Charging batteries with idling vehicle?

[huntingislife]

There has been some talk in the ice fishing forum about charging your ice house batteries with an idling vehicle. You have to use the 7-pin connector to run the charging wire to the ice house. Would it essentially be the same thing to use jumper cables and hook the vehicles battery directly to the ice house battery? Then let the idling vehicle charge the ice house battery. I was searching on the internet and found some people who say that an idling vehicle doesnt deliver too many amps and it would take a long time to charge. Other people say that an automotive alternator is designed to just maintain battery levels and not be used as an actual battery charger, so there could be damage that occurs to the alternator. Is there any truth to this?

[lawdog]

I would say yes and no. It doesn't deliver maximum charge at idling speeds. Its not turning the alternator enough. An alternater in a car does charge though, its not like a magneto on an ATV that is more for maintaining and doesn't usually have the power to charge much as I understand them...

[Whoaru99]

I agree with both points. A car alternator typically does not provide a ton of current at idle (although the newer ones seem to do a better job) and it's purpose is to maintain the battery and load, not to be a charger per se.

[beeonkey]

I teach auto mechanics and have used my truck to charge batteries for years. If you have no other way of charging them where you are it works just fine. The alternator will put out more amps up off idle but it will act as a battery charger at a low setting, maybe up to 10 amps. The alternator doesn’t know if its charging the battery in your truck or providing juice for the ignition system. Not only will the alternator charge the battery but your truck battery it self will also help charge the other battery. A battery will only accept so much charge and then the alternator will also stop trying to give it as much charge, and try to just maintain the battery. Will this take time to charge the battery? YES even on a charger it takes several hours to fully charge a battery. I would have an alternative way to charge for the long run but it will and can charge the batteries with out doing damage. The damage will come from people putting cables on negative first and causing a voltage spike. That can knock out voltage regulators in the alternator. Hope this helps.

[fishermn]

Also, if you plan to do this you would be better off to just use jumper cables. Less heating in the cables, and probably a lower chance of blowing a fuse or burning off a wire somewhere.

Of couse there is alsways the option of just carrying a 2nd battery....

[HaywardBound]

I would hook up my 12v power inverter to the truck battery and use my regular battery charger.

[Capt. Don*]

I have been charging the fishhouse battery, (and camper,trailer etc.) for years off of the 7 pin connector. That it why it is there, the wiring and circuit protection is heavy enough to do the job, while at idle it will take considerably longer, it will still do the job. Depending on the size of an inverter and the output of an a/c battery charger, you will be asking far more from the alternator while the inverter is doing its job than using the battery charge pin in the trailer connector.

[marine_man]

Quote:

---

I would hook up my 12v power inverter to the truck battery and use my regular battery charger.

---

I don't have the math on this, but I'm pretty sure that you'd be loosing a lot of efficiency there by converting 12V to 110V back to 12V.

marine_man

[Surface Tension]

As already stated you can charge your ice house battery with your vehicle. Thing is do your really want to do that.

Lets say you charge at 10 amps and you have a 115 amp hr battery.

If its dead it'll take 15 hours to charge while you burn 1 gal per hour idling.

I would get myself enough deep cycle batteries to last me the weekend. I'd also wire my lights and direct vent heater separately. Why because your furnace won't allow allow the valve to open the gas supply under a certain amount of voltage. So you swap out the battery and run the battery till its dead with your lighting.

[FullTilt]

What if you have an inverter hooked to your deep cycle to run a tv and a few lights in your ice house. The battery starts getting low. If you hooked the battery to your 7 pin charging system on your truck, while the deep cycle is still connected to the inverter, would you have the juice to power your tv and lights? Would the battery gain any charge or would all the juice just be running from your truck, through the battery and to the inverter?

I currently have one battery hooked to an inverter and I'm thinking the 7 pin charging system would allow me to leave the battery in the house and just hook it to the truck for an hour.

I'm not buying the 15 hours to charge a battery with an alternator. If that were the case it wouldn't be possible to jump start a battery and then restart the vehicle after an hour of driving. Doesn't the stay'ncharge system use this theory of charging batteries from the alternator, I don't recall it taking 15 hours with their system.

[picksbigwagon]

where would I be able to find a 7 pin charging system? A buddy has a cabin up north, okay it is a shed, but we use it in the summer and we lost our battery last summer on the 2nd of 5 nights, which meant no fan, did I mention it was day time highs of 95? being able to charge that battery as we drove to and from Mille Lacs would be awesome, or at least let the truck idle for a while every night at camp too.

Thanks..........

[Surface Tension]

I'm using the 10 amps that was stated already as a guide to how long it will take to charge a 115 amp hr battery. Simple math, 115 divided by 10 = 15. Your talking about the same rate as a battery charger, 15 hours isn't out of the norm.

Jumping a car battery with jumper cables or your trucks designated battery connected to battery cables is different then a 7 pin plug with light wire. Still the jumper cables are limited because you have to take in to consideration jumper cable clamps are only capable of handling so many amps.

Lastly I won't put a dead battery on my trucks charging system. I won't subject a deep cycle to it either.

[Whoaru99]

Quote:

---

As already stated you can charge your ice house battery with your vehicle. Thing is do your really want to do that.

---

Yeah, I agree. Even if it does charge, who wants to idle their vehicle for 3, 4, 5, or more hours? I've always believed that idling a vehicle is not too good for them.