Big Battery Charger

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timjet

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It seems strange but in looking for a battery charger it seems a large 100 to 120 amp 3 bank battery charger can't be found. There are several battery charger/inverter combo's that are this big, but not battery chargers.

Anybody know of any?
 
The bigger problem is that only on dock current or a large 10KW or larger noisemaker could a big charger be expected to produce near rated output..

Want big DC? , get a big alternator and a smart V regulator.
 
timjet wrote:
It seems strange but in looking for a battery charger it seems a large 100 to 120 amp 3 bank battery charger can't be found. There are several battery charger/inverter combo's that are this big, but not battery chargers.

Anybody know of any?

It's probably hard to find one because there is little need for one in the recreational boating industry.

Why would you need such a high powered charger?* Will your batteries accept a 120 amp charging current?
*
 
rwidman wrote:

It's probably hard to find one because there is little need for one in the recreational boating industry.

Why would you need such a high powered charger?* Will your batteries accept a 120 amp charging current?
*

*Referencing my "Understanding my Genset Alternator" thread below; I have 4 110 AH AGM's for house bank, soon to be added 2 Engine start wet cells and a single 92 AH genset start battery. It's my understanding the AGM's will take a 100 amp charge each, so with all these batteries I think I need at least a 100 amp charger or the genset is going to run many hours to charge up all these batteries.*

As noted in the referenced thread, my electrical use is about 150 amps per 12 hours period, so a large charger is necessary.
 
FF wrote:
The bigger problem is that only on dock current or a large 10KW or larger noisemaker could a big charger be expected to produce near rated output..

Want big DC? , get a big alternator and a smart V regulator.
*My genset is 7.5 KW and if my figures are correct: 7500 watts/120volts equals 62.5 amps. I believe the specs on a 100 amp/ 2000 watt magnum charger/inverter states an amp draw of 15 amps when in batt charging mode. Is my thinking not correct??


-- Edited by timjet on Monday 5th of March 2012 09:51:17 AM
 
timjet wrote:rwidman wrote:

It's probably hard to find one because there is little need for one in the recreational boating industry.

Why would you need such a high powered charger?* Will your batteries accept a 120 amp charging current?
*

*Referencing my "Understanding my Genset Alternator" thread below; I have 4 110 AH AGM's for house bank, soon to be added 2 Engine start wet cells and a single 92 AH genset start battery. It's my understanding the AGM's will take a 100 amp charge each, so with all these batteries I think I need at least a 100 amp charger or the genset is going to run many hours to charge up all these batteries.*

As noted in the referenced thread, my electrical use is about 150 amps per 12 hours period, so a large charger is necessary.

*Tim,

You don't want to mix wets and AGMs.* Even as separate banks.* Your chargers and Alt regulator can not be set to handle both at the same time.* One or the other. The charging voltages between wet and AGMs*are different as is the program.

You may get away with wet cells for the starts and gen start if you are using an Echo charge but you need to check with the Echo charge folks.* The higher voltage of the AGMs going to your wet cells may boil water out.

Two Grp 31 AGM*as start batteries should be fine.* One might be enough.* It really doesn't take much to start the engine.* It is high draw for such a short period.
 
*
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JD wrote:
*Tim,

You don't want to mix wets and AGMs.* Even as separate banks.* Your chargers and Alt regulator can not be set to handle both at the same time.* One or the other. The charging voltages between wet and AGMs*are different as is the program.

You may get away with wet cells for the starts and gen start if you are using an Echo charge but you need to check with the Echo charge folks.* The higher voltage of the AGMs going to your wet cells may boil water out.

Two Grp 31 AGM*as start batteries should be fine.* One might be enough.* It really doesn't take much to start the engine.* It is high draw for such a short period.

I believe you are confusing AGM batteries with Gel batteries.

AGM and flooded cell batteries use the same chemistry and the charging is close enough that it's not a problem.* Many chargers use the same setting for both and a different one for Gel batteries.
*
 
rwidman wrote:JD wrote:
*Tim,

You don't want to mix wets and AGMs.* Even as separate banks.* Your chargers and Alt regulator can not be set to handle both at the same time.* One or the other. The charging voltages between wet and AGMs*are different as is the program.

