Topping Up Batteries On The Fly

[Dodger1234]

Hello Everyone.
I have an onboard battery charger, it is a 2 bank charger 5/5.

My question is - If I bought an inverter that plugs into a 12 volt cig lighter and is rated at 110 volts AC producing 150 watts would it be safe on the wiring to the 12 volt cig lighter? I have a Nissan Titan with the 12V plugin in the box. Since I am travelling 2 hours to go fishing I thought I could put an extension cord wired to the trailer and plugged into the onboard charger and have it plugged into the 12V power supply in the box?

It may be a stupid question but safety is my "number one" concern !

Kind Regards, Dodger1234

 

[Silvertip]

Re: Topping Up Batteries On The Fly

You have a 12 volt charging system on the truck. No need for the inverter and the truck had a much higher output alternator so charge time is shorter.

 

[Georgesalmon]

Re: Topping Up Batteries On The Fly

your 12v cig socket is fused in the truck. worst case you'll blow the fuse. you won't damage the truck. but as said, you can run from the 12v socket right to your boat, no need for all that extra stuff. however, if you use your onboard charger and unplug it when you leave your boat batteries probably won't likely take any extra charge in the following 2 hours unless you have some electrical problems in your boat.

 

[bruceb58]

Re: Topping Up Batteries On The Fly

It will work but why not just have it charged before you leave for your trip?

 

[Dodger1234]

Re: Topping Up Batteries On The Fly

The boat is stored out of town and there is no power source. The batteries are generally fully charged when I am done fishing but sometimes I do use my electric motor for a bit. Instead of dragging the boat back to the city to charge it would be easier to charge while travelling.

I understand the comments about 12V direct to my batteries. But the onboard charger has a plug and if I use an inverter it has a plug. I can then plug the 2 together with just an extension cord.

Regards, Dodger1234

 

[bruceb58]

Re: Topping Up Batteries On The Fly

I understand the comments about 12V direct to my batteries. But the onboard charger has a plug and if I use an inverter it has a plug. I can then plug the 2 together with just an extension cord.

I actually think that's a good way to do it especially since you already have an onboard charger.

Still best to have your batteries stored fully charged. If batteries are stored discharged, even a little, they will sulfate and not last as long.

 

[fishrdan]

Re: Topping Up Batteries On The Fly

What is the input amp rating of your charger, is it less than 150W or 1.25 amps? Most likely, the input power rating is higher than the output rating. IE: 150W in / 120W out, 1.25 amps at 120V input and 10 at 12V amps output. Could be higher input rating...?

It would work, but a 5x5 charger isn't going to charge much on short trips, if you're traveling several hours it might help. If the batteries are at 80%, it would take 4 hours to recharge them. If the charger combines the outputs when one battery (engine) is charged, this setup would work better as it would charge the second (trolling) battery at 10 amps. (Guessing you have 1 engine battery and 1 trolling battery.)

 

[bruceb58]

Re: Topping Up Batteries On The Fly

Inverters are rated at the output power. 150W inverter may be marginal though as a 5/5 charger will probably draw close to 150W. If you are only driving a couple hours, the battery won't charge too much.

There is a big issue charging the boat battery directly from the vehicle's charging system. Unless you can limit the current, you need a huge cable from the vehicle battery to the boat. You also would need a relay to open up the circuit when the engine is not running as well as some sort of circuit breaker.

 

[Dodger1234]

Re: Topping Up Batteries On The Fly

To All - First off thanks for the comments. My knowledge and understanding of anything electrical is non existent. Sorry I have not commented in the last couple of weeks but I have been out of town working.

After reading threw this a couple of times and trying to put all the info together here's what my understanding is. Using the 12V supply in the box of my Titan I can plug in an inverter and use an extension cord to my 5/5 bank in boat charger. Knowing I am going to get a minimal charge in a 2-3 hour trip. I understand I may shorten the battery life but I seem to be getting 4-5 years out of my batteries with only charging while the boat motor is running and the few times I bring it back to the city for a full charge. I am comfortable with the battery life being a little shorter as I usually pay $100.00 a battery and this seems reasonable.

My biggest concern was damage to the electrical in the truck. Knowing there is a fuse for the truck box 12V supply my only worry is fuse failure and starting an electrical fire or melt down of wires. If this is a possibility then I should keep doing what I currently am doing and leave well enough alone.

Does this seem reasonable?

Again thanks to all who made comments.

Kind Regards, Dodger1234.

 

[bruceb58]

Re: Topping Up Batteries On The Fly

Your 5/5 charger will draw probably require up to 12A or so for your inverter. If your truck circuit can handle 15A or so, you are fine.

The reason it is 12 and not 10 is that the inverter isn't 100% efficient. I wouldn't run this very long without your truck engine running.

