hello,

Since my K100 is fully dissambled I figured it to be a good idea to replace some parts in the alternator befor reassembly.
When shopping for a new a voltage regulator, at the site where I order all my parts, I see that there are 2 types of voltage regulators .A 14.2V version and a 14.5V version.
They both have the same part number. does anyone know if the 14.5V would the better choice over the 14.2V one?
don't want to bring the Li battery issue but who knows .....

thanks, M

I suspect one of those two is a misprint. The voltage of a good battery when fully charged is 14.2 volts; a battery has six cells and each cell is 2.4 volts, not 2.0 as you would expect on a "12-volt battery". So, as the law of diminishing returns would prevent a 14.2 volt battery being fully-charged from a 14.2 volt regulator, my guess is that they should both read 14.5 volts.

OTOH, charlie99 and robmack are better electricity-heads than I am. Guys?

I doubt that there is any difference in the two regulators.  6 x 2.4 is 14.4V so the 14.5 is probably the better choice if indeed the 14.2 is the actual value.  Most alternators I have tested put out 13.8V when charging the battery.  The value shown is probably the point where output is regulated to 0.0 amps

I have found that 14.2V is about optimum for a Brick with a 32A alternator but that is when at 2500 to 3000 rpm across the terminals, which is what really counts.  I would be inclined to go for the 14.5V regulator as mostly we run with lights on and the electronics do put quite a load on the system due to ECU, ICU, pump running all the time and possibly the ABS. With that load I would reckon the actual volts at the battery terminals would be 14.2 - 14.3V.

Point-Seven-five wrote:6 x 2.4 is 14.4V so the 14.5 is probably the better choice if indeed the 14.2 is the actual value.

Gah. You wouldn't believe that I did both physics and maths at the highest level possible at school, would you? (And passed them).

6 tries to pass Calc 101.

thanks for the info.
This is the page where I buy all my stuff. You can see that there are 2 types of regulators :
https://www.hobbyist.nl/zoek_solr/?keyword=12311459286

The electrical side of a bike is my weak point so I just wanted to be sure that the higher output wil not present a problem with the ECU,......

I have to ask but will the 14.5V output open the door to a lithium battery?

thx,M

No problem with Li batteries. They're designed to work from a "standard" charger (the bike's generator or a bench-mounted battery charger).

Your bike's alternator doesn't know what sort of battery is bolted down in the tray, but, if using a Lithium ion (or iron) battery be sure not to use a pulse-type 'smart' charger (Battery Tender, Optimate, etc.) over the long term for storage purposes. These are designed to reduce calcification in AGM and flooded lead-acid batteries. They're OK for short burst charges of less an hour on an L-i. 

For L-i use an old-fashioned, low amperage, non-smart charger, or a charger designed specifically for L-i batteries as they don't pulse. L-i cannot absorb overcharge. When fully charged, the charge current must be cut off. A continuous trickle charge could cause plating of metallic lithium. Also, to minimise stress on the battery, keep the L-i battery's charge time as short as possible. They don't need to be fully charged like FLA and AGM's do.

With this technique learnt from my local battery guru, a multi-line motorbike dealer who stocks 'something for everything', I have so far got four good years from my first L-i battery and am converting all of my bikes to them as their current (pardon the pun) AGM, Gel or FLA slowly flatten. They're waaay lighter, too. That means an extra helping for me at the Sunday morning buffet, and she's right, mate.

There is no need to trickle charge a Lithium battery unless you have something on the bike (alarm?) that uses power while it is sitting doing nothing. A normal battery (lead acid, Gell, AGM) loses voltage a a far greater rate then a Lithium.
The only reason to use a Lithium is weight saving, 600 grams on my Ducati rather than the 3.6 kg standard battery. Can't understand why you would use on on a BMW K though, the thing is a heavyweight beast to start with, and a full tank of fuel weighs nearly as much as the rider! The Ducati was about 160 kgs, so over 100 kgs lighter than the K to start with.

The higher the voltage output is the maximum. if your battery is fully charged the alternator will not put any charge into the battery.
Using this as a known, I would put a higher rate alternator on as it will take less energy from the engine while working and last longer.

Stumpy wrote:The higher the voltage output is the maximum. if your battery is fully charged the alternator will not put any charge into the battery.
Using this as a known, I would put a higher rate alternator on as it will take less energy from the engine while working and last longer.

Alternators, they last forever why try and make it last longer?
I have a voltmeter on most of my bikes, have you ever seen a battery that has been cooked with over voltage.

BobT wrote:

Stumpy wrote:The higher the voltage output is the maximum. if your battery is fully charged the alternator will not put any charge into the battery.
Using this as a known, I would put a higher rate alternator on as it will take less energy from the engine while working and last longer.

Alternators, they last forever why try and make it last longer?
I have a voltmeter on most of my bikes, have you ever seen a battery that has been cooked with over voltage.

many times ,  spent years replacing agm cells in alarm systems , they just dry  out and become unreliable in ANY load situation , and it doesn't take as long as you would think for this to happen as they are constantly on trickle charge  with usually very poor feedback to regulate charge voltage .


a larger alternator will defiantly load up the engine whilst recharging especially after a high load discharge event , the 32 amp alternator will draw about 1/2 a horsepower from the engine the 50 amp will draw closer to 3/4  hp whilst under max load , not counting the gear ratio and rubber buffer (monkey nuts ) losses  so likely closer to 1 hp but possibly for a slightly shorter time . not an amazingly different amount of time .

having a higher voltage present causes more burn off of the hydrogen causing loss of volume , over time can cause plate distortion and general early failure .


good luck with lithium cells with over voltage , they just die unceremoniously, then catch fire

BobT wrote:have you ever seen a battery that has been cooked with over voltage.

Every... single... 1980s Suzuki GS-series bike... I've ever worked on. Except those that I stopped from cooking everything before it happened.

Stumpy wrote:as it will take less energy from the engine while working 

Have you just found free energy (power). There are nations spending billions trying to find such a thing.

Dai wrote:

BobT wrote:have you ever seen a battery that has been cooked with over voltage.

Every... single... 1980s Suzuki GS-series bike... I've ever worked on. Except those that I stopped from cooking everything before it happened.

I also had a steep learning curve with the '80s GS/GSX range of bikes. I then bought a 2002 Triumph Daytona 955 in 2003. The day after the warranty ended, It fried its charging system. I took the stator in to be rewound and the guy says "Old GS Suzuki, hey?". I explained what bike it was and he laughed. Triumph had used the GS/GSX stator in their new bikes FFS.

My Z1300 kept frying the alternator, mainly because they were too small for the needs, after about 5 of them and 2 under warranty I found a guy that wound the stator so it would not give any more trouble and it has lasted.

Hi guys i need some advise please i have a k100 83 model i have spark when i hold the plug about 5mm away from the body but when i put the plug against the body there is no spark i changed plugs and leads please any advise

It would likely not have much to do with this voltage regulator thread to which you've posted. As well, we think it swell when new members introduce themselves properly in the Members Introduction section before barging in with questions in unrelated threads. Thank you.