New Battery Charger

[HeartWarrior]

I have been working for the past year to upgrade and "clean up" my new to me 1988 IG 40. The current battery setup is simply 2 8D 200ah house/starter batteries(old school wet cell), one for each engine. It has a simple Perko 1/2/both switch, which is only used for the 2 house / starting batteries. The generator has its own group 31 starting battery (agm).

I am looking to replace my current 40 amp 3 bank charger with something new but not break the bank. The current charger is original.

Based on all my study, I see that everything I read says that for group 8D wet cells you need to jump up to the more expensive battery chargers. I'm just wondering if anyone is using the lower cost units at the same amperage (say 40amp output) to charge there batteries? I have new 70AMP alternators on each of the engines which is more than enough to keep the batteries at a full charge.

Thanks for any input or manufacture type recomendations.

 

[O C Diver]

Ok, first of all, wet cell 8Ds aren't deep cycle generally. So they're not going to live long in that capacity if you're pulling them down to 70%. Secondly, most wet cell deep cycle batteries don't want to be recharged faster than 15% of their rated capacity per hour. It's important to also understand that rated capacity in deep cycle has nothing to do with CCA (Cold Cranking Amps). So if you're planning to use a basic non programmable battery charger, the capacity of the charger needs to roughly match your battery size.

There's a lot to be said for a programmable battery charger that can be adjusted to bank capacity and changed to different battery chemistries should you desire to change the battery bank to something with more capacity.

Ted

 

[tiltrider1]

The problem with low end battery chargers, they are designed to charge one battery up to a group 31 size. As soon as you add a second battery they will charge for 48 hours and then go into a fault mode. This means they stop charging all together. Same result with an 8D or golf cart batteries in series. The cheapest battery charger that will do the job and that I am aware of is the xantrex 2 bank 10 amp charger at $180.

 

[Comodave]

I agree that 8Ds are not the best for house batteries. Maybe leave 1 for starting both engines and replace the other one with 6 volt golf cart batteries. I like Promariner battery chargers, but there are other ones that are also good. I would definitely want a dedicated house bank of deep cycle batteries.

 

[FlyWright]

I've had very good service from my single bank 55A Iota charger on my 660AH 6xGC house bank over the past 6 1/2 years. It replaced a worn out 3-bank 30A ProMariner. I use a switched combiner to share the charge with the start battery if/when desired.

https://www.altestore.com/static/datafiles/Others/DLS Owners Manual.pdf

 

[firehoser75]

HW,
You have received some good advise so far. Be aware, that most boat batteries don't die a "natural" death, they are murdered by their owners. Lead acid batteries (and many other types like AGM) do not tolerate operating regularly in a "partial state of charge". Doing so regularly will greatly shorten their "expected" life. This means that to obtain the best life from deep cycle batteries, they should be regularly recharged to 100% full charge (best after each discharge cycle). Relying on a "stock" engine alternator to achieve this is close to "folly". It can take 6 hours (or more) of run time to achieve a full 100% charge (and this is with a 'smart external" regulator), the last part of the charge cycle taking a very long time. Plus, these "internally regulated" alternators are not really designed to recharge deep cycle batteries effectively. They are designed to "top up" a start battery after just starting the engine. If you are regularly 'plugged in" to shore power, then a full recharge usually happens overnight with a good 3 stage (adequately sized) charger. A good solar system can "top up" batteries to a full 100% charge under the right conditions. Without solar, and using a "too small" charger will greatly increase the required generator run time to obtain an adequate charge (hours of run time). Or, the other alternative, is just to replace battery banks every couple of years. This is probably more expensive in the long run and can also lead to "issues" during your cruising.

The Iota charger with the IQ4 "smart charger" attachment could work well, and like some of the others, I like the Promariner chargers. Do not go too cheap, as the "savings" may actually cost you more in the long run.
You should "redesign" your entire system, unless you plan on either being a "dock queen", or are selling soon. Otherwise you could be spending good money after bad.
JMHO.

 

[Flatswing]

I recommend MarineHow.com as a trusted resource. Rod also has Sterling chargers on sale presently. Once your 8D's die their natural death, consider replacing with 6GC2's FLA or L16 FLA (if vertical height and $$ is not an issue). A couple of GC-2s will have more than enough cranking amps for your diesels and give you true deep cycle batteries for overnight. L16's & GC2's share the same charging parameters. optimally ensure that whatever charger you buy has a customizable output so that you can match it to your batteries manufacturers specs. and change in future with different batteries.

 

[FF]

Life gets complicated and chargers expensive if you want a rapid charge from the noisemaker.

Simplest now is to use one batt as house batt and charge it alone it until 14.4 or so is seen, then join in the other unused batt .

Swap batts , odd, even daily underway.

