battery charge SCR2700

[lowland gerry]

Gents, I have printed the manual from a more recent SCR2700, which states that when charging the battery I should have the switch
on either battery 1 or battery 2 but not on both. Does anybody know why, I have seen that when on battery 1 it charges a small current,
when on battery 2 nothing, when switched on both I draw 80% of the current the source can do.
Is there any reason why not charge both batteries in paralel.

[mmwjr]

Not sure how yours is wired but for most boats the charger is a dual bank with a bank wired directly to each battery and not through the switch. If the switch is in the both position these two banks will be tied together and damage the charger.

Trace he wires from thecharger and see how it is wired.

[Kevlar7r]

In general, you want to charge batteries under isolated banks. When paralleled, if one battery goes bad, it will prevent the other battery from charging. Conversely, if one battery is fully charged, it will hide the load draw of the other battery, again preventing the other battery from charging.

There is nothing "wrong" with doing it, but its not a good idea.

On my boat, each switch is specific to a battery, not each battery to a position on the switch. So, for normal operation, both switches have to be on 1. Putting one switch on 2 or both will do nothing unless the other switch is on 2 or both.

[Phillbo]

I turn mine off when plugged in with the battery charger on.

[mmwjr]

Originally Posted by Kevlar7r

In general, you want to charge batteries under isolated banks. When paralleled, if one battery goes bad, it will prevent the other battery from charging. Conversely, if one battery is fully charged, it will hide the load draw of the other battery, again preventing the other battery from charging.

There is nothing "wrong" with doing it, but its not a good idea.

On my boat, each switch is specific to a battery, not each battery to a position on the switch. So, for normal operation, both switches have to be on 1. Putting one switch on 2 or both will do nothing unless the other switch is on 2 or both.

Kev your wiring is different as have 2 engines and the OP has a single. You are also correct in your description of how 2 batteries will respond to charge when connected on parallel, however the issue is in the OPs set up he is connecting the 2 banks of the charger together which can damage it.

[mmwjr]

Originally Posted by Phillbo

I turn mine off when plugged in with the battery charger on.

IMO this is a good proceedure so that the batteries are the only load the charger sees other than the bilge pump which is typically not running. Since you are on shore power the boats load can be ran on that.

[shrew]

Keep I mind that even when plugged into shore power, shore power doesn't run any 12V. That comes through the batteries. 12v draws from battery and charger replaces amp draw back into batteries again. So this means, lights, pressure water pump, electric flush and vacu-flush toilets, etc.

[cruz'r]

On my 2400 SCR, when it is hooked up to shore power and battery charger is on, and the battery switch is in off position, it charges both batteries.

[Kevlar7r]

I keep my refrigerator on, so turning off the batteries wouldn't really work for me.

[mmwjr]

Originally Posted by Kevlar7r

I keep my refrigerator on, so turning off the batteries wouldn't really work for me.

Isn't your frig a dual volt? Most are and switch to shore power when plugged in.

[Kevlar7r]

Um, you're right... Uhh, lets just ignore my previous post. Shouldn't be posting while on a turkey hangover!

[mmwjr]

Originally Posted by shrew

Keep I mind that even when plugged into shore power, shore power doesn't run any 12V. That comes through the batteries. 12v draws from battery and charger replaces amp draw back into batteries again. So this means, lights, pressure water pump, electric flush and vacu-flush toilets, etc.

You are correct. If the batteries are not that low than running off them when charging should not be and issue if not to much load on the system, I.e. To many lights and stuff. However if the the load is high or the batteries are rather low than the charger will be stressed.

[Kevlar7r]

Thought of another excuse for leaving my batteries turned on. Mercathode system!

[shrew]

Incidentally, after re-reading the OP's post I suspect we are not referring to the battery charger, but rather charging batteries via the alternator while the battery is running. It is not uncommon for folks to attempt to recharge both batteries by setting the battery switch selector to BOTH. Technically, if you're using a dual battery setup (assuming single engine) properly, then one battery is dedicated as the Starter and the other dedicated as the House. Theiry being you could always switch to House to start the boat if the starting battery was dead. I wouldn't advise robbing from the starter to feed the house or using BOTH while on anchor.

It is not suggested to run the engine with the battery switch set to BOTH.

[mmwjr]

Shrew if he is attempting to charge both from the alternator how would he be determining they are drawing 80% of it's output as he stated in the initial post?

[Phillbo]

On my boat when the engine is running both batteries are charged when the switch is in the #1 position. If in the #2 position only the house battery is charging.

[shrew]

Originally Posted by mmwjr

Shrew if he is attempting to charge both from the alternator how would he be determining they are drawing 80% of it's output as he stated in the initial post?

I must have overlooked that detail. Battery charger is connected to the battery switch and not directly to the batteries?

[mmwjr]

Originally Posted by shrew

I must have overlooked that detail. Battery charger is connected to the battery switch and not directly to the batteries?

Oh well the OP has not come back since his initial post on 11/27 so I guess there is no sense continuing guessing what he meant.