Replaced the cells in my Kenwood Handheld with Li - Polymers and they last a lot longer. Here is a short clip in 3gp bad quality and i dont really like talking but it gives you an idea how i replaced the batteries. http://www.youtube.com/watch?v=8gDtAj3Jic0 Sean / M0GIA
In reply to 2E0BAX:
How are you charging them Sean and do you have good fire insurance on your home ?
In reply to MM0FMF:
Im using the charger supplied with the Kenwood ( rated @ 13.5v / 70ma ) and firstly gave it a 1 hr charge and checked voltage and temp the used the handheld on full power to see how much charge the battery had taken.
Battery was still cold and was flat in a few short overs so i then moved to 2hrs charge and it lasted 10 mins longer and was still cold so ended up in the garage for a 12 hr charge. Yes im aware of these things blowing up some lads at work do it for a laugh.
If for some reason the battery fails due to the charging being wrong the plan is to use a mobile phone and charger thus making use of the regulator and charging the battery’s in parallel and being a mobile phone engineer theres plenty of battery’s and phones! I have now built up another pack to run a set of ultra bright LED’s for lighting on Piel Island as im that impressed. Sean / M0GIA
I think Sean may be on to something here. I have just found I can get Li Polymer batteries for my mobile phone for as little as £1.35 each, they are 3.6v and 950mAh. It seems like a lot of “bang for your buck” when compared to NiCd or NiMH cells and lighter too.
I would also be interested in how Sean intends to charge them, but maybe an explanation of the fire insurance comment would be enlightening. I suspect Andy you are referring to exploding lap tops.
Regards Steve GW7AAV 73
In reply to GW7AAV:
Tesla Motors use Li - Polymer just google them…and if there good enough for them then there good enough for me.
Charging using the original charger and as i sais i will use an old mobile phone and charger if this does not work out.
Fire insurance? Yes im insured whether or not charging batteries is included i dont know however on the plus side we do have the latest smoke alarms fitted by the fire station.
Im on The Cloud Sunday so another testing and another excuse to play radio during a family walk. Sean / M0GIA
In reply to GW7AAV:
Unlike NiMH/NiCd/Alkaline cells, there isn’t any hard metal shell to contain all “the doings” in a LiPo cell. That’s why they can be made into all those funny shapes to fit inside things. Without the containment properties of this metal shell there’s nothing to stop the cells rupturing when incorrectly charged/discharged and lots of gas is produced. When they gas they get hot.
So if you consider we have under fault conditions
- high temperature
- flammable gas
- high flammable lithium metal
you can see why you might want to ensure you have some home fire insurance!
Most problems come from incorrect charging. Series charging is a no-no. Look at the multi-cell packs used in laptops etc. and you’ll see that the cells are charged individually. This is so the intelligent chargers can ensure they dont overcharge any one cell. Likewise most cell packs have over discharge circuits so you cant over discharge any one cell. If this isn’t built into the cell they it will be built into the phone/laptop etc.
The problem comes when you charge LiPo under conditions they were not designed for. Normally you put about 4.2V on a 3.7V LiPo cell oto charge it with control on max current. For NiCd the charger is current based and will apply “enough” volts to the cells to push a constant charging current through them. For handies with built in chargers designed for NiCd cells fed off 13.8V with say 7.2V and 1000mAh pack, then the charger will apply upto 13.8V to the cells to get a C/10, 100mA in this case into the cells. The actual voltage depends on the cells.
If you replace the NiCds with LiPo then you have the potential for the charger to apply its max voltage across the cells. i.e. 13.8V where the normal safe voltage would be 8.4V. So under some fault condition you can expose the cells to a dangerous overcharge condition. Result is the pyrotechnics that dumbtards delight in uploading to YouTube. Not so much fun if that is inside your handy and inside your shack!
Even if you know you are being naughty in how you charge them and make arrangements so you regularly check the temp/condition, if you don’t make the charge process failsafe then one day something will interrupt you and you’ll forget to check the charge state and that’ll be day the day something else goes wrong and then you’re calling 999 and looking for the insurance policy number!
I suppose the end of this long line of waffle is that you really, really, really must use a charger designed for LiPo if you want to be able to sleep at night. There’s loads of circuits on the net to build. Or use scrap phones/chargers to charge the cells and then move them into handy battery cases for use.
I thought the use of the engraver to open the plastic weld was inspired Sean as it can be a royal pain doing it other ways.
