Best batteries to use for chieftain

[Daniel Brooker]

Hi all
Getting close to installing motors test running etc just need to order up some batteries can anyone recommend a good battery to use plus best place to purchase from
Many thanks
Dan

[John Clarke]

Hi Daniel
You can't go terribly wrong with a new pair of YUASA REC22-12 AGM 12V 22Ah, they are usually quite robust. Ebay or Amazon usually do deals on pairs for Wheel chairs, Golf trolleys etc.

There are more exotic batteries, lighter, smaller, larger capacity out there, but they usually cost an arm and a leg and you'll need a particular charger to go with them.

I don't think anyone really knows how much running time you'll get from the two 12v 22Ah batteries, because it depends on driving conditions
But you should get up to couple of hours driving time on the flat.

Mark and Charles on the Chieftain Topic's will know more about it than I.

If you look after the batteries (I do suggest getting a quality 24v Charger) they should last about five years before renewing them. Not bad for around £90-£100 the pair.

Look forward to hearing about another Chieftain hitting the road.

[Dennis Jones]

Component Shop for batteries

Dennis

[Charles A Stewart]

Evening Daniel

As John mentioned my name, the only thing I can offer is that my total run time to date is about 30 mins.

Then break down.

Hopefully motors back tomorrow and will run until the batteries run down, which are those referred to by John.

Cheers Charles

[Jerry Carducci]

Then break down.

Hopefully motors back tomorrow.......

What's this then? Is there a story here? What broke down and how? Just curious and learning pitfalls to avoid.
If you covered this already in another thread, apologies and if you could reference the appropriate thread please.

Jerry

[Daniel Brooker]

Thanks all for the battery info much appreciated
Regards
Dan

[Gerhard Michel]

Well, I'm a friend of LiFe (LiFePO4) batteries. They are small, they are lightweighted, they are strong. Yes, they are not cheap and need special charging device, but they last up to 20 years when treatet 'species-appropriate'; so you may forget them when installed. Within 20 years you need up to four sets of lead acid batteries which are more expensive than one set of LiFes.

[Armortek]

This is where we get our batteries from:
https://www.tayna.co.uk/golf-batteries/yuasa/rec22-12/

[John Clarke]

Nice One Armortek.

Now then Gerhard, just how long have you had them there batteries

I heard tall stories before and got sold down the river many times.

Betamax video will out live VHS

Dat tapes are the future personnel Hifi

Oh and worlds oil will run out before 2020.

Those copper jumpers looks awfully shiny for such old batteries. 20 years old, never, unless you've been polishing em with Brasso

I should ask much are they? And how much is the charger? where can I buy them? I haven't brought my Chieftain batteries yet

[Stephen White]

Not all batteries are created equal.......

Some do the job, like takeaway burger, are cheap, do the job but don't last.

Some, like a vindaloo, are positively poisonous in the wrong hands and can produce spectacular and unwanted results in an instant.

Some cost the earth but give lasting satisfaction, nouvelle cuisine, there's not much of them but they satisfy for much longer.

The default answer is two 22Ah 12v lead acid AGM batteries. They are relatively heavy and take up a lot of space. They require maintenance, generally by keeping them at a stable temperature and preferably plugged into a charger providing a maintenance charge. If you don't do that, they will self-discharge at about 4% of capacity a week. They have a relatively short life cycle ie they will probably need replacing in the life of your tank. There are plenty of examples on this Forum of owners having to replace lead acid batteries.

The world is moving away from lead acid into lithium based chemistries. Be very careful here. Not all lithium batteries are suitable. The MUST AVOID is lithium polymer. Suffice to say that in the wrong hands, LiPo batteries can self-destruct with catastrophic results. They should only ever be charged outdoors and with constant supervision. If you want to see what can go wrong:



LiPo is old hat anyway. The safe chemistry for our models is Lithium Iron Phosphate (LiFePO4). Most of these come with a Battery Management System (BMS) built in. The BMS will prevent over-charging and over-discharging and will also trip a thermal cut-out if the battery is approaching an unsafe temperature. Compared with lead acid, they are more expensive but last twice as long. They are much smaller and lighter and don't require continuous maintenance. They can be stored for long periods as long as they are not fully charged.

If you're looking at the economics over the life of the battery, LiFePO4 wins. It costs more upfront but lasts longer. If you don't intend to use the tank much, lead acid is probably the better economic choice.

Some may argue that extra weight is a good thing for our tank models in that it makes them more realistic. I don't buy that argument. It only means the battery expires more quickly.

When Lithium Iron Phosphate first came out, I believe there was a concern that the regenerative power system in the Armortek motion pack might cause problems with exceeding the maximum charge rate but as long as the LiFePO4 battery has a BMS, this can be discounted. The one remaining issue is the concern that some may think all lithium batteries are the same. They are not. To be clear, for safe use, only an LiFePO4 battery with integral BMS should be considered.

