How to add additional batteries

[REO]

We are converting an Albin 27 that is set up as a day trip dive boat to an overnight cruiser. The current battery set up is 2 12 volt deep cycle gel cel 100 amp batteries in parallel as house batteries, two 12 volt gel cel 100 amp starting batteries in parallel as a starting battery. The two banks are linked by a blue seas ACR rated at 120 amps. I am replacing the original engine with a Beta Marine with a 150 amp alternator. We have a generator with a 12 volt 100 amp battery. A 20 amp shore power charger also charges all batteries.
I am not a fan of ACR's. For many years we had a cruising sailboat with a 1000 amp hour main battery bank and a single Optima as a starting back up battery. We lived on the hook for months at a time (with refrigeration) and never needed the Optima back up. We just carefully monitored the batteries and charged when we got near 50%. We kept the Optima charged with an occasional use of a 1-2-both switch. It was a simple reliable system.
We will have to replace the ACR anyways because of the larger alternator, but I'm not sure I want that setup. I need some expert advice.
Space is limited, but we do have room in the generator room for a few more batteries. Can I just add some larger capacity batteries in parallel with the current house batteries, and replace the ACR with the larger capacity model? Does it matter if all the batteries in this bank are not the same? The existing house batteries are not the best deep discharge, and any new batteries will be better quality as well as larger capacity.
I had a really good experience with one big house battery that also started the engine and a little backup battery for emergency starting, but this will force me to do a complete rewire. Am I being too old school by not trusting the ACR system?
I know this is kind of throwing a lot of stuff out, but I need to make some changes and I am afraid that I don't know what I don't know.

 

[DavidM]

I would replace the old gel cells in the house bank with two or four golf cart batteries wired in series/parallel. Replace the two gel cell starting batteries with one good Group 31 starting battery.

The ACR may or may not be ok. Even though your alternator is rated at 150 amps it may never put out that much, particularly if it is an internally regulated, fixed voltage output alternator. If you can, measure its current output when the house batteries are well discharged.

If it does exceed the rating of your ACR, upgrade it to a higher amperage. Yandina.com is a source of good, heavy current battery combiners, a simpler form of ACR.

David

 

[dhays]

I’m not an expert, but I think David’s idea is great. A simple group 31 start battery and a house bank made up of golf cart batteries.

The Blue Seas ACRs are incredibly reliable so I wouldn’t worry about that. Like you did on your sailboat, send all the charging sources to the new house bank and then use the existing ACR to keep the start battery charged. Since you would only be using the start battery to start the engine, there won’t be a huge amp draw so the ACR should be fine.

If you don’t like the ACR, another simple solution is a Xantrex Echo charger. It would keep your start battery charged with not fuss.

 

[REO]

I looked at the Yandina, and it seems to be a good simple unit that easily replaces the Blue Seas unit that I need to replace. I can't test alternator output because the engine is not yet installed (sitting in the bed of my truck). I think I will get the ACR, mostly because the wiring is already in place. The Yandina seems like a quick, easy and inexpensive solution.
I like the golf cart battery option. We had 6 volt trojans and got long life from them. The problem is that the space where the gels are is too small and short for the bigger batteries, and if I could squeeze them in I would not be able to check water in the confined space. There is room for 2 bigger batteries in the generator room. The location is close to the smaller batteries. Is it a reasonable solution to use a mixture of 12 volt gel and flooded golf cart batteries? for house power?

 

[Lou_tribal]

I looked at the Yandina, and it seems to be a good simple unit that easily replaces the Blue Seas unit that I need to replace. I can't test alternator output because the engine is not yet installed (sitting in the bed of my truck). I think I will get the ACR, mostly because the wiring is already in place. The Yandina seems like a quick, easy and inexpensive solution.
I like the golf cart battery option. We had 6 volt trojans and got long life from them. The problem is that the space where the gels are is too small and short for the bigger batteries, and if I could squeeze them in I would not be able to check water in the confined space. There is room for 2 bigger batteries in the generator room. The location is close to the smaller batteries. Is it a reasonable solution to use a mixture of 12 volt gel and flooded golf cart batteries? for house power?

