Battery charging voltage

[Leighb]

I have a problem with my alternator charging.

System consists of 2 110AH domestic batteries and an 85AH start battery. They are sealed lead acid type, so not possible to top up.

Charge is split by a BlueSea systems VSR there is a separate BEP switch for each battery and another to emergency parallel both banks.

This system worked fine with my old engine, this year I have had a new Beta 20 fitted with a 70A alternator.

I now find that when the domestic battery had been discharged a bit - after a day or two away from shore power, when I run the engine the VSR does not charge the domestic batteries at all. If I parallel the batteries then the domestic batteries get charged - as you would expect.

I thought that the VSR was perhaps faulty and got the electrical chap who installed it all to check it out. He found that the VSR was working perfectly, but that the alternator was putting out 14.82V, measured at the battery.

He said that the problem was that this is higher than the overvoltage disconnect setting thus preventing any connection to the domestic batteries.

He said this overvoltage limit could be increased allowing normal working, but that prolonged charging at this voltage could damage the batteries and affect their life. He suggests that the alternator regulator may be faulty. I have contacted Beta who are thinking about it.

Do the electrical experts on the forum agree with my electrical engineer or would it be OK to just increase the setting on the VSR?

 

[mainmarine]

On my similar set up, the domestic batteries are the ones that sense the charge, they are all charged in parallel at 13.7v cut in, however I have wind and solar charging as well.
I don't think that the VSR is adjustable, IIRC it is a sealed unit.

 

[Stu Jackson]

Page 12 of the manual has charging voltages for different types of banks: http://balmar.net/PDF/mc-612-dual-manual.pdf

 

[Leighb]

I don't think that the VSR is adjustable, IIRC it is a sealed unit.

The BlueSea Systems CL-Series batteryLink ACR has 2 adjustable settings, one for the combining voltage and the other for the overvoltage disconnect. It is this latter setting which is causing my problem.

Interestingly I note on reading the instruction leaflet that the default setting is 15V "This can be set lower for batteries which are sensitive to overcharging such as AGM and Gel Cell" As my batteries are neither of these I suppose I could reset this back to 15V, but as I said in my OP the guy who installed it specifically advised me not to do this as it could affect battery life, hence my query.

 

[Leighb]

Page 12 of the manual has charging voltages for different types of banks: http://balmar.net/PDF/mc-612-dual-manual.pdf

This seems a much more complex piece of kit than mine which is not a Balmar.

I note though that the "Bulk Voltage" is no more than 14.6 V for any type of battery.

 

[pvb]

I thought that the VSR was perhaps faulty and got the electrical chap who installed it all to check it out. He found that the VSR was working perfectly, but that the alternator was putting out 14.82V, measured at the battery.

He said that the problem was that this is higher than the overvoltage disconnect setting thus preventing any connection to the domestic batteries.

Blue Sea VSRs now usually have the overvoltage disconnect set at around 16v, but yours might be an older type. The alternator voltage is high. You should certainly get the alternator checked properly. If Beta aren't willing to help, get it checked and send them the bill.

 

[fastjedi]

I agree with your electrician .... A charge voltage of 14.8v is very high and could damage your batteries. Most battery chargers and alternators are regulated to a max of 14.2v.

 

[Leighb]

Blue Sea VSRs now usually have the overvoltage disconnect set at around 16v, but yours might be an older type. The alternator voltage is high. You should certainly get the alternator checked properly. If Beta aren't willing to help, get it checked and send them the bill.

Thanks, that's pretty clear, Beta are not (yet) unwilling they asked me for more details and said they would get back to me.

I agree with your electrician .... A charge voltage of 14.8v is very high and could damage your batteries. Most battery chargers and alternators are regulated to a max of 14.2v.

Thanks, good to have confirmation that I need to get the alternator sorted.

 

[markdj]

Hi

Contrary to what others have said, 14.8v is a normal voltage for boost charge with open lead acid batteries. For sealed batteries, 14.4 is the boost rate. If your alternator is putting out 14.8, that's too high for your batteries. Run your engine for a while at higher rpm and measure the voltage - if the voltage is going higher than 14.9v, then your alt. regulator is faulty.

Do you have an advanced alternator regulator? This would put the voltage up to 14.8v for a better charge rate but it may not be setup for sealed batteries - there will be a couple of DIP switches to change.

For more battery info, check out batteryfaq.org

Mark
www.boatdoctorni.com

 

[Leighb]

Hi

Contrary to what others have said, 14.8v is a normal voltage for boost charge with open lead acid batteries. For sealed batteries, 14.4 is the boost rate. If your alternator is putting out 14.8, that's too high for your batteries. Run your engine for a while at higher rpm and measure the voltage - if the voltage is going higher than 14.9v, then your alt. regulator is faulty.

Do you have an advanced alternator regulator? This would put the voltage up to 14.8v for a better charge rate but it may not be setup for sealed batteries - there will be a couple of DIP switches to change.

For more battery info, check out batteryfaq.org

Mark
www.boatdoctorni.com

Thanks for further info. I will try checking the voltage again at higher rpm.

No I don't have any sort of advanced regulator, just the one in the alternator. It sounds as if the alternator is set up for standard flooded lead acid batteries and is unsuitable for sealed?

If 14.8 is a normal output voltage then it is unlikely that Beta will agree that it is faulty

 

[Stu Jackson]

You also might be interested in the Ample Power Primer, a very good discussion about battery maintenance and health, both the batteries and yours!

