Max voltage for 12v DC system

I am getting a 2-stage battery charger which is supposed to allow 12v operating loads while charging. Both stages have higher voltages (14.1 and 13.5) than the nominal 12v DC. Will this harm the 12v equipment if they operate with these higher voltages as power supply? I was thinking of hooking the battery charger in parallel to the house converter in my 2007 23C.
Darryl

camperD said:

I am getting a 2-stage battery charger which is supposed to allow 12v operating loads while charging. Both stages have higher voltages (14.1 and 13.5) than the nominal 12v DC. Will this harm the 12v equipment if they operate with these higher voltages as power supply? I was thinking of hooking the battery charger in parallel to the house converter in my 2007 23C.
Darryl

Click to expand...

They shouldn't, Darryl. 14.1V is really a common voltage that you'll see from the alternator when your vehicle engine is running. All of your vehicle electronics "see" that voltage if that is the case.

But, I don't really know why you would need to use the battery charger in parallel with the converter charge circuit. More is not really better. All batteries do best if charged slowly.

If you just want to "maintain" the battery, get a "Battery Tender" or "Battery Minder" and use it by itself. When I return from a camping trip, I plug in the Battery Minder and in about 24 hours the trailer batteries are restored and being held in a full charge state.

- Jack

Jack,
Thanks for the info on the voltage.
I was thinking of hooking them up in parallel because the battery charger puts out a higher voltage than the converter (ca 13.2) but low amps (15 vs 45 for the converter). I was thinking that this would allow the converter to cover hi amp demands but also supply the higher charging voltage needed during charging ... both without me having to do anything.
Darryl

camperD said:

Jack,
Thanks for the info on the voltage.
I was thinking of hooking them up in parallel because the battery charger puts out a higher voltage than the converter (ca 13.2) but low amps (15 vs 45 for the converter). I was thinking that this would allow the converter to cover hi amp demands but also supply the higher charging voltage needed during charging ... both without me having to do anything.
Darryl

Click to expand...

Daryl, it is not a good idea to hook the two units in parallel, you will loose the auto sensing
feature on both units, and end up overcharging your batteries.

RR

Richard said:

Daryl, it is not a good idea to hook the two units in parallel, you will loose the auto sensing
feature on both units, and end up overcharging your batteries.

RR

Click to expand...

Agree, Richard, plus, if the charger is charging at a higher voltage than the converter, it would possibly tend to reverse the current flow in the converter, which doesn't sound good at all. (Although there may be diodes in the converter that would prevent this.) Either way though, the presence of one is going to "confuse" the other.

Darryl, save the battery charger for a discharged vehicle battery or any other 12V battery that you can't otherwise charge easily. And, don't try to charge a discharged battery with the vehicle alternator, that's a good way to kill the alternator. Alternators are not designed to recharge dead batteries, they are designed to maintain/restore the charge lost during starting.

- Jack

Richard and Jack,

Thank you for your advice. I had not thought about these things, so am really glad I asked. I will be hooking the battery charger up so I can charge the batteries while they are not hooked to the 12v system load.

This is a great forum! Thanks again.
Darryl

The reason for the higher voltages is that batteries need the higher voltage potential in order to charge. So if you charged a battery that reads 12.6 volts with a 12.6 volt charge you wouldn't gain anything.

RichR said:

The reason for the higher voltages is that batteries need the higher voltage potential in order to charge. So if you charged a battery that reads 12.6 volts with a 12.6 volt charge you wouldn't gain anything.

Click to expand...

Correct, and a SLOW charger will do the job at something above 13.0 Volts. If you charge a discharged battery at a "quick charge" voltage (14.0+), the electrolyte will "boil", the battery will "gas", the plates inside will deform and, the battery will be damaged. And, the goal is to never let the battery fall to a low charged state, because recharging from that condition causes deformation of the plates too, even if it is a so called, "deep cycle" battery.

- Jack

battery charger..

Get yourself a 5 watt solar panel and keep the battery charged for free. I bought a deep cycle battery at Sams and a 5 watt solar panel and it does the job.
I also bought a digital 12 volt DC voltage monitor that I leave connected right beneath the fold up panel in the battery compartment so that I can read the battery voltage without going inside to view the led panel (which isn't too accurate).

I don't think deep cycle batteries are designed to be charged at a high rate like a car battery. I wouldn't want to charge at a rate any higher than the trailer's converter puts out.