You should not mix battery types in the same bank.
Personnally I would send the charge to the start and the acr between the start and house. As the start would not in normal condition be extensively discharged ACR will quickly close and send the charge to house. The reversal may take longer and I want to be sure that my start is well charged before going.

L

 

[DavidM]

I too would not mix gel batteries with GCs. There is a big difference between the two in so far as their charging parameters.

I think it is generally better to wire the alternator to the house bank and charge the starting battery with the ACR because the big load will be the house batteries. But no big deal if you do it the other way as long as the ACR can handle the current.

David

 

[tego]

Our smaller boats are sensitive to weight locations. Make sure you balance the load to maintain trim. I personally believe that the KISS rule should govern any cruising boat as small as ours. I have a grp31 as a starting batt although even a grp 27 will start that BETA. My house bank is 4 golf carts in series/parallel and I've never needed more on a month long trip. Our engine rooms are slightly different, mine has the much larger stringers adopted in '87. I have plenty of room for the batt banks on the STBD side between the engine (Nissan) and my HW htr and waste tank shelf. They're balanced pretty well by my 40 gal fresh water tank to port. I'm curious, where is your generator? I've seen a couple mounted where my HW and waste tanks are located and one in a cockpit locker. By the way, DON'T mix LA and gel-cell batts- their charging regimens are different! Ben '87 27FC #302

 

[rsn48]

This is one way:

 

[ranger58sb]

We are converting an Albin 27 that is set up as a day trip dive boat to an overnight cruiser. The current battery set up is 2 12 volt deep cycle gel cel 100 amp batteries in parallel as house batteries, two 12 volt gel cel 100 amp starting batteries in parallel as a starting battery. The two banks are linked by a blue seas ACR rated at 120 amps. I am replacing the original engine with a Beta Marine with a 150 amp alternator. We have a generator with a 12 volt 100 amp battery. A 20 amp shore power charger also charges all batteries.
I am not a fan of ACR's.

We will have to replace the ACR anyways because of the larger alternator, but I'm not sure I want that setup.

Space is limited, but we do have room in the generator room for a few more batteries.

Were it me... I'd probably change your house bank to 4x 6V GC2s wired in series/parallel to 12V for approx 440 Ah capacity. If service is easy, FLAs are good value for money. If service is difficult, or if off-gassing might be an issue, Lifeline makes AGM versions. You'd want to match your charger's voltages to the battery recommendations... which might mean a new charger too if your current 20A model doesn't let you select voltages.

Then I'd do a single 12V G27/29/31 for your main engine start battery and a single 12V G24/G34 for your genset start battery. Very likely with only the engine alternators for charging these two... although with switches for occasionally paralleling with the house bank (just in case -- and a set of jumper cables might be even easier). For these, I'd pick good AGMs, specifically because they don't self-discharge much, don't usually need much in the way of shorepower charging.

-Chris

 

[FF]

I too am no fan of an ACR. The RV folks use a simple setup that is easy to operate as it is basically invisible to operate..

The key is to install a key starting switch that has an ACC terminal.Use a marine version , not an auto parts cheapo.

A 60 A solenoid (or up to 300A as needed ) is wired to the ACC terminal.

It joins the start batt to the house batt . There is no ALT drag while starting , the join is in the run position.

A once a month the key can be left in the ACC position when dockside to charge the start batt if the boat hasn't been run in weeks.

The ultimate KISS system. Cole Hersey makes Marine solenoids and marine key starting switches , with silver contacts.

 

[REO]

tego
Here is a photo of my generator room. It is in the center of the cockpit, under a seating unit and cabinets. I am adding a hot water tank on the port side across from where I think new batteries could fit, so weight distribution should be good. I am going to do some measurements today, but I don't think 4 golf cart batteries will fit. I'm also going to do some measuring in the engine room. My Albin was well balanced with the 4 little batteries, but I really need to up the amps.
Now that I know that I can't mix battery types in a bank I can start figuring out what fits where. Interesting suggestions on how to wire the system. This is why I find Trawler Forum so valuable.

