Charging a 12v 100A battery with cigarette lighter?
Tinggu said
05:45 PM Nov 30, 2019
In our Discovery we have a big fat cable running through to the back with an Anderson plug we use to charge the 12v 100A battery in the back which either powers the boat winch or runs the fridge in the caravan when we are rolling. Our new car is a Mitsubishi Outlander and I probably won't have time to chase some decent wiring to the back before we are off. So my question is whether a 12v Cigarette socket can be used when under way to recharge the said 12v battery? Probably not up to running the fridge in the caravan but should be OK to recharge the battery after running the Wayco overnight?
Thanks,
Pete
Mamil said
07:48 PM Nov 30, 2019
A flat 100Ah battery can pull quite a few amps from your alternator/start battery, more than you fridge will, and the only thing that will limit the current flow is the internal resistance of the battery... and the size of the cable and fuse between the two. The wiring and fuse on the accessory socket circuit, and the accessory socket and plug themselves are not designed to carry more than about 10A usually, so no don't do it.
Whenarewethere said
08:50 PM Nov 30, 2019
No you cannot use the socket even if it has a 20amp fuse. The lighter sockets are too thin.
Cut & paste from another forum:
The 12 volt power socket in the boot I replaced with an Anderson plug. I put a 3mm spacer behind the plug so it sits 3mm off the panel, another 3mm 27mm diameter disc to fit the 12 volt hole & used an Anderson T handle to clamp behind the trim panel with some Nyloc nuts. Drilled one new hole in the handle so it was in a better position. I drilled 2 holes in the back of the Anderson plug to pull the wires through, once the contact lugs were in place. At the back end of the plug, I had some large clear rubber feet, cut them a touch over size & pressed them into the back on the plug. When bolted in place you do not need to drill any holes in the panel. Also put a 2 way plug on the back of the new plug so I didn't need to cut any to the car's wires. Also put some large heatshrink over the plug although not really necessary. 12 volt power without the plug ever breaking electrical contact.
Pete,
Not only is the socket too light but the wires feeding it are totally unsuitable. I assume you don't want to utilise the services of the fire brigade to put the fire out.
In fact I wouldn't consider running the maximum 10A that the wires are rated to(?)
If you haven't the time, consider getting an auto-electrician to do it for you.
One other point - monitor the battery voltage carefully as batteries don't take kindly to being discharged below 50% (nominally around 12.2 to 12.3v).
Whenarewethere said
12:53 AM Dec 1, 2019
Depends on the car. Mine has three 60amp fuses supplying the boot which in turn feed various things. One of the 3 power outlets, each 20amp fuses, is feed from the boot. The other 2 are feed from the passenger fuse box which has 2 x 60 & 2 x 40amp fuses which in turn has fuses for the individual items.
The boot feeds the heated seats 2 x 15amps (don't have), caravan fridge 15amps (don't have), audio adds up to 80amps of fuses & I only have the cheap hi-fi. Then there are a pile of other fuses.
If you are not using a heated windscreen there is another 2 X 40amps to play with.
Wires running to the boot are more than adequate.
Tinggu said
07:34 AM Dec 1, 2019
Whenwearethere: Point taken and that is a very nice setup that I would aspire to.
One point, for running the Waeco overnight (just on 4 degrees) it would still be pretty well charged up at around 12.5v, the following morning so not really likely to draw big amps to top up?
I'm certainly not in a hurry to fry anything on the new car, just exploring possibilities and having the conversation.
Cheers
Pete
Tinggu said
07:39 AM Dec 1, 2019
I amend my last post (can't see how to edit on my phone)
I think the battery would be much closer to 12.7v. It runs the Waeco for three days on the boat without a charge from the sunshine panels.
Whenarewethere said
08:07 AM Dec 1, 2019
Tinggu wrote:
I amend my last post (can't see how to edit on my phone) I think the battery would be much closer to 12.7v. It runs the Waeco for three days on the boat without a charge from the sunshine panels.
Reply, Quote, More > Edit
Whenarewethere said
08:24 AM Dec 1, 2019
I don't use the car battery to run anything. Only use the cars system to charge which is typically 7 to 12amps via two 9amp DC-DC chargers. When the auxiliary is charged it's down to about 3amps charging. I have very good voltage & use a DC-DC charger actually so I can reduce voltage.
2 of my 4 auxiliary batteries under the seat.
What size fridge do you want to run?
Have you thought of running the fridge cold during the day & warmer at night or even off overnight which what I did before I had an auxiliary battery. Keep it full with thermal mass ie water bottles. As soon as you have room chuck another one in the fridge.
Our old fridge is a bit toey on adjustment so we just it be. I think it's a 45litre. The fridge in the caravan is a small Dometic 3 way that kills the battery on 12v but runs very nicely on 12v fed from the car when we are under way. That's the Discovery. Now we have the Outlander (not yet delivered) we would like to recreate a similar system. Picking up a decent 12V supply from the back end would be handy or perhaps it will be easy to run a separate !2v 40A supply from the battery through the floor or whatever. Remains to be seen. I'm happy with having a secured 12v 100A battery in the back which I take out when we are not travelling.
