Charging the batteries

[Marc1]

Hi there!
My little cruiser has been on he hard for 2 month for antifouling and some fibreglass work. Yes, don't ask.

My question is this ... I have one ordinary lead acid battery and one deep cycle both hooked up to a selector switch that can be B1,B2,B2-3, and off, another that I believe is a dual battery thingy, and on top of the cabin there is a solar panel permanently wired.

Considering the boat has been under a tree for so long with not much sun, I plan to give the batteries a good charge with a 15 amp smart charger.
Can i just clamp the charger to one of the batteries that are in parallel, regardless of the solar panel?

[thomm225]

Yes you can.

The batteries may be shot though depending on how long the boat has been under the tree.

[S/V Illusion]

Why would you have a start battery and a deep cycle battery connected in parallel?

Also, if you have a battery selector switch, they are not in parallel so - something is patently wrong with your description making any answer useless.

[tkeithlu]

Good Morning, Marc1.

Electrically separate your two batteries with the rotary switch; that's what it's there for. Then, charge each separately with your smart charger. Realize that if a battery is really dead, the smart charger may not reconize it; you may need a manual charger to get the charge up to where the smart charger says "yeah, that's a battery." Maddening, but true. Then, determine that the batteries are holding charges. There are very expensive and very complicateed ideal ways to do that, but an ordinary $15 load meter will do for your purpose. Get one at an auto parts store, Walmart, or Harbor Freight.

You don't have a complicated system here. There are lots of really terrific and very expensive batteries out there, but Rayovacs from Sam's or Interstate from wherever will serve your purposes. The deep cycle supplies house DC; the starter supplies the engine; keep them separate except in the emergency that you need them in parallel to start the engine because one is weak. Charge the starter from the alternator, and the house deep cycle from the solar array, unless you need to charge the house from the smart charger.

A really full charge is 13.7 for both. If you don't have a meter, get a digital multimeter for about $15.

Have a good time learning about your basic DC system.

[john61ct]

Originally Posted by Marc1

Can i just clamp the charger to one of the batteries that are in parallel, regardless of the solar panel?

Yes, but.

Proper testing and restore-charging of worn batteries is best done individually and with specific equipment. Can be cheaper to bring them to a pro rather than bring the pro to your boat, if you don't mind the extra work.

Sounds likely they will need replacing anyway, for the House deep cycles ask for reco's here first before buying, the likes of Rayovacs and Interstate are fine for Starter, but not House.

You also need to get a handle on **exactly** how the wiring is configured, and test that and its connections for continuity and (lack of) resistance. An ammeter of some type is useful, the clamp type will also include most functionality of a DMM.

Ideally produce documentation with detailed drawings, to be kept up to date as changes are made.

I believe your switch is what is usually refered to as 1-2-Both. There are many ways that could be wired, best practice these days is not for directing charge sources but loads.

For the goal of paralleling House and Starter circuits while a charge source is active, a VSR/ACR/combiner is best, rather than a manual switch.

Ideally all significant charge sources go to House, keeping Starter topped up from there is a trivial current.

[thomm225]

My boat came with an old worn out diesel which I used for a while at first. I bought a starter battery for it

After the diesel died, I bought a new 5 hp 4 stroke extra long shaft outboard with no alternator and pull start only.

I then bought a group 27 "Deep Cycle?" battery and ran it in parallel with the starter battery even though I knew this wasn't ideal for either battery. They served as my house batteries and powered my electronics, autopilot, inverter, lights, fan, etc

They lasted about 5 years like this being charged by solar only......

So you can run them in parallel, it's just not the best way

Mine are wired in parallel all the time regardless of where the battery switch is set so the batteries charge(d) simultaneously

I have two group 27 deep cycle(?) batteries in parallel now and may one day go to 6 volt deep cycle batteries although I do like the redundancy of the dual 12 volt batteries should one fail

Battery switch has no effect. Both batteries are on all the time handling the load however much it may be. Good news is they are constantly being charged by the solar panels as long as there is sunlight

[john61ct]

Being wired in parallel is what is happening in all cases where voltages of the two sides remain in the same ballpark, by definition.

