# Altimeter/Battery help

### Help Support The Rocketry Forum:

#### chanstevens

##### Well-Known Member
OK, veteran build/flyer who's hitting stupid newbie issues trying to rig a Perfectflite MinialtWD for basic apogee deployment. I've fired two test launches with motor-based backup, and am 0 for 2. First test was probably loose power connection, as it didn't even register an altitude. Second points to a battery problem--recorded altitude fine, but didn't fire the charge. It beeped fine pre-flight signalling adequate voltage and continuity to the drogue charge.

Battery--have to fit in a BT-50, so can''t use a standard 9V. Tried using a fairly fresh N-sized 12v battery (same one used to power the alt15K I've used for years), but it doesn't pass pre-flight voltage check. Perfectflite doesn't recommend these anyway. Switched to stack of (5) 1.5v cells (Energizer 375's) with a lead taped on each end of the stack. VOM meter likes it, pre-flight liked it, igniter didn't like it.

Igniter--home-dipped using 26 gauge shooter wire, 34 gauge nichrome, same basic approach I've used flawlessly with Magnelite's MF dip. For these, though, I'm using a buddy's ematch dip, much hotter/faster burn.

After the failed tests, I tried simply firing the igniter by connecting directly to the battery stack. Nothing. Couldn't light an Estes igniter either. Tried connecting my home-dipped directly to a standard 9v, popped instantly.

Clearly I'm either using a wrong/bad battery or stacking/wiring them wrong. Any tips/suggestions? If there's a single/simple battery I should be going with that will fit in a BT-50, that's my preference.

--Chan Stevens

##### Well-Known Member
Use one of the new Quest igniters.

##### Well-Known Member
Sounds like your problem is less battery related and more igniter related. Try using an actual ematch rather than your homemade igniter. MAWDs have a very short latch time on firing the outputs which makes their use with high current devices a problem. Perfectflite corrected this with the HA45K. It has a full second of firing time and it doesn't fire from the capacitor it opens all capacity of the battery up for that second.

I can't comment on the Quest igniters recommended since I have never used them. However, I know that both the HA45K and the MAWD will fire Mtek ematches without any problems.

#### Zeus-cat

##### Well-Known Member
If you use 357/303 cells you are supposed to use six to power the altimeter. I use the special battery holder sold by Perfectflite as the N cell battery holders at Radio Shack are just a fraction too small for a stack of 6 cells.

I use the X-mas light method for charges and haven't had any problems. I have only flown my MAWD twice so far, but I fired all the charges (1 drogue, 2 main) each time using the stack of six 375 cells.

One trick I learned in ground testing with the X-mas light bulb charge is to pack the powder fairly tightly or they filament won't set off the reaction. If the powder is loose, the filament burns and only smokes the powder. I make the charges per the instructions at Perfectflite and then test them for continuity. I think I have only had 2 rejects (broken filaments) out of 25 I made.

Last edited:

--Chan Stevens

#### DAllen

##### Well-Known Member
Buy e-matches at the launch and use the xmas bulbs for ground testing. That way you are technically operating under the LEUP of the seller just like when we used to have to buy motors that way prior to the ATF court win.

I've done a lot of xmas bulb ground testing and find them to be somewhat reliable. Those filaments are soooo delicate I just don't trust them that much. I figure about a 1 in 4 failure rate. Maybe its the way I prep them. :confused2: If I use xmas bulbs on a flight I double them up on each charge.

-DAllen

#### jcsalem

##### Well-Known Member
I love the MAWD and find it very reliable.
bobkrech gives an accurate summary of compatible igniters.

I started with Xmas lights because no LEUP was required but they have several problems:
1) The sockets corrode easily. I was often needing to sand the contacts.
2) Xmas bulb charges are very fragile. Dropping one on concrete could be enough to break it.
3) They took too much time to prepare.
I had an 80%-90% success rate with the bulbs but I'm looking for better.

I've pretty much settled on the Newton's 3rd hot wire canisters. I've had only one failure in two dozen launches with them (which was preventable).

Jim

#### Handeman

##### Well-Known Member
TRF Supporter
I love the MAWD and find it very reliable.
bobkrech gives an accurate summary of compatible igniters.

I started with Xmas lights because no LEUP was required but they have several problems:
1) The sockets corrode easily. I was often needing to sand the contacts.
2) Xmas bulb charges are very fragile. Dropping one on concrete could be enough to break it.
3) They took too much time to prepare.
I had an 80%-90% success rate with the bulbs but I'm looking for better.

I've pretty much settled on the Newton's 3rd hot wire canisters. I've had only one failure in two dozen launches with them (which was preventable).

Jim
I agree that the xmas bulbs can be problematic, but they can be reliable. I've used them on 10 DD flights, 20 charges, [cross fingers, knock on wood] and never had a failure.[/cross fingers, knock on wood]
1. I never use the sockets.
2. I pull the wire wrapped around the filament posts out so I get a true continuity reading on just the filament.
3. I always use two bulbs in parallel.
4. I solder the lead wire to the two bulbs.
5. I use hot glue to glue the two bulbs into a wrap of paper and seal the end.
6. I make the paper tube/bulb assemblies at home, never at the launch site.

With that said, I've been experimenting with making my own ematches with 44 ga. nichrome wire. That has worked very well with my HiAlt45. They didn't work near as consistently with a MAWD.

Although I haven't had a failure with the xmas bulbs, I feel the ematches would be even more dependable.