Tinggu said
06:45 PM Dec 1, 2019
Whenarewethere: Why the (to me) complicated DC charging system? On the Disco our secondary battery charges from the Anderson plug 40V cable direct off the car's battery/charger. OK you have 4 batteries, so perhaps that answersmy question. My next question: how many Amps do you have available from your 4 batteries and why do you need so much power? Are we looking at the caravan here or the car?
I'm a bit of a dunce but willing to learn!
-- Edited by Tinggu on Sunday 1st of December 2019 07:06:31 PM
Whenarewethere said
06:48 PM Dec 1, 2019
Ask them to email you a PDF of the manual, it will list all the fuse circuits.
My 28 litre Waeco is rated at 6.5amps, it's never used more than 4.0amps while running. I think the 40 - 50 litre models are rated at 7.0amps.
More info here https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/
Whenarewethere said
07:34 PM Dec 1, 2019
Tinggu wrote:
Whenarewethere: Why the (to me) complicated DC charging system? On the Disco our secondary battery charges from the Anderson plug 40V cable direct off the car's battery/charger. OK you have 4 batteries, so perhaps that answersmy question. My next question: how many Amps do you have available from your 4 batteries and why do you need so much power? Are we looking at the caravan here or the car?
My fridge uses about 12 - 15ah per 24 hours, so to 50% drain about 3 to 4 days & 4 batteries will charge about more efficiently. Plus charging phone & camera etc.
4 batteries gives me jump starting options, 380amps for 5 minutes or 1080amps for 5 seconds. My car needs 238amps.
Also I don't need to bother so much with the solar panels, saves me getting them on & off the roof.
The car has a smart alternator so to minimise issues I use a DC-DC charger. The car's 14.4 volts is a bit high to keep pushing into the batteries when charged & more often than not the batteries are charged.
I have thought about 12 to 24 volt DC-DC into the MPPT as it has an excellent battery charging profile. It's about the 10th project down my list currently!
I don't have a towbar. It's all in the car & we sleep in the car & carry up to 80 litres of water.
2 compressors under driver's seat, 3rd in the boot.
Custom heatsinks on ARB compressors & also fan cooled.
Wow! pretty nice s setup/ Very tidy. Quite unlike my bodgy jobs! What is your car? Was the existing alternator happy with the extra loads or did you need to upgrade or add another?
Whenarewethere said
11:07 AM Dec 3, 2019
Land Rover Freelander, everything is a bit over engineered, well mostly. I did rebuild their roof rails but that is an entire subject.
Tinggu said
08:26 AM Dec 7, 2019
I think I have solutions. I'll plug my solar MPPT controller into the accessory socket and charge the battery from that.
In our Disco we used the 40A cable to run the caravan 3 way on 12V when on the road. Remains to be seen if the MPPT can keep up with drain if we use the accessory battery for the same purpose.
I take my hat off to you Whenarewethere. I don't think anything I have done in my life has turned out so tidy. I bodgy along and it generally works but your work is art!
Jaahn said
12:32 PM Dec 7, 2019
Tinggu wrote:
I think I have solutions. I'll plug my solar MPPT controller into the accessory socket and charge the battery from that. In our Disco we used the 40A cable to run the caravan 3 way on 12V when on the road. Remains to be seen if the MPPT can keep up with drain if we use the accessory battery for the same purpose. I take my hat off to you Whenarewethere. I don't think anything I have done in my life has turned out so tidy. I bodgy along and it generally works but your work is art!
Hi Pete
I do not think that is a good solution. The losses from the cig socket, wires, through the MPPT and the wire to the battery, means the voltage at the battery will be too low for proper charging. Indeed the MPPT controller might not have enough voltage into it for working properly at all. At best I would think you might get the battery half charged perhaps.
Jaahn
dogbox said
01:48 PM Dec 7, 2019
most of my cig sockets are marked 120 watts max
Whenarewethere said
04:49 PM Dec 7, 2019
On my car the sockets power down after so many minutes so you don't end up with a flat starter battery with things left plugged in.
You can probably turn the sockets on permanently if you have the equipment to edit CCF codes.
The socket I removed from my car is stamped Ford. Looking at the terminals on the back even though my car has 20amp fuses. I wouldn't want to push more than 10amps through the socket.
In our Discovery we have a big fat cable running through to the back with an Anderson plug we use to charge the 12v 100A battery in the back which either powers the boat winch or runs the fridge in the caravan when we are rolling. Our new car is a Mitsubishi Outlander and I probably won't have time to chase some decent wiring to the back before we are off. So my question is whether a 12v Cigarette socket can be used when under way to recharge the said 12v battery? Probably not up to running the fridge in the caravan but should be OK to recharge the battery after running the Wayco overnight?
Thanks,
Pete
No you cannot use the socket even if it has a 20amp fuse. The lighter sockets are too thin.
