If I run 2 4s batts in series, is it easier on the esc than just 1 4s
 

For the electrically challenged, is there a difference on the esc running say 1 4s or 2 4s in series...just curious and could I run a lower "c" rated battery in series safely

IF you run two 4s in series, you are doubling the voltage over 1 4s. You need to run them parallel to achieve the same voltage. While you won't see any difference as far as the ESC goes, the packs would do better if you are talking 2 vs 1 pack of the same MAH. Running in parallel would double your MAH so if you are running 2 4000 MAH 20c packs versus 1, your amperage output goes from 80 to 160.

if you up the voltage and using the same motor, it will pull more Amperes...
if you want to use lower C batteries.. run higher voltage, and get lower KV motors...

not sure what ESC you're using, but if it's that MM in your sig, it'll make a nice fireworks show on 8s ;). Now, 2 4s in parrallel is do-able.

J.

2 4s batteries in series is 8s.

that's what I meant. :whip:

What controller are you going to use? If you are going for 8S (29.6v or 33.6v fully charged), you will need a controller like the MGM 12032, 9032, 16024 or a BK 3695 (only for 2 pole motors and is limited to 42000rpm). You will also need the right Kv motor for your application. A good motor for 8S would be 1521/1Y 1577Kv (46679rpm), 1521/2D 1425Kv (42180rpm), 1515/2.5D 1650Kv (48840rpm), 1515/1.5Y 1500Kv (44400rpm) or go crazy with a 1527/1.5D 1500Kv (44400rpm). Those would be my first choices mainly because Neu are sold by rc-monster and for repair if needed, they can be sent to a US address except for the Mega. Now for the Megas (I love them) I would go with a ACn22/45/2 1380Kv (40848rpm), ACn22/35/2 1500Kv (44400rpm) or go nuts with ACn22/50/2 1200Kv (35520rpm). If you want Feigaos, they would have only the following 540 12XL 1390Kv (41144rpm) , 13XL1283Kv (37977rpm) and 14XL 1191Kv (35253rpm). If you are using mechanical brakes, you could get one of those cheap 100A 10S or 12S Asian controllers.