 

[ranger58sb]

I am going to do some measurements today, but I don't think 4 golf cart batteries will fit. I'm also going to do some measuring in the engine room.

Even 2X GC2s -- real deep cycle batteries -- could be a good improvement for you, slightly higher original capacity and better able to withstand deeper cycling.

2x L16s wired to 12V, about 300-Ah capacity, could be a very decent alternative to 4x GC2s... if you have the extra height required.

An expensive alternative might be 2x Firefly Oasis Carbon Foam G31 AGMs, which seem to be gaining a decent rep for cycling and withstanding partial-charge operations. I still think 2x or 4x GC2s would be better, but then much can depend on your space measurements, and your wallet.

If your current charger isn't perfect, you might find it useful to consider an inverter/charger replacement that also gives you better voltage control at the same time.

Assuming decent capacity and good batteries, it would also be possible to eliminate your engine start bank altogether, use your house bank for starting the main and your genset battery as a back-up start batt. In that case, a slightly larger genset start battery (G27/29/31) could be better in that role, depending on main engine cranking amp requirements. And in this case, I would lean lean slightly toward 4x GC2s or L16s instead of 2x; that way if one 6V batt goes south, you can easily rewire it to a 2x/12V system until you can get new batts.

FWIW, Lifeline's 6V GPL-4CT, GPL-6CT, and GPL-L16s all seem to be a class act. $$$$$ and they have specific charge voltage requirements, but we found 4x 4CTs to be very well suited as a combined engine (450 hp) start/house bank (with inverter loads).

-Chris

 

[REO]

I'm half wat through the video that rsn48 posted, and it really opened my eyes as to how many battery options exist. I'll post some measurements and photos tonight. Even with my tight space constraints, it looks like I can find a good solution.

 

[REO]

I agree that a dedicated engine start battery may not be needed. I didn't have one on my sailboat, and never had a problem. Having the generator battery as a back up seems like a good way to go. With the small 50 hp engine a small portable jumper pack could start the engine if all else fails. If I don't need a starting battery, maybe I could eliminate the generator battery and use the space for a bigger house bank. Again, a portable jumper can easily start the generator. (Have I gone too far with this possibility? ) I didn't mention that I have a bow thruster. Does that necessitate a starting battery?

 

[mvweebles]

Interesting thread. Not sure I follow all the suggestions- surprised topic of DC-DC charger between banks of dissimilar chemistry hasn't come up. No mention of energy budget either. Or lithium - a very compact choice for a small boat. Deeper discharge, and much faster recharge as they can accept much higher charge rates off your new 150 amp alternator. 3x100 amp lithium would weigh less than 100 lbs and give more usable power than 4xGC2 (250 lbs). Unfortunately, lithium are very efficient and lightening your wallet.

Question: what is the concern about ACRs? My impression is they are much better than the older version of battery combiner technologies?

20-amp shore power charger to a 400-500 AH battery bank seems a bit lame.

Some generators have a small alternator on them. Might consider a 2x31 12v bank for engine/Gen start plus thruster. Charge wither by generator if it has an alternator, ACR to main bank if same chemistry, or via DC-DC charger if different.

If you go with FLA GC2, don't be swayed by cheap price at Costco. They're half the price as the Trojan T105s but last half as long. Given the PITA to swap, it's a net negative.

Good luck.

Peter

 

[REO]

DC -DC charger between banks of dissimilar chemistry???
Yipes! You are probably right, my beautifully installed 20 amp charger may now be too small for the increased battery capacity.

 

[ranger58sb]

I didn't mention that I have a bow thruster. Does that necessitate a starting battery?

No, I think not necessarily, but it might certainly influence your choice of options.

You are probably right, my beautifully installed 20 amp charger may now be too small for the increased battery capacity.

