Size of Battery Charger

[zboss]

I'm not sure it make's sense for me to invest $1300 in a Mastervolt MasterCharger 12/100 for $1300 when I can only use that power on the dock when there is ample power and time to charge the batteries. Also, when at a marina I am not using the autopilot, nav, nav lights, ET AL. that suck up power.

So, unless there is a compelling case that I will hurt my batts, it makes sense to buy the smallest charger needed that still tops the batts up during a usual 1 night marina stay and a honda 2000 which I can use on passage. I can get both for that $1300.

In the case of the Lifeline Batteries that would still mean a 100 AMP charger.

[stevebalbert]

Hi, A thought on your battery selection. If you plan to cruise in foreign waters I'd recommend lead acid golf cart batteries such as Trojan. These batteries are available worldwide, other types are not. And having a battery go bad is a very real concern. If you are cruising stateside other type of batteries are more readily available.

As for charging we have a 480 amp battery bank, 100 amp alternator, 50 amp 120V battery charger as part of an inverter, 10 amp 240V charger for those counties and marinas where 240V is the norm, like most of the world. As mentioned before our Honda 2000 generator will run the charging side of the inverter as long as all other loads are turned off.

Steve
S/V Farfetched

[smac999]

the batteries won't last as long with the small charger. with 500ah agm bank I would be at 100a min.

how much difference it makes to the batteries though. maybe not that much. even if they die 1-2 years eairler. putting that 1300 into new batteries might be cheaper then the charger

and if you're going to spend 1300 on a mastervolt charger, you'd be better off buying a 2000 or 3000w inverter/charger like the magnum. basicly the same price but you get the inverter as well.


I bet with that 30a charger you're only putting 10-20a into the battery though. as you're still using battery power when pluged into the dock.

[Forever Freedom]

Originally Posted by zboss

Folks,

I need a gut check.

I need to replace my battery charger. I currently have a 270 AMP (90x3) battery bank, the charger, and a 90 AMP alternator.

I want to move up to a 500 AMP battery bank to support our future cruising wants.

When I talked to our local Electronics guy at the marina he advised Lifeline AGM's (4 x GPL-31XT) but also advised that I would need a 100 AMP charger to appropriately charge that battery bank.

Question: is a 100 AMP charger really necessary? If I am going to be hooked into a marina I'll be there at LEAST overnight, so 8 hours with a 30 AMP charger to top up 250 AMPS isn't really a problem. Is there something I am not getting? Am I getting sold on a Bill of Goods?

- z

You don't say what sort of charger you have; is it constant voltage? Programmable? 3-Stage? 4-Stage? What are it's Bulk Charge settings? What are it's Absorption Charge settings? What is it's Float Voltage? Without this data, no one can give you substantive advice, only hearsay.

[zboss]

Originally Posted by Forever Freedom

You don't say what sort of charger you have; is it constant voltage? Programmable? 3-Stage? 4-Stage? What are it's Bulk Charge settings? What are it's Absorption Charge settings? What is it's Float Voltage? Without this data, no one can give you substantive advice, only hearsay.

It irrelevant what charger I currently have... its trash and so are the batts. As I said previously, I am looking at Mastervolt MasterCharger 12/100.

[Forever Freedom]

Originally Posted by zboss

It irrelevant what charger I currently have... its trash and so are the batts. As I said previously, I am looking at Mastervolt MasterCharger 12/100.

My mistake! The 12/100 is for battery banks 200/1000 Ah. The 12/50 is for banks 100/500 Ah.

[Stu Jackson]

The short answer is that AGMs will accept a much higher charge than wet cell batteries. And the larger the house bank when drawn down to 50% by simple math means that you'll need more charging capacity if you want to charge in minimum time. In this case, then, the bigger the better.

[zboss]

Originally Posted by Forever Freedom

My mistake! The 12/100 is for battery banks 200/1000 Ah. The 12/50 is for banks 100/500 Ah.

No problemo... where did you get that sizing info?

I now understand why he is recommending what he has... I have room for the lifeline AGM's due to the height of space available, and per the manufacturer directives for these batts I need a charger which is 20% of the capacity.

I think I need to redirect him to the Trojans or similar, which was my first thought. What size charger is recommended for Trojans on a % basis?

Also, I am having trouble grasping what 1/C, 2/C, etc. mean. I understand that C means "overall capacity" but don't get the '1' or '2' designation.

- z

[twinboat]

One of the benefits of AGM batteries is the ability to charge them at a higher rate, but you need a high amp charger, and the power to run it, to get thet benefit. If you are going to use a small charger then I would suggest, just get regular Lead Acid 6 volt golf cart batteries. 2 sets of 2 would give you about 450 amp hours and you don't have to charge them 100% for long life. The down side is that you have to check the water once a month. I have been using 4 sets of Sam's Club CG2 batteries since 2010, cruising full time. Before i installed 675 watts of solar in 2012, I ran them between 60% and 80% charge, almost every day. If I was anchored or on a mooring, the only way to cruise on my budget, I would run my EU2000i 3 or 4 hours a day with my IOTA 55 amp charger to get them to 80%. If I was cruising, my 150 amp alternator would charge them to 100%. Since I installed the solar, they now run between 80% and 100% charge and the EU2000i is only used for A/C on real hot days.

[Patacha]

Hi all.

Chargers are rated at their maximum current (which is used in the "Bulk" charging stage).

Though Lead Acid baterries can take up to C/3 current at the Bulk stage (C=ah rating capacity @ 20hrs drain), I myself confidently feel that C/5 max and C/10 min Bulk charging current is a good aiming point when selecting a charger.

