Lipo question about over current protection

Novice LIPO question... want to make space in my two stages rockets bays... so considering replacing the 9v batteries with Lipos.

From the forum, I have an understanding of the lipos to buy but want to ask about over current protection.

I see some smaller lipo (3.7v) stating "Battery includes built-in protection against over voltage, over current, and minimum voltage."

Larger lipo (v7.4) don't state the over current protection.

How you build/buy in the over discharge current protection, don't burn my stratologgers or start a fire?

PTC's are available to be wired inline with the battery or search for the thread about lipos and the RRC3.

Also the 9v Energizer Lithium Advanced have a max 5A ptc in them and they weigh about an ounce ( 30 grams or so ). I use them with my Missleworks RRC3's.

My $0.02 advice, might be worth less.

Do not use an active protection device on a altimeter battery. Here is my order of priority as far as protection goes.

1. Protect the rocket and safety of flight (way #1)
2. Protect the altimeter. Only if there is no compromise on #1.
3. Protect the battery. Batteries are cheap

If it were me I would just take care and avoid a short on the output.

If you must use a PTC put in the pyro output circuit not the supply circuit. This keeps voltage to the altimeter in a short situation and keeps the altimeter from browning out. This way you will still get the second programmed event. Make it slow acting so at least any pyro has a chance to fire before clamping down the current.