In addition to selectable voltages, size could matter... but the latter may also depend on how much recharging time you'll usually have available. At anchor, need quick recharge, higher amp charger may be good. Usually doing your serious recharging back at the dock, 20A may not matter.

-Chris

 

[DavidM]

Comments and questions in bold below:

Interesting thread. Not sure I follow all the suggestions- surprised topic of DC-DC charger between banks of dissimilar chemistry hasn't come up. No mention of energy budget either. Or lithium - a very compact choice for a small boat. Deeper discharge, and much faster recharge as they can accept much higher charge rates off your new 150 amp alternator. 3x100 amp lithium would weigh less than 100 lbs and give more usable power than 4xGC2 (250 lbs). Unfortunately, lithium are very efficient and lightening your wallet.

Question: what is the concern about ACRs? My impression is they are much better than the older version of battery combiner technologies? What can an ACR do that a simple combiner can't?

20-amp shore power charger to a 400-500 AH battery bank seems a bit lame. Well 20 amps will charge that 4-500 Ah bank from 50% to 100% in about 12 hours. If you are using the charger at the dock to bring your batteries back up after a few days out cruising, 20A works fine.

Some generators have a small alternator on them. Might consider a 2x31 12v bank for engine/Gen start plus thruster. Charge wither by generator if it has an alternator, ACR to main bank if same chemistry, or via DC-DC charger if different. That will work. But realize that with an ACR or a combiner you will have a high voltage pushing amps into the house bank while the start battery is fully charged and seeing the same voltage. It all seems to work ok for me though. And BTW generator alternators often have horrible voltage regulation, sometimes 15V.

If you go with FLA GC2, don't be swayed by cheap price at Costco. They're half the price as the Trojan T105s but last half as long. Given the PITA to swap, it's a net negative. How do you know they last twice as long. Members have reported 6-7 year life with Costco GCs.

Good luck.

Peter

 

[REO]

I did a careful measurement of the spaces I have to work with. It isn't a lot.
The four current batteries are in areas that are too small for adding and checking water. Two of these batteries are in a space that is 9" by 31" by 13" high, accessible from one end only. One is in a 9'" by 12" by 11" high space, also accessible from one end. The fourth battery is on a pad that could be as large as 11" by 21" by 18" high, and easily accessible.
I have room on the side of the generator for an additional one or two batteries - 12" by 18" by 24" high.
There are a lot of really good ideas and information in this thread, and I really appreciate the input. I need to sit down and absorb it before I can make a decision. With what I have learned at this point, I am leaning toward finding a set of 6 matching sealed deep cycle batteries and wiring them into one house battery that is also used as a starting, bow thruster and windlass battery. This includes adding two batteries in the generator room. I will also keep the small battery for the generator. The big house bank could be connected to the generator battery by an ACR. It also looks like I need to replace the small 20 amp battery charger. I think this is a relatively simple system that I can build without getting myself in over my head. There are no marine electrical experts in Eureka Springs Arkansas. This could all change as I absorb the thread and do more research. All comments and suggestions are more than welcome.

 

[Bacchus]

With limited space for maintenance it sounds like a case for AGMs. They work well as start and/or deep cycle and you will find many AGMs provide both AH and CCA specs as a result.
They will run roughly 2X the $ of FLA but I have been willing to pay a premium for lack of maint and associated corrosion. If charged up regularly they will provide good service. Mine are on their 8th season and still doing well.

 

[ranger58sb]

The four current batteries are in areas that are too small for adding and checking water.

With what I have learned at this point, I am leaning toward finding a set of 6 matching sealed deep cycle batteries...

Poor access is a good argument for AGM.

Be aware, there are "sealed" mostly automotive batteries that are AGMs, latter referred to as "valve regulated."

Also be aware most 12V batteries labeled as "deep cycle" are really "dual purpose." An exception to that might be the Lifeline 12V deep cycle AGMs (i.e., not their starting batteries), since Lifeline published a 1000-cycle chart for those as well as for their deep cycle 6V batteries. May be others, too, that I haven't come across.

