GROUP BUY - LiFePO4 batteries

[Armortek]

For a while now several forum members have been using LiFePO4 batteries.

They offer several advantages over Sealed Lead Acid batteries - the most notable being that:
(a) you can get SUBSTANTIALLY longer run time for a similar capacity battery - forum members have been getting full weekends of running or even multiple weekends of running from a single charge. (i.e TankFest without having to worry about running time)
(b) the lifespan is significantly longer (larger number of discharge cycles)
(c) they retain their charge for much longer when disconnected - lead acid drop about 4% a month and cannot be recharged once they have been discharged below a certain level
(d) they are lighter.

The disadvantage used to be cost - they were always a lot more expensive then Lead Acid batteries, but as their price has fallen considerably over the last couple of years combined with the fact that the Lead Acid have been going up in price, we have now reached an economical tipping point.

The above points, combined with the fact that we had a lead acid battery leak inside one of our tanks last week has prompted us to make a move to LiFePO4.

All of that leads me to the point of this post - we have been in touch with a Chinese supplier of LiFePO4 batteries and worked with them to produce a battery that would suit our tanks - i.e the same dimensions as a lead acid battery, capable of high continuous discharge as well as high instantaneous discharge, and high capacity for a weekend of running .. probably more.

We will be buying these batteries for the models in our factory and we are offering Armortek customers (only) the chance to purchase these batteries as part of a Group Buy.
One important point to note is that we are acting as a middleman on your behalf so we will not be offering any warranty on these batteries - we are purely offering to help facilitate the purchase. In the unlikely event that you have issues with the batteries in the future, you would need to go directly back to the manufacturer.

Details:
LiFePO4 battery 12.8V 30Ah
Nominal voltage : 12.8V - 4 cells in series, 2 cells in parallel (uses 32140 LiFePO4 cells))
Nominal capacity : 30Ah
Continuous discharge current: 50A
Short burst discharge current: 90A
Life: 4000 charging cycles
Integrated BMS with overcharge/ discharge protection


Packaging:
Dimensions: 180mm * 75mm * 170mm (for comparison, a Yuasa 22Ah lead acid is 181mm * 76mm * 167mm)
Hard case to protect the cells.


You pay : £99 including VAT per battery (for comparison, a Yuasa 22Ah lead acid is approx £51 incl VAT)
Shipping: Collect from our factory in Otterbourne
Timeline: Shipping from China by sea will be at the end of Feb. We expect to have the goods 2 months after that - so in time for summer running.

These batteries are design to fit all tanks except the Hetzer.

Group Buy terms:
If you want to participate in this Group Buy we will need your response by the 2nd Feb.
- Offer to ARMORTEK customers only
- 50% deposit will be required in advance. If you cancel before collection then you will lose your deposit.
- Collection from the factory. No shipping.
- We are covering our costs with this group buy and not making a profit so we offer no warranty - you are purchasing the products at your own risk and you will need to go back to the manufacturer with any issues.

[Stephen White]

What a good move - it gives the official seal of approval to a trend that’s been around for a while. It was way back in 2015 that I wrote the Knowledge Base topic advocating LiFePO4. Prices have fallen considerably since then. The battery you’ve obtained has a great spec - the 90A instantaneous limit is one of the highest I’ve seen. Interesting that you’ve gone for a 12V array. 24V batteries are much less common but are available. Good that a BMS is included - it’s a vital protection.

[Armortek]

Stephen - I think you were the first one I knew of who ran LiFePO4's in your Cent.

90Ah in a battery this size is not common - normally to get that high you need to go with a larger capacity battery (40Ah plus). The issue is that this also comes with a larger foot print and would be a real squeeze into most of the models we have made. The 40Ah battery that we were working on was 195mm*131mm*173mm - that's too big for the Leopard 2.

The reason for going with 2x 12V rather than one at 24V is again a question of size. I was keen to keep the footprint to the same as, or smaller than, the 22Ah Sealed Lead Acid that we use.

