S18 - can it be used without the rear battery packs? Waiting on replacements

[Unipsycho]

I'm waiting on replacement packs for the S18, and one rear pack seems to be the culprit for the S18 not charging properly.  Does anyone know if I can just unplug the two rear packs and just charge and use the EUC with only the front battery packs (which are 2/3rd of the pack anyway).

I've read people are saying it unsafe to use a wheel when one pack is dead as it can potentially go negative polarity and has an increase risk of fire during use or charging.  So, that's why I wonder if I can still use it with just the front packs plugged in to eliminate that risk and keep the front packs in working order and hopefully charging properly then.

I thought I had read something about people proving battery problems that way, but can't seem to find it again so thought I better ask, else I have to wait a LONG time for new batteries.

[Chriull]

1 hour ago, Unipsycho said:

I've read people are saying it unsafe to use a wheel when one pack is dead as it can potentially go negative polarity

This can happen with any pack having degraded cells under (heavy) burden.

1 hour ago, Unipsycho said:

 and has an increase risk of fire during use or charging.

Less packs means more burden per battery, so yes, some increased risk. 

1 hour ago, Unipsycho said:

  So, that's why I wonder if I can still use it with just the front packs plugged in to eliminate that risk and keep the front packs in working order and hopefully charging properly then.

This depends mainly on the configuration. The S18 has a 20s3p config.

So the rear packs are bigger and each a 20s1p config? And the front two 10s1p packs?

If so (or vice versa) and the firmware allows to ride it should be "borderline" to ride as the normal 3p config is already not the strongest?!

Depends now if the two front packs are 1/3 or 2/3 of the whole pack.

If the front pack is 1/3 the considerations could be taken serious, but most likely driving will be no fun at all - more or less just on the edge of overlean. With continous overburdening of the cells...

[fbhb]

12 hours ago, Chriull said:

Depends now if the two front packs are 1/3 or 2/3 of the whole pack.

@Lukasz made a 20s4p mod to his S18 by adding 2x rear packs and created a topic about it on the forum, confirming that the two front packs are 2/3 of the whole pack, as quoted from his topic here:

 

12 hours ago, Chriull said:

it should be "borderline" to ride as the normal 3p config is already not the strongest?!

I personally would not risk riding my S18 without the 2x 42v rear packs, as the voltage sag can at times be too much of a burden even with All 4 packs (2x 84v front & 2x 42v rear) available!

[Lukasz]

In general it is unsafe to ride on 2 packs out of 3 as S18 has 3p configuration- so is not really having much margin in case of heavier rider / going uphill / jumping etc. You can roll slowly for test purposes on 2 packs -- so without acceleration, but this shall be limited / test only - for sure not to ride for any extensive distance.