Cut & paste from another forum:
The 12 volt power socket in the boot I replaced with an Anderson plug. I put a 3mm spacer behind the plug so it sits 3mm off the panel, another 3mm 27mm diameter disc to fit the 12 volt hole & used an Anderson T handle to clamp behind the trim panel with some Nyloc nuts. Drilled one new hole in the handle so it was in a better position. I drilled 2 holes in the back of the Anderson plug to pull the wires through, once the contact lugs were in place. At the back end of the plug, I had some large clear rubber feet, cut them a touch over size & pressed them into the back on the plug. When bolted in place you do not need to drill any holes in the panel. Also put a 2 way plug on the back of the new plug so I didn't need to cut any to the car's wires. Also put some large heatshrink over the plug although not really necessary. 12 volt power without the plug ever breaking electrical contact.
Not only is the socket too light but the wires feeding it are totally unsuitable. I assume you don't want to utilise the services of the fire brigade to put the fire out.
In fact I wouldn't consider running the maximum 10A that the wires are rated to(?)
If you haven't the time, consider getting an auto-electrician to do it for you.
One other point - monitor the battery voltage carefully as batteries don't take kindly to being discharged below 50% (nominally around 12.2 to 12.3v).
Depends on the car. Mine has three 60amp fuses supplying the boot which in turn feed various things. One of the 3 power outlets, each 20amp fuses, is feed from the boot. The other 2 are feed from the passenger fuse box which has 2 x 60 & 2 x 40amp fuses which in turn has fuses for the individual items.
The boot feeds the heated seats 2 x 15amps (don't have), caravan fridge 15amps (don't have), audio adds up to 80amps of fuses & I only have the cheap hi-fi. Then there are a pile of other fuses.
If you are not using a heated windscreen there is another 2 X 40amps to play with.
Wires running to the boot are more than adequate.
Reply, Quote, More > Edit
I don't use the car battery to run anything. Only use the cars system to charge which is typically 7 to 12amps via two 9amp DC-DC chargers. When the auxiliary is charged it's down to about 3amps charging. I have very good voltage & use a DC-DC charger actually so I can reduce voltage.
2 of my 4 auxiliary batteries under the seat.
What size fridge do you want to run?
Have you thought of running the fridge cold during the day & warmer at night or even off overnight which what I did before I had an auxiliary battery. Keep it full with thermal mass ie water bottles. As soon as you have room chuck another one in the fridge.
Whenarewethere: Why the (to me) complicated DC charging system? On the Disco our secondary battery charges from the Anderson plug 40V cable direct off the car's battery/charger. OK you have 4 batteries, so perhaps that answersmy question.
My next question: how many Amps do you have available from your 4 batteries and why do you need so much power? Are we looking at the caravan here or the car?
I'm a bit of a dunce but willing to learn!
-- Edited by Tinggu on Sunday 1st of December 2019 07:06:31 PM
Ask them to email you a PDF of the manual, it will list all the fuse circuits.
My 28 litre Waeco is rated at 6.5amps, it's never used more than 4.0amps while running. I think the 40 - 50 litre models are rated at 7.0amps.
More info here https://thegreynomads.activeboard.com/t65059593/extra-fridge-insulation-wattage-test/
My fridge uses about 12 - 15ah per 24 hours, so to 50% drain about 3 to 4 days & 4 batteries will charge about more efficiently. Plus charging phone & camera etc.
4 batteries gives me jump starting options, 380amps for 5 minutes or 1080amps for 5 seconds. My car needs 238amps.
Also I don't need to bother so much with the solar panels, saves me getting them on & off the roof.
https://thegreynomads.activeboard.com/t65231112/custom-6x20-watts-solar-setup-with-mppt/
The car has a smart alternator so to minimise issues I use a DC-DC charger. The car's 14.4 volts is a bit high to keep pushing into the batteries when charged & more often than not the batteries are charged.
I have thought about 12 to 24 volt DC-DC into the MPPT as it has an excellent battery charging profile. It's about the 10th project down my list currently!
I don't have a towbar. It's all in the car & we sleep in the car & carry up to 80 litres of water.
2 compressors under driver's seat, 3rd in the boot.
Custom heatsinks on ARB compressors & also fan cooled.
Land Rover Freelander, everything is a bit over engineered, well mostly. I did rebuild their roof rails but that is an entire subject.
Hi Pete
I do not think that is a good solution. The losses from the cig socket, wires, through the MPPT and the wire to the battery, means the voltage at the battery will be too low for proper charging. Indeed the MPPT controller might not have enough voltage into it for working properly at all. At best I would think you might get the battery half charged perhaps.
Jaahn
On my car the sockets power down after so many minutes so you don't end up with a flat starter battery with things left plugged in.
You can probably turn the sockets on permanently if you have the equipment to edit CCF codes.
The socket I removed from my car is stamped Ford. Looking at the terminals on the back even though my car has 20amp fuses. I wouldn't want to push more than 10amps through the socket.