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Use of LiPo batteries and DC-DC converters, doubts


#1

Hi, I have been considering using LiPo’s but I have doubts… They have good capacity/size/weight, but requires special charging.
On the summit, you may need a DC-DC converter and some monitoring circuit, to make sure you don’t run them to hard or de-charge them below their limits. I.e. extra equipment you have to carry with you.
Also, they are known for their ‘instability’, I’ve seen videos of them burning voilently if handled wrongly, even just physical stress… Imagine falling hard, backpack hitting a stone… Little chance maybe, but consequences can be downright catastrophic.

On my recent SOTA activations, I used 8xAA for my little CW transceiver. Safe, not the best capacity, but enough for the hour I averaged at the summits. And they’re easy to get at, plus an extra set doesn’t weigh much in the backpack. Oh, and cheap too, compared to all the gear you need to handle LiPo’s safely.

Oh, and another question: One of the things I really enjoy at the summit, is the total absense of electrical noise! How does that compute with bringing DC-DC converters and uP controlled battery monitors? Usually we’re seated right next to the antenna, if not, then in its close vicinity.

Come to think of it, I could still use a DC-DC converter with my AA-cells, extending their life, if someone could recommend a low (as in no) noise unit, I’d appreciate it. Obviously I know all switched converters are noisy, but I think you know what I mean :wink:

So LiPo: pros and cons?

Thanks and 73


#2

I have been using a 3S 4Ah LiPo-Pack for three years without problems with my FT-817. Voltage is just sufficient at around 11.1 to 12.5 V for the FT-817 but may be too low for other gear. Now I swiched over to a 4.5Ah LiFePO4 which is also suitable for gear requiring more than 12.5V. Typically pack voltage is 12.8 to 13.3 V during my activations.
If you do not discharge your battery pack completely, normally you do not need to monitor single cell voltages at all. Normally the cells do not drift until they are nearly exhausted. I have a small voltage monitor in my rucksack but in fact never use it. Monitoring the complete pack voltage is sufficient and can easily be done with the FT-817 and also the KX3 supply voltage display.

LiFePO4 is known to be more stable than LiPo but I still carry the battery in a robust plastic box so it does not get mechanical stress during transport.

So my recommendation: Use a LiFePO4 without any DC-DC-converter. Ok, you require a special charger. But this is a one time investment of 30 to 60 €.

I completely stopped using SLABs due to their poor energy density. Why carry 2 kg if 0.5 kg can do the same?

73 de Michael, DB7MM


#3

Looking to invest in one also to run me Trio 120V

Something like this
Looks well man enough at that sort of MA/HR

http://www.hobbyking.com/hobbyking/store/_64794__Multistar_High_Capacity_4S_10000mAh_Multi_Rotor_Lipo_Pack_UK_Warehouse.html

Which charger would I require and would this be man enough for couple hours sota operation. I is asking please for looking to lighten me PSU as the one currently I use is a massive thing. Its a big yellow power house unit handy for pumping up tyres etc. Prob about 5kg to 8kg in weight thinks need to lighten load or bring me donkey :flushed:

Stupid thing is last year I ordered a car battery charger 5 amp and ended up with one of these instead.

Karl


#4

As an on-topic question that may help the OP decide if they are for him, does anyone carry their LifePo4 (or LiPo for that matter) batteries in an ammo box or similar as I have seen some RC people suggest?

I have mine in a cliplock plastic box to transport them safely (in terms of smashing about in a rucksack)


#5

That would rather seem to defeat the principal object of using LiPo batteries … i.e. to minimise weight.

Most subscribers to this forum will already know my views about lithium batteries. Having had the unpleasant experience of one bursting into flames in my car whilst I was driving along, I wouldn’t touch them with a barge pole.

YMMV.

73,
Walt (G3NYY)


#6

Just goggled it and man that,s bit out of my league price wise :open_mouth:

Karl


#7

Wow - if spontaneous combustion is an actual issue, I’d never in my life bring it in my backpack… I know the counter argument: ‘As long as you treat them well, then fine’, but still: All mountain safety revolves around thinking consequences…

I might be bringing AA’s for yet a while, maybe with a small DC-DC thingy…

best 73


#8

Hi Soren,
Here’s my findings (I know other will have their opinions, but these are my findings based on my actual usage).

LIPOs (never had one explode etc. however I accept LIFEPOs are safer - they weren’t available when I got my LIPOs).

I installed a 2500maH 3S LIPO in the battery bay of my FT 817 - fits in and works very well - you do need to scavenge the battery cable from the AA batteries holder though as you need a cable with the green sensor wire, which tells the FT817 NOT to charge the batteries if an external supply is plugged in).
I find a fully charged 2500 LIPO lasts me for 2 activations easily running the full 5W SSB output. I have a spare (identical) battery also in my pack for if the voltage drops too far and the FT817 shuts down.

