Alternator and Li Battery over amperage

Hello fellas, I have an RV6 with fuel inj and elec ignition 0320 with a plane power 55A alternator and recently installed a Shorai 18AH Li battery. Could be coincidence but after 1 flight where EMS confirmed proper voltage and amperage for charging, and good starting this morning with good voltage, the alternator when turned on was fine for voltage but had excessive amps when increasing throttle past idle. The amps increased linearly with increasing the throttle and I saw it go up to 26 amps and up with more throttle. Does this indicate I need a new regulator?

My Li battery does not like anything over 18amps, how can I limit the alternator from over amperage?

From the EarthX manual (Shorai and other Li batteries will be similar)

For example, a customer with a 60-amp alternator switches to our ETX680 (rated for a maximum of 60 charge amps) from a similar sized lead acid battery. Previously the peak charge amps with the lead acid battery was 25 amps. After installing the ETX680, the peak charge amps jumped to 54 amps. This is normal and as expected and within the charge current rating of the ETX680.

Remember - Amp/Hours is a description of how long a battery will provide current...

Cheers!

If voltage holds constant, the regulator is doing its job. The increasing amperage with RPM means that something, probably, the battery is taking the full output of the alternator. This is one of the characteristics of Lithium batteries.

wiring rethink

So I guess it is time to rethink the wire size from the alternator to the battery. How many amps should the wire and shunt and contactor be rated for?

Keep the rpm as low as possible for a a couple minutes. It should only take a minute or 2 to replenish what was drained during a normal start, cranking for 10 seconds or less.

At my idle rpm and pulley ratios, my alternator puts out about 22 amps, minus by typical idle load of about 10ish means it should be able to spare about 12 for changing after the start. This is about what I saw today on my 18 AH Shorai when I went flying.

I think Shorai say short excursions over the AH rating when charging haven't caused any issues. Starting with a run down one though and jamming 50 amps at it for several minutes probably wouldn't be a good idea.

My Shorais can sit 1-2 months with no charger on them and turn the engine over smartly every time. Very impressed with these 2.2 pound batteries so far.

Remember that the reserve capacity of these is closer to 6AH for extended current draw in the 10 amp range however.

PilotjohnS said:

So I guess it is time to rethink the wire size from the alternator to the battery. How many amps should the wire and shunt and contactor be rated for?

Click to expand...

More than the alternator can put out - and then put a fusible link immediately after the alternator so that it will blow if the alternator shorts internally and the battery tries to dump 200 amps through that wire into the alternator.