either use Bluerobotics’s MEGA 6S battery with the 6S splitter cable that terminates by a QS8-S connector
and/or we want to charge some 6S battery inside the blueboat which requires having some JST XH - 7 position
If I use 6S LiPo battery with a XT90, and I do not need charging inside the boat, and I indeed apply the Min/Max signal for the M200 motor to the specified values : 1200 minimum and 1800 maximum, can I happily plug the 6S’ XT90 connector directly into the existing 4S splitter cable?
It seems that the only difference left is the fuse which is 50A in the 4S splitter cable and 100A in the 6S splitter cable but since M200 would not draw too much current I guess this is fine too.
If you’re not using higher currents than would be used with 4S batteries, I believe that should be ok, but I’ll need to confirm internally as to risks involved if you’re not using the balance connector.
Assuming you’re staying within our specifications for using 6S batteries with a BlueBoat (i.e. maximum 500W per motor, and 1200-1800µs pulse-duration limits), the individual motor currents should remain below 25A.
A single battery may have some issues with the 50A fuse at max throttle, depending on the other power loads on the system, but a single battery is generally not recommended anyway, for weight distribution reasons. If you’re using more than one battery the 50A per battery limit should be fine (assuming you don’t have other high-current loads you’ve added to your system).
The effect of the splitter cable is to combine multiple batteries into a single “pack” with more parallel cells (resulting in higher energy storage and current capacity than a single battery, and typically nicer weight distribution between the boat hulls). Combining the balance connector lines keeps each corresponding set of cells matched, which is beneficial if you want to be able to charge and balance the whole pack at once (like it’s one big battery).
Cell matching is not required for discharge (confirmed internally - we’ll try to update our guideline/requirement wording where relevant). The critical factor is that if corresponding cells do not match, then connecting to the balance connectors will quickly self-correct their corresponding cell voltages, which may cause issues with sparking/overheating when the connection is established (and could overload the current capacity of the balance wires and/or connectors, causing them to melt/burn).
In practice:
If you intend to charge your batteries independently then you can avoid connecting the balance connectors of different batteries together beforehand
It’s still critical to to match the total battery voltages before connecting the batteries together for parallel discharge
It’s also still valuable to balance the cells of an individual battery as part of charging (to maintain battery longevity)
If you’re wanting to charge in parallel then you’ll need to make sure the corresponding cells are matching before doing so, which is a step you can skip if the cells are already connected in parallel
Note that storing the batteries without connecting the balance connectors can also lead to drift, so any time the balance connectors are not connected it’s important to check that matching cells have matching voltages before connecting the balance connectors together. Accordingly, if you never charge in parallel it’s likely most convenient / safest to never connect the balance connectors to the splitter cable.
That is all understood, thanks for the confirmation.
Actually, on that note:
We did encounter this issue in June 2026 where, with one 4S 18Ah battery in each hull:
we connected the 1st battery (XT90 and balance connectors)
when attempting connection the balance connector of the 2nd battery, before the XT90 connector it sparked and melted the plus-wire of the balance of one battery and the 0-wire of the balance connector.
Your manual does say to first connect the XT90 and then the balance plug. I guess doing it in this order reduces risk of sparking and melting. However, we reached the conclusion that the safest way was to never connect balance plugs inside the blueboat. While still checking the voltages on the XT-90 of each batteries before installing them of course.
I do think you should make an obvious warning in the manual about this risk.