In reply to MM0FMF:
Still going strong and will give them a couple of hours charge before going up The Cloud. Radio has done the Shining Tor and been on RX for most of day with no drop in power.
Yes the use of a proper charger as i said i can cobble together a charger and old mobile and charge in parallel. Why buy when you can use something that was made for the job? For me experimenting is a big part of the hobby and if things dont work the way im doing it then i will build a charger from a used mobile phone oh and hope theres no fire!
Getting through the plastic weld is a challenge and the use of an engraver makes the job so easy without causing any splits or cracks to the rest of the casing. Sean / M0GIA
In reply to 2E0BAX:
I’ve been using LiPo batteries with my FT817 for a considerable time and like Andy, I am extremely concerned at the risks you are taking by improper charging. What Andy has said is absolutely correct - what you are doing is a SERIOUS accident just waiting to happen. There have been more than enough examples of LiPo batteries catching fire when improperly charged and once they are alight they burn at a ferocious temperature and cannot easily be extinguished.
I am all for experimentation but what you are doing is plain foolhardy. Please take heed of Andy’s advice, which in summary is:
- You MUST repeat MUST use the correct charger
- Unless proper charge balancing systems are in use you MUST NOT attempt to charge LiPo batteries in parallel.
Please trust me Sean - this is not scaremongering. In another hobby I have seen what happens when an LiPo battery is mistreated and catches fire. The devastation from something so small was unbelievable. Research on the web for any amount of evidence. For starters:
“For safe handling it is useful to Think of Lithium Polymer Batteries as Fuel.”
In reply to G3WGV:
Yes as i said they do go up some lads at work have a thing about getting a few together charged and shorting them out in the carpark. I will look at charging them as they were ment by using a phone and charger one battery at a time. This will mean opening the battery case but far safer. Also by using a phone i will know when charging is complete and no over charging will take place as the regulator will stop this.
Batteries are plenty but house’s and lives not, funny how anything thats any good is lethal!
Will be giving them another airing soon today from The Cloud SP0-015 whilst on walk. Sean / M0GIA
In reply to 2E0BAX:
“some lads at work have a thing about getting a few together charged and shorting them out in the carpark.”
Any decent Safety Officer would have a litter of lizards at the thought!
For the record, a concentration of below 5 mg/m3 as an aerosol will cause severe eye, nasal and skin irritation and higher concentrations will cause damage to vital organs.
…but I would have done the same, once, I was a devil with nitrogen triiodide!
In reply to G8ADD:
Slightly off subject, apologies, but this reminds me of my apprentice days when we would turn on the unlit acetylene torch and let it fill the 20ft lengths of 6" diameter pipe, then sit and wait for some poor unfortunate to pass by and throw a lighted match in. It is best described as the Edinburgh Castle time canon going off when you are 10 feet from it and didn’t know it was about to be fired. Many a pair of soiled undergarment was attributed to our silly actions, but what fun, hi.
In reply to GW0DSP:
Thats so bad of you but i bet it was fun! I used to reverse the polarity of electrolytic caps on the end of long wires and hook up to a car battery charger.
Another is wiring a work mate up to transformer so it steps up not down and let him have the back EMF by tapping the contact fast on a battery…thats on youtube. I am sure there is a lot other pranks out there and always a laugh until something goes wrong that is. Sean / M0GIA
In reply to G8ADD:
I was a devil with nitrogen triiodide!
When I was doing ‘A’ level chemistry (Practical sylabus) we were locked into the laboratory by the history teacher who had a room across the corridor and complained about the smells we were making. The retaliation was to inocculate his blackboard duster (the type with layers of felt) with NI3…
Trinitro cellulose was fun stuff too.
This posting is definitely appropriate, but destructive, unfriendly and totaly unsuitable for the impressionable
In reply to M0DFA:
As i said i was going to do i took an old mobile phone that charges Li-Polymer cells and taped an very poor charger to it to make use of the conector. The black charger is a cheap Chinese charger that takes 2 days to charge a 900mah Li - Polymer. The batteries are arranged so when i have charged one you turn them over and the right polarity is connected to the contacts if that makes sense?
Downside you can only charge one at a time and around 3hrs each from totally discharged and the upside is its safe!
Did lots of reading about LIPO’s as they are referred to by many and decided this was wise to do http://homepage.ntlworld.com/s.amesbury/M3FVB/lipo.htm . Sean / M0GIA