Installing a 24volt charger.

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burgundyben

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Playtime has 2 engines, each one has a 24v alternator, both of the outputs from these are connected to a Guest unit, the unit has 2 outputs, one to each battery bank, two pairs of 95 AH batteries, one for port and one for stbd, stbd does engine starting only, port does domestics too.

The old charger had 2 outputs, each was connected onto the post on the Guest unit with the alternator feeds.

I have bought a Mascot 24v charger model 9740 with only one output, a red and a black pair.

Can I connect the red onto one of the inputs on the guest unit and let that decide where to send the charge?

Thanks.
 
The Mascot 9740 is a 3 stage automatic charger

If the Guest unit is a diode splitter it will lead to a voltage drop of around 0.7 volt, lowering the effective charging and float voltages by that amount.

It is designed to be connected directly to a battery.

While it will work the batteries will not be fully charged.

I note that charger has a 4 hour timer and that the 24 volt version has a maximum output of only 5 amps.
 
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VicS said:
The Mascot 9740 is a 3 stage automatic charger

If the Guest unit is a diode splitter it will lead to a voltage drop of around 0.7 volt, lowering the effective charging and float voltages by that amount.

It is designed to be connected directly to a battery.

While it will work the batteries will not be fully charged.

I note that charger has a 4 hour timer and that the 24 volt version has a maximum output of only 5 amps.
Click to expand...

Why could I not split the red output from the charger into two, one two each bank? Afterall I have a common earth.
 
burgundyben said:
Why could I not split the red output from the charger into two, one two each bank? Afterall I have a common earth.
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Not a good idea to in effect connect the batteries in parallel. One dud battery could lead to one dud battery and one flat battery.

A diode splitter ordinarily will split one charging source into two without that risk occurring but bog standard diode splitters impose the 0.7 volts loss.

A VSR rather than a diode splitter might be a compromise but they are not entirely without some snags. They at least only parallel the batteries while they are charging

Sorry but you should have bought a charger with two outputs and connected it directly to the batteries.

You can of course still use it to charge one battery or the other, perhaps even incorporating a change-over switch rather than manually swapping connections.
 
burgundyben said:
Can I connect the red onto one of the inputs on the guest unit and let that decide where to send the charge?

Thanks.
Click to expand...

If the guest unit is a diode splitter, dropping 0.7 volt, you are probably okay at 24 volt.

As the 0.7 is fixed, it is dropped across two batteries, nominally 0,35 volt each, now your charger has top voltage of 29.4 volt, or 14.7 per battery.

This is a little high, but with the 0.35 drop, to get 14.35 volt, so not bad. Float charge is 13.7 volt ( 27.4 volt ), so with volt drop around 13.4 volt, again not bad.

So you appear to be better of with the diode splitter, than direct to battery.

Brian
 
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VicS said:
Not a good idea to in effect connect the batteries in parallel. One dud battery could lead to one dud battery and one flat battery.
..
Click to expand...

I hate to disagree with you Vic, but don't most of us have batteries connected in parallel on our domestic banks?

Surely the reason why the banks are not connected in parallel is so you don't run down the starter battery when using the domestic?
 
nigelmercier said:
I hate to disagree with you Vic, but don't most of us have batteries connected in parallel on our domestic banks?

Surely the reason why the banks are not connected in parallel is so you don't run down the starter battery when using the domestic?
Click to expand...

Perhaps I should have said battery banks.

If the OP has a starter battery and a domestic battery, be they made up of banks of individual batteries or single batteries. there is a risk, small I suspect, that one dud one could discharge the other. Then you end up with both domestic battery ( bank) and starter battery ( bank) unusable.

discharging the starter battery at the same time as the domestic battery is another good reason for them not to be paralleled. They are no longer separate battery bank if they are . They just become part of one large battery. So an additional reason not to connect the single charger output to two batteries permanently.

One thing for sure is that if batteries or battery banks are not paralleled one will not affect the other

However if Brian feels that the highish charger output and a 24volt system remove the objection to the use of a diode splitter that is the satisfactory method.
 
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