Topics

Power requirement

McRuss
 

I have a AA battery holder, 8 cells, and I put 8 rechargeable AA's in it but I get 10.4 volts.  I know the UbitX V6 requires 12v @ 2 amps.  Will this battery pack power it (especially on TX)?
--
Newbie
K5FJR

ajparent1/kb1gmx
 

No, not at all well.  You may run the receiver on that but TX till have distortion, low power,
and worst of all the batteries will die fast.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Evan Hand
 

McRuss,
I would put a dc/dc boost supply to get to the 12 volts.  The current 10 volts will drop as the battery discharges to a point that it might not work.  

The issue with the boost supply is noise.  There have been posts on this board that explained what they did to prevent the PWM signal from getting through.  Involved adding 2 capacitors and an inductor to block the noise.  You would also want to shield it, preferably in a separate metal enclosure (could be mounted in the same case), or mounted on the outside.

Alternative would be to go to a 10 cell pack (using the NiMH batteries that I am assuming that you have based on the voltage).  The v3, v4, and v5 boards are all good on 13.8 volts.  (10.4/8 = 1.3 volts per cell, 10 cells = 13 volts, below what most "12 volt dc" ham supplies provide.  Most of those are 13.8 volts.  You would still have the voltage dip as the batteries discharge, but should have enough life for a few hours, depending on the milli ampere hour (mAh).  Average rechargeable (NiMH I assume again based on the voltage) are 1.1 to 2.8 Ampere hours.  Since all are in series, you probably have at most 1 hour of operation on full transmit, or 10 hours on receive only.   The pack would be able to supply the uBitx at least for short (less than one hour) and longer based on mode and power settings.

You could change to Lithium batteries that are rechargeable and have 1.5 volt per cell.  I would require the Litiom charger, as charging requirements are different.

Another option is to go to 12 volt LiPo gel cell.  Most can be charge with standard car battery trickle charger and would provide much longer run and power options.  See this link: 
https://ubitx.net/2019/05/01/battery-power-for-your-ubitx/

Above are just suggestions.  I have tried using one of the low cost buck/boost supplies and had the noise issue.  This was between the raw 13.8 vots dc in and the non-power amp connection to help reduce the 5 volt regulator issues. 

Above are just suggestions.  Please verify and follow all manufacturer's safety practices with batteries.
73
Evan
AC9TU

Evan Hand
 

I stand corrected.  Allison is MUCH more knowledgeable than I am.  Please disregard the part on the NiMH and just follow the link for a LiPo option.

Thank-you Allison for stepping in and giving us the better information.

73
Evan
AC9TU

ajparent1/kb1gmx
 

For 12V ops I use Nimh or NiCd x10 cells.  works well enough.
Problem is that the largest AA nimh is 2600mah (maybe 2800), with
a 150ma RX or more and 2A tx the run time will be short.  That
and 10AA cells are not light!  However that is the cheapest light
rechrageable option.  Non rechargeable cells will be costly to use.

Next size up gets out of the AA cell size, and the cost excalates.

For LifePo4 you need 4 and a specific charger but to get decent run time
you need cells (or battery ) over 5AH.  Advantege is weight, disadvantage cost 
and careful charging requirement.

Cheap, the usual 7-8AH 12 V gell cell battery.  Easy to charge being lead,
and 7Ah will give decent run time.  ITs a fairly benign battery compared to 
lithium chemistry.

Since you didn't say if portable or what other operations are desired its tough
to say use a specific thing.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

McRuss
 

That's what I thought.  As was asked, my intention is to use this radio as a portable and I do have a portable 12V power supply so will scrap the idea of the AA battery pack (the 12 V power supply is large and heavy but will do the job, was just hoping for a smaller/lighter option.)  Thanks for all the quick suggestions; I'm sure I'll have more questions once it arrives (next week) and I get it set up.
--
Newbie
K5FJR

Rene
 

I use 18650 batteries from old laptop accu and bicycle batteries. Works great. Bought chargers at Ali express and battery holders for 3 and 4 batteries....

David Wilcox <Djwilcox01@...>
 

I have a friend who flies expensive drones and gives me his battery packs when they start showing trouble or bulging.  Usually only one cell is going bad so after dissecting 3 or 4 packs I have all the batteries I need to make what ever pack I need.  Cheap and fun.  As a reminder here is where the Weller 200 - 250 w soldering gun works well for soldering wires and bars to the batteries: lot of heat for very short time.  Ask around.

David J. Wilcox K8WPE’s iPad

On Mar 15, 2020, at 4:44 AM, Rene <rmvanb@...> wrote:

I use 18650 batteries from old laptop accu and bicycle batteries. Works great. Bought chargers at Ali express and battery holders for 3 and 4 batteries....

ajparent1/kb1gmx
 

I  vary my use based on power needs and operating time between charges.
Using my Ft817 as an example its fairly power hungry on RX (.370-450ma)
so even on the 8cell internal NiMh pack it s pretty well down after an hour or 
two to transmit at anything but lowest power.  Sill handy for RX uses that
need portable.

So back up is external Pack of 3S2P  (5 hour useful) and 2S4P (11 hour useful)
and they are both small and light.      The term xSyP is number of cells in series
and parallel, so 3S 4P means  4 in parallel and 3 groups of those in series.
That gives a max full charge (for the LiPO I used) of 12.6V and working
voltage of  11.1V which is ideal for FT817.  The cels used were LG brang 2800mah
so 4 parallel give a usable amp hours of 11.2ah.

Generally lithium chemistry rechargeable cels come in two voltages when
fully charged  LiPo nominal full charge of 4.2V and LIFePo4 at 3.7V.  Its
important to know that.   For a radio that wants 13.8V the LiFePo4 cells at
3.7V as 4S is the best bet at 14.8 full  charge and 12.8 working during
discharge as ideal.  The cell size anything over 5000mah will run the radio
for many hours.  You can buy commercial made packs of suitable size
with matching charger.

NOTE: lithium tech is very good but mishandle it or charge it incorrectly
it does represent a fire hazard.  Fuses to protect against short circuits are
advised. to protect wires and battery.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

 

And discharging them below their minimum voltage can severly impact their recharge lifetime.

ajparent1/kb1gmx
 

That is true,

If he/she should , one would hope the proper battery protection board
is employed or commercial battery (usually has it) so generally they
are protected against over discharge.

Bite size pieces, first.

Most of this has been repeated in this forum at least once every 4 months 
for the last 3 years.

Allison
---------------------------------
No direct email, it goes to bit bucket due address harvesting in groups.IO