On Wed, 13 Oct 2010 18:18:13 -0700, Stephen Trapani
wrote:

Well, occasional microwave, charge cell phones, morning and afternoon
coffee, lights, and hopefully a TV/dvr.

Kind of putting it all together...

I haven't seen the "brick" powered TV's in quite a while. Maybe at a
flea market or something?

The Golf Cart batteries are the best. Two in series should be fine for
what you want, but let's see.

Daily power, taking your "list" above out of order:

First, to determine the daily power requirements you have to take the
current draw, Amps, of each thing and multiply by the number of hours
used to get the Amp Hours per day of each. Remember, anything powered
by the inverter is going to be the 120VAC Watts divided by 10 for 12V
Amps.

We'll do that below, with best guesses.

Lights: I'm sure your talking 12V ones. The anchor light is the
biggie, with incandescent at about 1.5 Amps for 12 hrs.

[ 18 Amp Hours ]

LED would be about 2 Amp Hours, but cost more than a couple more
battereis.

Inside lighting. Varies, but say 2.5 Amps for 5 hours.

[ 12.5 Amp Hours ]

Same as above for LED inside lighting, but not as expensive.

Charging cell phone: Negligible if you have a 12V charger.

Coffee:

We had a 10-cup with thermos type carafe. It drew 75 Amps and ran for
5 minutes. Just to make it easy, let's say 6 minutes, 1/10 of an hour
or 7.5 Amp Hours per pot. Morning and afternoon then are

[ 15 Amp Hours ]

Microwave: We get a bit iffy here. Our 800 or 900 Watt one, I forget
which, drew about 95 Amps. That works out to about 1.6 Amp Hours per
minute of use ( 95 / 60 ). So you don't want to use it too much.

Let's say a couple meals reheated and a few cups of coffee and put it
at 15 minutes. 15 X 1.6 =

[ 24 Amp Hours ]


TV/DVD: Ours, using both was about 5 Amps as I recall. Figuring 4
hours in the evening and 1 hour of news in the morning, that's

[ 25 Amp Hours ]


Adding it all up, the total is:

[ 94.5 Amp Hours per day ]

So you're looking at basically 2 days with your batteries.

With LED anchor and inside lighting,

[ 68 Amp Hours per day ] Quite a difference.

Basically almost 3 days.

Remember you don't want to totally kill your batteries.

Adding another pair of batteries will of course double that and is the
less expensive route then LED lighting.

Rick

On Thu, 14 Oct 2010 05:24:56 -0500, Rick Morel
wrote:

On Wed, 13 Oct 2010 18:18:13 -0700, Stephen Trapani
wrote:

Well, occasional microwave, charge cell phones, morning and afternoon
coffee, lights, and hopefully a TV/dvr.

Kind of putting it all together...

I haven't seen the "brick" powered TV's in quite a while. Maybe at a
flea market or something?

The Golf Cart batteries are the best. Two in series should be fine for
what you want, but let's see.

Daily power, taking your "list" above out of order:

First, to determine the daily power requirements you have to take the
current draw, Amps, of each thing and multiply by the number of hours
used to get the Amp Hours per day of each. Remember, anything powered
by the inverter is going to be the 120VAC Watts divided by 10 for 12V
Amps.

We'll do that below, with best guesses.

Lights: I'm sure your talking 12V ones. The anchor light is the
biggie, with incandescent at about 1.5 Amps for 12 hrs.

[ 18 Amp Hours ]

LED would be about 2 Amp Hours, but cost more than a couple more
battereis.

Inside lighting. Varies, but say 2.5 Amps for 5 hours.

[ 12.5 Amp Hours ]

Same as above for LED inside lighting, but not as expensive.

Charging cell phone: Negligible if you have a 12V charger.

Coffee:

We had a 10-cup with thermos type carafe. It drew 75 Amps and ran for
5 minutes. Just to make it easy, let's say 6 minutes, 1/10 of an hour
or 7.5 Amp Hours per pot. Morning and afternoon then are

[ 15 Amp Hours ]

Microwave: We get a bit iffy here. Our 800 or 900 Watt one, I forget
which, drew about 95 Amps. That works out to about 1.6 Amp Hours per
minute of use ( 95 / 60 ). So you don't want to use it too much.

Let's say a couple meals reheated and a few cups of coffee and put it
at 15 minutes. 15 X 1.6 =

[ 24 Amp Hours ]


TV/DVD: Ours, using both was about 5 Amps as I recall. Figuring 4
hours in the evening and 1 hour of news in the morning, that's

[ 25 Amp Hours ]


Adding it all up, the total is:

[ 94.5 Amp Hours per day ]

So you're looking at basically 2 days with your batteries.

