charging second battery

wombat50 · Veteran Member

charging second battery

KFT · Guru

Hi wombat50
Looking at what you have I would say you need to double your solar watts for the caravan and to charge the aux battery in the car I would suggest a DC/DC charger.

Peter_n_Margaret · Guru

Whether there is a need for more solar, or not depends entirely on what other loads need to be satisfied and Wombat has not given us that information.
When is the fridge hooked to the second battery?
The easiest way to charge it is from the alternator, since the solar on the van won't be available easily when unhitched.
Cheers,
Peter

wombat50 · Veteran Member

The 1 panel on the van has so far been enough for the van. The aux. battery does get charged from the alternator while driving. What im after is a way to keep the aux. charged if im unhitched from van and parked for a couple of days and using the fridge. I suppose the easiest way is to get a portable panel and hook it up to the aux. I was looking to see if there was an easy way to run a lead from the solar in van to aux. to keep it charged when unhitched.
Hope that explains more.

Thanks

Peter_n_Margaret · Guru

Long leads for DC power are usually a bad idea because of voltage drop - hence KFT's suggestion of needing a DC-DC charger in the car, that would work, but the power will still be wasted.
I would probably add a fixed panel to a pack rack on the car and it will keep both the car batteries charged all the time, including when you go off for a couple of days with the tent :)
Cheers,
Peter

Radar · Guru

wombat50 wrote:
I would like to be able to charge the 2nd battery in the car by using the solar set up from the caravan. In the car the 2nd battery is 60ampAGM.
The van setup is 1x130W panel and 2x120amp AGM batteries which works good.
I want to be able to keep the 2nd car battery charged while i have the car fridge hooked up to it .

Thanks

Hi WB50.

First off I have no numbers or piece of paper, just cheap experience.

We have the second 110amp battery in the car to basically power the 12 volt frig, 2 x 170 watts solar panels on the caravan roof and 1 x 110 amp battery.

Now when we are parked up I use a extension lead via anderson plug from the secod battery to the caravan battery to maintain the ute battery now for about 5 years.

The simple system is cheap, works great. I can not justify the cost of expensive dcdc charger.

My thoughts only are that you are running a very on light on solar.

Best of luck working threw this all.

BAZZA44 · Senior Member

Same connections as Radar. Working for 15 years. 480 watts solar on van, 2 x 120 amp agm in van ,1 x 100 amp agm in car and a lead to use when required with anderson plugs.

Circuit breakers at each end. 6 AWG is the biggest size wire to fit 50 amp anderson plug fittings

Barry

Whenarewethere · Guru

BAZZA44 wrote:
6 AWG is the biggest size wire to fit 50 amp anderson plug fittings

4awg into 6awg lug modifications:

https://thegreynomads.activeboard.com/t65662065/50amp-anderson-plug-expand-for-4-awg-cable/

& while at it if you haven't got a large enough soldering iron or two. A heat gun works a treat. Drill a hole in a block of wood to stand up the lug. With the heat gun you can heat the wire as well.

STRETCH ARMSTRONG · Senior Member

Hey wombat50. I'm have a similar set up to yours. As others have said l added a 125w pannel to the roof of my ute and have never looked back. I brought a fold up pannel and split it in half. Now l have 125w on the ute and a 125w portable.

oldbloke · Guru

Radar wrote:
wombat50 wrote:
I would like to be able to charge the 2nd battery in the car by using the solar set up from the caravan. In the car the 2nd battery is 60ampAGM.
The van setup is 1x130W panel and 2x120amp AGM batteries which works good.
I want to be able to keep the 2nd car battery charged while i have the car fridge hooked up to it .

Thanks
Hi WB50.
First off I have no numbers or piece of paper, just cheap experience.
We have the second 110amp battery in the car to basically power the 12 volt frig, 2 x 170 watts solar panels on the caravan roof and 1 x 110 amp battery.
Now when we are parked up I use a extension lead via anderson plug from the secod battery to the caravan battery to maintain the ute battery now for about 5 years.
The simple system is cheap, works great. I can not justify the cost of expensive dcdc charger.
My thoughts only are that you are running a very on light on solar.
Best of luck working threw this all.

We have a similar arrangement. When parked you should be able to plug a portable panel into the spare fridge battery. That's what I do.

wombat50 · Veteran Member

thanks for all the replies. today i brought a 200wsolar blanket which i will attach to the battery and when not using it for that ill have it plugged into the van to provide more charging to to van panel

Whenarewethere · Guru

What is the actual area of the solar cells of the 200 watt blanket.

Aus-Kiwi · Guru

Whatever is your solar requirement? If you double it ? It will work way better !! Best to take the load off extended battery so it draws off all of them . Its not 100% efficient!! 60/70 % if your lucky !! Then its only while Suns out ! So you gotta go for it when you can !!

oldbloke · Guru

Aus-Kiwi wrote:
Whatever is your solar requirement? If you double it ? It will work way better !! Best to take the load off extended battery so it draws off all of them . Its not 100% efficient!! 60/70 % if your lucky !! Then its only while Suns out ! So you gotta go for it when you can !!

