Launch System Update over the winter.

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1 month 4 weeks ago - 1 month 4 weeks ago #136 by admin
John dropped off the launch system for annual maintenance and update. It will be updated to the latest version including installing the more durable aluminum panels.So, we'll discuss things here.

First question, do we want to change the batteries? John has mentioned that the batteries have sometimes been a bit problematic. I don't know if this is due to the batteries themselves or if it's an issue with the cable connector I'm using. I'm already updating the connector by replacing it with the T-Connectors that are used in R/C car. This is a very reliable connector that will make for a much better power connection. What do you guys want to do about batteries? We currently use 12v 7.2 AH Gell Cells because they are cheap and easily charged. We can continue using those or we can try something different.

The battery options are:

Gell Cell
Pros
  • Pretty cheap, about $20.00 for 7.2 AH.
  • Easily charged - a simple wall wart charger is all that's needed.
Cons
  • Large size - will cut into cable storage area on the new box design.
  • Heavy.

NiMH 

Pros
  • Small size won't cut into cable storage area.
  • light weight.
  • Easily charged - a simple wall wart charger is all that's needed.
Cons
  • More expensive - about $20 per 2 AH. Multiple batteries can be connected in parallel for more storage.
LiPO

Pros
  • Medium size - won't cut into storage area.
  • Light weight.
Cons
  • Fairly expensive - About $40.00 per 5.5 AH battery pack
  • Requires a more expensive and more complex balanced battery changer and two connections for charging so the case will also need modification but I'm doing mods anyway.

Please weigh in with your opinions ASAP so I can get the updates going.

Mario
 
Last edit: 1 month 4 weeks ago by admin.

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-1 years 10 months ago #137 by achoward
I like the Gel cell (option 1) for:
-Not having to deal with a balanced charger for LiPos.
-Safety of storing vs LiPo potential problems
-It's ok to cut the space for cables, seems like we have lots anyway for the cables.
-The stronger top will be good. We had several antenna connections get broken. Might have occurred when box was on container and got pushed off by the wind or a careless person. Needs to be suitable for intended use.
Thanks!

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1 month 4 weeks ago #138 by TomLaird
I would concur with Alan.  While the LiPo would be nice, I don't think the extra money is worth it.
Plus the extra work in the more complex charger.  One LiPo battery would pay for a couple extra
AGM batteries.
Thanks again to Mario for all the work in this system.
Tom

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1 month 4 weeks ago - 1 month 4 weeks ago #139 by admin
Good, we're in agreement on continuing to use the Gel Cell batteries; I think they are the most cost effective solution. Here's another option. Instead of using the 12V batteries we currently use, let's consider switching to two 6V batteries connected in series. Two of these batteries will fit nicely in the bottom of the box with minimal impact on cable storage while still delivering the same current. The existing batteries that we've used for the last 2 to 3 seasons could be packaged in parallel connected pairs to be used as booster battery packs whenever an internal battery gets low or you feel you need extra power for a rocket with several motors clustered together. After three seasons, it's probably time to refresh the batteries anyway and repurposing them is better than tossing them since they can still serve a very useful function. I will draw up the plans for the box design and post it here for comment.

Edit: I just did a quick paste-up with battery dimensions from Amazon. There are two 6V sizes available. They only vary in one dimension and I think both can be made to fit well. One battery is 7AH so two of them will be about what we have now. (Our current batteries are either 12v 7.2AH or 12X 9AH) The other option is 6V 12AH so even more power would be available. All three options cut into storage with the current battery being the worst.
 
Last edit: 1 month 4 weeks ago by admin.

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1 month 4 weeks ago #140 by admin
 

This image shows a phantom view of the launch pad controller with the larger 6V batteries installed. As you can see, you lose about half of the storage area.

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1 month 4 weeks ago #141 by admin
I also need someone willing to make new igniter leads. The connectors change on the new design so they all need to be updated.

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