With LED anchor and inside lighting,

[ 68 Amp Hours per day ] Quite a difference.

Basically almost 3 days.

Remember you don't want to totally kill your batteries.

Adding another pair of batteries will of course double that and is the
less expensive route then LED lighting.

Rick


I'm not sure of US prices but LED anchor lights are cheaper then
batteries over here :-) We can also get pin based LED replacements for
hi-intensity bulbs for reading lights.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Thu, 14 Oct 2010 05:24:56 -0500, Rick Morel
wrote:

Adding it all up, the total is:

[ 94.5 Amp Hours per day ]

So you're looking at basically 2 days with your batteries.

With LED anchor and inside lighting,

[ 68 Amp Hours per day ] Quite a difference.

Basically almost 3 days.

Remember you don't want to totally kill your batteries.

Good point.

If you want normal life from your inverter batts it is important to
limit the discharge level to less than 50% (about 11.7 volts when
under load). The net result is that you need twice as many amp-hours
as your energy budget, perhaps more if your recharge time is limited.
It take quite a while to bring the charge level back to a full 100%
because the acceptance rate tapers off once you are above about 80%.
A good design point for A-H capacity is 3 times your energy budget.

AGM batteries have a higher charge acceptance rate but cost about
twice as much. They are worthwhile however if limited by size and/or
weight. Gel cells have good acceptance rates also but are easily
damaged by higher charging voltages. Not worth the risk in my opinion
since AGMs are coming down in price.

On Thu, 14 Oct 2010 08:43:16 -0400, Wayne.B
wrote:

If you want normal life from your inverter batts it is important to
limit the discharge level to less than 50% (about 11.7 volts when
under load). The net result is that you need twice as many amp-hours
as your energy budget, perhaps more if your recharge time is limited.
It take quite a while to bring the charge level back to a full 100%
because the acceptance rate tapers off once you are above about 80%.
A good design point for A-H capacity is 3 times your energy budget.

Wayne, the 50% rule doesn't really apply to golf cart batteries. Back
in my electric car days there was a "trick" we used when we were
stupid and came to a stop from totally discharged batteries. Wait 10
to 20 minutes for the batteries to "self charge", then play
egg-on-accelerator and we'd get another mile or two. Wait and repeat.
Sometimes it took three or four of these cycles to get home.

Having said that, it's a good idea to limit to 20%, simply because
most inverters will shut down around that point.

A good point on taking a while to bring to a full charge. A lot of
folks think you can just pump in the Amps with a big alternator, but
it doesn't work that way in the real world.

A bit of golf cart battery advice. There are two battery manufacturers
in the USA, and they pretty much do the same thing. We bought the
same batteries from Sam's for $72 each as the local dealer had for
$160 each. By same I mean the same brand and model.

Re microwaves and coffee pots. It boils down to personal preference
and the boat systems. In our case we had enough solar so it was "free"
renewable energy as opposed to burning propane that we had to replace.

Rick

On Fri, 15 Oct 2010 08:19:56 -0500, Rick Morel
wrote:

Wayne, the 50% rule doesn't really apply to golf cart batteries. Back
in my electric car days there was a "trick" we used when we were
stupid and came to a stop from totally discharged batteries. Wait 10
to 20 minutes for the batteries to "self charge", then play
egg-on-accelerator and we'd get another mile or two. Wait and repeat.
Sometimes it took three or four of these cycles to get home.

Having said that, it's a good idea to limit to 20%, simply because
most inverters will shut down around that point.

I'm sure that it's possible to get away with an 80% discharge for some
period of time. I've seen some fairly convincing life cycle charts
however that seem to indicate greatly increased battery life at the
50% level as opposed to 80%. I like to baby our house batts as much
as possible given the expense and difficulty of replacing them.

See "Cycles vs Lifespan" at:

http://www.windsun.com/Batteries/Battery_FAQ.htm

http://img32.imageshack.us/img32/9595/batterydod.gif

(from site: http://www.mpoweruk.com/life.htm )

On Fri, 15 Oct 2010 12:21:15 -0400, Wayne.B
wrote:

I'm sure that it's possible to get away with an 80% discharge for some
period of time. I've seen some fairly convincing life cycle charts
however that seem to indicate greatly increased battery life at the
50% level as opposed to 80%. I like to baby our house batts as much
as possible given the expense and difficulty of replacing them.