There is one crucial operational difference between lead acid and lithium iron polymer. They have very different discharge curves. In simple terms, lead acid will start to fade quite early and will gradually run out of steam until you can run no more. So you only get full power in the early part of a running period. Lithium Iron Phosphate has a "cliff-edge" discharge curve. The battery will continue to deliver nearly its full voltage until it suddenly doesn't:

The BMS will shut the battery down as it approaches its minimum discharge voltage and the tank won't run no more. This point however is reached much later in the discharge cycle than with lead acid. By a large margin. This is a crucial performance advantage of lithium iron phosphate. It's simplicity itself to fit a voltage monitor in the motion pack circuit.

To illustrate this advantage, I've run my Centurion pretty hard over four days of TankFest without the need for any charging. The battery still had lots of life left to get the tank home. I've only had one occurrence of the BMS shutting down the tank. It was at the end of a long day of running in very hot temperatures and I was attempting to turn sharply on longish grass. The tank simply stopped. I checked the battery temperature and it was within limits. I let the tank cool for 15 mins and the BMS was reset without fuss.

The other advantage of Lithium Iron Phosphate is size. They take up considerably less room than lead acid and therefore allow you a lot more freedom in where you put them. In my Cent, the battery sits in the driver's cab, leaving the rest of the hull free. This freedom also helps with getting the centre of gravity right.

If you want to read more, I've put together some references in the Knowledge Base, here:

viewtopic.php?f=34&t=5790

I've put a link to this post in my Chieftain thread, where I've also put my personal choice of battery.

It's great to see the Chieftains getting to the stage where motion packs are being installed.

[John Clarke]

Stephen,
You missed out Donna Kebabs, you don't always get what you pay for.
But the runaway train though the body can be quite exhilarating, with some added benefits.

Your argument is sound, the cost is extortionate. If you had one model I would agree. Money no object, not a problem

But if like me, you have more than one model, the cost of batteries laying around doing nothing for most of the time. The investment seems a waste.

It maybe that in the future after these dark times finally desist, we could spend a bit more time together and run the tanks. Though it will depend how much time an individual wants to spend driving around. And of course If the model is capable of driving around for any length of time too.

Me, I like to participate, but also to view and enjoy others workmanship, chat and enjoy the nouvelle cuisine.

As long as the tank batteries don't fall off the cliff before embarkation in to the wagon home, that is a good day.

[Gerhard Michel]

Hi John,

the life time prognosis was made by the manufacturer, not by me. My shown CALB batteries (40 Ah) are three years old. This type will be used in manned aircrafts (CALB = China Aircraft Lithium Battery) and has the necessary specifications.

A BMS is helpful but not necessary to avoid overcharging when used in tank models, because LiFes can endure much higher currents than lead acids. I use battery sets with and without BMS. With BMS it may be charged and discharged like a lead acid battery (including lead acid charging device), but is more expensive and has a little lack of capacity. When the set is at its end of capacity, the BMS will shut down it immediately, and your tank will stop in the field without warning.

Without BMS you have to monitor the set permanently and automatically while being discharged (e.g. via telemetry, which makes my RC equipment). So I can see (and hear warning levels) at any time if my tank must be returned to its base in a few minutes. You need a charging device with balancer which is more expensive than a lead acid charger, but becomes economic when using more sets of LiFes without BMS in your tanks. LiFes are chargeable with much higher current than lead acids; some cell types up to 4 C, what means that a cell of 40 Ah can be charged up to 160 A in less than 20 minutes, if your charger is able to do that! The shown cells can be charged with 40 amps in about an hour, perhaps in the lunch hour of a prolonged mission. My charger has 2 channels with up to 40 amps output each.

[John Clarke]

Gerhard it is truly fantastic what you have shown, You'll have to forgive. There's so much hype on some things these days it's sometimes difficult believe.
I love this B$ advert

iphone 5 ??????

If you use the model a lot I can understand the outlay, I'll get the models out two or three times a year, it's probably not such a good investment.

I wouldn't buy a CD player for 5 years, because technology tends to leave you high and dry as the "New Thing" supersedes it.
Yep, I brought a digital tape player.
Some people will jump out of a perfectly good airplane for fun. Me I take the safe bet and wait for it to land.

I'm a fuddy duddy, trust very little these days, So many people offer so much, but give so little, so I usually stick to what perceive I know.

[florian rudolf]

I also use the LiFePo4 but in a kit. I use the Headaway.

[Gerhard Michel]

My 5 tanks are equipped with one lead acid silicone type battery and 4 types of LiFes, one with BMS and 3 without. I intended to try out these various types of cells and techniques to find out the most suitable for my tanks. Now I can say that all types of LiFes are usefull, depending on the space available. LiFe cells should be mounted in upright postion, and not always there is room enough for the big CALBs with 40 Ah. The following cells with 36 Ah each are much lower and fit better to small tanks: