Running parallel battery packs

[jrohland]

I built a parallel battery harness as see here:



Here is the harness and 2 battery packs in my pede:




The second battery is slung under the chassis to keep the center of gravity low



The straps are bicycle toe-clip straps made of nylon.



I timed the stock pede with a 2400 mah pack and got between 7 and 8 minutes of run-time per pack. With two 2400 packs in parallel I got almost exactly 20 minutes.

These runs are what I would call a typical run by my son. Which is to say, the trigger is full on about 98% of the time. The runs are about 1/2 blacktop and 1/2 grass/woodchips/dirt.

A single 3300 mah pack runs about 18 minutes. I have not had a chance to run two 3300 packs in parallel. I will do that tomorrow.

To keep things interesting, I replaced the wheel bushings with 5-11 stainless bearings tonight.

Does anyone care about this? If not, I will stop posting updates.

jrohland

[arceeguy]

Originally posted by jrohland
....Does anyone care about this? If not, I will stop posting updates.

jrohland

It's always good to see and hear what people are doing!

I'm happy you are satisfied with the results of your "mad scientist" experiments.

[monsterpede13]

that is a good idea. Im surprised ther XL-1 handled it. Usually, people cay that it frys on 7 cells, but on 12, and it doesn't? Am i missing something here

[jrohland]

Originally posted by monsterpede13
that is a good idea. Im surprised ther XL-1 handled it. Usually, people cay that it frys on 7 cells, but on 12, and it doesn't? Am i missing something here

The battery packs are wired in parallel. That means the voltage presented to the ESC is still 7.2 volts.

The batteries supply up to twice the current (amps) when wired this way but, if the motor (stock stinger) does not request more current than the ESC can pass, there should be no problem.

For example:
Let's say a single battery pack can supply 30 amps and, the motor can draw a maximum of 20 amps and the ESC can handle 35 amps, adding more battery packs in parallel will not cause the ESC or motor any harm.

If, however, a single battery pack can supply 30 amps and a dual parallel pack can supply 60 amps. Further the motor can draw 40 amps but, the ESC can only handle 35 amps, well, in that case, I will be in the market for a new ESC soon.

Does that help?

jrohland

[Cubman]

Originally posted by jrohland
I built a parallel battery harness

Wiring in Parellel doubles the available amps/runtime, where as series wiring would double the voltage.

EDIT: I got beat, same minute post though

[KylefromVa]

Great idea... the truck must have an intresting feel to it with the added weight.

When you switch to the SS5800 system you will want to change the Plugs over to deans. Should be intresting to see how much runtime you get with the novak system and two 3300 packs wired in parallel. You'll have to update us.

Just wondering... what are you using to cover those solder joints with?

[Misbehavin']

The battery packs are wired in parallel. That means the voltage presented to the ESC is still 7.2 volts.

The batteries supply up to twice the current (amps) when wired this way but, if the motor (stock stinger) does not request more current than the ESC can pass, there should be no problem.

That's true. However, keep in mind that when you increase the runtime, you're giving the motor less of a chance to cool down between runs, potentially making it run hotter. This can damage the batteries and/or motor over a period of time. Especially in warmer weather.

[jrohland]

Originally posted by KylefromVa
Great idea... the truck must have an intresting feel to it with the added weight.

When you switch to the SS5800 system you will want to change the Plugs over to deans. Should be intresting to see how much runtime you get with the novak system and two 3300 packs wired in parallel. You'll have to update us.

Just wondering... what are you using to cover those solder joints with?

Because the extra pack is slung under the chassis, the center of gravity was lowered. This had the effect of a lowering kit as far as rollover.

The folks selling Deans plugs and such indicate they have better current pass capabilities then the wire attached to them. One thing I know is all hobbies are full of "snake oil salesmen". I wonder if these connectors are really needed.

The stuff over the solder joints is silicone glue. I could not find a good way to use shrink tube and I feared electricians tape would not hold up to the abuse.