I look forward to not having dead tanks sitting around our factory in the future !


Below is an image of the 30Ah battery disassembled:

[Jerry Carducci]

Didn't I read here, somewhere in the Forum there were certain considerations that had to be observed when charging two separate
batteries of any type that have an integral BMS unit? Don't they need to be charged separately; perhaps always a good idea to charge
separately regardless?

I'm using two 12v LiFePo4 units (without BMS- but I have them) in my King Tiger and one giant 24v pack in my Lee. They
do give terrific performance. I have yet to switch over my Sd.Kfz. 7 to LiFePo4 packs.

I have already purchased cells to make a 24v pack for my JagdTiger, so I'm committed.

If I was closer, I'd buy into to this group purchase as there are other models in the 'queue' that will need them...

Jerry

[Gerhard Michel]

In my opinion 30 Ah is enough for running over a weekend. In my tanks I'm using LiFes from 20 Ah (e.g. Jagdpanther) up to 40 Ah (e.g. Königstiger). My cells are cubic; therefore they can be easier combined to batteries and I need only one row of cells to receive the desired capacity. I'm not a friend of using 2 BMS batteries to get 24 V; 24 V BMS units are also available.

Please keep in mind that a BMS is a also good protection against forgotten switching off your model, but not for longer times. The BMS cuts off the load when the battery is nearly empty, but a longer self-discharge period following the cut off may yet damage the cells.Therefore it is a good idea to charge the battery straight after a running period; at least up to storage voltage.

[Simon Peck]

I’d be interested in this. I have currently have two 12v lead acid in my Tiger I, would this be a straight swap? Do I need two batteries? What about chargers? Thanks.

[Gerhard Michel]

Hi Simon,

for 24 V you need 2 of these recommended batteries. Due to the BMS you need only a simple automatic charger which also fits a lead acid battery with same voltage and similar capacity. I would charge each battery seperately with a 12 V charger to obtain best results.

[Armortek]

Yes, the 12V LiFePO4 batteries are a straight swap for the 12V Lead Acid Batteries.

We have had a few questions about charging sent to us by email. Here is a summary of the answers:

1. The batteries must be charged individually. They must not be charged as a 24V pack.
2. We will not be proving chargers, but there are several available on the market. As an example, here is a link from Amazon:
AMAZON - 12V LiFePO4 Chargers
You should purchase a 12V LiFePO4 charger. The charger should be rated at 5A or 10A. Going higher than this is not recommended by the manufacturer.

LiFePO4 batteries are inherently more stable then some other lithium chemistry batteries but they do hold a high energy density. As a minimum the following must be observed:
1. Always use the correct charger for the battery type
2. Charge the batteries individually (do not charge both batteries as a 24V pack)
3. Never leave the charger on once the charge cycle is complete unless specifically recommended by the manufacturer
4. Never charge unattended.

[Simon Peck]

Gerhard, Armortek, thanks for the replies. I’ll order four batteries.

[Andy Walker]

Sounds like a good deal. I'll order four please.

[Armortek]

1 day left to jump on the band wagon.

[Dave Goodwin]

For those of us not in-country, can you provide any link to the manufacturer and the model number of the batteries so they could be ordered, if the manufacturer is open to that?

[Armortek]

The Group Buy offer is now closed.
We will contact everyone who has confirmed their order (both on this forum and also by emailing us directly) by Monday.

Enjoy the weekend.

[DaveMacri]

For those of us not in-country, can you provide any link to the manufacturer and the model number of the batteries so they could be ordered, if the manufacturer is open to that?

Dave contact me-we have a source here for a single 25 volt LI battery

[Armortek]

Having consulted a legal expert, I am sorry to say we will not being going ahead with this Group Buy.

Apparently as a company we would remain liable for the batteries - there is nothing that we can do to limit this liability. Since my intention was to offer this as a benefit for you, if something does go wrong it would come back to bite us. It is not worth us losing time and money over this.

Back to making 1:6 scale kits now.