Disappointed with LIPO batteries.

[gil]

I thought LIPOs were going to be the best batteries for my QRP rigs.. And why not? They are light, high capacity and a three-cell pack is about 12.6V fully charged. Perfect for portable operations; on paper...

I destroyed three LIPO batteries... Brand new ones, even though I monitored their voltage. Like today... I was running a 650mAh Rhino battery with my MTR, which probably draws 40mAh on receive. It lasted all day and I still had close to 11V when I unplugged it to break for dinner. All cells were pretty well balanced. The next time I plugged it in, the first cell was dead! It is the third time this happens. It seems like LIPOS are meant to be discharged quickly, and in that role voltage can be monitored reliably. When drained slowly, they will keep their voltage up for a very long time, but I suspect cell damage happens way before the voltage goes down. So, you think your battery is all right, but it's really not.

Sure, it's only about $6 per battery, but it adds up.. I don't know how to monitor voltage reliably if cells behave that way. I think each cell had about 3.4V when I unplugged the battery. They supposedly can be taken down to 3V, even 2.85V. I might have to stay at or above 3.6V if I want to get my money's worth and keep using my three remaining batteries. No amount of cell balancing and charging could bring the dead ones back.

Maybe it's the brand I tried (Rhino) or just LIPOs in general.. Anyone else experienced the same problem?

Gil.

[cockpitbob]

I don't have any experience with them, but I've read of similar problems.  I'm thinking the extra few ounces for NiMH is worth the robustness.

[KK0G]

I've heard similar things about LiPo's not liking low current draw. Don't know if you've seen it but this site has tons of info on the different battery chemistries. http://batteryuniversity.com/

This link has some good info specific to portable QRP but not about LiPo's. http://www.wd3p.net/qrp/batteries/battery_index.htm

There's something to be said for plain old boring alkaline cells, they're often what I use for portable work. They have an almost immediate voltage drop when discharging but they'll keep right on discharging for a long time as they have a huge capacity compared to most rechargeable cells. Fortunately rigs like the KX1 will operate on a wide range of voltages just dropping power output as voltage drops. I buy AA cells in bulk for dirt cheap at Costco, not sure how many I have total but it has to be hundreds. ;D

[gil]

Thanks for the links Chris. I have NiMH AA cells and I think I'll stick to those in the future. I can recharge them with my solar panel as well which is a big plus, and they can be used in other devices. The LIPOS, I'll use until they go bad, but I probably won't buy new ones.

Gil.

[KK0G]

I found what might be a very stern warning concerning these types of batteries......... I think. ;D

[KC3AOL]

I found what might be a very stern warning concerning these types of batteries......... I think. ;D

Bang. LMAO!  ;D

How about a gel cell?

http://www.power-sonic.com/images/powersonic/sla_batteries/ps_psg_series/12volt/PS-1208_12_Oct_6.pdf

[gil]

SLAs are too heavy.. Good for base operations but not portable. That's why I like AA cells. This is why low current draw is very important. You never know how far you'll have to hike or how difficult recharging batteries might be in an emergency situation. Or just camping for that matter..

Gil.

[KC3AOL]

The SLA I linked to is only 0.77 lb.  Is that really too heavy?

[KC3AOL]

Ooooh...how about these:
http://www.eneloop.info/eneloop-products/eneloop-batteries/eneloop-lite.html

They don't have the capacity of the Eneloop XX, but they're also much lighter.

[gil]

The SLA I linked to is only 0.77 lb.  Is that really too heavy?

That's reasonable.. It really is a matter of choice..

Gil.

[KK0G]

The SLA I linked to is only 0.77 lb.  Is that really too heavy?

It depends on how you determine if it's too heavy. If we're only concerned with the total weight of .77 lb, then no, it's not really all "that" heavy. If on the other hand you look at it from a power to weight ratio then yes, it's very heavy because out of all the battery chemistries, lead acid has the lowest power density. In other words for the same .77 lb of weight you could get roughly double the capacity with alkiline, NiMH, or NiCd, and roughly triple the capacity with Li based batteries.

[Luigi]

If you can find a battery that is Lithium Iron Phosphate rather than Lithium Cobalt Oxide, you will be better off. They can handle higher current and more charge cycles. You get a battery that is slightly heavier and slightly lower capacity, but it will last a LOT longer. I have a 36 volt 20 Ah battery that is LiFePh and it works much better than LIPO. I blew up two LIPO batteries because of current. After switching to LiFePh the issue was never a problem again. I regularly pull 30 A for short periods of time. I am not using them for radios. I use them for an electric bike.

Luigi

[gil]

Hi Luigi, the current problem is not pulling too much but too little. I pulled 40mAh from my LIPOS, and maybe 700mAh on transmit, which is only for fractions of seconds. The LIPOs don't like being drained slowly and will keep a high voltage beyond the damage point..

Gil.

[Luigi]

I see. For those prices, you can go for a high capacity NiMH and use a Smart Charger.
I use this one: http://www.mahaenergy.com/mh-c9000/
The charger needs 12v @2000 mA. The power requirement can be changed by opening it and disabling the light. If the power requirement is too high, there are other smart chargers with lower power requirements.

Batteries will cook in other rapid chargers. The Powerex will charge them properly and you can check the battery capacity by running them through a capacity test every now and then.  Match the cells by capacity. Normally you can write the capacity on the battery for cell matching. The written capacity number rub off every now and then. By that time it is time to test capacity and write the mAh rating on the battery.
Amazon Basic batteries work well for a lot of people. Their discharge rate is pretty low while sitting on the shelf. Your application is a low drain one, so you might get some good performance overall.

[cockpitbob]

I have a KX1.  I love that I only need to connect 2 wires to it:  antenna and ear buds.  But, will hold only 6 AA batteries internally.  Even with Alkalines the voltage is so low that it barely puts out 2W.  With NiMH batteries it's below 1W.  I now have 4 of the AA size, 600mAH, 3.2V LiFePO4 batteries in it.  That gets the voltage up to 12-13V and the powe is around 4W where it belongs.  For casual use on a weekend campout 600mAH batteries are fine and I have an external battery for a backup.  Needing a seperate charger for them was a drawback, but to me it was worth it.  And so far they've been reliable.