Upgrading house batteries to Golf Carts

centerline · Jan 7, 2016

yes, it can be done, but it isnt cheap....
the (2) GC batteries could give you the 300ah if you go to something like the trojan T-1275 12v GC batts at 150 amp hr each, but if you are thinking 6v gc batts, you would need to go to something like a trojan L-16....
the reason is, when wiring 6volt batts in series to get 12volts, the, volts will double but the amp hours stay the same as if you only had 1 battery, ... when paralleling 12 volt batts, the voltage stays the same as if you only had one , but the amperage doubles.....

the banks do need to be the same voltage...... and all the batteries need to be of the same technology, (agm, wet cell, ect).... and all the batteries in an individual bank must all be the same size and matched..... but as long as you are set up properly with a charge relay, the 2 different banks can have a different number of batteries of a different size, as long as it matches the voltage of the other bank..

it would seem from your description, you have 2 banks with one battery in each bank.... going to 2 GC batts for your house needs will be a huge difference, but I have no input for you on the use of an inverter, and how much battery you will need to run it, as I dont see the reasoning behind this on a boat where inverters are such a waste of energy when on an energy conscious budget like so many of us live by when on our boats...
a 1500w inverter running at 50% load will pull the 300amp bank down below recommended limits in about 20-30 minutes.... the difference is you are pulling amps from your batts and converting them from 12 volts to 120 volts...
even though many people have done what you are suggesting you want to do, for everyday use it just isnt a feasible option unless you have lots of charging capability... in which case you would probably have a generator which makes the inverter redundant..

seadaddler · Jan 8, 2016

Depends what you want to run off the inverter and I would recommend a inverter with a battery monitor.
I have a 2500 inverter/ charger with remote and 4 -6 volt T-105
Trojans and can use any thing 110 appliance and even microwave but the microwave does use a lot of power.
Nick

kloudie1 · Jan 8, 2016

Roger, welcome.. Here is a thread that has a few references to your thoughts.. Maine Sail's (Compass Marine) posts on this subject are indeed excellent for education and planning..
http://forums.sailboatowners.com/in...agement.175771/&highlight=golf cart batteries

druid · Jan 8, 2016

Remember a larger battery doesn't give you more CURRENT (Amps), just current for a longer time (Amp-hrs). There's no reason you couldn't run a 1500W inverter off a 100 A-H battery - it just wouldn't last long. You also have to understand that a larger battery will take longer to charge (think of batteries like a bucket, and electrons like the water in a bucket. A bigger bucket has more water, but takes longer to fill back up). If you're going to be sitting at anchor for days, you might want to look at a solar panel to keep the battery charged.
And a "1500W Inverter" doesn't necessary draw 1500W - it draws whatever is connected to it (plus inefficiency). So you need to add up what you'll be connecting to the inverter, and see how much current you will be drawing. Then, assuming you'll be running the engine and charging the battery during the day, see how big a battery you need to run those things for like 12 hours.

I've heard that the two banks need to be "the same" but they don't... kinda. They should be the same technology (agm, sla, etc) but if they're different and you hook them together to charge them... well, they act like two buckets of different sizes connected together by a hose. The height of the water (voltage) will equalize through the hose (water flow = current) and if the smaller bucket has a higher level than the larger bucket it will go down much more than the other bucket will go up. but you can still fill both buckets.

druid

Stu Jackson · Jan 8, 2016

druid said:
You also have to understand that a larger battery will take longer to charge (think of batteries like a bucket, and electrons like the water in a bucket. A bigger bucket has more water, but takes longer to fill back up).

That analogy only goes so far.

If you use the same amount of water every day, it doesn't take any longer to fill it back up on a daily basis. Regardless of how big the bucket is.

It just means you can go two days without refilling with the bigger bucket.

Of course it would take longer to fill after the second day; two days worth, right?

gettinthere · Jan 8, 2016

What is it you want to run on the inverter? And for how long?

Daveinet · Jan 8, 2016

The battery banks can be anything you want them to be. We do it in motorhomes all the time. What you will need is a battery isolator. Don't waste money on a relay. I bought one of these several years ago from AutoZone like this one below:
http://www.autozone.com/batteries-s...tery-isolator/noco-battery-isolator/1326_0_0/
It will allow you to charge from one source, but will prevent you from inadvertently running your engine battery dead.

Stu Jackson · Jan 8, 2016

Battery isolators are sooo way old technology, it's funny they should even be mentioned. Why? They drop up to 1.0V, just when you need it for charging. Who comes up with these 60 year old ideas in 2016?

Yandina combiners earlier sold by WM, and Blue Sea products are far superior with no voltage drop inline.

You might be interested in this, not knowing what it is you know about boat electrical systems:

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

Daveinet · Jan 9, 2016

No they don't. These are not just diodes. They typically are MOSFET output, for a very low output resistance.

Stu Jackson · Jan 9, 2016

Thanks for clarifying that, Dave.

For Roger, this is another way to disconnect your two banks when chjarging sources are not present.

Lots of options.

Your boat, your choice.

Maine Sail · Jan 12, 2016

Daveinet said:
What you will need is a battery isolator. Don't waste money on a relay. I bought one of these several years ago from AutoZone like this one below:
http://www.autozone.com/batteries-s...tery-isolator/noco-battery-isolator/1326_0_0/

Diode isolators are simply outdated technology not well suited to cruising boats for numerous reasons. The Noco isolator you link to is a copy-cat of the Sure Power isolator only the Noco is made in China.

Daveinet said:
No they don't. These are not just diodes. They typically are MOSFET output, for a very low output resistance.

Unfortunately someone has apparently mislead you... The Noco's are nothing more than old-school diode isolators. Noco fully admits this product can induce a voltage drop of up to 1V in the circuit. While Noco says "solid state" in their marketing material they are absolutely not FET based isolators and are nothing more than standard old-school diode isolators. Aluminum, epoxy potting and old school diodes nothing fancy. Think about it like this, if they did not drop so much voltage they would not require a large heat sink. Heck even the $400.00 Mastervolt isolators, which are a FET design, still drop as much as 0.4V.

A key or oil pressure excited solenoid/relay, like cheap RV builders use, is also a down & dirty way of paralleling banks and is also not really a good or smart way of doing so.

Hunter used this method for a while too and it smacks of Rube Goldberg. It is penny pinching only. I've replaced a fair number of the non-constant duty relays that Hunter used with the incredibly reliable & purpose built Blue Sea ACR's. Duo Chargers, Echo Chargers and Sterling Battery to Battery chargers are also excellent products for charge management..

A proper voltage sensitive relay is a far better choice for charging two banks than an old school diode isolator and it will work with solar, wind or shore chargers too.