If you add power consumers like radio amp, electric grips, gloves, jacket, ect..you need a bigger alternator, not more batteries.

 

 

By the high voltage coming across, the regulator is reading all that draw. However, it is still charging. As long as your voltage does not drop below 12.9, it is charging and keeping up. Not sure how accurate your almost 15 volts is but under load, 14.5 is normal at 2000 rpm (test rpm)
You are probably OK. Remove the amp and grip load and what do you have? Do both test at 2000rpm.

Just out of curiosity, what are you doing powering 4 amps for?

 

He is a parking lot queen!!

T

 

 

Parking lot queen wearing a TEAM FRENCHIE garb

 

 

You betcha

 

Why would you ask a question like that in an Audio Forum?

 

maybe this will answer the OP's original question.
you stator max output is what it is, depending on your year and model bike. i'll use mine as an example because i know the specs and have tested them. 50 amp charging system(upgraded from stock 45) with a max output of 53.5, tested with my Sunn VAT40, which is an automotive high amp voltage and load tester. you specs wil vary from year to year and model.
no matter what load is placed on the system, the max output amperage of the stor is fixed. so while riding your bike, if your system and the other systems in play on the bike have a draw of (in my case for the specs) have a draw of say 40 amps, there are only 13.5 max amps left to go towards charging the battery. the amount of amps being drawn will very with the type of music, the other systems on the bike, ignition, injection, lighting etc. The amp for the auido will draw more amps with more volume and trying to reproduce higher levels of bass. Now say your're cruising down the road and you really like the tune in play and you crank it up to max, you might start to draw say a 60-70 amp load on the system. Once you exceed your 53.5 amp max output (at a given rpm, which makes this a variable), the amp draw will come from the reserve capacity of the battery and line voltage will begin to drop. the longer you demand more amps than your max, the more they come from the battery and it's reserve capacity is lowered, the more it is lowered the more the line voltage drops.
This is all relative to engine rpm as at slower rpms there is less output than at higher, and the amp draws more current the louder and longer it's turned up. Unlike a car, the system runs from battery voltage and the stator and regulator are there to keep the battery and line voltage up. Now lets say you want to install a Big Boy very killer amp that has something like a max amp draw of 120amps. If you turn it up with heavy high demand music playing on it, the system wont have enough to keep up with it for too long, so you have to find a source for more current(amps). one way is to use a more powerful stator and regulator set up. something that puts out more amps with a regulator that can keep it under control. this is great, but they only go so big for a HD motorcycle, and most others. So how do we get more capacity? bigger charging and MORE batteries to increase the reserve capacity of the system. the more batteries the more reserve capacity, but we all know the limits of how many batteries you can mount on a street ridden bike. then the issue of keeping them charged when not loaded and some sort of isolator to keep the starter battery from draining to the point where it cant crank the bke.
bigger charging system, battery isolator to keep the starter battery at max charge and extra batteries to run the system of of. this is all much like how Motorhomes and Boats are set up. one battery as a cranking battery and one more(or multiples) to run the other fun stuff. on the better systems an isolator(built into the unit)works like a splitter,letting the cranking battery be used by anything except starting and operating the engine, but still charge all the battteries.
most of it depend on what the average loading the amp produces and how long it's at max load will determine the amperage draw. to my knowledge, lithium battereis are not as good as agm batteries for the deep cycle process that extra batteries need to have. they can work great as a starter battery producing high current for short periods, but do not have the resverve capacity to work as a deep cycling load battery like an agm.
so knowing all this, you need to test how much amperage your system draws under different conditions, averages and max values and under the load conditions and ouput of the bike. this is best done with a clamp on amp meter that you can clamp of the various wires used in the system and actually measure the current draws under different conditions.
most of the time, bikes with more than one battery on board are set up so that they can play the music, keep the lights on longer or power other extra accessories(warmers, etc) without the bike acutally running.
the newer bikes have bigger and better charging systems on them, so they have an advantage.lowering loads in other areas (lighting etc) helps, like led bulbs and such can also help a little.
hope that helps.
m