removed and substituted by a modified A&A
Engineering "smart charger" board. I think these are obsolete now, but the
heart of them is the uC3906 IC. I set mine up for a bulk charge rate of 25A
(~C/4). I'm not going to design it for you but I imagine the IC can do the
trick for this battery chemistry.

On 7/12/2016 12:57 PM, Clay Autery wrote:

> Thanks Jim!!!
>
>
> Here is what I take from that.... Say, you have a 100+ Ah battery and a
> 10 amp max charge current (limited) on the charger. (And assuming the
> charger meets other requirements for CC/CV voltage during CC and the
> desired Voltage during CV (trickle current cell balancing).
>
> Assuming a K3s/P3 for instance with only the 100W internal PA...
>
> During Transmit, the rig pulls anywhere up to about 15 amps or so on
> peaks (my experience).
> On receive, the rig is pulling well less than 1.5 amps...
>
> So, on receive... MOST of the time, the charger will be charging the
> battery.... and when at rest, even with the rig on say overnight (I
> seldom do this), the battery will easily reach full charge and enter CV
> cycle which is where the cell balancing happens.
>
> On a contest where the TX duty cycle is much higher.... say 50+%, The
> battery will be averaging somewhere around it's 10 Hr charge current in
> power draw... So, for the duration of the contest (or high duty cycle
> session) the battery will remain in the CC charge cycle.
>
> At the conclusion of the high duty cycle use, the battery will continue
> in CC until it is fully charged and thence to CV for maintenance/cell
> balance...
>
> I don't think there is going to be anything super tough about this one...
>
> IF a commercial solution doesn't present, I will proceed on the path of
> finding/building a linear supply that will provide at least the required
> voltage and trim (if necessary) it with a well-designed linear regulator
> circuit to the CC voltage required. Add a second linear regulator that
> provides the CV voltage.... Then add a sense/feedback circuit that
> monitors the battery for the event/events that signals the need to
> switch from CC to CV or CV to CC...
>
> Seems pretty doable... unless I am missing something...
>
>
> 73,
>
> _____________________
> Clay Autery, KY5G
> MONTAC Enterprises
> (318) 518-1389
>
> On 7/12/2016 2:16 PM, Jim Brown wrote:
>> This is what I got from Kevin. We also spoke on the phone.
>>
>> On the phone, Kevin clarified that as long as the charger was "proper"
>> for LiFePO4 chemistry and charge current was safely limited, an
>> LiFePO4 battery will NOT be damaged if charged during discharge. His
>> only concern was that the battery might not reach full charge simply
>> because more current was being drawn than was being supplied by the
>> charger.
>>
>> SO -- the bottom line is that LiFePO4 batteries ARE suitable for use
>> as the main power source in a station where a charger is always
>> connected as long as the charger has the proper charging
>> characteristics for the LiFePO4 in use. In general, battery life is
>> maximized if the maximum charging current is no greater than the 4-10
>> hour discharge current. For example, a 10A charger is sold by Bioenno
>> with their 40 - 100Ah batteries. Higher charging currents reduce
>> battery life.
>>
>> Kevin also said that they have taken our concerns seriously with
>> respect to RFI from chargers, and that they have begun working on
>> sourcing chargers that are RF quiet. He noted that it typically takes
>> 3-6 months to find potential candidates, evaluate them, and get them
>> in inventory. I've volunteered to evaluate them in my station for noise.
>>
>> Bioenno also works with Powerwerx, so they are generally aware of
>> connector issues. He said that they are using the larger connector as
>> standard because some of their customers need the larger connector
>> with the higher current rating. The grey SB50 connectors used in the
>> ham world are rated for 50A.
>>
>> 73, Jim K9YC