"Dual purpose" isn't a bad thing, if that's what you want/need, just pointing out the distinction. I've had very good luck with Odyssey Extreme dual purpose batteries for combined start/house loads.

FWIW, I have read that more than four 12V batteries in parallel isn't a good thing, but I don't know why that might be.

-Chris

 

[mvweebles]

FWIW, I have read that more than four 12V batteries in parallel isn't a good thing, but I don't know why that might be.



-Chris

Challenge is keeping batteries balanced and consistent resistance. Daisy chaining cables across terminals doesn't work well in larger banks. Decent article explaining.

In short, using power post with positive from each battery is best.

https://thecampingnerd.com/how-to-wire-multiple-12v-or-6v-batteries-rv/

Peter

 

[rwidman]

I looked at the Yandina, and it seems to be a good simple unit that easily replaces the Blue Seas unit that I need to replace. I can't test alternator output because the engine is not yet installed (sitting in the bed of my truck). I think I will get the ACR, mostly because the wiring is already in place. The Yandina seems like a quick, easy and inexpensive solution.
I like the golf cart battery option. We had 6 volt trojans and got long life from them. The problem is that the space where the gels are is too small and short for the bigger batteries, and if I could squeeze them in I would not be able to check water in the confined space. There is room for 2 bigger batteries in the generator room. The location is close to the smaller batteries. Is it a reasonable solution to use a mixture of 12 volt gel and flooded golf cart batteries? for house power?

That is not a reasonable solution. Connecting batteries together, either in parallel or in series requires them to be the same chemistry and ideally, identical, from the same manufacturer and the same manufacturing date.

Also, you need to put all the batteries from a single bank in the same physical area. For example, it's a bad idea to put some in the engine room and others in the bow or stern. The resistance of the cables becomes a problem.

 

[Jeff F]

I'm not sure I see a need for more batteries. You've got 400 ah in place now for house and start. Gel batteries aren't discussed much here, but they're excellent for dual purpose. I'd combine the four existing into a single pack for house and start and go boating. That's hardly a complete rewire.

What makes you think you need more deep cycle capacity than that?

 

[catalinajack]

DC -DC charger between banks of dissimilar chemistry???
Yipes! You are probably right, my beautifully installed 20 amp charger may now be too small for the increased battery capacity.

The charge acceptance rate of four golf car batteries is about 60 amps. You need at least a higher output charger. A Sterling DC-DC charger is an elegant and simple installation but is at least four times the size of a Blue Sea ACR. Both get the job done but I prefer the DC-DC charger. I use one of each on board. See my pic with both an ACR and DC-DC charger installed.

Also, I am surprised no one has commented on a 150 amp alternator on a 50 HP engine.

1. Requires more horsepower to spin it.
2. Requires double-belting or a serpentine belt.
3. Is way overkill for a 400+ ah battery bank with a charge acceptance rate of 60 amps.
4. A 100-amp alternator is more than sufficient and can be run with a single v-belt.

 

[REO]

I ordered the optional 150 amp alternator with a wide serpentine belt to increase output since we will likely often draw the batteries down. We plan to anchor out a lot, and have a good size reefer. The Beta rep thought it was a good idea. At this point we will have to stay with that decision since the new engine is sitting in my truck waiting to go in. We had a similar alternator set up on our 60 hp Perkins. I had it converted to wide serpentine belt and never had a problem.
The discussion of too many batteries in parallel got my attention. Maybe I need to stick with 4 batteries. To add to the concern, the current batteries are located on either side of the engine room. To parallel both banks will necessitate a long battery cable across the aft engine room bulkhead. How big a problem is this. I don't see many options since I need more power and the space for the batteries is where the space is.
Another question is amp hour rating. My current batteries are cheapies. All batteries will be replaced at the same time, and I now see the reason to make them all exactly the same. Can I get higher amp hour rated batteries in the same size as I now have? Maybe the lithium option with the ability to discharge much further down isn't as cost prohibitive as it first seemed??? Seems like i'm asking a lot of "how long is a string" questions, but this issue of how many batteries can be run in parallel and how far apart they can be seems critical. Does a power post and larger cable solve the problem.
If I don't add batteries in the generator room I could move the charger to that space. A bigger charger will allow faster charge from the generator if we are at anchor for a few days.
My wife just pointed out that if we move the generator battery and expansion tank, we can locate two batteries in the generator room against the bulkhead. On the other side of this bulkhead are two engine room batteries. That move may also help balance weight distribution since we have added a 14 gallon aux water tank, 6 gallon water heater and counter height reefer to the other side. Again I want to thank you guys for all the input. Every single post has helped me think this through. It's lonely out here in Northwest Arkansas if you want to talk about trawlers.

