questions re batteries

[blighbaum]

Is there any particular brand or type of batteries you all recommend that can survive the deep discharges that can occur in a solo offshore trip? Do you recommend one starting battery and one deep cycle house battery, or two dual use batteries? On the LongPac, I had two dual use marine batteries from Costco, and I found that after a deep discharge they would no longer take much of a charge. In fact, the circuit breakers on the alternator would trip when I tried to charge them, compounding the problem.

Thanks for any help you can give me. - Tom Kirschbaum, Feral

[AlanH]

I don' t have an engine to start now, but I have to say that I HATE the dual-use batteries that a certain retailer whose name rhymes with "nest between" sells.

If you need a starting battery for a big engine, then have a starting battery. If you need deep-cycle, get deep-cycle. Beyond that, I dunno.

Also, I've learned on this last long sail that chatting on the radio at 25 watts really does drag down the batteries.

[Lightspeed]

Tom - You bring up a very good question. I have heard that 2-6 volts batt ganged together will give more amp hours output for the house bank than 1-12 volt of the approximate same size. Perhaps we can get a battery expert out there to answer that question....Rick....Lightspeed

[tiger beetle]

I have heard that 2-6 volts batt ganged together will give more amp hours output for the house bank than 1-12 volt of the approximate same size.

A 12v single lead-acid battery has just as much energy available as 2x6v lead-acid batteres of identical capacity. Each will discharge to 50% voltage (12.0v).

There is a slight charging efficiency gain to be had by going with 6v golf carts wired in series as compared with a single 12v battery. Along those same lines, physically taller batteries have an longevity gain. That said, during the conversations over the radio on the return sail from Hawaii the general consensus has been that the best bang for the buck is to utilize inexpensive 6v golf cart batteries in series/parallel wiring to produce 12 volts, with a separate 12v dedicated starting battery.

Beetle's battery bank is 4 x 275AH 6v lead-acid golf carts for the house (from American Battery Company), and a mid-size truck starting battery (from Kragen) to fire up the diesel. The house bank can be parallelled with the starting bank (via a 1000 ampere current-handling solenoid) to push all avaiable energy to the engine starting motor. This has worked well for the last four years in the boat, and has done two runs across the pond. The house batteries were $70 eaches, and the start battery was similarly priced. I've been careful to inspect and to up the water monthly and prevent the top surface of the plates from being exposed to the air (which kills them).

If you are into the ULDB experience then advanced gas matte (AGM) batteries have a slightly higher energy density and are therefore lighter for the available energy than lead-acid, though you have to accurately set the charge-points to avoid cooking the batteries. If you really want to go lightweight there is experimentation going on with Lithium (L-ion) dry cell batteries in large banks - though this is possibly beyond the pocket book of most of us, and also represents a significant fire hazard.

- rob/beetle

[AlanH]

Beetle's battery bank is 4 x 275AH 6v lead-acid golf carts for the house (from American Battery Company), - rob/beetle

Rob, just your informed opinion, since at $75 a pop, these aren't much more expensive than "regular" 12 deep cycles....

What say you to teaming up two of these babies in a SC27? Would that give me 275 amp-hours at 12 volts? I might build a specialized box for this, amidships if it seems sensible. 275 amp hours sounds really nice, as I find that I burn through the 150 ah's in my two "regular" wet cells awfully fast.

While you're at it, care to explain how you have your solar panel output run into your battery bank?

[blighbaum]

A friend recommended Optima batteries, which have spiral shells and which cost more than double what a regular deep cycle battery would cost. Does anyone have any experience with these? I'd be willing to pay if they can indeed survive a deep discharge. BTW, I am not too concerned about weight and my engine is a tiny BMW MD7 that I can start with a crank (except in emergencies!) so I don't need a big starting battery. - Tom Kirschbaum, Feral

PS: Alan, congratulations on your qualifier, and thanks for the new forum!

[tiger beetle]

What say you to teaming up two of these babies in a SC27?

I would be concerned about putting all eggs in one basket for a run to Hawaii; if you have effectively a single battery on board and any one cell fails you have no backup. I would lean towards two independent 12v batteries wired in parallel through a battery switch such that if one battery fails you can take it out of the loop (via the battery switch) and still have one battery left. If you go with 2x6v batteries and either one fails you've lost the entire house bank - not a good position to find one's self in mid-ocean.

Look at ABC and US Battery Company - both make good products which can be purchased locally from distrubitors at reasonable cost - no need to pay for the markup at a marine retailer.

While you're at it, care to explain how you have your solar panel output run into your battery bank?

The panel streams electrons to a NC25A-12 charge controller made by Flexcharge, with a hi-power diode (16 amp) on the positive lead purchased from Allied Electronics in Texas.

It's completely automatic, there's a voltage drop through the diode which is a bummer but that's how diodes operate, and I simply don't have to think about it - which is nice.

The backside of the controller is wired directly to the house bank (via the Ample Power Energy Monitor II shunt) on 2/0 battery cable - bigger is better in cabling and be certain the connections are clean without no corrosion. Definitely carry a bit of 120 grit sandpaper on board for cleaning battery terminals and cable lugs.

Allied Electronics
http://www.alliedelec.com/
part:
http://www.alliedelec.com/Search/Pro...&tab=specs#tab

Flexcharge
http://www.flexcharge.com/
part:
http://www.flexcharge.com/flexcharge...c25a/nc25a.htm

- rob

[haulback]

Alan:
I'm mid way into replacing solar array on my boat, using 5-43 watt Kyocera panels. ($235 USD each from an outfit in Renton Wa.) They come well recommended as a quality PV module - take care, all solar panels are NOT created equal!!!

Previously what I was using to control flow from panels to batteries more or less allowed full flow of power until batteries were full, then shut down solar input flow altogether. I could do this because I had a relatively low potential power output as compared to battery storage capacity. The fancier ones start to stage down flow to batteries as they reach a higher charge. Much like an battery/alternator/regulator system on an engine-driven charging circuit

New set-up required something a bit 'smarter' - Looked around at what was available in the way of controllers and found out about what they call MPPT charge controllers (maximum point power tracking) here's an explanation....

http://www.blueskyenergyinc.com/solarboostreview.htm

Almost sounds like getting something for free. doesn't it???

I ended up buying the Solar Boost 2000E (best price was CDN $209 and another $29 for battery temp sensor) There are a few others out there that are made for small boat-sized systems, but this one seemed to work best for my application

Food for thought

Jim/Haulback

[seabird51]

A battery wholesaler in Fresno is fascinated with our SHTP and probably thinks I am crazy but he has been very helpful to me. He supplies most of the golfcart batteries in the Central Valley. He handles many brands including Optima's and Trojans.
Seabird is a 24v boat and has 8 6v Trojan T-105's @225 AH each in series and parallel (one big housebank). He talked me away from the Optimas and the higher end Trojans as not worth the extra expense for a few more amps.
I installed the T-105s in April 2006 for the SHTP and they are still doing very well and need a little water every 4 months living on a Heart Interface charger.
For the basic 12 v installation a pair of 6v T-105's in series should work very well.

Does anyone have some knowlege of reliable flexable solar panels to mount on the bimini?

Lou

[glythcott]

Does anyone have experience using small gas-driven generators. I'm wondering if I could run one a couple of hours each day to charge my battery system. Also could I use it while I was transmitting or would it cause interference?