smokinbarracuda

Hi,

I have an upgraded hobby engine abrams which currently has the electronics in the turret with a 2000 mah nicad and a 2000 mah nimh in the hull. The main switch is accessed via the turret hatch as well as access to the 2 battery connections which I charge and discharge separately. Ideally what I would like is to connect the 2 batteries in parallel and have 1 connection in the turret where I can charge and discharge. Now I've recently found out that you can't safely charge both in parallel even if they were the same type but you can discharge. Does this also mean I can also discharge the nimh and the nicad in parallel?

Once the above is etablished I would still have to charge them separately even with new nimh packs I think. The only way I can think to do this would be to rig 2 charging ports on the hull for each battery but they would still be connected in parallel. So therefore, could I install a switch next to the charging jacks that once I am finished discharging I could flick and it would break the parallel connection and charge the batteries separately.

Any help would be greatly appreciated. I would go out and buy 2 nimh packs but money is tight at the moment, darn economy! Thanks

swathdiver

Save your valuable time and money and buy a 4200+ mah battery, they're pretty inexpensive now. Use fishing weights to make up for the lost weight of the deleted battery if need be.

Green Amphibian

I was informed that you should not discharge or charge, in parallel, different types of batteries. This is due to the different rates that they have or use.

RodgerB

Buy the 4200 as suggested. You have two different  types of batteries there the Nicad and Nimh. Both have different charging and discharging curves! It would be possibel to have a meltdown due to that in that the current drain is all togehter different. Buy the 4200 and eliminate possible disaster and performance.

shenlonco

My Feedback: (2)

Also you should not link the 2 batteries together because they are not the same chemistry...(NICAD -NIMH)

SouthernSteel

Danger Will Robinson danger!

smokinbarracuda

Ok guys thats that then, thanks for the replies. I'll leave these packs alone. Ultimately what I wanted with the system I described above is 2 new nimh 4000 packs so the capacity would be about 8000 mah. This is a heavy tank and draws a lot of power which is why I'm looking for that capacity. I reckon 8000 would give me about an hour runtime. It does get put through some tough terrain!

If I got 2 new identical packs to discharge in parallel and charge separately would the system I described above using the switch etc work? Or would you advise against that as well? Thanks again for the help.

shenlonco

My Feedback: (2)

Hi First off why are you discharging them? You really do not need to discharge NIMH they don't have memory like the older NICADS did...just use them and then charge.
Tanks do not draw that much current get yourself one good 5000NIMH battery pack and you will be fine I see you are using 2 of the HL junk batteries a good 5000 will last 3 or 4 times longer than those sorry joke of a batieries!!!.

shenlonco

My Feedback: (2)

this is not the best pack but for $34.99 it will work great in the tank.
http://www3.towerhobbies.com/cgi-bin...?&I=LXAAGG&P=7

smokinbarracuda

Shenlonco, sorry, by discharging I meant using. That 5000 pack is cheap. 2 of those would make this thing run for ages but if that setup doesn't work then 1 would last long enough. Thanks

Panther G

One 5000 thousand will last plenty long enough. 2 batteries are really notnecessary. Although i do run 2 5000mAh nimh. in my Tiger HL/Tamiya conversion, just because they fit nicely in the Asiatam hull. So, 1 for the DMD and 1 for the MFU. Now this tank will run most of the day on one charge and it weighs 15 pounds. I have the same LEO and it doesn't even come close to that weight.

smokinbarracuda

As long as its safe to use 2 new identical nimh's in parallel I really do want to give it a go because I do want a massive capacity and after all it does have the space inside, and the weight of the extra pack balances the tank perfectly. 10000 mah would be sweet! If anyone can tell me what sort of switch I would need and how to connect it it would be much appreciated. Thanks for the help.

RodgerB

By putting the two batteries in parallel the voltage stays the same and the availablecurrent will double. just put a single pole single throw (SPST) switch in line withe the negative leads. Bring both neg. leads to one side of the switch and on the other side bring your negative out conuctor. I would put an ampmeter in series to see what the current draw is in amperage and at least triple that amount to arrive at the amperage rating of the switch. The greater the rating the better. Bear in mind that as the voltage of the battery drops the current draw will increase. An added safety feature would be a circuit breaker.

shenlonco

My Feedback: (2)

You should just need a connector that makes the both plus wires connect together and both negitive wires connect together on the batteries going to a normal battery plug that connects right to the one on the tank.
Always make sure the batteries are both fully charged before attempting to use 2 as one big cell... But to tell you the truth with your set up i would not bother 1 5000 will last probably long enough that you won't run your tank that long in one time using it when the battery is fully charged.

smokinbarracuda

Great thanks guys, the reason I want such a high capacity is that I often put my tank in my car and travel to a place in the coutryside to play so to make it worth it I do want as long a run time as possible. For some reason this tank does suck a lot of juice. The kenny kong tracks weigh a tonne on their own with it being a long hull and it doesn't have ball bearings on the wheel shafts, just metal axles and bushes and there's a lot of them! I'll let you know the run times I'm getting when its all hooked up. Cheers