The various isolating/joining devices we're discussing here, including both automatic manual switches and automatic combiners are also operating "in parallel", it is the parallel connection they are dis/connecting.

So if you mean, your House and Starter are always combined, whether a charge source is active or not, then you in effect just have one big bank, would be a terrible design, no separate House and Starter at all.

In which case you'd best have all component batteries match, and of course you have zero redundancy, House loads or a fault somewhere can leave you stranded if you don't have another backup you haven't mentioned.

[thomm225]

What I liked about having the old starter battery and deep cycle battery in parallel was that it allowed for much longer lasting 12 Volt Power and I could run my fan all night and have the depth finder on at anchor

If you do have a loading problem pulling down your batteries, you can troubleshoot that pretty easily by either totally disconnecting all loads and bringing them back online one by one (or only one at a time) or if you're lucky, you may find the problem as you are switching off the various loads if you are watching your battery voltage monitor as you do it you might see you voltage jump back up to normal

I had a battery pulling my system down one time and just disconnected it and was able to come in under autopilot and have on the other electronics since it was during the day and I had some solar also

[Marc1]

I can't double check this since the boat is not here, but I believe the connection is done via a dual battery regulator, or whatever it is called, round small thingy similar to the 1/2/1-2 switch, that directs the charge according to where it is needed.
This is most likely... the charge from the alternator and from the solar panel.
if the solar panel charges when underway and the motor running or not I don't know either.
The solar panel is supposed to keep both battery charged, not only the deep cycle one.
The switch allows to select which battery I am going to use, so selects the load. If I select battery one, battery 2 that is not being used is still getting charged (?)

If the boat is stationary and I clamp the charger to one battery terminals only without disconnecting anything, will it charge both batteries? It does so in my 4wd that has two batteries ... although that does not count because they are hard wired in paralell without a dual battery system ...yet it did so in my Searay that also had a dual battery system with the same switches.
The only difference with the Searay is that she had a port for the charger wired by the electrician that installed the dual batteries and switches and smart dual battery thingy.

So if I clamp the charger as it is to one battery will it charge that battery only ... or both ... or do some damage to the solar panel, or something else?

Next I am near the boat I take some pictures. For now must rely on the little I know about the installation that was as it is when I bought the boat. Both batteries have remained fully charged by the solar panel and I can start the boat with either battery with no problems, even after weeks of the boat being moored.

PS

If I want to wire a port for my charger so that it is permanently there and all I need is to plug in the charger ... how do I wire it?

[john61ct]

Originally Posted by Marc1

I can't double check this since the boat is not here, but I believe the connection is done via a dual battery regulator, or whatever it is called, round small thingy similar to the 1/2/1-2 switch, that directs the charge according to where it is needed.

The advice I gave about your learning exactly what you have and how it works should be a priority for you once you get back to the boat. There are so many possibilities how things are done, so your land vehicle is not relevant.

Pictures will only go so far, use an ammeter and DMM to thoroughly analyse your setup and get it well documented. Hire someone to teach / help you if necessary, but get your own tools.

The goal is, while the boat is in regular usage, for **all** charge sources when active to service both banks, priority (higher amps) being House.

You should not worry about damaging anything unless something's broken.

Your charger - I guess you mean from AC (shore) power, should be wired to House, just like the solar controller.

[thomm225]

Originally Posted by Marc1

I can't double check this since the boat is not here, but I believe the connection is done via a dual battery regulator, or whatever it is called, round small thingy similar to the 1/2/1-2 switch, that directs the charge according to where it is needed.
This is most likely... the charge from the alternator and from the solar panel.
if the solar panel charges when underway and the motor running or not I don't know either.
The solar panel is supposed to keep both battery charged, not only the deep cycle one.
The switch allows to select which battery I am going to use, so selects the load. If I select battery one, battery 2 that is not being used is still getting charged (?)