See "Cycles vs Lifespan" at:

http://www.windsun.com/Batteries/Battery_FAQ.htm

http://img32.imageshack.us/img32/9595/batterydod.gif

(from site: http://www.mpoweruk.com/life.htm )


I agree about babying one's house bank, as long as it doesn't limit
the use of them. Like everything else, it's a trade off.

Here's data from real world experience. It's simply what was, with no
claims:

Back in my EV days, we had a group of about 30 that had built our own
cars or pickups. Each one of them used 20 golf cart batteries in
series.

Note that we all recharged at the C/10 rate ( Amp Hour Capacity
divided by 10 ) and recharged daily. Next to overcharging, the next
best way to destroy a lead / acid battery is to delay charging,
allowing sulfation. We made very sure to keep the electrolyte above
the plates and we did an equalizing charge monthly.

We got an average of 3,600 charges, with a few getting about 7,000.

To explain, our batteries lasted 8 to 12 years. These were our regular
cars. Some of us commuted to work daily. Some barely took the surface
charge off the batts most days, some slmost killed them dead each
workday. That doubled figure were for the few that had really long
commutes and/or their workplace supplied sockets to recharge.

Two of the group rigged up a generator on a trailer to extend their
range. Note they couldn't pull a large enough generator to go
indefinitely, just enough to double or triple the range. The motors
drew about 140 Amps or so at highway speeds.

This seems to say that lead / acid batteries are somewhat like a clock
- wind it up once and it's going to work for X length of time. The
fact that regular car batteries seem to last about 2 years says the
same thing.

Note that we all had several batteries fail at one time or another
during that period. I had one go after a couple months that was
replaced under warranty. I don't remember now just when, but I had two
others go out over the years.

To repeat, we all got 8 to 12 years from our batteries, whether we
discharged them to 10 or 20 or 50 or 70 or 90 per cent daily. We got
many more cycles than the graphs say - most of us should have gotten a
year or two or three. Maybe because we did otherwise baby them, or
maybe because the published figures are worse case, or both?


In any event, if I were to be a weekend sailor and planned on
discharging to 20% or so, I don't think it would be worth it to buy an
extra pair of batteries and have the extra weight and space taken up.
I'd still be getting a pretty long life out of them. Long term
cruising is a different story - I packed 'um in, as many as I could!

Rick

On Sat, 16 Oct 2010 07:43:46 -0500, Rick Morel
wrote:

On Fri, 15 Oct 2010 12:21:15 -0400, Wayne.B
wrote:

I'm sure that it's possible to get away with an 80% discharge for some
period of time. I've seen some fairly convincing life cycle charts
however that seem to indicate greatly increased battery life at the
50% level as opposed to 80%. I like to baby our house batts as much
as possible given the expense and difficulty of replacing them.

See "Cycles vs Lifespan" at:

http://www.windsun.com/Batteries/Battery_FAQ.htm

http://img32.imageshack.us/img32/9595/batterydod.gif

(from site: http://www.mpoweruk.com/life.htm )


I agree about babying one's house bank, as long as it doesn't limit
the use of them. Like everything else, it's a trade off.

Here's data from real world experience. It's simply what was, with no
claims:

Back in my EV days, we had a group of about 30 that had built our own
cars or pickups. Each one of them used 20 golf cart batteries in
series.

Note that we all recharged at the C/10 rate ( Amp Hour Capacity
divided by 10 ) and recharged daily. Next to overcharging, the next
best way to destroy a lead / acid battery is to delay charging,
allowing sulfation. We made very sure to keep the electrolyte above
the plates and we did an equalizing charge monthly.

We got an average of 3,600 charges, with a few getting about 7,000.

To explain, our batteries lasted 8 to 12 years. These were our regular
cars. Some of us commuted to work daily. Some barely took the surface
charge off the batts most days, some slmost killed them dead each
workday. That doubled figure were for the few that had really long
commutes and/or their workplace supplied sockets to recharge.

Two of the group rigged up a generator on a trailer to extend their
range. Note they couldn't pull a large enough generator to go
indefinitely, just enough to double or triple the range. The motors
drew about 140 Amps or so at highway speeds.

This seems to say that lead / acid batteries are somewhat like a clock
- wind it up once and it's going to work for X length of time. The
fact that regular car batteries seem to last about 2 years says the
same thing.

