Jump to content

PenrithBeacon

Adventures In Radio Control

Recommended Posts

Thanks for that. I do have a voltage booster in stock, perhaps that's the way to go.

I noticed in your post above you use the term balance charging. On the 2S batteries I've looked at on eBay they have a balance lead and a discharge lead so I'm wondering if I might need to have two charging sockets on the model if I use a 2S battery with a balance lead, ie one for charging, one for balancing.

If that's the case it's a question of wiring in the booster or changing the motor to a 6v one

Cheers

David

Share this post


Link to post
Share on other sites

Usually with multiple LiPos the connections to each cell are brought out at the charging point - so a 2S LiPo will have three wires at the charging socket. In effect this allows each cell to be charged separately - which is what balance charging is.

 

Compared to  model airplanes or racing boats or cars model trains are very gentle on batteries and balance-charging may not be necessary every time. However if you have a proper charger for a 2S LiPo it is probably simplest to use it all the time.

 

I have 1S LiPos and a voltage booster (boosting to 5.5v) for Kato n-gauge tram chassis in 009 locos. I remove the batteries for charging and I made a simple charger using an MCP73831 charge control chip. Because I have very small cells (240mAh) I was afraid that off-the-shelf chargers would provide a too-high charge current.

 

...R

Edited by Robin2
  • Thanks 1

Share this post


Link to post
Share on other sites

I've been standardising on 1S batteries so far, but the battery life was so shortened by using voltage step-ups I found that I think I'd rather use tender-mounted 2S batteries in the big locos to get a better turn of speed out of them, though I'm perfectly happy with the little tank locos using 1S and clanking around at 15mph.

 

Glad to hear that the Tx re-calibration was a success :)

Edited by Corbs
  • Thanks 1

Share this post


Link to post
Share on other sites
9 hours ago, Corbs said:

I've been standardising on 1S batteries so far, but the battery life was so shortened by using voltage step-ups

Out of curiosity, what was the voltage stepped up to?

 

...R

Share this post


Link to post
Share on other sites

Some 8v, some 9v, some 12v, but the batteries are so small to begin with I need all the life I can squeeze out of them.

Share this post


Link to post
Share on other sites
18 hours ago, Robin2 said:

Usually with multiple LiPos the connections to each cell are brought out at the charging point - so a 2S LiPo will have three wires at the charging socket. In effect this allows each cell to be charged separately - which is what balance charging is.

 

Compared to  model airplanes or racing boats or cars model trains are very gentle on batteries and balance-charging may not be necessary every time. However if you have a proper charger for a 2S LiPo it is probably simplest to use it all the time.

 

I have 1S LiPos and a voltage booster (boosting to 5.5v) for Kato n-gauge tram chassis in 009 locos. I remove the batteries for charging and I made a simple charger using an MCP73831 charge control chip. Because I have very small cells (240mAh) I was afraid that off-the-shelf chargers would provide a too-high charge current.

 

...R

Thank you for that.

 

I gather from eBay that although this true from some batteries it isn't true for others , and balancing chargers aren't cheap although they are reasonably so on eBay (although the cheaper ones might not be so reliable).

 

I imagine that most tender locomotives will have sufficient space for PP3, AAA or AA batteries, but my interest doesn't particularly lie there.

 

Now that the Sentinel is finished I'm going to buy more components so I can do the other three locos I have that have been converted to P4.

 

Cheers

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

An alternative is to make up your own 2S battery from 2 small single cells and charge them separately but you would need to be able to remove them from the loco. Another idea is to make up your own larger single cell with smaller cells connected in parallel. This acts as if it is a 1S battery and the individual cells automatically balance themselves.

 

How many mA the loco uses in normal service is important. My rule of thumb is if the loco pulling its normal train at normal speed draws less than 250 - 300 mAh then a Pololu booster will do the job with a 1S battery.

 

How do you find the loco power requirements?

 

I am lucky in having a continuous circuit so I charge the battery, couple up the wagons etc and mark the throttle position for normal running. Then charge the battery again and let it run until the Rx LVC stops the train. note how long this took. for example if you have a 250mAh battery and the loco/train runs for an hour the loco is drawing about 250mA.

 

as a refinement my operating sessions last up to 3 hours. I give the loco 30 minutes of moving which needs 125mAh in the above example. My Rx/Pololu combination needs about 20mA when idling so add 2.5 hours of this giving 50mAh for a total battery size of 175mAh. Actually my locos usually only run for 10-20 minutes.

  • Informative/Useful 1

Share this post


Link to post
Share on other sites

Casting my mind back further than I would like to, am I right in concluding that if a step-up converter is used, for a given current consumption, the runtime will be reduced, so if we subtract a nominal 15% then double the voltage, we would get roughly 43% of the running time? Or have I got that wrong?

Share this post


Link to post
Share on other sites
54 minutes ago, wasdavetheroad said:

...

How do you find the loco power requirements?

...

As a beginner my approach was a lot less sophisticated. I measured up the physical space I had (the loco is tiny) and then searched on eBay for a battery of that size or less with the greatest electrical charge. It came out as 180 uAh.

Now I'll suck it and see. I'll probably run it up against a buffer stop and run it. That way I'll get an idea of how long the charge will last with the motor on full load ie the weight of the loco.

Cheers and thanks for all the advice

David

Share this post


Link to post
Share on other sites
1 hour ago, PenrithBeacon said:

Deleted, triplicated post! Correction quadruple post, don't understand why.

This happened to me a few days ago and someone kindly pointed there is an option to HIDE a post. 

 

...R

Share this post


Link to post
Share on other sites

Just before the Covid-19 crisis emerged the Sentinel stopped working. After a bit of testing it became clear that the problem lay with the Rx or at least with the ESC part of the PCB. I think I zapped it with handling the thing. 

At the time Micron didn't have any in stock, so I made my interest known and waited. Last week they arrived and now installed ok but this time, in addition to having the power and motor leads soldered on, I had the PCB insulated with heat shrink wrapping. Better safe than sorry.

Cheers

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.