Crossfeed stbd bank with outback

[Chasemmc]

1981 56': house/starter bank port, starter only stbd, gen has own 12v and dedicated charger, thruster has own 24v & dedicated charger. Outback inverter charges port. Original charger still mounted in stbd ER (don't know if it works) so thats the set up.

Scott mentioned in prior post that it was possible for outback to charge both banks by fooling it into thinking they are one bank.

Stbd cables go into fuse box mounted aft engine room. Original gen switch disabled.

How do i wire the outback into the stbd bank. I assume an isolator switch on the hot lead. Can use common ground?

Thanks in advance

Mark

[Boatsb]

Not this Scott.

Charging 2 banks on one charger leg makes for bad results.

[Chasemmc]

Sorry scott, my memory did not serve me well. I guess i will research the prior thread to get it right.

[Boatsb]

If you tie the 2 banks together you have only one bank and when it dies you don't start the boat.

[MikeP]

If you want the outback to charge both banks, you have to combine them into a single bank. I wired our banks to be able to "combine" with a battery switch into one bank, charged by the outback. It's worked great for 10 years and I have never turned the switch to de-combine, but whether that's a good option depends on your use of the boat and, IMO, whether the generator has it's own, independent start battery.

From an electrical system point of view, one larger bank is more efficient than two smaller separate banks BUT one thing to be very aware of is that if one battery in the bank has a bad cell and it goes unnoticed, it can cause ALL the batteries in the bank to be overcharged/damaged, regardless how "smart" the charger is.

IOW, if you have two separate banks - 4 batts each - and there is a bad cell, 4 batts could be damaged. If you combine the banks to have one 8 batt bank, one bad cell could damage 8 batteries!

OTOH, routine batt maintenance should provide detection of a bad cell/battery before it causes any problem with overcharging of the other batteries but still, the possibility remains and if you want to combine the banks, you need to be aware of that.

[Boatsb]

http://www.samsmarine.com/forums/sho...-power-voltage

[Chasemmc]

It was mike p that has been successful with this approach. I understand the risk of the combined bank being susceptible to a bad cell damaging the whole bank as well running the bank too low to start the engine.

In my case i have a separate battery & charger for the generator, so that helps to mitigate the risk of a dead starter bank.

A separate charger looks like it runs $750, which would purchase many cases of beer.

[Boatsb]

Or new batteries.

We do not suggest combining start banks for inverters as a good idea.

Best to have separate inverter banks and start banks.

Then again if you find buying beer more important than setting up a proper starter and inverter bank that's your choice.

[Chasemmc]

In a world of plentiful resources perfect choices are easy.

Unfortunately, i don't live in that reality, but am constrained to consider less perfect options.

Hey, if i had real money i'd buy a new 70' hat.

So, i will continue to explore all the alternatives, weighing the costs and associated risks.

Thanks to everyone for surfacing those alternate solutions.

That's why this forum is so helpful.

Ps: the beer comment was levity.

[carolinacoast]

I have been happy with my choice on this one for the last 9 years. my compromise: outback combining both banks (following MikeP's design), and no regrets. However: I have 2 generators, and 1 has a dedicated start battery., AND I have never installed the inverter side of the outback. If I did that , I would likely add another charger and de combine.

We continiue to get 5 years per set of deka batts and they only seem to go dead when on the hard when a yard leaves things on.

When we use the boat, we seem to always need 240v power on or off the dock. at least one of the generators seems to always work, thankfully so far.

our decombining switch is in the port engine room on the bulkhead in the side of the first 32V box. There are many valid opinions on this one, and our choice has worked fine so far. Have not decombined yet, but would take seconds to do if inverting were important.