Battery modifications

[Robert Cardew]

I have a leopard a26 and Bradley ifv where I installed two admiral 3500 mah batteries in them parallel together. Get lots of run time. If interested on doing this contact me at robertcardew2@gmail.com

[keilau]

I prefer to use a single 2S2P Lithium Ion pack. It is easier to install and to charge. I build my own pack using high quality protected Li-Ion cells. Total cost is less than $20 plus elbow grease. I have a mini spot welder making the job very easy. The pictures below show battery pack in original HengLong Leo and Torro Leo.

It is very important to have a smart charger. 1/16 RC tank uses only 2 small motors. The battery pack needs only low current charging capacity, but the balance charging is absolutely necessary. If you connect multiple battery packs in parallel and they are not equally charged, it can lead to a run-off and small fire.

[Robert Cardew]

I disconnect the batteries from each other when charging to eliminate potential problems then they charge equally

[keilau]

I disconnect the batteries from each other when charging to eliminate potential problems then they charge equally

The balance circuit is an integral part of the Li-Ion battery pack. The smart charger uses it to assure equal charge to all the individual cells. I discourage connecting separate packs in parrallel for the danger of potential fire harsh.

If you want longer run time, purchase a high quality 2S2P pack is the only way to go.

[Evan D]

There is no "balance circuit" there. The balance circuitry is on the battery charger side and through the balance tab.

[keilau]

There is no "balance circuit" there. The balance circuitry is on the battery charger side and through the balance tab.

You are right that the balance circuit is on the charger side. However, you need to wire the battery pack in a certain way to connect to the balance circuit. If not, the individual cells in the pack will not be charged equally.

[Robert Cardew]

I disconnect battery packs from each other and connect to two different chargers so both battery packs charge separately.

[Robert Cardew]

The balance circuit is how each battery is charged by the charger so they are not connected together when charging is done. That is why it works my way.

[keilau]

I disconnect battery packs from each other and connect to two different chargers so both battery packs charge separately.

The balance circuit is how each battery is charged by the charger so they are not connected together when charging is done. That is why it works my way.

If you charge the two 2S battery pack to the same full charge voltage, it should work fine.

I like the convenience of the 2S2P pack and automatic foul proof charging. I see that MotionRC had been out of the 2S2P Admiral pack for a while and don't seem to restock anytime soon.

[ti84calcultor]

That’s a solid setup discussion. I like how you’re managing the balance charging part — that’s usually the most sensitive area. I’ve been studying how parallel packs affect current draw, and it’s amazing how a small voltage difference can shift the load.
Thanks for sharing your setup; it’s a good reminder about keeping both packs at equal voltage before connecting.

[Robert Cardew]

Dual 3500 mah admiral batteries in Abrams being charged by two chargers via battery balancers with one battery disconnected from tank during charging then connect both batteries to the tank when operational

[keilau]

Dual 3500 mah admiral batteries in Abrams being charged by two chargers via battery balancers with one battery disconnected from tank during charging then connect both batteries to the tank when operational

I strongly recommend you to invest in a intelligent balance charger. It charges your Li-Ion pack fast and record the charge results such as final voltage, mAh and individual cell voltage too. You can download the SkyRC software to monitor the charging progress and pack temperature too.

https://www.banggood.com/Original-SKYRC-IMAX-B6-Mini-60W-6A-Balance-Charger-Discharger-with-Power-Supply-for-LiPo-Li-ion-LiFe-Nimh-Nicd-Battery-p-1422718.html?rmmds=detail-bottom-viewalsoview&cur_warehouse=CN&ID=47184

There are many knock-off of the iMAX B6 charger from China at a fraction of the price. Those cheap imitation do not have functioning software and should be avoided.