Dynamite passport ultra ?
 

Im thinking of buying this charger,I need a charger for life/lipo reciever batts and lipos for 1/10th scale electric racing.any feed back would be appreciated,may consider another brand of charger in the $100-$120 range

This is a solid charger, its 100watts and would take care of your present needs and allow for those needs to grow in the future with larger lipos or larger LiFes. Theres several using this charger here and feedback has been good.

This is another, less powerful AC/DC charger that will take care what you have presently. Its 50watts and would charge uo to 5000mah 2S lipos at 5amps. 2S lipos above 5000mah or above 2S will run into current limiting as the charger limits current to stay under its 50watt power limit. You wouldn't encounter limiting as soon with the Passport and its 100watt output power.

http://www.hobbypartz.com/thac6smbachw.html

What he said.

I have the Ultra, and it's great. But, truth be told it does nothing the one linked above doesn't do really, apart from an ability to charge at a higher rate. At that price, it's hard to beat. I bought the Ultra because I have some 5000mAh batts that I can charge at a higher rate, so the time reduction (and that it was available at my LHS for a competitive price) was worth it to me.

I'm still figuring out the math to come up with charge times. So, how long does it take to charge a 5000mAh lipo using the Passport 100W charger?

Depends on if your battery can take higher charge rates.

Charge times?
 

So with a lipo 5000 mAh 20C the charge time would be?

Or 5000 mAh 40C the charge time would be?

Would a 100W lipo charger allow you to charge two 2S batteries at the same time?

The point of the 100w output is that the Passport will allow you to carry the 5 amp charge rate to higher voltages. If you know you'll never charge more cells than 2s then 55w is fine, if you think someday you might run a 4s battery (1/8th scale for isntance) then the 100w will allow you to charge a 4s at 5 amps, with 55 watts you'd be limited to lower amperage and longer charge times.

At 1C, its about an hour. The 40C or 50C has nothing to do with charging time.

The only way toi shorten charge time is to use a fast lipo charge mode which just eliminates the CV part of the CC/CV lipo charge. You get about 85-90% charge with the shorter time. The other way is if the lipo allows 2C or higher charge rates, anything abive 1C will shorten charge time.

The Passport has a max charge rate of 8amps and is 100watts. If you try the two 2S 5000mah lipos in series, thats equiv to trying to charge a 4S 5000mah lipo and the Passport would be able to deliver a 1C charge to a 4S lipo - 16.8v x 5a = 84watts. Passport doesn't have enough power for a 2C charge.

If you tried charging them in parallel, would be trying to charge a 2S 10,000mah equiv and you'd be limited by the max charge rate - you couldn't charge at 10amps, just 8amps, but otherwise, it could charge them in parallel. It would take some time to charge in parallel since you'd be charging at less than a 1C charge rate.

For this charger and these lipos, series charging would be better, assuming you can solve the balancing connection (for either case).