You may get away with wet cells for the starts and gen start if you are using an Echo charge but you need to check with the Echo charge folks.* The higher voltage of the AGMs going to your wet cells may boil water out.

Two Grp 31 AGM*as start batteries should be fine.* One might be enough.* It really doesn't take much to start the engine.* It is high draw for such a short period.

I believe you are confusing AGM batteries with Gel batteries.

AGM and flooded cell batteries use the same chemistry and the charging is close enough that it's not a problem.* Many chargers use the same setting for both and a different one for Gel batteries.
*

*You may be correct as to charging rates.* Sorry.
 
If the AGM batteries are thin plate technology then the charge characteristics are much different from flooded cells. The best way to charge batteries is to use a charger that will react to the needs of that particuler bank, a multi bank charger will usually react to the active bank and the other banks will be over charged. Check the battery recommended charge and look at how the charger works, hopefully it is fully adjustable and doesn't just use presets.
 
The charger should correctly charge what ever kind of batteries you have.*That is why I have recommended having more than one charger and being able to gang charge the batteries.*The best bang for the buck is still the good old flood/wet cells for start and/or deep cycle house as they do not require a fancy expensive charger.* Gel and AGM are not recommend as a start battery and both require a 14.2+ volt and a 3 stage charger.* So before you spend the money make sure you have the correct charger and understand the battery requirement.* The gel over all is a better house battery than the AGM.*****
 
timjet wrote:FF wrote:
The bigger problem is that only on dock current or a large 10KW or larger noisemaker could a big charger be expected to produce near rated output...
*My genset is 7.5 KW and if my figures are correct: 7500 watts/120volts equals 62.5 amps. I believe the specs on a 100 amp/ 2000 watt magnum charger/inverter states an amp draw of 15 amps when in batt charging mode. Is my thinking not correct??


-- Edited by timjet on Monday 5th of March 2012 09:51:17 AM

Tim:* You're right but I think you will only get the published output out of your charger/inverter*under the conditions that FF*has stated.* I don't know the reason why but that's been our experience and we have learned to live with it.**We have a 125 amp charger on our 2800 watt inverter and get ~102 amps max out of the charger powered by an 8kW generator.* Our last boat had basically the same specs on the charger/inverter with a smaller (5kW) generator and we saw the same thing.* We have now added a second 40 amp charger and get a maximum of about 132 amps out* both chargers running at the same time, about 80% of the charger specs combined before they taper off.* Maybe someone can explain why?
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Typical (Sears Diehard Platinum Marine for instance) AGM batteries can be dropped in place of flooded cell batteries with no adjustment to either the engine's alternator/charging system, or an external charger powered by shorepower or a genset. These batteries are fine for starting the engines or genset.

These AGM batteries cost a little more than the equivalent flooded cell batteries, but they do not need periodic inspection and topping off with water. On some boats (mine) this is a significant advantage as the batteries can be hard to get to and hard to see into or add water to.

While Gel batteries may or may not be better than AGM or flooded cell batteries for a house bank, having a combination of Gel and AGM or flooded cell batteries on a boat really complicates the charging system. Seperate appropriate chargers can be connected for genset or shorepower charging, but it would be very difficult to rig the engines to supply a proper charging voltage and current for two different requirements. Flooded cell or AGM batteries are much more readily available than Gel batteries if you find tourself needing a battery in a hurry in some out of the way place.
 
Thanks Ron.

From my research you are correct, mixing wet cell and AGM's is OK because the bulk and float charges are very close. No so with*Gel Cell's

I'm still trying to decide on a battery charger. There are some pretty cheap ones out there that I don't think will hold up in a marine environment.

I have a 30 amp 3 bank Charles battery charger and wonder if I can incorporate this into my future setup. I'm thinking of moving all my house batteries to one battery bank, that;s 4 AGM with a total of 440 AH, buy a charger for these batteries and use the current 30 amp Charles charger to charge the gen start and engine start batteries which are on separate banks.

