long term battery storage

[graemevw]

Usual story, I had loads of cars, all shelf queen vintage. Sold most of them except my boomerang and wild dagger.

I have my nephew coming to visit in a couple of weeks so thought id dig them out. 

Getting them going again has inspired me and ive ordered 2 more kits and am once again hunting for anything first 50 ive not owned before.

 

Ive been trying to get some charge in my cells. My good nimh are shot. My ancient nicads will hold enough run time for about 1m30s.

So, I need some batteries.

Figured I might go lipo as it wont cost much more, my old charger isnt spectacular anyway.

My question though is what will store best? I know what will happen, ill build some, run some then ill end up running them less and less but still collecting. Then 6 months down the line when the nephew comes to visit again ill be desperately trying to revive old cells.

 

What battery tech, if any, will cope with long term storage best?

Or am I condemned to buying new batteries after every period of inactivity?

 

If lipo wont stand long term storage I may as well just buy some more cheap nimh.

 

[lentner3]

Some of my Lipos only get used once or twice a year. Just put a storage charge in them. You can even use them without charging them after a long time. Very little self discharge if any at all. Just as long as you have a decent charger and somewhere safe to store them all. You may even be so impressed with the run times and power delivery that a couple of packs will do. I have a few 5000mah packs and normally get bored or break something before the packs are drained. You also don't get the voltage drop when the pack is getting drained. Near full power right to the end. Don't forget low voltage alarm if you don't have a cut off on your esc. I like the turnigy packs from hobbyking but loads of options.

[graemevw]

Hello again

 

Sounds like its worth the small bit extra to set up for lipo then. If I get more nimh then no doubt they will die over winter from lack of use.

I am reasonably confident ive read up enough on lipo. I dont really need mega run times, 20 mins would probably be fine. I was looking for something around 3000mah to keep costs down a bit. I could maybe even go lower. Id rather have 4 lower capacity packs than 2 higher then we can both use 2 packs each.

I guess that would mean getting a charger that can charge two packs at the same time. Such a thing exist cheaply? I was previously looking at the usual imax b6.

 

Edit, seems the b6 can charge 2 packs. How do you do that?

 

What sort of run times would you expect from 2500mah lipo?

[Jonathon Gillham]

If you're running silvercan or similar then 2500mah should give 20mins or so. You can't run a lipo to empty though like you can a NiMH so it may be a bit less than that. Personally I would stick to a bit higher to give that headroom and not risk taking them too low.

I've heard mixed reviews about the B6 chargers, it seems to be that there are a lot of fakes out there and they cause the problems. There are some decent duo chargers that aren't horredously expensive, SkyRC do the D100 I think which gets good reviews. With your nephew there it would make sense to have a dual charger so you can charge both at the same time.

Is it worth considering selling the batteries rather than storing them and then buying new each time? Or buying secondhand and selling once you stop running them?

[graemevw]

Ill look at that charger.

I am aware there are fake b6, id buy from a uk retailer rather than hunting a few quid cheaper on ebay. I have read it can charge 2 packs though. Is that not true? Ill search some more.

 

As for buying and selling packs, im always mega suspicious of second hand batteries, I guess other people are too.

Ill look for some bigger packs, starts to add up though. I found 2500 for £15. Anything much bigger and im looking at £25. I cant do that right now, £100 in packs, plus charger, bag, connectors, alarms etc and its getting too pricey to buy all at once. 

As I need some batteries for in two weeks time id have to revert back to wasting money on some temporary cheap nimh.

 

Other option I guess is to just get two packs and hope he breaks it. He's only 6 and not even seen a RC car before. If he can manage to break it quickly it takes the pressure of needing it all quickly.

[Jonathon Gillham]

6 hours ago, graemevw said:

Ill look at that charger.

I am aware there are fake b6, id buy from a uk retailer rather than hunting a few quid cheaper on ebay. I have read it can charge 2 packs though. Is that not true? Ill search some more.

 

As for buying and selling packs, im always mega suspicious of second hand batteries, I guess other people are too.

Ill look for some bigger packs, starts to add up though. I found 2500 for £15. Anything much bigger and im looking at £25. I cant do that right now, £100 in packs, plus charger, bag, connectors, alarms etc and its getting too pricey to buy all at once. 

As I need some batteries for in two weeks time id have to revert back to wasting money on some temporary cheap nimh.

 

Other option I guess is to just get two packs and hope he breaks it. He's only 6 and not even seen a RC car before. If he can manage to break it quickly it takes the pressure of needing it all quickly.

For that price difference I would go with the 2500mah lipos then, you will still get decent runtime from them and 4 of those will be better than 2 bigger ones. With a decent dual charger you could probably almost run continously as one benefit of not being able to fully discharge them like NiMH is that they charge from halfway so take less time.

I don't think the B6 is a dual charger, but I've never had one so can't be sure

[TheMidnight Pumpkin]

I've generally had great results with storing lipo's like mentioned above. But recently these Turnigy hard cased 5000's did this, and I have no idea why. They were stored charged and not touched for a couple months, and obviously not puffed when I stored them. So I would advise you to avoid this model of batteries. The other Turnigy's that I have are fine with no storage problems.

[graemevw]

I have been reading and the b6 isnt a dual charger but you can apparently trick it into thinking its charging one 4s rather that 2 2s packs.

[Backlash]

What you are talking about is charging multiple battery packs in series or parallel off a single output charger.. Personally I would not do it as the risk of it ending badly (i.e. a fire) is just to great, and it seems that I am not alone in that regard...

