Connecting multiple sources of charge to one bank

[Bart Man]

Hi all

If I have solar generated power charging my house bank through an MPPT controller can I connect my alternator to my house bank and charge simultaneously?

I was under the impression that the batteries could only accept charge from one source at a time but I have just been assured that its no problem to pump it in from both as long as they are both multi-stage regulated.

Please set me straight.

Also what is the general consensus. Alternator charges house bank first then VSR diverts charge to Start Battery? or the other way around? I am getting conflicting advice.

Thanks to all in advance!

[jkindredpdx]

I've been charging simultaneously with alternator and solar, with appropriate isolation. My overflow goes to the water heater.


JimK

[belizesailor]

No problem charging from multiple regulated sources.

[Stu Jackson]

Originally Posted by Bart Man

Please set me straight.

Also what is the general consensus. Alternator charges house bank first then VSR diverts charge to Start Battery? or the other way around? I am getting conflicting advice.

Multiple sources are just fine.

Consensus:

In the USA - house bank takes priority, simply 'cuz it's the bank that NEEDS it

In the UK - they like to do it the other way around, probably afraid they won't be able to start their engines, due to Lucas starters in their cars!

[duck55]

You can have an issue that one charger put's out a high voltage reading under bulk charge and the rest of the chargers pick it up thinking that's what the battery bank voltage is. It can reduce the output of the rest of the chargers.

With multiple chargers you need to make sure all the chargers are connected to the battery or with large battery cables. Voltage drop can play nasty games with multiple chargers. Not all charging is 100% a flat line DC; like an alternator output has a nice ripple that some electronics and other chargers will not like. The batteries help to flatten out any voltage spikes.

You might want to check that if all the chargers are at 100% you will not charge the batteries to fast.

[belizesailor]

Yes, you can get into various controllers confusing each other, but with all good regulators you wont hurt anything. My solar and alternator systems get along, but if I accidently flip on the shore power charger (200 amps) at the same time they get upset. No harm done, I just turn it off.

Re start vs house. In my case all charge sources go direct to house and then starts are automatically paralleled in after house hits 13V. I can manually override this if necesary.

[Stu Jackson]

Originally Posted by duck55

You might want to check that if all the chargers are at 100% you will not charge the batteries to fast.

You simply can't do that unless your voltage is too high.

Overcharging with Combiners or ACRs The MYTH:
Overcharging Batteries with a Combiner or ACR

[Bohemian17]

Typically you charge the Start batteries first once they hit 13 . 7volts the regulator opens up and all the amperage goes to the house batteries. The voltage sensing regulator will switch back and forth as the start battery requires amperage. Properly configured the idea is that no matter how far you run your house battery down you've always got start battery full to the top you know you can always start the engine and generate power. My new yanmar has a 120 amp alternator and does not take long before that voltage sensing regulator opens up and starts to fill the house up. The other thing that I've done is i have run an on off battery switch between the start and the house batteries that way if the house batteries ever get really low I can start my engine turn on that switch and even before the house batteries get up to their normal voltage from the voltage regulator I can have my electronics and lights on . Remember it's always somebody leaving something on the kills that house battery bank and if you don't have a full start battery isolated you are in trouble.

[Bart Man]

Thanks everyone.

How many people have had VSR's fail? I have heard they are pretty lame and eventually fail leaving themselves set in one position?




Sent from my iPad using Cruisers Sailing Forum

[Stu Jackson]

Originally Posted by Bart Man

Thanks everyone.

How many people have had VSR's fail? I have heard they are pretty lame and eventually fail leaving themselves set in one position?

The only thing that is lame is what you've heard. I've had a Yandina combiner on our boat since 1998. Works just fine. So do the newer ACRs.

The other thing to remember is the B position on your switch. It's there for Both as well as Backup. There is really no reason to run charging current for a house bank through an ACR/relay of any kind.

Run the charging sources to the house bank, the reserve/start bank takes all of a few ahs to start an engine, which means it's almost always fully full. Think about it....

[duck55]

Originally Posted by Stu Jackson

You simply can't do that unless your voltage is too high.

Overcharging with Combiners or ACRs The MYTH:
Overcharging Batteries with a Combiner or ACR

Go look at some of the DYI stuff out there, grab you meter and look at there voltage drops. I have seen 2 boats over the years that had the problem.

[goboatingnow]

In bulk mode, terminal voltage of any large battery bank is solely controlled by battery chemistry, hence all charge sources, regulated or other wise will be paralleled into an effective low resistance load, Hence all charging source will contribute what they can.

As the voltage rises, different charge sources will regulate according to their particular settings and you will find that one charge source pre-dominates. In absorption, since the current is significantly lower then bulk, it really doesn't matter at this stage what particular source is charging the battery.


dave