Charging 6V & 12V batteries in the same boat

Outlawman · Jun-30-2009, 08:31 PM

I have 2 banks of Gel 2x6V batteries for the house and 2 banks of AGM 12V for the engines (one per engine). Additionally I have an inverter / charger, but it's not specifically made for Gel or 6V in series.

After doing some research, it seems that there's no best multi=bank charger that would do the trick for my needs. I am stuck charging batteries individually, and with 6 of them, it's quite a PITA.

If you have anything similar to the above, whether AGM, gel or lead acid, please post your charging proceedure / recommendations. Thanks.
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sickcat · Jun-30-2009, 08:58 PM

What inverter/charger do you have David? Do you already have a combiner to charge the house bank(s) while underway? If not I would add one to the house batts all charged without messing with a switch. If you have a good 3 stage charger it likely has settings for flooded, AGM or gels which is just a small change in max voltage. With all AGMs you should be fine. 6 volts in series doesn't matter.

Outlawman · Jun-30-2009, 09:16 PM

Quote:

Originally Posted by sickcat

What inverter/charger do you have David?

Magnum ME2000 (or 2,500... don't have any paperwork and boat's in storage)

Quote:

Originally Posted by sickcat

Do you already have a combiner to charge the house bank(s) while underway?

Yes, the system is actually quite sweet and well done. It's probably my own shortcommings on understanding the whole shebang, and the fact that the boat sits on a trailer in storage way too much. I'm re-reading the Magnum manual tonight to understand it better.

Quote:

Originally Posted by sickcat

If you have a good 3 stage charger it likely has settings for flooded, AGM or gels which is just a small change in max voltage. With all AGMs you should be fine. 6 volts in series doesn't matter.

Actually they are all gels... my mistake in typing this up.

sickcat · Jun-30-2009, 10:32 PM

Going by memory here so certainly double check. IIRC the Magnums do have settings for battery type but you need the fancy remote console to set it. I would bet the default is for flooded batteries. Don't overvoltage those gels! Sure way to kill most gels.

The inverter/charger is only going to charge the batteries that power it so picking up the cranking batteries would depend the combiners. Most go both ways so as soon as the voltage on the bank powering the inverter comes up the combiner will close and charge the battery that is connected. Both cranking batteries are combined with the house bank? If so then everything will be charged (assuming both house banks are either connected via a switch or combiner. But then you know that part already... Some inverter/chargers have an aux battery charging lead but not the magnums IIRC.

Surg · Jul-02-2009, 03:31 AM

No need for combiners on this boat. He has twin engines, and each alternator (105 amp) is dedicated to a battery bank (House bank, Engine bank). His issue is while in storage, not on the water.

I talk to David today after getting an E-mail from him the other day about this.

Here's a bit of history.

I got a call from Dave a couple of months ago. "Hey my house batteries are not holding a charge" the boat is mostly stored in a lot with no shore power plugged in, and not used that often. (Doesn’t surprise me under those conditions) Dave made arrangements to swap batteries out at a West Marine (four 6v GEL's). According to Dave the batteries were sent to the manufacturer for testing, and reports came back as nothing wrong with them.
Now he has some basic meter to tell him the state of charge on batteries. It seems that they are not coming up to charge. He has been trying to charge each 6 volt battery independently with some AGM automotive battery charger. Sure that can be a PITA!

The boat has a nice “Magnum Energy” sine wave Inverter/Charger with over 100 amp charge output that also charges in three stages. It also has the battery monitor kit installed/programmed. This tells you the state of charge, and remaining amp hours.

Normally I also install a separate battery charger for the engine batteries, so everything charges independently, but I think Dave opted not to have another charger on the boat. Either way he is not having issues with the engine batteries that I’m aware of.
The house bank seems to have a slight draw on it from a non switched load while in storage, but that’s another issue. Not sure what load since he did the rewiring of the branch circuits himself (appears to be a nice job so far).

Why not just plug in the boat, and let it charge the way it was intended?

Do any of you try to charge 6 volt batteries on a boat independently with a portable battery charger?
What is your preferred method?

