Help understanding generator output & battery charge rate??

[johncar]

I have two boats with these things, one running dual start batteries and dual AGM house batteries and granted in a different rig it may behave differently, but mine running from the alternator of a DF250 Suzuki OB.
I have observed the VSR's indicator and it doesn't seem to send charge to all batteries as soon as the engine has started. It is sometime later I assumed dependent on the state of discharge of the start batteries. I could be mistaken though or perhaps my VSR is faulty.
I will refrain from much more comment until I check it out again.

To be honest I have never studied the things, I just made assumptions on what they do based on basic electrical theory.
They may in fact parallel as soon as the engines alternator is running, I just thought there was some delay in that happening.
I will check out both systems I have and report back what I find.

[cormorant]

The VSR in the end parallels the batteries making it one big battery.

You must also have a selectable battery switch and keep it on Batt 1 ( start batt) not on 1+2 which is a mistake many people make.

Stick with the manufacturers supplied battery chemistry. Different chemistry requires different charge requirements to get the best out of them. Many outboards now offer a dual battery circuit direct from the alternator so might be worth checking if your ski has that option as it means both batteries would be charged independently direct by the the alternator makng the vsr pointless.

The question to ask the ski manufacturer is what is the amount of free amps avaliable from the alternator and it's duty cycle. As a general rule 5-10 times the free amp output was what I was always told was reasonable battery size to have and have charged in a reasonable time. . So 10 amps free , 50% cycle is 5 amps and 5 to 10 times is 25-50 amp hour battery it should support.

[Lovey80]

FishHunter....a jetski has a generator/stator much like a dirt bike.....

I'm assuming due to lack of space there is no alternator...remember an alternator is belt driven which would take up a large amount of space...etc....

Regardless...it seems my questions have been answered...the stator will only really be charging a single battery, not both batteries..once the first battery is charged to 13,7volts the VSR unit opens or closes ?? and starts charging the second battery...case closed.

Thanks for all the advise seems I have solved the issue......love this site!!!

I have a VSR on one of my boats and what you have just said is exactly what I thought to be the case. However, some of the posts above have me confused.

It seems what I thought (and have observed) is completely different to what CATchin'Em is saying.

When I start my engine I am 100% certain both batteries are not being charged. Depending on how low the starter battery(the one given priority by my switch) is, is directly related to how long my VSR will give priority to it. Once the starter battery reaches 13.8v it then switches over to the house battery.

On one occasion when I forgot to charge my house battery before leaving, I used it a lot with my electric motor and drained it down a fair way, so much so the sounder went off. After starting the engine, the VSR kept the starter battery charging for about a minute before switching over. After a minute or so, I turned my sounder on (which has the battery volts on the screen) I was watching the volts slowly rising. It got to about 12.2v before momentarily switching back to the starter for about 15seconds. Then back to the house battery. This went on for about half an hour or so until the house battery would show 13.8v while charging, then drop back to 12.7v when the VSR was charging the starter battery.

[juggernaut]

A VSR does not switch from one battery to the other to deliver the charge output. It simply electrically combines the batteries or it uncombines those batteries based on the preset voltage protocols in the VSR.

In an uncombined state the battery hooked up to the alternator/generator/charge source is the only battery to receive the charge output. In a combined state both batteries are capable of receiving the charge as they are now electrically switched together. However, the extent to which either battery will accept the charge output is based on the internal resitance of each particular battery. All things being equal the battery in a higher state of charge will have a higher internal resistance in which case it will accept a smaller charge compared to the battery in a lower state of charge. Once both are fully charged the VSR will stay in a combined state as both batteries would still now have voltages exceeding the VSR's voltage protocols, but the charge source amp output demands would be reduced accordingly.

And this is the beauty of the VSR because it is able to maximise the charge output to both batteries depending on the internal resitance of each battery at any given time, subject to the voltage protocols programmed into the VSR. In contrast with a 1, 2 both switch you are only sending the charge to one battery or the other (unless you have it on both), thereby wasting precious charging capacity if the battery receiving the charge is fully charged, until such time the charge is directed to the other battery by manually switching the battery switch.

[CATchin'Em]

try this site. This is the same information I have as provided by Registered Training organisation.
I do believe this to be fact and not what somebody thinks.
http://www.w8ji.com/battery_and_charging_system.htm

If you still don't believe this then get a multimeter and test it for yourself.