Logic dictates that series charging is the safer option due to each cell being monitored by the balancer in the charger, and it may work OK for batteries that are always being used together like a 2S saddle pack battery, or a pair of 2S/3S batteries being used together in a 1/8 buggy/truggy etc., but I just cant see it working that well for batteries that are used individually... Most balancers only balance at 200mA so if you are trying to series charge 2 batteries of the same capacity that are at different levels of charge, then the time that it takes to charge the battery and balance all of the cells, it may end up being quicker to just charge them individually.. You will also need a custom charge and balance lead to connect the 2 packs to your charger..

Do some research on series and parallel yourself, but as I said, its not something that I would do..

I see that someone mentioned low voltage alarms..,. Are you aware of the needs with LiPo's like charging sacks, and that hard case LiPo's are best for cars etc, etc..

 

[graemevw]

Yes, im aware of all the other lipo safety.

 

The one thing you mentioned there that I hadnt read about and hadnt crossed my mind, is maximum cell inbalance before charge.

I see no reason other than that to not pretend it is one 4s pack. I think it is enough to put me off.

 

I havent found any reasomably priced dual chargers, but two b6 wouldnt be a major issue.

 

I have been thinking about the upcomming visit though and im not sure how much time we will even have. I think really, I can probably do with 2 packs for now. That gives me loads of time to buy more packs.

 

Im currently convalescing after spinal surgery so I currently have no income untill I get back to work. This is why immediate high outlay is less than ideal.

 

Thanks for bringing the potential imbalance issue to by attention.

[Wooders28]

Personally I wouldn't start messing with trying to charge 2 at once, if you can get a 2500 mAh that will charge at 2c a 5A B6 charger will charge it in half the time? 

Otley Modelsport have this 2500 2s on offer atm, not sure if it's able to be charged at 2c, but it's worth a phone call?

https://www.modelsport.co.uk/voltz-2500mah-2s-7-4v-30c-hard-case-lipo-stick-battery-with-deans-connector/rc-car-products/367906

[graemevw]

I decided to see if I could sort out my old batteries. I had two very good (in their day) 4200mah matched cell packs. I checked what cells werent taking charge and put a 8.4v pack together and its fine. Got about 15 mins wide open stupidity out of my wild dagger on its first recharge.

No major drop off till the end either.

 

Too fast for a 6 year old though so ill put it back to 6 cells tomorrow.

 

Going to see what I can do with the other packs for now. At least I can put off the lipo changeover for a little bit.

[Peter_B]

On 11/08/2017 at 7:48 AM, TheMidnight Pumpkin said:

I've generally had great results with storing lipo's like mentioned above. But recently these Turnigy hard cased 5000's did this, and I have no idea why. They were stored charged and not touched for a couple months, and obviously not puffed when I stored them. So I would advise you to avoid this model of batteries. The other Turnigy's that I have are fine with no storage problems.

This is the sort of thing that troubles me about lipo.

I would quite like to get in the lipo train. But I'm not a regular user of my car's. With having cars for myself and my boys (both 3), when they do get a run the batteries often don't get used up.

It's been known for them to be put away and then run a week later without having been charged in the interim.

Not ideal for performance I know, but for the type of running we do it's fine.

Now if we had lipos (or even 1 or 2 just for my use), as I understand it, after each run I'd have to charge/discharge them to storage level to make them safe. Which would then mean having to charge before use rather than grabbing and going.

With the autumn and winter on the way, I imagine running opportunities will be reduced. So then the batteries could be left for weeks or months at a time.

I'd be wary that, whilst sitting doing nothing, the lipos could go wrong with possible serious consequences. Even if treated and handled correctly.

Perhaps if I ever venture back near a track I might get the regular use to warrant/benefit from lipo.

Am I over thinking it all?

On a related note why aren't there more 3S 9.9v li-fe packs around? I believe li-fe is more robust (in terms of not needing storage charge etc) than lipo.

[Jonathon Gillham]

@Peter_B that is what I do. We have NiMH for the bashers which are used and abused, then I have a few lipos for me, 2 shorties for racing and a stick pack for mucking around too, it sure makes the car faster. The lipo doesn't get used much for the reasons you described. I'm toying with the idea of adding a touring car to the stable though so this would be used for racing...maybe next year.

TBH i wouldn't bother with lipo for bashing unless you want the speed, but to really take advantage of this you really need a programmable ESC

[TheMidnight Pumpkin]

@Peter_B  I found out a few things about storing these lipo's recently. I was doing the right thing with them as my charger has a "storage" function to charge them to the correct level. (The storage level is less than a regular charge.) But these obviously have a quality problem. Then I dunked them in salt water, and trashed them (recycle).

On normal use, I use a lower charge rate to charge mine slower. Yes it takes a bit longer to charge them. But it makes them last longer, so its worth it. Plus its the puffing that is the visible red flag for you to know the battery is failing. Plus if you are fast charging them to the battery size limit, and they poof while you are charging them. That is the sequence for lipo's to experience spontaneous combustion. The flame from a burning lipo is invisible to the human vision spectrum. The smoke you see from a burning lipo is the plastic the case and wires have. So my advise for anyone on the fence about lipo's would be to buy a high quality (expensive) charger and read and understand the directions before use. They will get you in the ballpark to safe operation with them.

Everything I said here is mostly true for most circumstances. But those of us who fly RC planes (and other toys) these rules do not fully cover all those situations. Just a little disclaimer.