I strongly suggest you all study the newest A2B product line (Sterling and Digital Mobile Charge).

This line of products provide controlled 3-4 Stage charging to "dumb" (internal regulator) Alternators, effectively converting them to smart ones - without the need to modify the Alternator.


More over, it supports two banks (prioritizing the Starter bank), AND, most importantly, it will turn any "dumb" 12v power supply (available anywhere and cheap as hell...) to a smart charger (just connect a "dumb PS" with the alternator).

In this scenario, only one single charging controller manages the charging of the batteries...

[Patacha]

Originally Posted by zboss

No problemo... where did you get that sizing info?

Also, I am having trouble grasping what 1/C, 2/C, etc. mean. I understand that C means "overall capacity" but don't get the '1' or '2' designation.

- z

The rating convention of Deep Cycle is the Ah you get out of them when darining them from 100% (12.6-12.7v) to 0% (10.5v) over a preiod of 20 hrs.

For example: a 150Ah @ C20 mens that at 7.5 amps discharge over 20 hrs the battery will go from fully charged to fully dicharged.

When refering to a C/5 charge applied to such battery, we mean charging it at 150/5 = 30 A at the Bulk stage (up to roughly 80% of the rated capacity).

hope it is more clear now, Z...:-)

[Saltyhog]

Z- Where are planning on installing your new batteries? I ask because I believe our boats are very similar. Mine is a 1987 B-Plan. If your plan is to keep the batteries under the pilot berth, I don't think there is room height wise for golf-cart batteries. Your "electronics guy" is correct in that a Lifeline AGM bank of 500 AH would be best served by a charger of at least 0.2C, and that is 100 A. I've heard good things about Mastervolt. That's something else you should keep in mind, relative quality and lack of problems with the equipment you are selecting. Lifeline's are good batteries if used correctly. While your at it, you probably want to consider solar/wind and be sure you have a good external regulator for your alternator. Energy needs, production, and storage is a package deal that all need to play well together.

[stevebalbert]

Originally Posted by stevebalbert

Hi, A thought on your battery selection. If you plan to cruise in foreign waters I'd recommend lead acid golf cart batteries such as Trojan. These batteries are available worldwide, other types are not. And having a battery go bad is a very real concern. If you are cruising stateside other type of batteries are more readily available.

As for charging we have a 480 amp battery bank, 100 amp alternator, 50 amp 120V battery charger as part of an inverter, 10 amp 240V charger for those counties and marinas where 240V is the norm, like most of the world. As mentioned before our Honda 2000 generator will run the charging side of the inverter as long as all other loads are turned off.

Steve
S/V Farfetched

Currently in Vanvatu

Some more info: We have 440W/over, of solar. This setup is continually charging the battery bank during the day. Over night anchored we see a drop in the 45A to 65A range.which is easily made up once the sun rises.The drop is mostly due to the reefer, and if are doing an over nigh passage and using the under deck hydraulic auto helm. Some nights it is necessary to start the engine and run it for an hour. This is where the larger alternator works well...less engine time.

By late morning or early afternoon, assuming not to many clouds, we have full charge. Then time to run the water maker, which the solar can easily handle with no drain on the batteries.. Lead acid batteries continually cycled in this manner have lasted us 7 years and were preforming well when we replaced them before leaving Mexico to the Marquesas. Cost to replace 4 deep cycle 6V Trojan 125 batteries is just under $700.

[zboss]

Originally Posted by Patacha

The rating convention of Deep Cycle is the Ah you get out of them when darining them from 100% (12.6-12.7v) to 0% (10.5v) over a preiod of 20 hrs.

For example: a 150Ah @ C20 mens that at 7.5 amps discharge over 20 hrs the battery will go from fully charged to fully dicharged.

When refering to a C/5 charge applied to such battery, we mean charging it at 150/5 = 30 A at the Bulk stage (up to roughly 80% of the rated capacity).

hope it is more clear now, Z...:-)

OK - THAT makes sense. Thanks.

[zboss]

Originally Posted by Saltyhog

Z- Where are planning on installing your new batteries? I ask because I believe our boats are very similar. Mine is a 1987 B-Plan. If your plan is to keep the batteries under the pilot berth, I don't think there is room height wise for golf-cart batteries. Your "electronics guy" is correct in that a Lifeline AGM bank of 500 AH would be best served by a charger of at least 0.2C, and that is 100 A. I've heard good things about Mastervolt. That's something else you should keep in mind, relative quality and lack of problems with the equipment you are selecting. Lifeline's are good batteries if used correctly. While your at it, you probably want to consider solar/wind and be sure you have a good external regulator for your alternator. Energy needs, production, and storage is a package deal that all need to play well together.

Yes, planning on putting them under the pilot berth. There are currently 3 x Group 27 plus hardware mounted in there but there is a good 4-5 inches available above the top of the existing batteries. Just enough to squeeze in the lifeline batts I think. The electric guy is checking it out this week.

I believe I have room for six 6V lifeline GPL-6CT batteries. The existing 3 DC27s sit side by side... I can squeeze four lifelines into the same space. Then there is room for one more in that location. I would put the sixth into the starting battery area.

A four winds II came with the boat but I am not sure its working. We plan on adding Solbian panels to the dodger (2 x 50 watt) and probably (4 x 50 watt) to the bimini top. That would give us 300 watts of solar and maybe a working wind generator. We currently have a 90 AMP balmar alternator. I'm not sure if its externally regulated or not... have not gotten that far in my analysis of the vessels electrical system yet.