Batteries

[Ray Brown]

G'day Guys & Girls,

I purchased a 24v 20 amp LifePo4 battery and installed in in my PzIV. Weight is 6.2kg. I took it to the local footy fields and drove it continuously to get a run time of this battery. For the first hour I drove it at full speed as much as possible. For the second hour I turned the Armortek exhaust smoker on. At the end of that second hour I had to load up and head home due to time not flat battery. A check of voltage read a discharge of just 1.5 volts +/-. I believe I may have been able to get another 30 mins at least. My next test will be the lipo in the centurion. The dimensions can be customized with minimum height 65mm.

I will post results when done.

Cheers
Ray

[Adrian Harris]

Hi Ray.

I'm intrigued by you saying the dimension can be customised as that battery in your Pz IV looks have a solid case

I've have a couple of LiFePO4 packs made from Headway 40152S cells, which can be arranged in many configurations. Keeping things electrically isolated is an issue though

One of the benefits of LiFePO4 is that you won't see much drop in voltage, especially if measured when stationary, until the point when the battery management system (BMS) shuts the battery down. My little T34 seems to run and run with the LiFePO4 battery installed, but I don't have a smoker fitted, which must help

Adrian.

[Ray Brown]

G'day Adrian,

The company I dealt with provides the standard sized batteries as per photo however can manufacture a 24v 20amp custom lipo. The minimum height is 65mm which means the length and width must be greater than the battery in the photo. This is achievable due to the fact the lipo batteries are individual cells in banks.

Basically I could have a 24v 20amp battery 65mm high that fits in the bottom of the tiger or centurion the length from the motors to the back/front and as wide as floor plate. Low CG and battery weight (6.2kg) distributed evenly.

Hope that makes sense, because it did in my head.

Cheers
Ray

[Stephen White]

Ray

It's great to see you embracing the new LiFePO4 technology, which looks like a good way forward. I believe there is still some work to do to quantify the effects of the Armortek regenerative power system but as our collective experience increases, I think the case for LiFePO4 becomes very strong. Notwithstanding the obvious benefits of weight, size and performance, I believe the cost issue is also in favour - they have a high capital acquisition cost but demonstrably have a better whole life cost - and our models are made to last.

Some have expressed concern about safety but I think this is to confuse the various types of lithium batteries. The concerns relate to Lithium Polymer (LiPo) but not to Lithium Iron Phosphate (LiFePO4). For that reason, I think we should try to avoid referring to LiFePO4 as "lipo".

If there is anything you think could be added to the Knowledge Base on this subject from your experience, I'd be happy to add it (same goes for our increasing body of LiFePO4 users).

All the best

Stephen

[John Heath]

With the advantages of the LiFePO4 I've decided to go with them for my Tiger 131. Bought them a few months ago when they were on sale. Decided to go with two 12v batteries as it gives me a few options as to where they can be fitted. Pretty small packs. 165mm x 125mm x 110mm and 2kg each.

Will be interested to see if there are any significant quality differences among various brands of batteries as people post their experiences with them. The Tracer ones I went for seem to be very good quality but anyway we will see how they actually work.

John

[duncanallender]

Hi Guys,
All very interesting stuff, as am still looking for some small and lightish batteries for my M3 half track. Think now will invest in those Life po ones. Will let you know how it goes.
Thanks Chaps
Duncan

[Ray Brown]

G'day,

I believe the pros does justify the price. With a 2000 cycle life, the ability to hold charge when unused, 50% reduction in weight and a recharge time of 5 hrs I will slowly repace my lead batteries as they die. The cost is higher but with a 10 year, +/- life it makes economical sense.

Cheers
Ray

[Ray Brown]

G'day Again,

Does anyone know the current draw (amps) of;

1. Armortek exhaust smoker,
2. the motors,
3. traverse motor,
4. amplifier.

Cheers
Ray

[Iacopo Di Giampietro]

Goodmorning everyone.
I apologize, but I would like to get information about the batteries that you use.
Even I and other friends here in Italy, we use LiFePO4 batteries on our tanks and to date we are very satisfied.
Seeing the photos posted by Ray and John, but I felt a curiosity but the batteries that you have not used the power balance? They have an internal BMS? As you balance the various internal cells? You could put some links where you have purchased?
Thank you all and ... sorry my english !!
Ciao!
Iacopo

[Ray Brown]

G'day,

http://www.superstart.com.au/tabid/108/ ... thium.aspx

This from my battery supplier:

The built in BMS will shut off the battery when the battery reaches approx. 21V under load. SO when the load is removed the battery voltage will recover to 25 or 26v. It could be that the cells internally are slightly unbalanced, and when one cell pack gets low the battery will switch off in order to preserve that pack. Then the cells may equalize slightly and recover somewhat, allowing another half hour of operation.

Charge the battery again and give it another go and see if there is any improvement.

At the very least, you will know when the battery is nearly flat and that it is time to move the machine towards its transport.

[Stephen White]

Iacopo hi.

I bought mine direct from the manufacturer and have been very impressed with it.

http://www.tracerpower.com/24v-20ah-battery-slab.html

Best regards.

Stephen

[Dennis Jones]

Hi John,

How much did you pay for the Tracer batteries and the associated charging and control equip.

Dennis.

[John Heath]

They were £149.00 each delivered and include the chargers. Picked them up from an Astronomy shop Firstlightoptics that was having a sale. They're back up to £219.00 now. They're popular for powering telescope mounts.

John

[Adrian Harris]

A quick message about the LiFePO4 batteries.

I've just cleared a space on the work bench to take a look at the T-34, and found that the LiFePO4 battery pack was still attached. I think the last time I used the tank was TankFest, in June. I might have charged it up when I got back but I'm not certain.

I was expecting to find it stone dead, and beyond saving due to the vagaries of Lithium battery technology. When I checked the output, it was still at 26 volts, and each pair of cells was almost measured 6.5V, so the pack is still 'balanced'.

It's on the charger now, and I won't know if these are phantom voltages till I try and move the T-34 again, but it's looking promising.

I'm hoping that the BMS board, which is built into the battery, has protected it from being discharged.

Adrian.

[Stephen White]

That's reassuring to know, Adrian, how many of us put the tanks into store at the end of the season and hope for the best?

I've been delighted by the performance and ability to hold its charge of the LiFePO3 I've got in my Cent. Conversely, I found quite severe corrosion around the terminals on the two lead acid batteries I've got on my Pz III, despite keeping them on an Accumate maintenance charge. Perhaps that's the problem?

You can debate the economics of LiFePO3 cf lead acid, although I happen to think the whole life cost come out pretty evenly balanced but the performance benefits are much more clear cut. If I could afford them, I'd use LiFePO3 in all my models.

All the best.

Stephen