2 batteries vs. 1 battery...

[Jim Duda]

(you can charge 2 2S lipos by just hooking them up like a 4S anyway)

I'm new so bear with me: How do you Balance Charge 2 batts simultaneously with a charger that can only do 1 batt at a time? With one 4S you connect the charger balance plug and charge away. My brother just purchased the "31" and we are trying to decide whether to go the stock 2 batt setup or a single batt. According to Mr. Jordan the boat can handle the weight of two 4S.

I compete in a different venue and already have a dual port charger that handles 1S-6S up to 20 amps each port and was curious if the boat could handle the two larger batts in case I wanted to join in the fun...hence, the question(s).

[eboat]

Other than lateral balance issues would there be any difference in performance - speed, run time, etc. - by using ONE 4S1P instead of TWO 2S1P in series? It would seem to simplify charging...

I thought your whole idea for getting a single 4S battery was you wanted it easier to charge (you can charge 2 2S lipos by just hooking them up like a 4S anyway)
Now you are going to have to get a bigger charger (or slower charge times)to take full advantage of the 2 4S lipos
Nothing wrong with 4S (one or two) just going to be more weight in the boat if you were keeping track of that part of it also

[Darin Jordan]

Perfect! I guess you could laterally ballast it with another 4S pack and make up an appropriate connector to parallel the 2nd battery for longer run times. Would you then recommend upgrading the ESC to something like a Hydra 120 to allow you to "Sport Drive" it around at less than WOT? I'm familiar with the wrap-over Velcro strap method and most likely use that.

Yes, I Hydra 120 would be a great choice, though the stock ESC can handle quite a bit more than it's actually rated for. It will fail, eventually, but they've been known to handle quite a bit of abuse (disclaimer: this statement is in no way reflective of official "Pro Boat" response and in no way implies... blah, blah, blah... )

If you are going to use two packs, then YES, by all means, leave the battery holder the way it is, put in two 4S packs in parallel, and go run for longer, and FASTER, runtimes... The extra weight will NOT hurt the performance. In fact, I actually believe it will help it handle batter...

[Jim Duda]

Another 4S for ballast?

Perfect! I guess you could laterally ballast it with another 4S pack and make up an appropriate connector to parallel the 2nd battery for longer run times. Would you then recommend upgrading the ESC to something like a Hydra 120 to allow you to "Sport Drive" it around at less than WOT? I'm familiar with the wrap-over Velcro strap method and most likely use that.

[Darin Jordan]

I don't have the boat yet but I presume the 4S would fit.

The battery tray is setup with a post in the middle that holds a battery hold-down over a pair of packs. It's designed to use two packs with this setup. However, If you wanted to run a single pack, you can do this in one of a couple different ways. You could remove this rod and just rely on the velcro to hold the batteries down or come up with another method to help hold them in place, or you could place the single pack on one side and balance it's weight with an appropriate amount of ballast on the other side.

I think if you removed the battery hold-down, and put some good velcro in place, you'd be fine. Or, you could get some of the velcro wrap around straps and fit them into the boat.

The battery area of this boat has a TON of room, and the battery combos that would fit in there are endless. I'm sure you'll get something appropriate figured out. You will have to modify the contact arrangement on the ESC for a single pack, or make a jumper for one of the sides, as it comes from the factory with a Y-Harness meant to series two packs together.

[Jim Duda]

I'm leaning toward the 4S1P method...

Darin - Thanks for your comments...it seems that using ONE 4S1P is less expensive and less weight than the 2 batt stock setup - as long as your charging equipment can handle a 4S pack. I picked a popular brand -5000mah - and found 1 battery would weigh 525 gr. vs. 556 gr. for 2, and would cost about $10 less. I don't have the boat yet but I presume the 4S would fit.

[Darin Jordan]

Other than lateral balance issues would there be any difference in performance - speed, run time, etc. - by using ONE 4S1P instead of TWO 2S1P in series? It would seem to simplify charging...

One would expect that a single 4-cell pack should have less losses do to resistance in wires, etc. And it does simplify charging.

The reason why most of there RTRs come with a 2-2S setup is that most of their target market has the general equipment available to charge 2S packs reasonably.

[Jim Duda]

Other than lateral balance issues would there be any difference in performance - speed, run time, etc. - by using ONE 4S1P instead of TWO 2S1P in series? It would seem to simplify charging...