I see you are in Northern VA. Anywhere near Arlington? I'm looking for some good bashing tracks.

jrohland

[KylefromVa]

Originally posted by jrohland

The folks selling Deans plugs and such indicate they have better current pass capabilities then the wire attached to them. One thing I know is all hobbies are full of "snake oil salesmen". I wonder if these connectors are really needed.

I sort of felt the same way till I saw a guys melted Tamiya plugs with my own eyes.
Deans Plugs are pretty much a standard in the hobby...
The people at Novak recomend you install them on the SS5800...

Originally posted by jrohland

I see you are in Northern VA. Anywhere near Arlington? I'm looking for some good bashing tracks.

I'm in Centreville, not too far from you. I normally just bash around my house.

There are no outdoor offroad tracks around here (that I know of) yet... I hear one is in the works around the Centreville/Chantilly area.

In the mid to late spring/summer/early fall there are 2 hobby shops in Manassas that host parking lot races (one might not be hosting races this year, it's up in the air right now). TC's, F1, Monster truck, staduim/buggy---both nitro and electric. I raced in the stadium truck class at one of them this past summer for the first time... I had a blast.

I'm not sure what RC's you have... There are a couple indoor tracks in MD that some people in the area travel to. Both are for onroad electrics (tc's, t-spec, f1, 1/12 and so on). One is a carpet track, thats in Gathersburg. The other isn't open yet, it's a asphalt track in Frederick. It should be open sometime this month.

[Nitrous SSC]

Originally posted by KylefromVa


I sort of felt the same way till I saw a guys melted Tamiya plugs with my own eyes.
Deans Plugs are pretty much a standard in the hobby...
The people at Novak recomend you install them on the SS5800...

I also melted the stock white connectors.

[imPEDEd]

No question that Dean's (or Powerpoles) make a huge difference! As others said, the stock Tamiyas will melt- especially if you run a more powerful motor than the Stinger. Right after a run, feel the Tamiya. With a Dean connector it will be no warmer than the wire.

Bearings help save wasted kinetic energy, Dean's save electrical energy!

[mekong]

I had flames leaping out of my Tamiya connectors while running my ss5800!

How clean does the soldering on the deans plugs need to be? I am really bad at soldering and gave my self a huge burn! I gave my soldering iron to goodwill and bought a soldering gun.

Has anyone tried "cold heat"

[newfrontier45]

I melted my Tamiya plugs running a 17x2 with the XL-1. After a full run, feel the plugs themselves to see how hot they are.

[chuck101]

Originally posted by mekong

Has anyone tried "cold heat" [/B]

I'd like to know as well.

[bschiltz]

Do a search for "cold heat", then don't bother with it...

[RCcarnut]

Deans plugs are no gimmic. You will need them with your Novak SS and good batteries.

[bd12345678]

For example:
Let's say a single battery pack can supply 30 amps and, the motor can draw a maximum of 20 amps and the ESC can handle 35 amps, adding more battery packs in parallel will not cause the ESC or motor any harm.

If, however, a single battery pack can supply 30 amps and a dual parallel pack can supply 60 amps. Further the motor can draw 40 amps but, the ESC can only handle 35 amps, well, in that case, I will be in the market for a new ESC soon.

Let me add this: When you run in parrallel, you increase the capacity and therefore runtime of what you were previously running (with one battery pack, to two battery pack in parallel you get double the runtime.). If you run two 2400 mah packs in parallel, you really have 4800 mah of capacity, increasing the runtime and decreasing the amount of stress each cell is put under. The capacity is rated in milliamp-hours (Mah), not amps. Amps are for current, so mah stands for the amount of time (the industry standard is one hour) a battery can sustain a certain amount of current, or flow of electrons. A standard 6 cell 3000 mah pack can provide one hour of 3 amps of current at 7.2 volts.

Series is different. When you hook up two packs in series you increase the voltage. Although this doesn't reduce the origional values for capacity it will lower you runtime due to other causes. If you hook two, six cell 3000 mah, 7.2 volt packs in series, you still have only 3000 mah of capacity but now at 14.4 volts.

[rbonad]

I too thought about the idea of wiring 2 packs in parallel. I know it will definitely increase runtime. But with the added weight, what does it do for the speed and jumping ability of the Pede.