If the boat is stationary and I clamp the charger to one battery terminals only without disconnecting anything, will it charge both batteries? It does so in my 4wd that has two batteries ... although that does not count because they are hard wired in paralell without a dual battery system ...yet it did so in my Searay that also had a dual battery system with the same switches.
The only difference with the Searay is that she had a port for the charger wired by the electrician that installed the dual batteries and switches and smart dual battery thingy.

So if I clamp the charger as it is to one battery will it charge that battery only ... or both ... or do some damage to the solar panel, or something else?

Next I am near the boat I take some pictures. For now must rely on the little I know about the installation that was as it is when I bought the boat. Both batteries have remained fully charged by the solar panel and I can start the boat with either battery with no problems, even after weeks of the boat being moored.

PS

If I want to wire a port for my charger so that it is permanently there and all I need is to plug in the charger ... how do I wire it?

You should learn to do this yourself. It will be much easier than taking pictures and posting

For example, you can hook up your shore power charger to one of the batteries then measure the voltage on that battery with a voltmeter (there are plenty of videos on youtube that explain how to use a voltmeter or volt ohm meter)

It may be around 13.7 and up. Then you can go measure your other batteries. If they have similar voltage levels, all batteries are getting charged but if the others are near 12 volts are less they are not receiving the charge

[tkeithlu]

Centrally, at the core of some wonderfully detailed guidance above, get the structure of the system in mind. You have two batteries, house and starter, and three sources of energy (alternator, solar, charger) to put into those batteries. You have two uses, house and starting. You have a switch that within limits lets you attach source to battery in various combinations. You have a volt meter. Now, what do you want to connect to what? In a pinch (low battery) the house battery can start the engine and the solar can charge the starter battery, even if that is not the usual arrangement.

Rig your system to do what you want to do. Mine is a bit more complicated (genset, multiple alternators), but the same principle applies - I don't get caught not being able to start the engine just because its battery is low, or not being able to charge the genset starter battery just because its alternator fails.

Get to know your system, and it will protect you.

[S/V Illusion]

Originally Posted by Marc1

If the boat is stationary and I clamp the charger to one battery terminals only without disconnecting anything, will it charge both batteries? It does so in my 4wd that has two batteries ... although that does not count because they are hard wired in paralell ...
it?

You still haven’t addressed my question earlier which determines if we are all wasting time here.

If your two batteries are connected in parallel as you state, that is the fundamental problem.

[thomm225]

Originally Posted by S/V Illusion

You still haven’t addressed my question earlier which determines if we are all wasting time here.

If your two batteries are connected in parallel as you state, that is the fundamental problem.

Actually, having those dissimilar batteries in parallel isn't a problem as far as them being low, it's just not the best way.

I had a deep cycle battery and a starter battery hooked up in parallel for about 5 years before one failed. The starter battery was originally purchased to start the diesel but after the diesel failed, I replaced it with a pull start outboard. The two batteries in parallel gave me much more available power for longer periods than just the one deep cycle battery

I kept them charged with a 65 watt solar panel and the controller was one of those $12.00 Chinese PWM Controllers that limited the upper charge level to 14.4 volts

I had it connect with alligator clips so after it reached full charge, I would disconnect the controller and solar panel

[tkeithlu]

Having them in parallel is not ideal for charging or using, given different characteristics and tasks for the two. But as Thomm says, it's not awful, either. If you want to improve the system, remove the hard wiring and design a system that lets you connect each battery to each energy source and each use, and to put them in parallel when you need both at the same time, either for use or for charging. It's not complicated; it can be switches, or Thomm's alligator clips, or jumper cables. Just get control over your system, and enjoy being able to do what you want with it.