Supervision of xs2p lipo packs??

[Van Aelst Jozef]

Hello guys, I was looking on an answer for following.
One motor, one brushless controller and 5s2p lipo.
How can I supervise each lipocell? Have seen that sensing
wires from the two separate packs are connected into parallel to the liposaver. What happens if cell 2 from lipo 1 is below the critical value (3.1V)? Cell 2 from lipo 2 has still 3.6V . How can the liposaver detect this low battery condition and put the controller in low stage mode??

Thanks for any clarification.

Regards.

Jef.

[CrunchiX]

Hello Jef.

Is your lipo 1x 5s2p or 2x 5s1p?

If it is only one than you have to connect with the balancer wire to the liposaver, it detects of each of the 5 cells which is down.
The cells connected parallel are "automatically balancing" themself and have all the time the same voltage.

If you have 2 lipos than I think you have to connect both to the liposaver but I don´t really know.

Regards
Josef

[AustriaAT]

Hello Jef,

please take a look at the usermanual of the SM-Modellbau Lipowatch, especially the pictures may help you.

Best regards AT

[Van Aelst Jozef]

Thanks for answers.
@ crunchix: I have 2 x 5s1p. If by 1 x 5s1p the lipocells were connected internal in parallel, then I suppose that for the 2 x 5s1p the balancercables from each pack can be connected in parallel to the liposaver.

@austriaAT: Nice site, fine equipment. Regret to inform you that I could not find any examples or pictures from a xs2p lipo configuration.

Regards.
Jef.

[CrunchiX]

oh, thats problematically.
You can´t really connect parallel the balancer cable of both packs.

If there is a difference in voltage of the cells from pack 1 and pack 2 than you get high currents. Your balancer cable could burn or you damage your cells.

[AustriaAT]

Hello Jef

you use 5s1p parallel as 5s2p. the configuration many people use is as a 10s1p and the balancer cable is there only for checking the voltage. So don´t take the balancer cabel prallel on a liposaver. Use it serial as it is shown in the lipowatch picture. Because the Liposaver cable ist connected with the Speed Controller an the cable of the lipo saver is connected to the reciever. If you have low voltage in one cell the speed controller gets the signal to stop from the liposaver.
http://www.sm-modellbau.de/pdf/SM%20Anleitung%20LiPoWatch%20v1.00.pdf

Regards
Albert

[MiSt]

Connection of the two balancer ports in parallel is highly dangerous, as written by the other commentors.

http://www.rc-raceboats-world.de/forum/showthread.php?t=4892

According to this thread, you already have two supervisory circuits in use. Just connect one to each pack.

Receiver ==> supervisor1 (pack1) ==> supervisor2 (pack2) ==> Y-cable ==> motor controllers

[Van Aelst Jozef]

Michael, thanks. Understand your comments. This is for a 2 motor cat

Please note however that there is only one motor used with a controller in the cat.
Left and right in the sponsons is a pack 5s1p 4000mAH. Packs are mounted so low as possible resulting in a lower center of gravity.

Packs are connected in parallel to obtain a higher capacity and a longer runtime.
How is supervision done?

Thanks in advance.

Regards.

Jef.

[MiSt]

Receiver ==> supervisor1 (pack1) ==> supervisor2 (pack2) ==> motor controller

[AustriaAT]

Hallo MiSt,

ähm schau Dir bitte mal das Lipowatch an, dem Teil sit es doch egal ob ich 10s1p oder 5s2p anhänge, da ich ja nur die Spannung der einzelnen Zellen abgreife und diejenige mit der niedrigsten Spannung sag dem Regler er soll zumachen.
Also ich sag es reicht in Controller.

Gruß AT

[MiSt]

Maybe some supervisors are able to check two different packs with the same Ground reference, as it is the case for two packs in parallel: This is not a common feature. Usually they expect all cells to be monitored connected in series: This applies at least for the respective products sold by Schulze, robbe and Graupner.

The approach I suggested (use two supervisors) works with any supervisory circuit(s), and from the other thread I estimated Jef to own <two> of them ...

... if I am wrong, he may follow your recommendation if this particular supervisory circuit is able to check two seperate packs with same ground, but:

EDIT:

From my understanding of the Lipo-watch instructions, the connection of two packs in parallel (with same ground) to a single LiPo-watch is not possible.

As Jef wrote: None of the examples given deals with a Xs2p configuration!