Splitting a single amp trickle charger to 2 banks with a off/1/2/both switch

[Dougcole]

I have a 4 amp Guest trickle charger that I am considering using for my single G31 FLA start battery and my single G24 FLA gen start battery, but I am not sure how well it will work.

I realize that the amperage would be very low to each battery and I am totally fine with that, I just want it to be a maintainer, the entire purpose of this charger would be to keep the banks up while they are not in use, not to bring them back from a deep discharge. The alternators (my genset has one too) would be the primary charging source.

I recently switched my house bank to Lithium, and I dedicated my primary shore power charger, a 50 amp pro mariner, to it since I did not want to mix two diffferent battery chemistrys on the same chargers. My original plan was to get another small two bank charger dedicated to the house and generator batteries, but I already have this little Guest charger, so I'd like to use it. I also have a 1/2/both battery switch on hand that I could use.

The plan would be to connect the charger to the common incoming terminal of the switch, then run a cable from terminal one to the engine start battery, and a cable from terminal two to the gen start battery. I know it would work fine for the selected battery if I select either "1" or "2" with the selected switch, but what if I left it on "both?" Would it simply split the charge equally between the two batteries or would that somehow mess up the charger's little pea brain causing it malfunction?

I think when it is on both, for charging purposes, it would be essentially paralleling the two batteries into one bank.

Second question, a harder one for you really smart electrical types, what would be the simplest way to use that setup, and perhaps one more battery switch (I have a simple on/off switch on hand) to parallel the gen and start batts together for starting if needed?

Thanks!

Doug

 

[O C Diver]

I have a 4 amp Guest trickle charger that I am considering using for my single G31 FLA start battery and my single G24 FLA gen start battery, but I am not sure how well it will work.

I realize that the amperage would be very low to each battery and I am totally fine with that, I just want it to be a maintainer, the entire purpose of this charger would be to keep the banks up while they are not in use, not to bring them back from a deep discharge. The alternators (my genset has one too) would be the primary charging source.

I recently switched my house bank to Lithium, and I dedicated my primary shore power charger, a 50 amp pro mariner, to it since I did not want to mix two diffferent battery chemistrys on the same chargers. My original plan was to get another small two bank charger dedicated to the house and generator batteries, but I already have this little Guest charger, so I'd like to use it. I also have a 1/2/both battery switch on hand that I could use.

The plan would be to connect the charger to the common incoming terminal of the switch, then run a cable from terminal one to the engine start battery, and a cable from terminal two to the gen start battery. I know it would work fine for the selected battery if I select either "1" or "2" with the selected switch, but what if I left it on "both?" Would it simply split the charge equally between the two batteries or would that somehow mess up the charger's little pea brain causing it malfunction?

I think when it is on both, for charging purposes, it would be essentially paralleling the two batteries into one bank.

Second question, a harder one for you really smart electrical types, what would be the simplest way to use that setup, and perhaps one more battery switch (I have a simple on/off switch on hand) to parallel the gen and start batts together for starting if needed?

Thanks!

Doug

So you want to try to remember to switch the 4 amp battery charger between batteries?

Here's your simple answer:

Ted

 

[Dougcole]

So you want to try to remember to switch the 4 amp battery charger between batteries?

Here's your simple answer:

View attachment 165170

Ted

Yeah, I know I could go with a two bank charger, but I already have this single bank and the switch sitting here on my workbench.

 

[SIBERNUT]

Im not an Obi -Wan electrician, but if i did this id put a big sign on the dash to remind me to return to normal before starting. BIG-BIG.

 

[O C Diver]

Yeah, I know I could go with a two bank charger, but I already have this single bank and the switch sitting here on my workbench.

Is it marine rated?
Is the 120 VAC neutral tied to the negative battery, tied to the negative generator, and tied to the bonding system. Or is it a marine battery charger with isolation between the 120 VAC neutral and the 12 VDC negative?

