Seat positioned boosters for 3 year olds?

Can you do a booster at age 3 and 30 lbs?

There are some, but it's not recommended. Four years and 40 pounds is the MINIMUM recommendation for a booster, preferably much longer, as a five point harness is much safer than a booster seat. At 30 pounds your child could probably ride rearfacing in their convertible seat, which is also much safer than forward facing (my nearly four year old was just turned back rearfacing).

I'd stay away from the booster seats for at least another year, preferably two or three more. Three year olds generally can't be trusted to sit properly in a booster (not only not putting the strap behind their arm, but they wiggle about, and may not sit up properly so that the seatbelt would actually hold them in an accident. Add to that the distraction factor of you having to check on them constantly and it's not a safe situation). Plus it also depends a lot on the size of your child's torso. A long torsoed three year old would fit into a belt positioning booster, but a short torsoed one would still not fit even with the belt positioned as it should be in the booster.

So I guess my recommendation would be to investigate rearfacing in your convertible seat, and if that doesn't or won't work for you, then leave them in the convertible seat until they max it out, either height or weight, and then depending on their age at that time look into a booster or a higher weight harnessing seat.

What seat do you have, btw?

Wendy

I have a Britax RA but wanted to use that for the new baby. I'm trying to fit 3 in the back of my Honda civic.

I found this Booster
'TurboBooster' that says that it can be used from 30lbs and 3 years old and it seems to have good saftey ratings?

The problem with putting a 3 yo in a Turbo Booster (or ANY booster) is that they are too young to sit properly in it. A TB will ONLY make the adult seatbelt fit properly - it will not actually retrain them in a crash.
You need a harnessed seat for your 3 yo.

My suggestion would be a Marathon or a Sunshine Kids Radian, because it can be passed down to the baby when the older child outgrows it OR the baby outgrows the RA or the RA expires.

The new Turboboosters that are labeled as the Safeseat 3 actually say 4 and up. I think the Sunshine Kids Radian is GREAT for getting 3 across. We have one for AJ and it's very narrow and harnesses till 65#.