I think I still need a 100 amp charger or one close to that capacity if I don't want to run the genset for hours. Using 150 amps every 12 hrs would require an hour and a half gen run time with a 100 amp charger. Actually it's much longer than that because from what a tech at Magnum said AGM's will take 100% charge until 80% full then the AGM's acceptance charge falls off rapidily, like a wet cell.* BD has mentioned that AGM acceptance rate is 100% until full. Which ever is true I can accept an 80% charge which should take an hour.
 
timjet wrote:
Thanks Ron.

From my research you are correct, mixing wet cell and AGM's is OK because the bulk and float charges are very close. No so with*Gel Cell's

I'm still trying to decide on a battery charger. There are some pretty cheap ones out there that I don't think will hold up in a marine environment.

You're welcome.

I wouldn't use anything but a charger designed and built for marine use on a boat.* And if your boat is gasoline powered and the charger is in the engine space, you need an ignition protected charger as well.

There are a few well respected brands so try to select one of them.* Their customer service people may be able to help with your choice.

My choice was a Pro Mariner when I had to replace a failed Xantrex charger a year or so ago.

*
 
" about 80% of the charger specs combined before they taper off. Maybe someone can explain why? "

Small noisemakers make some power , but the sine wave they produce does not have the power of a shore power sine wave, its as tall (the voltage is OK) but never as broad .

Power is ALL the area included in the sine wave so a skinny wave has less power to offer the batt charger.

Also many batt chargers rating is BS, they claim and make full rated out on a dead battset 10.5V or similar.

Far different concept to make that full rated output at 14.4 , do the watts and see.

*

10.5 x 100=** or 14.4 x 100=


-- Edited by FF on Tuesday 6th of March 2012 05:55:07 AM
 
both chargers running at the same time, about 80% of the charger specs combined before they taper off.* Maybe someone can explain why?
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That brings up a question. Would there be a problem with charging a 3 bank set up if one charger was connected to charge all 3, and an inverter charger was connected as an additional charger to the house bank? Moonstruck has a 12 kw generator, and should well be able to handle the load.
 
For the fastest charge of a batt set that has the ability to accept a huge charge , an alternator and smart regulator still makes the most sense.

A small charger can handle the tiny loads of the starts.

The alt setup should monitor the batt case temps during the charge.

FF
 
For the fastest charge of a batt set that has the ability to accept a huge charge , an alternator and smart regulator still makes the most sense.

A small charger can handle the tiny loads of the starts.

The alt setup should monitor the batt case temps during the charge.

FF

Thanks FF. I am looking into that. However sometimes we will anchor in one spot 3 or 4 nights. I am looking for a way to charge quickly without firing up a couple of 500 hp diesels. It seems in that case the generator and large charger is a better option. Just wondering how the 2 chargers would work together.
 
First, multi-bank chargers which are programmable so that the charge profile for each bank can be seperately specified to suit different battery technologies, are readily available: Victron & MasterVolt have produced these for some years and most recently, Charles Industries has released a new "Intelligent Marine Charger" (IMC) series that does this. These were favourably reviewed in PassageMaker last month. It is really no big deal and since different battery technologies SHOULD be used for different on-board applications, they are a good idea. Second, it has been pointed out on another post that an alternative approach is to have a single charger focussed on the House bank and to charge start/genset/thruster/electronics batteries using programmable (for different battery technologies) charge-transfer devices off the House bank: products like Balmar's Digital Duo Charger or the Ample equivalent. Third, most competent installers of battery chargers will use the dip-switch or other control devices within the charger to de-rate the maximum output of the charger at least somewhat: for a 120A charger, it is not uncommon for an installer to de-rate these to 105-110A, for example....just so the charger is not operating right at its design limit. Further, the max rated output of a charger is achieved only at a specific ambient temperature, most often 20C; if you are in Florida in Summer...or if your charger is in a hot/poorly ventilated space, it will de-rate itself. (Good idea to install a brushless computer fan to cool the charger - or inverter - adjacent to help minimize this ambient temperature de-rating). Finally, if you only have a 440AH bank, that is not very big by today's standards and the C20 rule would suggest that for AGM or Flooded, the max charge should be only 88A anyway. C25, the absolute top end, would require 110A...not 120A...and I cannot imagine why you would go there. If your biggest concern is minimizing generator run time, then go for AGM's as they will accept the 88A charge for longer (ie they will stay in Bulk Charge mode longer) and so will re-charge faster overall....but you are reducing generator time at the expense of higher-cost, more charge-volt-sensitive battery technology. If you really want to impact genset run-time, get a quality, multi-stage external regulator that has BOTH battery and alternator temperature sensors so your alternator(s) are operated at maximum output consistent with not overheating either alternator or battery; and then to take it even further get a high-out alternator (120A+); and if you have twins, direct the charge from both alternators to the house bank. You will then find that even short cruises of 1-2 hours between anchorages put a lot back into the House bank such that genset operation for battery charging can be just something that happens in the background when you operate the genset for cooking, water heating, air-con or whatever.
 