 

[agallant80]

Re: Topping Up Batteries On The Fly

Few thoughts on this.

1. If you do the inverter you are going 12V-->120V then to the charger which goes 120V-->12V so you are not very effecent doing this.
2. Does the cigirette lighter turn off with the truck? If not and you forget to unplug it you may find yourself pulling one of the battries out of the truck to start your boat

In your situation I would be tempted to, well I don't know. I don't think there is a really good answer to this. Plugging in your boat charger to a 150W inverter will be like plugging your cell phone in to the wall for 5 min. It will put a little charge on it but not much also the charger on the boat will draw more than 150W. You will more than likely end up tripping the breaker on the inverter. 150W at 120V is only like 1.2 amps. The charger will want to draw more than that. My 17" work laptop tripped the breaker on my 150W inverter in my truck before.

 

[bruceb58]

Re: Topping Up Batteries On The Fly

2. Does the cigirette lighter turn off with the truck? If not and you forget to unplug it you may find yourself pulling one of the battries out of the truck to start your boat

huh?

 

[bruceb58]

Re: Topping Up Batteries On The Fly

A 150W inverter is not going to cut it. I would get a bigger one. I would also not use a cigarette lighter plug to power it.

 

[agallant80]

Re: Topping Up Batteries On The Fly

huh?

If you turn off your truck does the cigirette lighter that that inverter is plugged in to turn off with the truck? If not then its going to draw from the battery in the truck and drain it. You will have to remember to unplug the inverter if that is the case.

 

[Dodger1234]

Re: Topping Up Batteries On The Fly

Few thoughts on this.

1. If you do the inverter you are going 12V-->120V then to the charger which goes 120V-->12V so you are not very effecent doing this.
2. Does the cigirette lighter turn off with the truck? If not and you forget to unplug it you may find yourself pulling one of the battries out of the truck to start your boat

In your situation I would be tempted to, well I don't know. I don't think there is a really good answer to this. Plugging in your boat charger to a 150W inverter will be like plugging your cell phone in to the wall for 5 min. It will put a little charge on it but not much also the charger on the boat will draw more than 150W. You will more than likely end up tripping the breaker on the inverter. 150W at 120V is only like 1.2 amps. The charger will want to draw more than that. My 17" work laptop tripped the breaker on my 150W inverter in my truck before.

These comments are what I was looking for. As for comment #1 I understand how it seems inefficient but my power source ( 12V in truck box ) is 6' away from the plugin for the onboard charger. It just seemed like a possible way of topping up my boat batteries while driving to the lake.

I am just going to stick with what I have been doing. Thanks for taking the time to comment.

Sincere Regards, Dodger1234

 

[Auger01]

Re: Topping Up Batteries On The Fly

Some battery chargers dont like the square wave that cheap inverters produce and that can damage the charger.

You might consider a solar battery charger to keep the boat batteries charged while the boat is being stored. A 50 to 75 watt solar charger would be about right I think.

 

[jimbo_jwc]

Re: Topping Up Batteries On The Fly

If its factory wired for the brakes with huge plug it has heavy enough wiring for charging batteries . Chevy ,Tahoe's ,Suburban &Trucks come with this feature as the electric brake coils on most trailers pull a lot of current. With a small modification .

20/30 amp = 240/360 watt
40amp = 480 watt

 

[jimbo_jwc]

Re: Topping Up Batteries On The Fly

View attachment 214767View attachment 214767If its factory wired for the brakes with huge plug it has heavy enough wiring for charging batteries . Chevy ,Tahoe's ,Suburban &Trucks come with this feature as the electric brake coils on most trailers pull a lot of current. With a small modification .View attachment 214766

I think it was the heavy red wire in engine compartment we hooked up to run a 12volt compact freezer for our Canadian Trips But not Sure on Foreign vehicals I don't have the Surburban anymore but my Tahoe and Silverado have this feature even if the reciptical isn't back at bumper .

It was easier than you think , Grandpa always said keep it simple stupid and not sure if he was calling me simple or stupid so I look at things clear different than most . It sure turned might light on at the end of the tunnel or his old coal mine in side of our hill .

Necessity is the mother of all inventions and sometimes it can be to crude to be true and there is a time to be fine .Just depends on your time frame for your needs .

 

[jimbo_jwc]

Re: Topping Up Batteries On The Fly

I bet this reply might have some wires smoking as you have to gauge wire on your hook up accordingly .

 

[bruceb58]

Re: Topping Up Batteries On The Fly

Some battery chargers dont like the square wave that cheap inverters produce and that can damage the charger.

Not likely. Square wave could be bad for something like an electric motor but not a charger at all. Its going to a rectifier and then to a transformer in the charger. Why would you think that could possibly harm it? Probably one of the easiest thing to run off an inverter.