Click on the tech tab and download it at www.amplepower.com

Most of what I've read here on this forum seems to indicate that charging voltages appear to be much higher than what we use in the US. Same batteries, I still don't get it.

 

[pvb]

Contrary to what others have said, 14.8v is a normal voltage for boost charge with open lead acid batteries.

I think many people would disagree with that. Regardless, the OP is talking about a normal alternator voltage, and it's too high.

 

[Plevier]

Leighb
In your first post you say you have "sealed lead acid" batteries but in a subsequent post you said they are neither AGM nor gel.

This is an area where there is confusion.

If your batteries are what is often called "sealed maintenance free" but have liquid sloshing around in them, then they are conventional wet batteries just made with a bigger than normal liquid reserve. In that case the higher voltage would be OK but you may use more water and need to top them up. You will normally find a removable cover strip over the vents under the label on top. There are one or two where you can't.

If your batteries are true "sealed lead acid" or "SLA" or "valve regulated", the sort without free liquid in that you can turn on their sides, then they are indeed either AGM or gel, there are no other true sealed technologies. In that case you must be more careful and observe the voltage advice.

 

[William_H]

Charge voltage

I am inclined to agree that the charge voltage is too high. You expert friend failed to mention that if you leave as is the engine battery on its own will be getting the high voltage and so will be more susceptible to damage. The damage will be in proportion to the amound of engine running you do. So if it is quick run to get under way then shut down for sailing. No problem but if you ran the engine for a number of hours you would damage the batteries.

Now I am familiar with the modifications to fit a stepped or smart charger which would charge at high voltage then reduce the charge voltage when it senses the battery(s) are near charged. I have however got the impression that this style of charge control may be becoming common on standard alternators. Built in with no outward sign of any difference from the old type. (as fitted to vehicles) it might be worth researching that a little if it is a new alternator. if that is the case then the charge voltage will fall after some engine running. All you need do then is adjust the high voltage cut out on the VSR to above 15v. good luck olewill

 

[Alex_Blackwood]

Beta alternators are battery sensing through a small brown wire conncted to the ignition switch. The alternator regulator will "see" the voltage in the engine battery and react accordingly. When you have both banks in parallel it will see the resultant combined voltage.

 

[Leighb]

Leighb
In your first post you say you have "sealed lead acid" batteries but in a subsequent post you said they are neither AGM nor gel.

This is an area where there is confusion.

If your batteries are what is often called "sealed maintenance free" but have liquid sloshing around in them, then they are conventional wet batteries just made with a bigger than normal liquid reserve. In that case the higher voltage would be OK but you may use more water and need to top them up. You will normally find a removable cover strip over the vents under the label on top. There are one or two where you can't.

If your batteries are true "sealed lead acid" or "SLA" or "valve regulated", the sort without free liquid in that you can turn on their sides, then they are indeed either AGM or gel, there are no other true sealed technologies. In that case you must be more careful and observe the voltage advice.

Thanks, I think mine are the latter type, AFAIK there is no means of topping them up but I will certainly investigate.

 

[Leighb]

I am inclined to agree that the charge voltage is too high. You expert friend failed to mention that if you leave as is the engine battery on its own will be getting the high voltage and so will be more susceptible to damage. The damage will be in proportion to the amound of engine running you do. So if it is quick run to get under way then shut down for sailing. No problem but if you ran the engine for a number of hours you would damage the batteries.

Now I am familiar with the modifications to fit a stepped or smart charger which would charge at high voltage then reduce the charge voltage when it senses the battery(s) are near charged. I have however got the impression that this style of charge control may be becoming common on standard alternators. Built in with no outward sign of any difference from the old type. (as fitted to vehicles) it might be worth researching that a little if it is a new alternator. if that is the case then the charge voltage will fall after some engine running. All you need do then is adjust the high voltage cut out on the VSR to above 15v. good luck olewill

Thanks the electrician did say that the engine battery might have reduced life, but he felt it was better that the single smaller less expensive one take the punishment as it were.

Beta alternators are battery sensing through a small brown wire conncted to the ignition switch. The alternator regulator will "see" the voltage in the engine battery and react accordingly. When you have both banks in parallel it will see the resultant combined voltage.

That is very useful information, but if that was the case when it "saw" that the engine battery was fully charged and reduced the voltage would the VSR not open as the voltage would be below the overvoltage setting? Or perhaps I have misunderstood?

 

[pvb]

That is very useful information, but if that was the case when it "saw" that the engine battery was fully charged and reduced the voltage would the VSR not open as the voltage would be below the overvoltage setting? Or perhaps I have misunderstood?

Standard alternators don't "reduce" the voltage, they just pump out a pre-set voltage. The only reason some alternators have a battery-sensing connection is to exclude voltage drops due to diode splitters.

 

[Heckler]

You also might be interested in the Ample Power Primer, a very good discussion about battery maintenance and health, both the batteries and yours!

Click on the tech tab and download it at www.amplepower.com

Most of what I've read here on this forum seems to indicate that charging voltages appear to be much higher than what we use in the US. Same batteries, I still don't get it.

Sterling, in his instructions mentions stuff about charging rates recommended in the States. He is slightly scathing, if i remember right!
Probably due to the litiguous society you live in!
Stu

 

[Stu Jackson]

Good one, Stu, thanks. Brought to you, perhaps, by the same people who suggest that the charge should first go to the start bank (which is almost never depleted) rather than to the house bank.

Maybe that's why there's an ocean between us?