Knight Star

Will two batteries at 6V each wired in series with a rating of 10ah each provide more run time than a single 12 volt battery rated at 10ah?

mrbassman

I don't think it would make a difference. It's kind of like asking if two 5lb weights would weigh more than a single 10lb weight. Having two batteries would give you better weight distribution as opposed to one.

LtDoc

There are several things that make that a not so simple question, depending on how you look at it. The first is that anything in series means the voltage is additive, 6v + 6v = 12v, but the current isn't. If two 10 A batteries are in series then the total available is still 10 Ahrs. (Looks like you already knew that, huh?) It ought'a go like @#$$ for a while, but not as long as if the the Amp-hour rating was doubled instead of just the voltage. And if the voltage being doubled means the motor's rating has been exceeded it means smoke production and a dead motor. There's some 'slack' in those ratings but they certainly can be exceeded.
If you're only looking at run-time, put those two 6 volt batteries in parallel, that means 20 Ahr instead of 10, about twice the run time (not quite, but close), bigger 'fuel tank'. Increasing voltage equates to higher 'octane' rating, sort of.
There are other considerations too. One being, will the prop cavitate at the higher rpm? Sort of a 'stretch', but not much.
So, answering your question without all the 'other' qualifications, No. The power hasn't changed. 12 volts at 10 Ahrs gives 120 watt/hrs. Doesn't really matter if that's one 12 volt battery or two 6 volt batteries in series.
- 'Doc

bigford

doc

if i wire 3 X 12volt 7amp to get 12 volt 21 amps, it's the amps
that give you the drive time? what will all the amps do the the esc
or is this not a problem? or like you said a bigger fuel tank and no
problem

mfr02

The current is drawn out by the load, in this case the motor. You could have a couple of hundred 12 volt batteries in parallel, the motor would take the same current. The only time this is not true is if the battery is unable to supply the current in the first place.
The proper rating on the battery is "Ampere-hours". This tells you how long a particular current can be delivered, in theory if not in fact.

Knight Star

Thanks for all the info. I had figured the Ahrs would stay the same for the 6V batteries in series. My motors are running on 12 volts and I was trying to simplify my wiring. The two Werker 6V batteries I purchased are dimensionally the same as one Werker 12 volt battery but the Ahrs for the 12 volt is 12 not 10 like I originally stated. This is all for a Robbe Happy Hunter that I am finishing.

bigford

a little eye candy for you knight



these pics are with 3 12 volt 7 amp gel cells and a 8.4 volt stick and she is still sitting
above the water line i think each battery weighs 10 pounds

LtDoc

Having a larger Ahr rating usually doesn't affect the ESC particularly. The 'load' (motor) is only gonna draw so much current no matter how much is available. A larger Ahr rating does usually affect the weight of the battery, which can affect other things in a not so good way (if the thing sinks the boat, it's too big!). Keeping the weight and size of the battery(s) in mind, bigger is almost always better, until it gets totally ridiculous (20,000 gal fuel tank on a Ford Fiesta??)...
- 'Doc