The basic about Heng Long RC tank battery packs

[keilau]

What I liked about the EBL 3.7V 26650 Battery 5000mAh Li-Ion batteries I acquired is that they are internally protected. Assembly of the battery packs was simple and quite easy to do. Thanks to the battery circuit diagram that 'keilau' had posted in a different thread. The hardest part of assembly I had was getting the PVC shrink wrap to cover the battery packs. That took some practice and patience to get it right.

The 2S pack built with EBL26650 is the best money value for RC tank today. The material cost is less than $20. It works very well for driving HL tanks in difficult terrain including glass lawn. But I always have this lingering concern whether the low drain spec battery is a handicap for hard maneuver battle condition.

3 months ago, I was tricked into building 2x2S2P EBL26650 packs for a forum member. He lied to me to get me build them for his son's robotic project. The son promptly drained the packs completely with his robot. He ended up with 2 dead battery door stops. I was extremely unhappy for being lied to and wasting my time.

[cmdrcody]

A much better solution for HL battery pack is the DIY 2S EBL26650 pack. It will be interesting to hear from @cmdrcody on how he fits the 2S2P EBL26650 pack onto a HL battery compartment.

It was of coarse a snug fit for the new 2S EBL26650 long battery pack in the compartment of my Leopard 2A6. So much, I had to modify the compartment to relocate the male battery connector. You can see what I did in the following photos. You can see how much room was taken up even before I put the wrap on the battery pack.

[keilau]

I will discourage others trying what I did.

I successfully separated the cells in 2 of the packs. The glue used are strong enough to tear the individual cell plastic sleeve open and exposed the bare metal cell surfaces. On the third pack, I allowed the bare metal skin of 2 adjacent cell to touch and create a shortcircuit. It burnt holes on 2 of the metal skin. I blew out the fire immediately. No smell or burn mark left on the bench. I cannot emphasize enough how dangerous this is when the protective plastic sleeve of a lithium battery cell is torn open.

My idea of rearranging this battery pack doesn't work.

After I disposed of the damaged pack, I carefully put the other 2 packs with separated cells aside for 2 weeks to recover. I finished reconfigure the packs to long packs for HL. I worked very carefully, using a lot of electrical tape to cover the exposed battery area along the way. I tested the finished packs to 3840 mAh for 6V to 8.2V. It is consistent with the Kluosi 2S 18650 pack I tested earlier.

Reconfigure the Kluosi 2S2P pack for HL long pack is a bomb defuse operation. Not recommended.

A much better solution for HL battery pack is the DIY 2S EBL26650 pack. It will be interesting to hear from @cmdrcody on how he fits the 2S2P EBL26650 pack onto a HL battery compartment.

Be safe always.

[cmdrcody]

One warning about the "sale" or "popular" 18650 battery cells from them. These are unprotected cells intended for building packs with user provided protection circuit. Not recommended for the average end users.

What I liked about the EBL 3.7V 26650 Battery 5000mAh Li-Ion batteries I acquired is that they are internally protected. Assembly of the battery packs was simple and quite easy to do. Thanks to the battery circuit diagram that 'keilau' had posted in a different thread. The hardest part of assembly I had was getting the PVC shrink wrap to cover the battery packs. That took some practice and patience to get it right.

[keilau]

Good advice. I've been buying Batts from them for years (because I vape)...the selection is pretty awesome. +Bonus for me there in Houston.

One warning about the "sale" or "popular" 18650 battery cells from them. These are unprotected cells intended for building packs with user provided protection circuit. Not recommended for the average end users.

[keilau]

I cannot emphasize enough how dangerous the lithium battery, all chemistry, can be. I prefer Lithium Ion because it is available in commercial cells with protection circuit. When used properly, it can have more recharge cycles than most other chemistry type.

I have one 2S and one 3S lithium polymer battery pack in the protective battery storage bag that I don't use anymore. LiPo are cheap, light weight, support high current operating conditions. I gave up on it for lack of built-in protection. Besides, the Li-Ion is cheaper when you consider the usage life time. I am not a battery professional. These are just personal opinion from a RC tank user prespective.

[Zippersnapper]

Good advice. I've been buying Batts from them for years (because I vape)...the selection is pretty awesome. +Bonus for me there in Houston.

[keilau]

Red 390 motors. See post numbers 57 & 59. Not Abrams - Leopard 2A6!
Batteries were $5.88 each shipped purchased from Walmart. Came in packages of 2. Arrived in 1 week.
I figure that in building the long 4 cell ELB battery pack I got a total of $30 invested including the extra materials to assemble. You can't buy this much power from any retail seller for this amount!

