Wiring mains battary charger to serve 2 battary bank

[smeaks]

How is this usually achieved?

i want to use an intelligent charger to maintain the batteries when on shore power and so will hard wire a charger in. Will i need a dual output charger?

Is it possible to use the connections on the battery selector switch and locate the charger remote from the batteries? or will the volt drop on the dc lines cause a problem.

thanks for any advice.

regards

steve

 

[macd]

My Sterling charger has outputs for three banks; if only two banks are present, two of the outputs must be made common. If your charger doesn't support such a system, there are other ways although, to be frank, a starter battery in a healthy system does little and needs very little charging (assuming a smart alternator regulator).

All chargers are wired remotely...it just depends how remote yours needs to be for a convenient installation. You may have to go up on cable size. The charger manual should tell you all this.

 

[TradewindSailor]

The voltage drop will only be significant if you have dirty terminals or improper sized cables for the charging current.

No problem with wiring into the selector switch assuming it is rated for the job. Check the voltage drop between the charger and the battery. It should be no more than 0.1v ... if more you have resistance in the circuit so use the voltmeter to check where it is coming from.

I prefer wiring the charger to a VSR (voltage sensitive relay that is intended for charge distribution between battery banks). Make sure the default pole is connected to the largest/heaviest used battery bank ..... and that the VSR is rated for the charge current of coarse.

 

[VicS]

If you are buying a charger then it makes sense to buy one with multiple outputs. Otherwise you could use a system based on a VSR. This may be the way forward if you already have a VSR for distributing the alternator output between the two batteries.
Your choice may therefore be influenced by the existing charging arrangements as well as any future plans to add solar panels and/or a wind turbine.

 

[john_morris_uk]

My Sterling charger has outputs for three banks; if only two banks are present, two of the outputs must be made common. If your charger doesn't support such a system, there are other ways although, to be frank, a starter battery in a healthy system does little and needs very little charging (assuming a smart alternator regulator).

All chargers are wired remotely...it just depends how remote yours needs to be for a convenient installation. You may have to go up on cable size. The charger manual should tell you all this.

Exactly what we have been using for the last ten years. Three outputs, two bridged together feed the domestic bank and one feeds the engine start battery. No problems and the sensor(s) keep the batteries topped up perfectly when we are plugged in to the mains.

(I am on a mooring so a wind generator keeps them charged most of the time.)

 

[sailorman]

How is this usually achieved?

i want to use an intelligent charger to maintain the batteries when on shore power and so will hard wire a charger in. Will i need a dual output charger?

Is it possible to use the connections on the battery selector switch and locate the charger remote from the batteries? or will the volt drop on the dc lines cause a problem.

thanks for any advice.

regards

steve

I have a VSR in the system, it senses both batteries & links both banks whether the charger or alternator is providing the charge

 

[VicS]

and a dual sensing VSR would enable the system to be wired so that the starter battery is the first priority to charge from the alternator whereas the house battery has first priority from the mains charger.

 

[sailorman]

and a dual sensing VSR would enable the system to be wired so that the starter battery is the first priority to charge from the alternator whereas the house battery has first priority from the mains charger.

Yes Vic thats my system, fitted a Victron Cyrix

 

[pjobson]

How is your alternator set up to charge both banks? I assume it will be via a split-charge diode. If you attach your Charger output to the common (+ve) of your split charge diode and your negative to any of your batteries then you should be able to charge both banks in the same way your alternator does.

 

[sailorman]

How is your alternator set up to charge both banks? I assume it will be via a split-charge diode. If you attach your Charger output to the common (+ve) of your split charge diode and your negative to any of your batteries then you should be able to charge both banks in the same way your alternator does.

mine is via the Cyrix

http://www.shop.solar-wind.co.uk/acatalog/marine_battery_split_chargers_relay.html

 

[ditchcrawler]

If you go to energy solutions website www.es-store.co.uk you will find the Cyrix VSR combiners at less than half the solar wind price.

 

[VicS]

How is your alternator set up to charge both banks? I assume it will be via a split-charge diode. If you attach your Charger output to the common (+ve) of your split charge diode and your negative to any of your batteries then you should be able to charge both banks in the same way your alternator does.

except that there will be a volts drop across the diode splitter.
An automatic charger will normally control its output volts at its output terminals. What then reaches the batteries is likely to be 0.7 (ish) volts lower.

I suspect a good few automatic battery chargers wont work connected like this anyway. The diodes will prevent the charger from "seeing" the battery and it may well simply deliver an error message. I'm pretty sure mine will do this although I've not tried it.

 

[BabaYaga]

If you are buying a charger then it makes sense to buy one with multiple outputs. Otherwise you could use a system based on a VSR. This may be the way forward if you already have a VSR for distributing the alternator output between the two batteries.
Your choice may therefore be influenced by the existing charging arrangements as well as any future plans to add solar panels and/or a wind turbine.

If you use a single output charger in combination with a VSR, do you not risk that the engine battery will see prolonged periods of absorption level voltage (ca 14,4 V or more) without dropping to float charge? For instance if you are hooked up to shore power while living aboard, thus using power from the house bank.
To me, this sounds as it could be harmful for the starter battery in the long run (several days).
On the other hand, VSR's seem to be common, so maybe not a problem?

 

[Vara]

I have a battery charger to the domestic bank and a link switch which connects the engine battery and starter battery. In depths of winter I just link the battery's and they all seem to charge OK. Plays havoc with the battery monitor though.

 

[Stork_III]

I have a battery charger to the domestic bank and a link switch which connects the engine battery and starter battery. In depths of winter I just link the battery's and they all seem to charge OK. Plays havoc with the battery monitor though.

+1 cheap, simple and effective.

 

[halcyon]

If you use a single output charger in combination with a VSR, do you not risk that the engine battery will see prolonged periods of absorption level voltage (ca 14,4 V or more) without dropping to float charge? For instance if you are hooked up to shore power while living aboard, thus using power from the house bank.
To me, this sounds as it could be harmful for the starter battery in the long run (several days).
On the other hand, VSR's seem to be common, so maybe not a problem?

Many years ago we solved the problem by linking the mains charger to the VSR. It charged the service battery through it's charge cycle, then sent a signal to the VSR and put the engine battery on charge, on completion it switched to float charge. When charging from the engine it operated as a normal VSR.

If you are on board and plugged into the mains, once charged the charger should run at float voltage, so no problem to the engine battery, unless you have a very high load and a charger that re-cycles at low voltage.

Brian

 

[john_morris_uk]

except that there will be a volts drop across the diode splitter.
An automatic charger will normally control its output volts at its output terminals. What then reaches the batteries is likely to be 0.7 (ish) volts lower.

We have our battery charger connected straight to the batteries and the alternator via a diode splitter. the alternator smart controller is sensed from the battery side of the diodes so the alternator is forced to charge 0.7 volts higher and all is well.

Works perfectly and no relays in a VSR to worry about wearing out. (I appreciate they are very reliable but I inherited the diodes so went with it.)