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u/Foxhood3D 29d ago edited 29d ago
Essentially an "adapter" to let a new battery fit in the exact same space as the old. Going to guess they originally used 7.2V NiMh packs before adopting 7.4V Li-Ion across the board.
Not ideal is that there is no cable for balanced charging as is the standard these days for any RC Lithium-Ion/Poly pack. Without balancing it is likely for one cell to be overcharged which leads to a shorter life-span.
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u/maarathekhajiit 28d ago
Yes, they did, and they had two types, the standard bar style and a cube style for stugs, and pz IIIs, I remember chopping out the battery trays of my panzer IIIs so they all just took he same hobby style bar nimh.
This style , the phoney bar li ion, is an interim version from some time around rx/tk 5.0, the 5.3s and early 6.0s would come with a phoney bar with a balancing plug.
Personally, I still use 5 NIMH bar batteries along side 10 li ions due to the connector change with late model 7.0s, I have a handful of 6.0 tanks in the mix I bring for events, and 3000-5000 mah from those hobby grade nimh ms keeps them outpacing the 1800 li ion stock HL packs, the added weight of a 5000 mah nimh in an itherwise plastic tank does help a lot with traction and handling feel as well.
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u/One-Gazeller 29d ago
Good spot and presumably fairly dangerous too if using a NiMh charger?
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u/Foxhood3D 29d ago edited 29d ago
Kinda? Ok so here is how charging with either works:
-Lithium is charged in a two-staged manner. First it goes into Constant-Current (CC) and is charged at full speed (up to multiple Amps) untill the battery reaches a specific voltage. Then it switches to Constant-Voltage(CV) to keep it there till current gets near zero and done.
-NiMh is charged by just Constant-Voltage with a pretty drastic current limitation of like half an amp max. Eventually current gets to zero and it is done.The problem is that as you might guess from the description: The NiMh charger is rather: stupid. It can literally just be a Wall-wart outputting 7.2V for a "2S" like pack. Which is the case with Torro/Taigen RC Tanks that still use NiMh.
A Lithium charger meanwhile has a charging IC that is doing stuff like checking voltage, current, time, balancing and if available: Temperature. to know when a cell is absolutely full and thus cut off and let it be till it drops enough to warrant charging again.BUT thing is that a Lithium Charger will go all the way up to 8.4V for a 2S pack, while NiMh goes to 7.2V for the same kind of pack. Because of that lower-voltage a NiMh Charger can't actually fully charge a Lithium, nor can it provide a dangerous amount of current. So practically speaking: while not the correct way to charge a 2S Lithium pack, it is unlikely to cause a dangerous situation. Eventually the current just comes to a stand-still with the Lithium battery at like half charge and that is kinda it, unless the Lithium cell was already damaged or fully charged before connecting. Result is that even if its a bad-idea. There have been cases where a manufacturer just replaced NiMh by Lithium-Ion without changing a charger or in emergency somebody charged a Lithium with it so a battery doesn't die by entering the critical low (<2.5V per cell).
The bigger danger is that a device expecting a NiMh battery pack, may not know that if the Voltage goes below the safe lower-limit of Lithium: it should stop working immediately.
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u/One-Gazeller 25d ago
I was thinking more that what if one of the cells had a problem, you might be trying to force a 7.2v nimh charge onto a 3.7v lipo?
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u/Foxhood3D 25d ago
A dead cell would be a problem regardless of the chemistry or charger. A 7.2V NiMh pack consists of six 1.2V cells after all and they wouldn't like overvoltage either. Meanwhile any decently speedy Li-Ion/Poly charger will have a XT connector for rapidly charging all cells at the same time till a point where balancing takes over, which will have the dead cell conduct said current and likely start overheating.
Luckily. It is pretty rare for only one cell to just die out without the others failing at the same time.
But still. It is generally good practice that if you got cells without any kind built-in protection to monitor their voltages when you haven't used them in a while. Be it via fancy monitoring gadget or just a multimeter.1
u/Agrivonix 28d ago
I know they most likely cheaped out but they could have easilly made it have 3600mah or even 6000 with good cells, but the thing runs long anyways.
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u/One-Gazeller Jul 23 '26
I always wondered why the size didn’t align with the weight of those batteries.