Ted

 

[Dougcole]

Im not an Obi -Wan electrician, but if i did this id put a big sign on the dash to remind me to return to normal before starting. BIG-BIG.

If I just did the basic install no cables from the starters would go to the switch. I'd wire the positive cable from the charger to the input post and the negative to my ground bar. I'd run a cable from post one on the switch to the positive post on the start battery and a second cable from post two of the switch to the positive post on the gen-set battery.

 

[Dougcole]

Is it marine rated?
Is the 120 VAC neutral tied to the negative battery, tied to the negative generator, and tied to the bonding system. Or is it a marine battery charger with isolation between the 120 VAC neutral and the 12 VDC negative?

Ted

It's one of these, except the one I have is the "Magnum," which is 4 amps instead of three.

2603-B Guest Charger

2603-B Guest Charger

batterysales.com

 

[O C Diver]

It's one of these, except the one I have is the "Magnum," which is 4 amps instead of three.

2603-B Guest Charger

2603-B Guest Charger

batterysales.com

I would expect that Guest charger is marine rated, but I would certainly check the manual. With battery clips, I would would be concerned that it was for trailered boats.

Ted

 

[Dougcole]

I would expect that Guest charger is marine rated, but I would certainly check the manual. With battery clips, I would would be concerned that it was for trailered boats.

Ted

The one I have came with ring terminals, and there are mounting holes, but I will check the manual. Good call.

 

[NoRain]

If I just did the basic install no cables from the starters would go to the switch. I'd wire the positive cable from the charger to the input post and the negative to my ground bar. I'd run a cable from post one on the switch to the positive post on the start battery and a second cable from post two of the switch to the positive post on the gen-set battery.

Don’t forget the fusing.

 

[Dougcole]

Don’t forget the fusing.

Yeah, its got an inline fuse on the DC side, I've got an AC outlet in my ER that is on a breaker on the panel, I'll plug it into that.

 

[Bacchus]

I have used and like maintainers for keeping batty up over extended non use periods. IMO it isn't necessary to do it constantly 24/7. You might consider using just clips to the GP31 and get a second maintainer... most about 2 amps which should do fine on the GP24.
I've used an 8 A maintainer for a bank of 8 GCs 6V in series/ parallel but haven't ever tried in on different battys.

 

[Tjohn]

This is old news, but if you have never had a battery explode in your face, you may get sloppy and spark one off. This happens easy in confined spaces, just a reminder!

 

[Dougcole]

This is old news, but if you have never had a battery explode in your face, you may get sloppy and spark one off. This happens easy in confined spaces, just a reminder!

Thanks. I have had them spark a few times and accidentally arced one with a wrench many years ago, but never had one explode. I’m always hesitant when I drop that last terminal onto the post, and I put a 3” extension on my socket wrench to get it well above the terminals.

One nice thing about my new lithium batts is you can turn them off.

 

[Kjeld]

The plan would be to connect the charger to the common incoming terminal of the switch, then run a cable from terminal one to the engine start battery, and a cable from terminal two to the gen start battery. I know it would work fine for the selected battery if I select either "1" or "2" with the selected switch, but what if I left it on "both?" Would it simply split the charge equally between the two batteries or would that somehow mess up the charger's little pea brain causing it malfunction?

With the switch in "both" position the charger will see one single battery bank with the voltage of the mostly charged battery. For the charger that is OK and it will provide a corresponding current.
However, if the batteries are not charged equally, or are not of the same chemistry and condition, the fullest battery will also charge the other battery and will discharge until both batteries level at the same Voltage.
So the "both" position is OK for the charger, but will probably not result in two nicely topped-up batteries.

 

[Portage_Bay]

Before you use a trickle charger on valuable batteries read what Rod Collins has to say about trickle chargers

Choose Your Battery Chargers Carefully

The Victron IP-65, IP67 are the best values in marine chargers under 30A.

marinehowto.com

 

[BruceK]

Uh oh, just bought one for the car. Made by Ctek, rebranded and ? refined for the car mfr.