Dockside simply join with the both switch , and overnight all should be fine.

 

[Iggy]

As someone else said, all good advice! I would not cheap out on the battery charger. I good charger will extended the life of your batteries and save you money.

 

[tiltrider1]

What does break the bank mean? Because of the size of my boat I am used to 800-1600 amp hour banks and 125 amp chargers. $2,000-3,000 for an inverter charger would be normal. For a back up charger of 40 amps the average price was $700-800. Xantrex makes a 40 amp charger for $350. Normally I shy away from xantrex but a back up charger is something I use once every 5 years. The $125 40 amp chargers are single battery chargers and won’t charge multiple batteries nor 8D’s.

 

[FF]

"The $125 40 amp chargers are single battery chargers and won’t charge multiple batteries nor 8D’s."

Most 40A chargers can output a Total of 40A , splitting it into 2 or 3 outputs does not create an 80A or 120A charger ,,, 40A is all it can output.

 

[HeartWarrior]

This is what I love about this group. Lots of great information quickly! The 2 8D's are ok for now and the current charger and alternator setup works fine. I am in the process of rewiring the crazy mess that the PO left and make it simpler. I was thinking as an interim solution to put in a low cost 40 amp unit like were mentioned above to get rid of what I have now in case these batteries continue to live for another few years. (As far as I can tell the PO put them in about 2 to 3 years ago). The decision was really if I could use a $200 or less unit as a 1 for 1 on my current old unit and then step up to an "intelligent" charger when I replace the batteries. I am also in the process of installing a Simmarine tank and power system monitor and will finally have good data this coming year on how much power I really use.

 

[firehoser75]

HW (Daniel),
I don't understand why you would want to buy a "cheap" charger that would probably be actually adding to battery damage by not properly recharging your batteries as an "interim" measure, only to replace it in a "couple of years"? It does not make sense to me, but it is your boat, your money, and your decision. I would buy the "future" charger now, but that is just me.

I also suggest reading up on all things battery, charging, etc. on marinehowto.com. Rod is one of the best and offers all kinds of free info complete with very complete real world testing results. Power monitoring is essential, IMHO, otherwise the boater is "guessing" as to what is actually happening.

Good luck with all the changes you are contemplating, and I hope what you have "lasts" and "works" for you before you make the changes.

 

[Flatswing]

The decision was really if I could use a $200 or less unit as a 1 for 1 on my current old unit and then step up to an "intelligent" charger when I replace the batteries. I am also in the process of installing a Simmarine tank and power system monitor and will finally have good data this coming year on how much power I really use.

Don't waste the $200. Spend $350, buy the 40A Sterling charger from Rod @ Marinehowto.com which can be custom programmed for almost any battery in the future plus 5yr warranty. KISS

 

[Duvie]

+1 on the Sterling. I have the 40 amp, 3 bank unit to charge my two 8D batteries and my generator group 27. I believe the sterling is the same unit as a Pro-Mariner but at a lower price point.

 

[BruceK]

Rule of thumb is/was charger should put out at least 10%A of battery rated Amps. So 40A total output for 2 is minimum. But,for the future, you can get 8Ds up to near 300AH, same case size.
Odd how IG sticks with 2 x 8Ds doing everything but the genset. Integrity of course followed suit. Used to them, I`m no hater of 8Ds.
You could use 2 multi stage automatic 20-40A chargers,one for each bank, short or long term. But one state of the art 2 channel 60A charger like Sterling/Pro Nautic might be better. Pretty much any of them would cope with a move to AGMs from FLAs via the settings.

 

[FF]

"and then step up to an "intelligent" charger when I replace the batteries."


What do you expect an "intelligent" 40A charger to do that your current unit does not do with LA bats?

 

[tiltrider1]

"The $125 40 amp chargers are single battery chargers and won’t charge multiple batteries nor 8D’s."

Most 40A chargers can output a Total of 40A , splitting it into 2 or 3 outputs does not create an 80A or 120A charger ,,, 40A is all it can output.

Most 40 amp chargers can not charge 8D batteries nor 2 GC’s in series nor two group 31’s in parallel. Most 40 amp sharpers can only charge one single battery. Most 40 amp chargers cost $125. For $300 you can find a 40 amp charger that can charge multiple banks or 8D batteries or 2 GC’s in series or multiple group 31’s in parallel.

 

[FF]

"For $300 you can find a 40 amp charger that can charge multiple banks or 8D batteries or 2 GC’s in series or multiple group 31’s in parallel."

True , but the total amperage to whatever collection is being charged is still 40A.

With a big need the house batt may take a long time as the thruster , windlass , noisemaker and other batts share a piece of that 40A.

Simpler and faster to just use a rotary switch and give the overnight house the full output , then combine the banks to top up the group.

 

[LegendintheRainforest]

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