915iS and Earthx ETX900

The ETX900 should work fine with the 915iS.

Why did they recommend a voltage regulator? What would you need regulated? The battery is 13.2 volts and that is fine for the engine.

The 9151S already has 2 voltage regulators.

It doesnt need another one.

Ex is just trying to upsell you one of their voltage regulators ( think fast food supersizing )

Maybe you should consider other lithium options.

Andy Harris wrote:

The 9151S already has 2 voltage regulators.

It doesnt need another one.

Ex is just trying to upsell you one of their voltage regulators ( think fast food supersizing )

Maybe you should consider other lithium options.

I don't think so. Their batteries are explicitly able to be charged at the voltages provided by the 915iS. I would make a guess that they don't know that the 915iS has stable voltage regulators and is assuming that it will be charged from a really unstable alternator like in some older planes. It's exactly as they say: Earth X needs a voltage regulator. Rotax has that.

This is because Lithium batteries need a relatively stable voltage source or the BMS (the on-board computer that protects it) will disconnect the battery because it thinks something is wrong. If the engine doesn't have a stable voltage regulator then you would need to use a lead acid battery which can take all kinds of abuse. So all Earth X is telling you is that you have to charge it with from a stable, regulated source. Rotax engines absolutely provide a stable enough voltage source that you can charge Earth X batteries.

And also they don't even SELL voltage regulators themselves.