Problem with 2 independent chargers both connected to same battery/bank is that their voltage sensors will confuse each other: each will 'see' the charge voltage being applied by the other charger and not the real charge of the battery and so will step back their charge delivery, wrongly sensing a charged battery. You can gang together chargers of the same type often, but then you only connect one voltage sensing wire (and one battery temp wire) not two.
 
Problem with 2 independent chargers both connected to same battery/bank is that their voltage sensors will confuse each other: each will 'see' the charge voltage being applied by the other charger and not the real charge of the battery and so will step back their charge delivery, wrongly sensing a charged battery. You can gang together chargers of the same type often, but then you only connect one voltage sensing wire (and one battery temp wire) not two.

Thanks, both posts are excellent info. I like your and FF's suggestion of a larger alternator and multistage regulator. I am looking into that. It looks like I will just have to put up with a little longer generator run time for the 60 amp charger. My house bank is AGM 510 amps.

My present set up is an 80 amp alternator on each engine. The port engine is dedicated to the house bank. That bank can be tied in with the others via a parallel switch which has never been used. I believe the larger alternator on the port engine will take care of it.

Thanks for the good info. All of you guys with the real technical skills are a huge asset to this forum.
 
Don, with 510 amps AGM the total capacity of the charging system doesn't need to be bigger than 100 amps or so. I have 1300 amp AGM capacity and they will only absorb around 220 amps for 30 minutes before the absorbtion rate starts tapering off. This is from a 35% rate of discharge.

For future reference, Ample Power in Seattle makes a modular ac charger that goes up to 220 amps 12 or 24 Dc.
 
The noisemaker would spin the alternator NOT the main engines.

Most noisemakers have a kit to install a pulley on the set as Hyd power , bilge pumping , deck wash, mechanical refrigeration or an alt. are common.

The noisemaker engine mfg will usually have a MAX for the power that can be front extracted.

This is usually just a side load limitation , so a dual pulley with another user on the other side may allow a really large alt.

The limit is frequently a Hyd problem , as some can eat BIG HP.

A second advantage for a cruiser is an alt can be rebuilt or carried as a spare.

Sending some majic box back to the Mfg may take lots longer.

FF
 
rvolkjr

Tim: I really appreciate the comments from all on the battery charger size issue. By the way I do have a 2011 brand new, in the unopened box, Xantrex 60 AMP three bank charger/inverter for sale. Drop me a note if you have any interest.
I have an 1981 IG36 which we restored completely and part of that included changing out the charging system. I have twin Ford Lehman 120s and a 5.0KW Onan genset. We carry three batteries: and 8D, and 2 4Ds. The vessel originally had a 30 AMP charger which we changed to a 60 AMP Mastervolt which seems to work just fine. We also have 2 inverters aboard (400 & 2000) which we run when we want quiet and not the gen set running. Over the past 5 years we have had this system it has worked well with flooded batteries, which we check every month. So far, so good! Bob
 

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