For 2S2P 26650 long pack, you may have to get creative to find space for the connectors. For 2S2P 18650 long pack, there is room at the side of the pack for the connectors.

I received my spot welder, but have yet to try it.

[keilau]

On the subject of DIY Batts..they ship fast

https://www.imrbatteries.com/

Good information. They have many imported brand 18650 at $10 to $15 per cell range. These are excellent price. I paid $9 for the low discharge rate EBL18650 per cell. For whatever reason, the EBL store at e-bay still sells the higher capacity 26650 at much lower price.

For HL applications, the EBL26650's low discharge rate is not a limiting factor. I can charge a 2S EBL26650 pack in less than 2 hours using 3A charge rate. The pack does not get warm outside, but the xMAX B6 charger indicates an internal temperature of over 60°C. I did not try any higher charge current and don't want to.

[Zippersnapper]

On the subject of DIY Batts..they ship fast

https://www.imrbatteries.com/

[cmdrcody]

I suppose that this is the 2S 26650 pack using 2 cells each. Are you using 390 motors or 560 motors on the Abrams?

I paid $5 each for the EBL26650 battery. For the HL, I cannot think of a better battery deal.

Red 390 motors. See post numbers 57 & 59. Not Abrams - Leopard 2A6!
Batteries were $5.88 each shipped purchased from Walmart. Came in packages of 2. Arrived in 1 week.
I figure that in building the long 4 cell ELB battery pack I got a total of $30 invested including the extra materials to assemble. You can't buy this much power from any retail seller for this amount!

[cmdrcody]

Delete

[keilau]

Ran the ELB 5000mAh long battery pack in my HL Leopard 2A6 Professional Edition today. 360 motors, Mato metal tracks and 1/4 pound of weight added to front to balance the tank. Got a full 1-1/2 hour of run time - full out full speed running. Readjusted settings on my Imax B6AC V2 charger for these new battery packs. Did a balance charge at a 2A rate and got a reading of 4,625mAh, 8.4V after a 2-1/2 hour charge time. These batteries are very close to being exactly what they're rated at. Very happy with the results of this battery pack combination. Probably would run a good two hours or more in a tank battle.
P.S. Just weighed the tank - 12.5 lbs.

I suppose that this is the 2S 26650 pack using 2 cells each. Are you using 390 motors or 560 motors on the Abrams?

I paid $5 each for the EBL26650 battery. For the HL, I cannot think of a better battery deal.

[cmdrcody]

Ran the ELB 5000mAh long battery pack in my HL Leopard 2A6 Professional Edition today. 360 motors, Mato metal tracks and 1/4 pound of weight added to front to balance the tank. Got a full 1-1/2 hour of run time - full out full speed running. Readjusted settings on my Imax B6AC V2 charger for these new battery packs. Did a balance charge at a 2A rate and got a reading of 4,625mAh, 8.4V after a 2-1/2 hour charge time. These batteries are very close to being exactly what they're rated at. Very happy with the results of this battery pack combination. Probably would run a good two hours or more in a tank battle.
P.S. Just weighed the tank - 12.5 lbs.

[cmdrcody]

Wire got delivered today and completed the battery packs.

[cmdrcody]

This is how the long pack batteries are connected. And then folded to be straight inline.

[keilau]

Got my long and short battery packs ready for when my wires for completing them get delivered.

Very professional look. My silver soldered packs are not as neat. I have a spot welder on the way. It should make my building process easier.

[cmdrcody]

Got my long and short battery packs ready for when my wires for completing them get delivered.

[keilau]

I have used Tamiya to XT60 converters like those. There isn't any real issues with doing it until the Tamiya connector on the battery starts having a loose connector. At that point I will solder in a new XT60 connector in leu of the Tamiya one.

The Tamiya plug was an very old design for reliability in the early day of RC hobby. It served its purpose well for many years. It was not cheap to make nor easy to repair. I bought an expensive "pin extractor" to change or repair the Tamiya plugs.

That was before modern plastic and molding technology making the XT-60 and similar type of plug possible. The XT-60 plugs are cheap to buy and easy to solder. I had changed all Tamiya plugs to XT-60 when I received the slightly older Heng Long tanks. When I bought the SkyRC smart charger a while back, it came with Dean's and others only so I made a Dean's to XT-60 converter.

[tank_me]

I have used Tamiya to XT60 converters like those. There isn't any real issues with doing it until the Tamiya connector on the battery starts having a loose connector. At that point I will solder in a new XT60 connector in leu of the Tamiya one.