 

[ranger58sb]

Can I get higher amp hour rated batteries in the same size as I now have?

I've seen where you've mentioned your current (nominal) battery capacities -- 100-Ah each -- but I think I haven't seen you say physical size designators.

Your 100-Ah (capacity) batteries might be Group 31 size? If so, that's a common semi-standard size/capacity. Some G31s might say 105-Ah, Lifeline has a 125-Ah version, Fireflies are 116-Ah... but in general that's a typical range for that physical size. Typical smaller 12V G24s, G27s, G29s... would also fit your space, but wouldn't offer any advantage.

The 6V batteries (GC2s, L16s, etc.) tend to be slightly smaller in horizontal dimensions, but taller. But you need to use those in pairs to get to 12V.

GC2s might give you ~220-Ah/pair, while two Lifeline G31 XTs would nominally give you 250-Ah. Or 2x L16s, if you have available height, is about ~300-Ah, maybe another way to get there from here. Some difference, maybe or maybe not enough to suit.

OTOH, 4x GC2s (~440-Ah) will almost fit in the same space as 3x G31s, so sometimes fitting stuff in with a shoe horn can help.

Two other options: 1) AGMs can usually be installed in non-standard ways,
i.e., on their sides or ends, etc., and 2) Odyssey has a strange shape battery -- PC-1800, I think, taller and skinnier than some -- that might fit where other options won't, especially if mounted sideways or whatever.

-Chris

 

[REO]

I'm going to measure and report on the actual size of my current batteries-they are all the same size. Then start to look at what is available that will fit.

 

[REO]

My batteries are g27. About 12 x 6.5 x 8.5 inches. I think I can find space for something a bit larger, but not much. I'm going to do some online battery shopping to see what is available.

 

[sbman]

The discussion of too many batteries in parallel got my attention. Maybe I need to stick with 4 batteries. To add to the concern, the current batteries are located on either side of the engine room. To parallel both banks will necessitate a long battery cable across the aft engine room bulkhead. How big a problem is this. I don't see many options since I need more power and the space for the batteries is where the space is.
Another question is amp hour rating. My current batteries are cheapies. All batteries will be replaced at the same time, and I now see the reason to make them all exactly the same. Can I get higher amp hour rated batteries in the same size as I now have? Maybe the lithium option with the ability to discharge much further down isn't as cost prohibitive as it first seemed??? Seems like i'm asking a lot of "how long is a string" questions, but this issue of how many batteries can be run in parallel and how far apart they can be seems critical. Does a power post and larger cable solve the problem.
If I don't add batteries in the generator room I could move the charger to that space. A bigger charger will allow faster charge from the generator if we are at anchor for a few days.

You might consider reducing the size of the generator start battery as well if that helps with the space. An oddysey that provides the necessary cranking amps is likely smaller than the G27 you have now.

If your parallel batteries are going to be more than a few feet apart, you can run equal length cables from each set to a heavy duty bus bar. If the farthest battery is say 36" away, then all the batteries need 36" cables of the same gauge, all joined in parallel at the main bus bar.

That's one advantage of using 6V batteries, they are as physically as large as a single 12V but you join two 6V to make a 12V battery reducing the number of units needed to be in parallel in the same space.