Adding a receiver battery.

BeachBuggyPhil · #1 25-09-2012

I want to add a receiver battery to my single cell Mardave.
I plug it straight in to the receiver and bin the voltage booster but do I need to do anything else? Will the red wire need removing from the ESC lead or anything else like that?
I'm just wondering if the 7.4v from the receiver batter will have clash with the 3.7v coming from the single cell.

sosidge · #2 25-09-2012

Yes, you should remove the red wire from the ESC receiver plug. Just unclip it and heatshrink it, don't cut it!

BeachBuggyPhil · #3 25-09-2012

Ok, thank you.

RudolfXC · #4 26-09-2012

Make sure your receiver and servo will take 7.4V, otherwise use a 6.6V LiFe.

BeachBuggyPhil · #5 26-09-2012

They are both 2 cell items which is the reason for me wanting to power them from a two cell battery rather than a single saddle.
The extra weight should help as most in the club run 2 saddles anyway I just can't fit two saddles in and don't want a car that fast.......yet!

Rat Monkey · #6 26-09-2012

Phil, try adding a capacitor on to your receivor like this one

http://www.modelsport.co.uk/spektrum...products/25493

Should solve any problems, I have to run one on mine or my servo "glitches" but works beautifully with it.

Much lighter than a receivor pack as well

BeachBuggyPhil · #7 29-09-2012

Few things
I have this battery

If I plug it in the receiver with the red wire of the Tekin receiver lead removed and the new little battery plugged in the receiver instead of the voltage booster the esc doesn't work.
Plug it back in works fine.
Will I damage the 1 cell battery or the tiny 2 cell battery or the esc with it plugged in like this?
I have two of the 2 cell batteries and would like to think that 350mah would power a servo, receiver and transponder for 5 mins if I recharge between races.

SlowOne · #8 29-09-2012

Each speedo is different, and you can't say that taking the red lead out applies across the board. LRP and Tekin work with the red lead in but you must not switch the speedo on at the switch with either - only the receiver pack. The capacitor will make no difference at all with a 1S pack on your Mardave. I've run an RS with a LiPo receiver pack and not had any problems, but that was using Futaba 603FS receiver and 9650 servo - high-quality parts. Your mileage may vary...

Tekin do not recommend using a LiPo receiver pack straight into the receiver. They accept a LiFe as it is lower voltage. If yours is a Tekin RS, RS Pro it takes 3-cell inputs. If it is, then the correct way to wire it is as per the attached.

This wiring method will allow you to use the voltage regulator in the speedo. As it is a 6v regulator, it means you no longer have to worry about your receiver being over-voltage, or the servo. It also means that you should be glitch-free when using good quality receiver and servo. Wire it up like this and then switch it on from the speedo switch. HTH

PS - yes, you should use about 80-100mAh per race, so a 350mAh pack is fine. I could get two eight-minute races out of a 250mAh pack. Don't forget to recharge it otherwise...

BeachBuggyPhil · #9 29-09-2012

Thank you.
If I leave the switch off for now I should be ok?
I understand your diagram and will try to build that in to my install ASAP but I don't have any micro deans.
It's an RS Pro, a receiver like the one shown and a Savox 1251 low profile.

Can you explain this bit again please?
LRP and Tekin work with the red lead in but you must not switch the speedo on at the switch with either - only the receiver pack.

BeachBuggyPhil · #10 02-10-2012

It worked a treat. Very pleased.
Used between 90 and 130 mah depending on practise laps.
I bought mini deans but due to the tiny size and delicate soldering I'm not going to fit it as mentioned ^^^^^ up there but I will if I have to rebuild the car.
Very happy.

dodgydiy · #11 03-10-2012

surely using that diagram you could get away with an additional 1 cell lipo. the switch interrupts the supply from battery to the voltage regulator in the esc. with that diagram surely the voltage reg would be seeing 3 cells or 11.1 volt. a single lipo cell added in that way should give you 7.4 volt and put less strain on the esc voltage regulator and be lighter as well

BeachBuggyPhil · #12 03-10-2012

I plugged the battery straight in to the receiver and left the switch on the esc off so there should be no 3 cell mix up.
It worked great so I'm not going to change a thing.

SlowOne · #13 03-10-2012

BBPhil, sorry not to reply earlier. You've clearly got it, and it works so I guess there's no need to explain it again!!

You don't switch the speedo on because the voltage it is seeing from the receiver pack is then 'opposed' by the voltage it would see from the internal regulator. Something has to give, and it is usually the smoke capsules fitted as standard to every electronic device!!

Dodgy, you are spot on. It will work with a 1S cell as well. There's no issue with straining the voltage regulator as the Tekin it will take 3S fully charged, and with a 1S cell and a 2S receiver pack the input voltage to the speedo regulator is the same as that coming from a 3S pack.

This is the reason Tekin like this system with their speedos. They know their voltage regulator will take the 3S charged voltage (12.6v) and output the correct voltage to power the speedo. If you put 7.2v straight into the receiver (8.4v charged) then it by-passes their voltage regulator and the speedo control circuits see that voltage directly, and it is a bit high for some components and can cause issues.

The only speedo I know it works for is the Tekin. I don't know if it works for any other speedo so you try it at your own risk. In order to know which receiver pack to wire in check the voltage rating for the speedo. If it is 4v-9v then it is 2S only - it may also say 2S or 4-6 cells - so you can only connect a 1S receiver pack into the line. If it says 3S, or 4v-12v, then you have 3S capability and a 2S receiver pack is fine. However, you have to know what line the switch is in.

In the case of the Tekin, it is seeing the input voltage directly from the main battery pack, so adding in the extra voltage to support the 1S main pack works. Not sure if it would work for an LRP or HW, etc. HTH

BeachBuggyPhil · #14 03-10-2012

Thanks for the reply.
It works for me but I won't encourage my friends to try it with different ESC's.

My car was dialled on Tuesday, took 3 evenings, hopefully I can maintain it for the rest of the winter series.

dodgydiy · #15 03-10-2012

putting a cell in the switch line works with an ezrun, (35A v1) tried it about half hour ago!!!! should work with most speedo's without any problems, as long as you are not exceeding the voltage limit of the built in regulator

SlowOne · #16 04-10-2012

Hi Dodgy - yes, I reckon they all work on the same principle and it would work with most, but without trying it one each one, people should only use this on Tekin, and now HW! Thanks for confirming that, it will be very useful to a lot of the 12th and GT12 racers on 1S!

As you say, if you don't exceed the limit of the regulator, you're in. The limit if the regulator is the limit of the number of cells the speedo is rated for.

I found the original thread on this, so for those who love the detail, including notes from the Tekin guys themselves...

http://www.rctech.net/forum/electric...packs-bad.html

BeachBuggyPhil · #17 12-10-2012

I think I'll purchase a lipo regulator which you can buy from eBay.
The lipo receiver pack is working plugged straight in the receiver currently but I don't want to cause long term damage to the receiver, servo, esc or transponder by supply them up to 8.4v instead of a steady 6v and I don't have a life charger if I wanted to try that route.