All the power in the world and not enough battery!

I have used LiFePO4 batteries as well and I end up with flat batteries while operating. The 4S LiPo's give me much better life and are smaller and lighter. A display / warning buzzer monitors the overall voltage and individual cell voltages. I take the in line rectifier out once battery voltage is safe for my radio. While operating the heat sink stays cold.
It works well for me, so Derek can take his snide comments and place them strategically...

 

Well I give you credit for admitting you do not know what you are talking about or doing. Of course LeFePO4 is flat, that is what makes them so appealing and useful. At full charge in 4S the voltage is 14.2 and exhausted at 12 volts which is perfect for 12 volt equipment. You get to use all the energy and not waste any as waste heat. Pb on the other hand is a bit steeper of 14.2 down to 10.5 volts. 4S LiPo has a very steep charge/discharge curve of 16.8 volts at full charge, down to 10 volts exhausted.

That forces you to use some method to bleed off voltage. You say two diodes which will work which means you have to burn off as waste heat of roughly 15% of your battery capacity is burned off as waste heat doing nothing. Sure you can keep them cool with a large enough heat sink which adds weight, takes up space, and rund cost up. LiPo's only have 100 to 200 cycles vs about 1000 for LiFePO4. Everything you gained from using LiPos is wasted and thrown away by hacking it. Sure it can work, just a piss poor way of doing it adding eggs to an already fragile basket.

Fine for an emergency to SOS, but not a good choice or practice on a permanent station. With LiFePO4 you have access to all the battery capacity from 14.4 down to 12 volts. With LiPo's you can only access a fraction of the battery capacity. You have to burn off 15% of the energy using diodes, and cannot access the energy below 12 volts.

Now what could be done but complicated is to use a switch mode DC to DC Converter. Those are on the order 95% efficient and would allow you to utilize all th energy capacity. But again that is a band-aid for using the wrong battery type, adding expense, weight, space, and another egg in the basket.

 

The guy on the link below uses LiPO4 without problems on his FT-897. Yes, the full-charge voltage exceeds the 13.8V+/-15% slightly but that seems to be no problem at all. In fact, most transceivers only apply the 13.8V directly to the PA transistors, which are rated for 17V in an FT-897. The remaining circuitry is behind voltage regulators. And of course, the moment you start transmitting, the voltage will definitely drop to a level that's within specs.
https://uuki.kapsi.fi/fnb78li.html

 

https://www.skillsyouneed.com/ips/interpersonal-communication.html

 

I want hydrogen fuel cells!

BTW, please explain why it is detrimental to batteries when connected in parallel for a prolonged time without some sort of battery isolation. I have tried to explain the reason to some people with limited success. They cannot understand why their lead acid batteries fail unexpectedly when not being charged.
And still the myth of leaving batteries on a concrete floor will kill them persists.
I know, apples and doughnuts comments in this comment

 

Batteries are like chemistry and electricity or something.

Some Batteries are really heavy, like they are made from lead or something.

Some Batteries have liquid in them that burns, like acid or something

Batteries will not keep my flashlight lighted all night, it’s like they discharge and die or something.

 

The fuel cells have run their course. Seems to have run out of gas.

 

Are you sure?
I thought they were still used on the ISS for the crew member recycled water supply and power generation?
I know that H is not the safest fuel but the power density (density?) is extremely high but also not very efficient to make H.
I know H batteries/cells have been around for over a century.
H is also the most abundant element in the universe. H cells continue to get better, but still H ain’t so efficient to make, easy to make but not really efficient. But, maybe a good way to store excess solar, wind or other “alternative” power production.
You may be correct though, could be better power production technology that’s better and more efficient.
73

 

They have their place in more exotic applications but in everyday use most of the developers have given up. I'm close to someone who ran one of the big programs and when they decided to stop they couldn't even give the technology away.

 

WOW!
Bought stocks in Ballard, Plug Power and another one or two some years ago. Guess they went the way of PageNet.
Would like to have played around with the stuff.
You don’t think they will ever be feasible? Really thought they would be a competitive energy source.
73

 

Huh ?
Was that OP an article about lead acid battery or NOT?
I admit NOT reading it very carefully , but did it explain why LEAD ACID BATTERY has 13,8V at the terminals and when ?
Charging / discharging etc. ?

"The traditional voltage for our amateur equipment is 13.8 Volts. Why not 12 Volts you ask. The short answer is chemistry, but let's move on, there is lots to cover."

To the original poster:
Does anybody technically edits / checks your articles before posting?
This is not the first one you have posted in your "voodoo style".

IMHO you should have stopped and provided LONG and real answer to the "chemistry".

But if the audience buys your voodoo article , there is not much sense to "post edit it " by me.
Would get flamed if I did it.

73 Shirley

 

Not in the near future. Like many technologies they may emerge in the future in a different form than envisioned to day. Through the 60s everyone thought there would be a computer in every home. Except they all envisioned mainframes with tape storage and large front panels with blinking lights. 20 years later we did start getting computers all over. But implemented a lot differently.

Lithium battery development reduced the need for fuel cells in many applications. Today it's more practical to generate electricity and store it in batteries than it is to convert it to a fuel and then reconvert after distributing the fuel.

 

H is a little difficult to 'mine' though; most of it seems to be on the surface but it is locked up in a liquid compound known as "water".

 

re: "The traditional voltage for our amateur equipment is 13.8 Volts. Why not 12 Volts you ask. The short answer is chemistry, but let's move on, there is lots to cover."

The REAL reason 13.8V vs 12V is engine running/charging batteries versus NOT.

 

You do realize his solution is over 90 pct efficient.

Burning off 1.2 volts over two diode dropping network is almost 92 to 93 pct efficient when compared to his 16 volts to start with.

Math is easy, for some of us.

100-(100/16)x1.2=92.5

Not to mention, if he has a 25 amp bridge, there is no problem with current draw. Especially if not running fm at 100 watts.

This also completely bypasses the probability of some cheap ChiCom dc/dc switcher causing interference on rx as well as causing switching sidebands if he doesn't also add appropriate filtering on the output of the switcher.


--Shane
KD6VXI