I also have a ramsey QAMP, which I have modified to be usable on 40, 30 & 20m (switchable LP fiters) - this needs 13.8v to give me 25W on 40 & 30m and 15W on 20m. To get this 13.8V, I have a 3S (11.5v) 5000maH LIPO battery and a 150w capable battery booster to take the voltage up to 13.8V. I also wondered whether this would generate RF noise - it doesn’t (at least not on HF - I can’t comment on VHF - when I wouldn’t be using the HF amp in any case).
I also have a warning beeper module for cell voltage monitoring. The times I have used it - no RF noise. I very rarely use it however as I know I can get 2 x 40 minute activations from the battery and still have it 60+% full on all cells. I also carry a second 5000mAH LIPO, to put on for the third and forrth activations if required.

So IN MY EXPERIENCE - I have no problems using LIPO batteries, battery boosters or voltage warning beepers, however If I had to equip again, I would most likely go for a 4S (~14V) LIFEPO 8000mAH battery and power everything from it as it wouuld be a lighter solution to what I currently have.

As far as I know there is no LIFEPO battery small enough to fit within the FT817 as the LIPO does, but that could have changed. The LIPO in the FT817 compared to the Yaesu NICAD option is a world of difference, the NICAD would not even last one activation!

73 Ed.
PS for charging the LIPOs I use the same balanced charger. set to 1A charge for the 2500maH battery or 2A for the 5000maH ones.


#9
 Talking of dodgy batterys had one burn hole on pocket once forcing me to stop the car and jump out . It was one of the square 9V batts with a two pence coin in same pocket. It shorted out the terminals producing quite a hot effect one me leg and it did burn the pocket liner and me leg.

Lesson learnt

One thing we must remember when voltage drops the currant increases and major heat is produced in such a way it can do combustion. So when transporting. storing or even charging of. Precautions should be taken .
Walked into a workshop, mate was grinding away next to a charging fork lift and yes there was one hell of a bang and fire hose came out to hose him down to reduce the acid effect, luckily damage to him was minimal fork lift was well damaged.

Karl


#10

Thanks Ed, - very detailed :slight_smile:


#11

Soren, from what you write you should avoid Lithium batteries at all costs as the worry and stress they will cause you will massively exceed the advantages they have.


#12

I have been using 3S LiPo batteries (2500mAh) for my FT-817 (the 817 does NOT require 12V to generate full TX output) and 4S LiFePO4 batteries (8400mAh) for my FT-897 at power levels up to 100W. Both battery types are easily rechargable with a balanced charger (about US$28) and I have not experienced any issues with either battery type.

Like anything, you will hear horror stories about how someone experienced problems with them including some burning up, but conversely there are many thousands of people who have not had any problems with them. I have seen videos where people have abused the hell out of them including shooting them without them burning up - I would suggest that people experiencing problems with them are in a minority. Amusingly the only time I have had a problem with a battery has been with a 9Ah SLA that I inadvertently shorted with the power cable (on my very first activation of all things) - was rather disconcerting when smoke started to pour out of the battery bag as the insulation on the power cable burned up!

As with anything, if you exercise basic care and there is little to worry about. I will never go back to SLA if a lithium type battery pack is available to me! 150g for the LiPo and 1kg for the LiFePO4 versus 2.5kg for the SLA - an easy choice for me (not even sure where the SLA is these days as it hasn’t been used for years).

Matt
VK1MA


#13

There are many hundreds of millions of people who have not had any problems.


#14

Count me in that number. My 4AH 3S LiPOs are now well over 6 years old and still going strong… and I carry them in my backpack … and I have fallen over several times when out on the hills with no issues whatsoever. I’d love to change over to LiFePO4, but while these are still doing fine, it doesn’t make sense.


#15

I throw my lifepo4 batteries in my rucksack just as I used to treat my SLABs. I charge them with the supplied charger which doesn`t look anything special to me. They are expensive, but the weight saving and potential longer life make them worth the investment for me.


#16

Been using LiPo Zippy 3s 1000 mah (2, one for backup), same ones, every activation for 130 summits now, to power an ATS4B or a HB1B. That sizing is in fact overkill for those radios. 500 would do it fine. 3-4 activations per charge per battery. Never a peep of an issue. Also took three of them through check in to EU and back last Sept without a peep from the Gestapo. No clue what the worries might be, as I think they are nothing short of a miracle. (I HAVE shorted them a couple times by accident and that is truly exciting, mini arc welders).

Cap
W0CCA


#17

I use this battery:

http://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-9ah-lifepo4-battery

It is placed at the bottom of this “customized” case, that I carry in my pack:

The battery weighs about 2.6 pounds and I can use it on multiple outings without getting the battery anywhere near too low. I attached connectors to the battery with mating connectors attached to the radio and the charger ($10 dollars more) so I can easily connect/disconnect from either.

As for monitoring the voltage etc, the 817ND shows the voltage, so if you are using that radio, you can see if it gets too low. Also, these batteries do not have a memory, so you can charge them as often as you like without compromising the battery life etc.