Note that we all had several batteries fail at one time or another
during that period. I had one go after a couple months that was
replaced under warranty. I don't remember now just when, but I had two
others go out over the years.

To repeat, we all got 8 to 12 years from our batteries, whether we
discharged them to 10 or 20 or 50 or 70 or 90 per cent daily. We got
many more cycles than the graphs say - most of us should have gotten a
year or two or three. Maybe because we did otherwise baby them, or
maybe because the published figures are worse case, or both?


In any event, if I were to be a weekend sailor and planned on
discharging to 20% or so, I don't think it would be worth it to buy an
extra pair of batteries and have the extra weight and space taken up.
I'd still be getting a pretty long life out of them. Long term
cruising is a different story - I packed 'um in, as many as I could!

Rick

Interesting, great project!

Our house batts have not done nearly as well since we are now on our
3rd set in 6 years. The latest was installed last year before our 6
month Caribbean cruise and they show signs of doing better than
previously but there are reasons for that. We are now using Trojan
T-145s instead of T-105s, and I'm being really, really careful with
them. The first set was from Sam's Club and they were half dead after
just 6 months of liveaboard cruising but I'm sure some of that was my
fault.

My quest now is for an alternator that can recharge them without
toasting itself in short order. Meanwhile I have to be careful to
only recharge one bank (4 batts) at a time.

On Sat, 16 Oct 2010 09:35:29 -0400, Wayne.B
wrote:

Our house batts have not done nearly as well since we are now on our
3rd set in 6 years. The latest was installed last year before our 6
month Caribbean cruise and they show signs of doing better than
previously but there are reasons for that. We are now using Trojan
T-145s instead of T-105s, and I'm being really, really careful with
them. The first set was from Sam's Club and they were half dead after
just 6 months of liveaboard cruising but I'm sure some of that was my
fault.

Written with a smiling tone of write....

It does sound like you are doing something wrong. They should last
much longer. Maybe some rambling about the care and feeding...

The quickest way to destroy is to allow the electrolyte to get below
the top of the plates.

Number 2 is to consistantly overcharge. A possibility here is the
alternator. Another that I've seen do the job is a non-automatic AC
charger or an automatic one that is not cutting off, or cutting off at
too high a voltage. I had one that suddenly upped its cutoff voltage
to the point it would rarely cut off. It's now a mini fish reef.
Another battery murderer are solar panels with no regulator.

Number 3 is periods without recharging. It's best to recharge within
24 hours, if possible. One scenero is not using the boat for a while
and not using an automatic charger. The batteries will of course
self-dischagre.

Number 4 is not doing an equalizing charge regularly. This is like
Number 3 in that some of the cells will wind up at a lower charge and
those cells tend to be more and more discharged as time goes on. This
is also a reason to change both of the batteries in a series bank when
one fails. The idea to to match the series pairs as closely as
possible. It's not necessary to match on the parallel side. You can
mix those up any way you want, even to sticking a 12V, 100 AH battery
in there with no harm.

Note that if one cell on one battery is very much more discharged or
"bad", the rest of the pairs will be constantly "charging" that pair.
This results in ruining the other battery of the pair from constantly
"overcharging", and has occasionally resulted in the "bad" cell
actually getting a reverse charge (swapping + and - poles).




My quest now is for an alternator that can recharge them without
toasting itself in short order. Meanwhile I have to be careful to
only recharge one bank (4 batts) at a time.

Do you have temperature sensors hooked to the regulator? That's a very
good idea on a high-output alternator. Another "battery saver". Also
be aware that charging at more than C/10 will shorten the life a bit,
and of course like everything else battery, the higher the charge rate
the more effect.

Hope this is some food for thought.

Rick

The microwave goes overboard.

Use the stove for cooking.
When heating water, make extra and store in a thermos.

I'm still using my laptop for "TV".
No external display yet.

All lights converted to LED.



Remember you don't want to totally kill your batteries.

Adding another pair of batteries will of course double that and is the
less expensive route then LED lighting.

not so sure about that one...


Rick


--

Richard Lamb

On Thu, 14 Oct 2010 11:35:31 -0500, CaveLamb
wrote:

The microwave goes overboard.

Oh no, don't do that. How will you reheat the left overs, cook the
instant frozen dinners and warm up the coffee? The microwave also
makes a good bread box when not heating things and I understand some
people have used them to dry their wet cat (once).

In all seriousness, they are very efficient at quickly heating things,
and for you propane and alcohol users, provide an alternative way of
cooking if the fuel runs out.