Building A couple of classic Light Cannons

I have a couple of projects on the go at present.
Namely a Larry k12 and a 400 Watt Blitz conversion.
I am going to use RC CAR Lipo batteries.

My question is this.
Are there any downsides, or things I really need to be aware of when using these lipo's
in this way?

The larry K draws around 20A and the Blitz/Lightforce mod just over 11Amps.
I chose the batteris specifically for their High current rating 25C(25x5aH=125 A continuous).
And because I can match the required voltage to the lamps I am using almost exactly.

Is there anything I am missing?

Will I need regulators at all?

I know I will need a charger. Any ideas for a charger that will charge a

-5800mah 8S 25C (29.6v)
-5000mah 5S 20C (18.5v)


Thanks
James
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