Adding 2 more batteries

[Joshie]

I currently have 1 starting and 1 starting/house battery connected to a promariner 2 bank charger. I’m looking to upgrade by adding 2 more house batteries. I’d prefer to keep the 2 bank charger...
So, can I wire two starting batteries in parallel on one circuit, and two house batteries in parallel on the other? I recognize this would mean purchasing 4 new batteries to keep the parallel batteries having the same chemistry, but haven’t found anything to say there would be an issue with using a 2 battery parallel circuit to start both engines. Everything says one battery per engine.

 

[Stee6043]

On a boat that comes from the factory with 4 batteries the two banks are wired as you describe above. Two sets wired in parellel, positive to positive, negative to negative.

I think you may have an issue with your current charger, however. It may not tolerate the load of 4 batteries. Is it the original from 1987? If so I'd highly recommend you add another $500 to your budget and install a new charger. ProMariner makes some great units. The install is easy. It would be a shame to smoke 4 new batteries with an old charger ready to give up the ghost...

 

[Joshie]

It’s a newer Promariner12 Pro Sport 12 with 2 banks...

 

[Joshie]

Should each engine be on it’s own bank, or one bank for engines and one bank for house?

 

[Stee6043]

The manual for your Pro Sport 12 says "no. of batteries = 2". Sell it on craigslist and get a proper charger. Or plan to smoke it and replace it anyway

 

[Stee6043]

Should each engine be on it’s own bank, or one bank for engines and one bank for house?

Hopefully someone else will chime in here. How house and starting are configured is out of my paygrade. I've got three banks, 2 x 2 batteries and one single for my generator. Supported by a ProMariner Pronatic series charger (new last year after my OEM rig smoked two new batteries). How the loads on the boat are distributed is not entirely clear to me...

 

[Joshie]

The manual for your Pro Sport 12 says "no. of batteries = 2". Sell it on craigslist and get a proper charger. Or plan to smoke it and replace it anyway

The manual actually says 2 banks....but you’ve given me food for thought. I recognize the time to recharge will be longer, but I typically just do day outings, so the time isn’t that important to me.
Will 4 batteries actually smoke the charger?

 

[Stee6043]

The manual actually says 2 banks....but you’ve given me food for thought. I recognize the time to recharge will be longer, but I typically just do day outings, so the time isn’t that important to me.
Will 4 batteries actually smoke the charger?

Negatory. The bigger chargers are spec'd in banks. The smaller in "number of batteries". Check page 12/13 of the ProMariner manual. The Pro Sport 12 is rated for 2 batteries, not 2 banks.

http://www.delzer.com/powerproducts/prm_cat_003/12/

I guess I don't know if this will damage the batteries. I'm just being dramatic. But the fact that it is not rated for 3 or even 4 batteries leads me to believe you will not be pleased with the performance.

 

[Southern Pirate]

Find out which of your 2 batteries is set up for engine starting. Once you know this, the rest is easy. My suggestion is to get the Blue Seas ACR switch with a new disconnect switch. Look at your DC panel, remove the battery switch and replace it with the new Blue Seas switch. The new switch will have an A and B bank looking at the rest of the DC panel you will see that the battery charger has 2 breakers listed as 1 and 2. determine which 4/0 lead will be for starting and connect that battery lead to the top of the switch along with one of the charger's leads. then connect the 4/0 lead from your starter to the bottom terminal along with the lead marked for the helm. connect the other battery 4/0 to the other top lug along with the other charger lead. then connect the house breakers to the bottom lug. the 2 top lugs on the switch should have the 2 battery cables and the 2 positive charger leads at this time. the 2 bottom lugs should have starter and helm on one side and house stuff on the other side. This is how I connected mine. I also connected the ACR switch to the top 2 lugs on the switch. I am currently using the 2 batteries that came in the boat as bank 1 and 2. When I get some more time, I will take the 2 starting batteries and move them to bank 1 and but 2 deep cycle batteries on bank 2 and move the alternator lead off of the starter to the bank 2 batteries. remember to take the positive leads off of all batteries and disconnect the AC power before you start this project. As far as the battery charger issue the others are talking about, I will leave that to them because they sound very knowledgeable.

 

[Pirate Lady]

Ok, having had a '87 268 for a long time and knowing its needs, now follow me on this. I just installed a ProMariner ProSportHD 20 (20 amp) because my 28 year old PM was about done. Installed and recommended by marine electrician. I would confidently say your '12' is way under powered. that said, both the 12 and 20 are for 2 batts, not banks. you could move up to a ProSortHD 20Plus which is rated for 3 batts. i aint an electrician just going by what the guy told me when i bought this setup. but as southern pirate said, it can be simple (if you understand it) or complex. bottom line is this, i have a starting batt and a deep cycle (2 batts), if i wanted an additional deep cycle i should have got the 20PLUS but how long you plan to anchor out in a 268 that you need 2 Deep batts? I make it thru a weekend anchored with fridge running on 1 good deep cycle. anybody want to tell me i am an idiot on this, feel free, just passing along what the elec guy said.

 

[paulswagelock]

The 12 amp is undersized. It could take so long to charge the group of batteries it could time out and shut down. I believe promariner is set for 18 hrs to go to safety shut off. Rule of thumb is charger amps should be minimum 10% of battery bank capacity. So assume your batteries are 100ah x 2 per bank, you would need a charger that is 20 amps per bank, or a 4 channel 40 amp charger.

 

[Pirate Lady]

here is the charger i recently got. It replaced the original ProMariner 28 years old, so i got another same make. highly recommend this. PS - my electrician wired this direct to batts, not thru perko switch. so it is monitoring and charging no matter what the switch is set on. This thing has lots of little lights and graph bars, looks like something out of Star Trek in the engine room. just fyi, i was going to get the 3 batt charger 'in case i ever decide to add a third batt'. Electrician said cant do that, if you get the 3, you must have 3 batts hooked up to it. (I am not electrician, just passing what i was told).

this is for 2 batteries
https://www.amazon.com/gp/product/B0821X14TM/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

this is for 3
https://www.amazon.com/ProMariner-4...PZ2XC8Q0K3Z&psc=1&refRID=EHJ4KWVQWPZ2XC8Q0K3Z

 

[ttmott]

The 12 amp is undersized. It could take so long to charge the group of batteries it could time out and shut down. I believe promariner is set for 18 hrs to go to safety shut off. Rule of thumb is charger amps should be minimum 10% of battery bank capacity. So assume your batteries are 100ah x 2 per bank, you would need a charger that is 20 amps per bank, or a 4 channel 40 amp charger.

Yes it is undersized even for the existing application. If you have, for example, 200 amp hours of batteries in a bank, that little 12 amp charger will never get them fully charged; 70 amp hours used from the bank is 5 hours of bulk charging plus another 3 hours of absorption at 12 amps..... As a result the batteries will probably never get to float and that means their life will be greatly shortened.
So, yes not a problem adding extra batteries in parallel but you will need to step up to a proper charger/converter like a ProNautic 1230