Combine house and start?

[ranger58sb]

Then your batteries are nearing the end.... I am a HUGE Odyssey fan by the way.

It may also depend on the specific starters used on the engines in question. Some have a spectacularly large power draw when you first hit the key. Mine are bad about that, being old school (big) direct drive starters, not modern reduction drive units.

Might be approaching end of life, but... the voltage drop thing has been that way since day 1 of installation. Well, at least since the first time I started that engine with electronics already turned on, probably after several hours of trolling on the other engine only.

Could be something else about our system, of course...

-Chris

 

[rslifkin]

Another thought on separation: engine rooms aren't an ideal place for batteries due to heat. So if you've got a suitable location that stays cooler, it makes sense to put the big, pricey house batteries there and just keep what you need for starting within a short cable run of the engines.

In my case, the start batteries are in the engine room, the house bank is under the forward stateroom against the forward engine room bulkhead (where it stays much cooler).

 

[ranger58sb]

Might be approaching end of life, but... the voltage drop thing has been that way since day 1 of installation. Well, at least since the first time I started that engine with electronics already turned on, probably after several hours of trolling on the other engine only.

Could be something else about our system, of course...

And I committed a semi-brainphart, too. When I mentioned the Odyssey bank that if getting a bit long in the tooth, I linked that with voltage drop to our electronics suite when we start an engine.

Actually, all our electronics run from the OTHER engine bank. The rest of what I described was semi-accurate, though; many of the electronic components drop out when starting that engine... and it's mostly always been that way. The earlier bank of Odysseys on that engine have since been replace by a bank of 6V Lifelines, not quite a couple years old now, same results (just retested, a few minutes ago). Plotter, radar, autopilot, and at least one VHF radio drop out... That's while connected to shorepower/charger, too.

-Chris

 

[rslifkin]

That matches my experience with a lot of setups that power electronics and engine start from the same batteries.

 

[Tom.B]

As a fellow Navigator owner, I will give you a few bits of advice. First is that you should totally reconfigure the DC system. If it is anything like our 2000 model, it is a really bad design that was one of the first things I changed. The switch config is silly and ineffective. Second is that the 8Ds are junk. Replace them.

Two banks is ideal. You need the ability to use both banks for both jobs, and what will start a Leman or Perkins will not work as well for our big six-liter Volvos. The rotating mass is huge and compression is high. However, there is no need for separate starter batteries for each. I opted for eight GC2s for a nice large house bank and three Group 27 dual purpose batteries combined in parallel as a single start bank and backup house bank. You will need to make new battery boxes, but that's easy enough.

If you want to see my config, I would be happy to share it with you. I would also say to join our Facebook group. We share a lot of ideas over there.

 

[4mo]

Hey Tom,

Thanks! I would love to see your config, I'll DM you.

I am part of the facebook group, I joined a year ago when we decided on the Nav 53, since then have flown from Cordova, AK to San Diego looking for the right one. Finally found ours in Newport Beach.

 

[Portage_Bay]

One of the topics I'm not seeing on this thread is the relative design difference between start batts and deep cycle batts. I'm talking FLA batts. They really are different animals and not necessarily well suited to the other task.

I've got 6 golf cart batts for house bank and one 8D to start two 3208s. I can tie them all together but I'm not at all sure it's a good idea.

 

[obthomas]

I have twin engines. Each engine has a start battery. My generator battery is entirely independent. One of the engine start batteries is actually a house bank of 2x 4Ds. My 12 volt power panel has a selector switch and I can select either the start/house bank or the other start battery. I can also temporarily combine the batteries and start either engine. My engine alternators are on a combiner and charge both sets of batteries. My generator has its own alternator. My 40 amp three bank battery charger is separately connected to each engine bank and the alternator battery.
This arrangement has served me well and my batteries are lasting about 7 years. I'm 3 years into my third set.

 

[audioshark]

If you replacing everything why not do it the correct way and use dedicated batteries for start and genset and separate for house bank, put a switch in a place so you don't have to crawl down in engine room or lift hatches to jump banks, Also get a larger charger 40amps is too small for your house bank, you want 10% min.

 

[stevemitchell]

I redid my DC systems this year, and opted to keep a start bank for the main engines, and a start battery for the generator, mainly for redundancy, but also because I chose to move to LiFePO4 for my house bank, and didn't want to mix chemistries.

I ended up combining the two start batteries into one bank instead of two separate individual batteries, each dedicated to one engine.

Even on a 42' boat, I would prefer to have this setup than one big house bank, unless you only do day cruises and plug in every night, which it does not sound like the OP was doing.

 

[markpierce]

My house batteries died, totally. Thankfully, the engine battery still functioned so was able to motor to the boatyard for replacements.

 

[rslifkin]

My house batteries died, totally. Thankfully, the engine battery still functioned so was able to motor to the boatyard for replacements.

Yup. This is the reason any engine or generator should have a choice of 2 banks to start from. Stuff breaks and mistakes happen.

 

[4mo]

Okay, thanks everyone for the opinions and information.

At this point I'm going to replace 2 8d House bank with 6 Dyno 6V golf cart batteries, separate the house and start (but keep it switchable in case of emergency), and add a separate generator start battery on an ACR. I'll also keep the inverter bank separate as well. I would have preferred a bigger house bank but I guess we'll see how it works for us this summer and go from there.

This many different banks seems like overkill but also seems like the easiest and cheapest solution for now.

I imagine battery technology will change in the next 5 years and I can rewire things then if I see fit.

 

[Beaverlake]

Okay, thanks everyone for the opinions and information.

At this point I'm going to replace 2 8d House bank with 6 Dyno 6V golf cart batteries, separate the house and start (but keep it switchable in case of emergency), and add a separate generator start battery on an ACR. I'll also keep the inverter bank separate as well. I would have preferred a bigger house bank but I guess we'll see how it works for us this summer and go from there.

This many different banks seems like overkill but also seems like the easiest and cheapest solution for now.

I imagine battery technology will change in the next 5 years and I can rewire things then if I see fit.

IIRC Fisheries Supply is having a battery sale right now (late Jan 2020). Create a "commercial account" to save even more (that's what I've done). Dyno batteries aren't the lowest price, but they have a reputation for quality and they are made locally.

 

[4mo]

I think it’s still cheaper to get them direct from Dyno. They quoted me $156 per battery with no core charges.

 

[Beaverlake]

Good to know!