Battery Choices (House vs Start)

[Harrison]

Does anyone see a problem with using a deep cycle battery along with a starting battery? They are separated with a Perko combiner. 3 years ago when the boat was new I added a “starting” battery with the combiner to the factory bat. Now, finally, the stock factory bat has gone bad, so I’m looking into some options. Thoughts?

Thanks,
---Harrison

[Bobby T.-26X #4767]

most on this board have indicated a preference to have two of the "same type/brand" battery when replacing under your system configuration.
a deep cycle and regular will work; however, ideally, two of the same battery type/brand (i.e. 2 deep cycle or 2 regular) seems to effect the best result.

Bob T.
"DāBob"
'02X w/ '04 90-TLDI (14" x 11 pitch)
Dinghy Motor: '06 2.5-Suzuki

[Catigale]

...and you dont need a starting battery on these boats - are outboards are small compared to the kind of marine engine requiring a high current starting battery imho...

[James V]

Don't mix batteries types. I have had not problems with my wet cells and for the price you can get 2 for 1 gel. Pleanty of amp hours for my needs.

[baldbaby2000]

...and you dont need a starting battery on these boats - are outboards are small compared to the kind of marine engine requiring a high current starting battery imho...

Is this true even when it's cold? There are times when it's close to freezing where we sail. I now have one dual cycle and one deep cycle but wonder if I should go with two deep cycles.

[Harrison]

What is the real problem with mixing two types, with a combiner/isolator? Just curious.

Here’s my situation. I’ve got 2 starting bats. One is dead. One is “almost” a year old. (I'd really rather not just throw it out) I wanna replace the dead one with a deep cycle. Work my way to running 2 identical deep cycles. Eventually the other will die as well. When that one goes south, I’ll replace it with the same type/brand etc deep cycle.

---Harrison

[Frank C]

...and you dont need a starting battery on these boats - are outboards are small compared to the kind of marine engine requiring a high current starting battery imho...

Is this true even when it's cold? There are times when it's close to freezing where we sail. I now have one dual cycle and one deep cycle but wonder if I should go with two deep cycles.

I agree w/Catigale. In fact, I might have started the idea that a starter battery isn't needed. Consider that we dedicate 50-pounds of starting battery for a 800 cc Honda 50, when that same battery starts a Ford that's 4 times the engine displacement. Meanwhile, a 50-pound starter battery just sits there and wastes away, essentially unused.

I thought the most we should commit is a motorcycle or garden tractor battery ... about 10 to 15 pounds. But then another user reported that his big outboard needs a big starting battery because of .... maybe fuel pump, or .... ???

But I still think the principle is valid, alternating usage of identical batteries. Two deep cycles could be used alternately, like even dates vs. odd dates, for both house & starting duty, and the 'resting' battery remains as a backup. Even/odd dates is the system used at my sailing school (batt#1 if the date is odd). Both deep cycle batteries are rotated that way, and used equally ... and that's for lot more rigorous starting of a Yanmar diesel. YMMV.

[Moe]

Harrison, you should be okay with a starting battery "combined" with a deep cycle battery if you charge with just the outboard alternator or a single-stage charger in the 13.6-13.8 volt range.

Where you could harm the starting battery, which hardly discharges at all starting our small motors, is if you charge with a 3-stage charger with a bulk mode in the 14.2-14.4 volt range and the deep-cycle battery is discharged more than about 20%. In that case, I'd disconnect the deep-cycle battery negative cable and apply the 3-stage charger cables directly to the deep-cycle battery terminals.

--
Moe

[Harrison]

Guys,

Thanks for all the good advice.

---Harrison

[teethlaw]

We have deep cycle/standard batteries on the boat we recently purchased. Is there any harm in putting the Perko on combined once the motor is running so we can charge both at the same time? We've basically been running of the deep cycle all the time, starting or otherwise, and now the standard is starting to run out of juice (we don't have a way to charge it without removing it and taking it home with us). Wasn't sure if it would harm one or the other if we used the combine setting.

Thanks for any help!

[opie]

Check your cell water level. The previous owner could have let it go almost dry which would result in it not holding charge, or worse.

[Harrison]

We have deep cycle/standard batteries on the boat we recently purchased. Is there any harm in putting the Perko on combined once the motor is running so we can charge both at the same time? We've basically been running of the deep cycle all the time, starting or otherwise, and now the standard is starting to run out of juice (we don't have a way to charge it without removing it and taking it home with us). Wasn't sure if it would harm one or the other if we used the combine setting.

Great question, I'd like to know the answer as well.

---Harrison

[Frank C]

We have deep cycle/standard batteries on the boat we recently purchased. Is there any harm in putting the Perko on combined once the motor is running so we can charge both at the same time? We've basically been running of the deep cycle all the time, starting or otherwise, and now the standard is starting to run out of juice (we don't have a way to charge it without removing it and taking it home with us). Wasn't sure if it would harm one or the other if we used the combine setting.

Great question, I'd like to know the answer as well. ---Harrison

I think there are distinct versions of Perko switches. You need to be sure your Perko is a "make before break" style. That's essential to prevent even a fraction of a second, during switching, when the the battery load might be absent from the Alternator -- zero-load is bad news for most Alternators.

An easier, no-brainer solution (no user action req'd) is using West Marine's Battery Combiner, or the other brands called generically, ACRs. It's a magic box that parallels the batteries when the alternator is providing net current in-feed, but breaks the connection to prevent drawing down the backup battery. IIRC, the charging current is shunted to the weakest battery, first.

I launched a different thread to debate the Odd/Even approach, and that thread has a commentary on implementing that scenario using our currently existing batteries.

[Catigale]

This is a bit of a SWAG, but I doubt you need a 'starter battery' all the way down to freezing point to turn over the 'standard' 50 HP outboard.

Especially true for a 4 stroke EFI which crank for about 1 second before starting.

[Boblee]

I run with the two house and one starting batteries combined but usually isolate the starting battery overnight, one house battery is temp and is hooked up by 50amp anderson plugs and can be moved to the tow vehicle.
After mucking around with different batteries over the years have found it better and cheaper to just use good quality wet cell batteries.
We charge from the motor when running, two 65w solar cells mounted on an arch, from the vehicle, have a car alternator (50amp) hooked up to a honda motor, and if camped on land in a park a 14amp battery charger.
Our boat is used as a caravan on land and water, we use the 4 wd to tour hard to get places on land and the dinghy on water so need plenty of alternatives.
We run a 300w invertor for 240v chargers (phone etc) but the boat is basically 12v.
As our fridge/freezer usually draws av 3 amps (= 75amps day) the batteries get a fair workout.