Outlawman · Jul-02-2009, 09:49 AM

Quote:

Originally Posted by Surg

No need for combiners on this boat. He has twin engines, and each alternator (105 amp) is dedicated to a battery bank (House bank, Engine bank). His issue is while in storage, not on the water.

I talk to David today after getting an E-mail from him the other day about this. Here's a bit of history.

I got a call from Dave a couple of months ago. "Hey my house batteries are not holding a charge" the boat is mostly stored in a lot with no shore power plugged in, and not used that often. (Doesn’t surprise me under those conditions) Dave made arrangements to swap batteries out at a West Marine (four 6v GEL's). According to Dave the batteries were sent to the manufacturer for testing, and reports came back as nothing wrong with them.

Now he has some basic meter to tell him the state of charge on batteries. It seems that they are not coming up to charge. He has been trying to charge each 6 volt battery independently with some AGM automotive battery charger. Sure that can be a PITA!

The boat has a nice “Magnum Energy” sine wave Inverter/Charger with over 100 amp charge output that also charges in three stages. It also has the battery monitor kit installed/programmed. This tells you the state of charge, and remaining amp hours.

Normally I also install a separate battery charger for the engine batteries, so everything charges independently, but I think Dave opted not to have another charger on the boat. Either way he is not having issues with the engine batteries that I’m aware of.
The house bank seems to have a slight draw on it from a non switched load while in storage, but that’s another issue. Not sure what load since he did the rewiring of the branch circuits himself (appears to be a nice job so far).

Why not just plug in the boat, and let it charge the way it was intended?

Do any of you try to charge 6 volt batteries on a boat independently with a portable battery charger? What is your preferred method?

Thanks for your input Surg. You certainly did a great job in helping me set this up and installing the inverter / charge system. I'm sure this is just all me but in the past I've plugged the boat into shore power and the Magnum charging has not brought the 6V's back to full capacity / charge.

Bottom line for me since this boat sits in storage on the trailer most of the time, I really need to get some solar panel charging going to maintain the batteries better.

Thanks again for your valuable help with my boat and with this concern.

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Surg · Jul-02-2009, 03:17 PM

These batteries have some of the lowest self discharge rates, so if you disconnected them from the 24 hour circuits they should hold their charge without solar panels.

It just depends on how long you want to keep the boat parked between trips.

Outlawman · Jul-02-2009, 06:58 PM

Quote:

Originally Posted by Surg

These batteries have some of the lowest self discharge rates, so if you disconnected them from the 24 hour circuits they should hold their charge without solar panels.

It just depends on how long you want to keep the boat parked between trips.

I'm going to add a switch on those and disconnect the 24hr's so when it's parked, there's no drain (except for the stereo memory

).

And it's not about want... it's been ongoing projects, with the latest being an engine rebuild along with both outdrives. Of course, this depressing economy doesn't help anything either. I'll let you know how it turns out...

Surg · Jul-03-2009, 11:33 AM

Ouch, sorry to hear about the rebuilds.

On a side note. Since you have charged the batteries (6 volts) independently you should "match" the pairs before you wire them in series. With nothing connected to the batteries get a set of jumper cables, and parallel two batteries for at least 5 minutes (+ to +, - to -). This will balance the state of charge between them, and let them charge evenly when they are back in series.

BTW: Nice Avitar.
Was that this season?

Outlawman · Jul-03-2009, 09:29 PM

Quote:

Originally Posted by Surg

Ouch, sorry to hear about the rebuilds.

Yeah, shit happens. I was going to take a mechanic with me to check 'em out before buying the boat, but he wanted $500. to do it... wish I paid him now

, or just didn't buy it in the first place...

Quote:

Originally Posted by Surg

On a side note. Since you have charged the batteries (6 volts) independently you should "match" the pairs before you wire them in series. With nothing connected to the batteries get a set of jumper cables, and parallel two batteries for at least 5 minutes (+ to +, - to -). This will balance the state of charge between them, and let them charge evenly when they are back in series.

Great to know.... Thanks.

Quote:

Originally Posted by Surg

BTW: Nice Avitar. Was that this season?

Yeah, 1st time out fishing too... link (First fish on the Paddy Hopper II...). Hopefully that was only a prelude to some great summer fun ahead...

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