Shore Power Battery Charger Question

[jdratlif]

I have a Shipwright shore power battery charger installed on my O'day 25. I have never used a unit like this and I have questions on how to use it. As a prenote, I have searched the web and this site for information and could not find any.

I have opened the unit up and it appears that it is wired and installed properly. One question I have is how many batteries can I charge with a unit like this? It has two fused power output leads coming out of the the unit. Does this mean that I can safely charge two batteries at the same time with the unit? My other question is, how many Amps will this unit pull? I have it fused to a 15 A power fuse and I do not want to over load the circuit. The unit has a meter that scales up to 10 A. Does this mean the max output for this unit is 10 A?

These are the basic questions I have. A picture of the unit installed is below. If you have any other insight on units like this I would appreciate any additional advice.

 

[Stu Jackson]

Without dealing with the issue of the charger itself, could you please define more clearly how your batteries are set up? Do you have two separate "banks" or are the two batteries paralleled together to form one "bank"? Do you have a 1-2-B switch?

Then we can help you a lot more.

 

[jdratlif]

I have 2 batteries and they are connected to a 1-2-B switch, so the bank is type is dictated by the switch. They are however connected to the ground bus in parallel.

 

[Ron20324]

...Does this mean that I can safely charge two batteries at the same time with the unit? ...how many Amps will this unit pull? I have it fused to a 15 A power fuse and I do not want to over load the circuit. The unit has a meter that scales up to 10 A. Does this mean the max output for this unit is 10 A?

In theory, you could charge any number of batteries, but they would only get 10 amps charge between them, and you'd be charging them forever. Otherwise, it looks like my slip-neighbor's C30 charger. Yes, one battery (or bank) per output would be the normal arrangement. If you have two batteries in parallel, that would be a "bank", and could be wired to one output. Again, though, all the batteries would share the 10 amps of output. I assume this is already wired and working as-is? It would depend on you electicity consumption, but 10 amps is not a whiole lot of charging ability. If the budget allows, something bigger (40 amps?) would be a good upgrade.

 

[jdratlif]

Thanks for the information. What I was really looking for is the max amp draw the charger will pull from the AC supply circuit and from what you say it is 10 A.

What is the thought on using your batteries while charging them? Can this damage them?

Thanks again

 

[Ron20324]

Thanks for the information. What I was really looking for is the max amp draw the charger will pull from the AC supply circuit and from what you say it is 10 A. What is the thought on using your batteries while charging them? Can this damage them?

No, not 10 amps of AC. You said it is fused at 15 amps. If the fuse (or circuit breaker) has never blown, i'd say you are okay, but that the ACTUAL draw is probably a couple of amps less. 15 amps from the AC circuit is normally used/fused. I could be wrong, but that looks like an older unit and not very efficient.

Using the batteries when the charger is running will not bother the batteries other than the batts will not receive the full charge current since you have some other appliance that will be using some of the charge current. Where you might have a problem, though, is the appliance you are using may not like the 14-plus volts that the charger can put out. As far as I know, the charger's high voltage will not be a problem with anything you are lekily to use when on board. Just check the appliance for any manufacturer's high-voltage input concerns.

Your charger setup looks like a home-made installation. Most important is the two fuses- they should be located at the battery end of those wires, not at the charger end.

 

[kloudie1]

JD.. 10 amperes at 12 V is 120 watts .. 120 watts at 120 volts (input) is 1 ampere.. given the efficiency (looks like an old "ferro resonant unit) of the charger, I would expect the it to pull no more than 2 amperes from the AC shorepower. The inrush current (when ya first turn it on) is a lot bigger for a half second or so, so a bigger breaker than 2 is prudent.. It sounds like you are set up well.

 

[Ron20324]

If the AC draw is all that important... It looks like you have one of the screw-in circuit breakers under that cap? Take it out and replace with smaller fuses until one pops. Then back up a size and see if that works forever. Can you open it or the AC box and see what size wires are used?

Also, upon blowing up the picture, I see it is a constant-voltage output. Not the best way to charge a battery.

 

[Bill Roosa]

The breaker is sized to protect the wires feeding the unit not the unit itself.
You would want to check the connection between the two battery + wires to make sure there is no connection between them. If there is a connection between them and you connect directly to two battery banks you are effectively making it one battery bank with a low amp connection. This would allow you to think you where draining only your house bank when in fact you are draining both house and start banks.

 

[Barnacle Bill]

Maybe this isn't helpful, but I don't recall reading this: You should be able to look at the battery charger and see how many batteries it is designed to charge based on the number of wires from the charger to the batteries. The person who installed it, if in fact the boat carries two batteries, should have bought a charger to accommodate two batteries. I am sure the company makes chargers to accommodate various numbers of batteries and also various ampere outputs. So, if the charger is designed for two batteries, there should be wires attached to each with proper polarity. Then, on the AC breaker you should have a breaker dedicated specifically for your charger. You wouldn't need in line fuses on the wires and the charger itself probably has a fuse in it or a breaker in it if things go wrong. At least better chargers do. Buy, if you have a breaker for the charger that is a typical AC designed breaker, then you should be amply protected (no pun intended).