Aus kiwi. Would you mind clarifying that in lay terms?

wombat50 · Veteran Member

Dimensions: (Open):	1110 x 1105 x 4.6mm
Dimensions: (Closed)	530 x 370 x 95mm
Panel Weight (incl accessories):	5.95KG

or did you want size of each cell

Whenarewethere · Guru

wombat50 wrote:
Dimensions: (Open):
1110 x 1105 x 4.6mm
Dimensions: (Closed)
530 x 370 x 95mm
Panel Weight (incl accessories):
5.95KG
or did you want size of each cell

The actual cell area.

The area of your blanket is 1.110 x 1.105 = 1.226 m²

Let's say the cells are 170 watts/m²

1.226 x 0.170 = 208 watts

But the actual cells only have a coverage of 70%

208 watts x 0.7 = 146 watts

& that is when the panel is square to the sun & doesn't overheat, ie ventilation front & back.

So if you do not have a DC clamp meter you will have a realistic idea of the output of the blanket.

Aus-Kiwi · Guru

On good day the float light on regulator is flashing green . But on overcast day ? It may not ever get to that point of charge . Way back when I only had 180 watt solar it was way after midday on a good day . Then I doubled the solar with extra panels wired in parallel. ( seperate wired from each panel) from then on even on overcast day the regulator light was flashing between 10 to 12am midday!! If I added up usage and so called theory of the solar ? It doesnt work 100 % efficient! Maybe 70% ? For safety etc I would say around 50% is better . So imo twice the solar you need in
Theory ! More batteries dont help . Its like have many bank accounts . Especially if they are not charged in reasonable time . Yes extra batteries if voltage drops too low .

oldbloke · Guru

Auskiwi. Now I'm more confused. To further clarify. Can u pls explain.

"Best to take the load off extended battery so it draws off all of them"

Did u mean plug the ute battery into the van all the time? I ordered to draw power off both Ute and van batt.?

Whenarewethere · Guru

Hopefully the blanket's cable is not under size.

For example, let's say 6 metres & 12amps, so 12m for both + & - voltage drop:

6awg 0.190v

8awg 0.302v

10awg 0.481v

12awg 0.776v

14awg 1.217v

oldbloke · Guru

Whenarewethere wrote:
Hopefully the blanket's cable is not under size.
For example, let's say 6 metres & 12amps, so 12m for both + & - voltage drop:
6awg 0.190v
8awg 0.302v
10awg 0.481v
12awg 0.776v
14awg 1.217v

I have NFI what AWG means. And I'll bet a few others who reads this.

Whenarewethere · Guru

I profusely apologize.

I should have stated AWG (American Wire Gauge)

Whenarewethere · Guru

I have no idea what Nation Forest Institute has to do with wire, maybe fencing wire?

-- Edited by Whenarewethere on Friday 12th of March 2021 08:35:33 PM

oldbloke · Guru

Whenarewethere wrote:
I profusely apologize.
I should have stated AWG (American Wire Gauge)

Aha, your forgiven.

So AWG must be the copper core diameter of 1/8"...right?

And FYI the Nation Forest Institute use this guage wire to fence the NPs. Lol

Aus-Kiwi · Guru

Theres so many types of wire sizing its not funny . In domestic elect its different again . Its the cable only and squared . Then theres the type for each strand . Like 7/14 . 7 strands / 14 gauge before metric . Confused ? Lol

Jaahn · Guru

Aus-Kiwi wrote:
Theres so many types of wire sizing its not funny . In domestic elect its different again . Its the cable only and squared . Then theres the type for each strand . Like 7/14 . 7 strands / 14 gauge before metric . Confused ? Lol

Hi Kiwi smile

Yes it is stupid. Some numbers go up as it gets bigger, some go down, WTF. Some include the insulation with the wire diameter also ??

The only sensible way to compare wire is the area of the copper in square mm. It a seller does not give you that he is scamming you because no one knows what all the others mean. aww That is why the house wiring standard quotes the wire area required.

Jaahn

-- Edited by Jaahn on Saturday 13th of March 2021 02:06:39 PM

oldbloke · Guru

Jaahn wrote:
Aus-Kiwi wrote:
Theres so many types of wire sizing its not funny . In domestic elect its different again . Its the cable only and squared . Then theres the type for each strand . Like 7/14 . 7 strands / 14 gauge before metric . Confused ? Lol

Hi Kiwi
Yes it is stupid. Some numbers go up as it gets bigger, some go down, WTF. Some include the insulation with the wire diameter also ??
The only sensible way to compare wire is the area of the copper in square mm. It a seller does not give you that he is scamming you because no one knows what all the others mean. That is why the house wiring standard quotes the wire area required.
Jaahn

-- Edited by Jaahn on Saturday 13th of March 2021 02:06:39 PM

Yes, very confusing. I think the diameter of the copper core is a good way to go.

Some of wire from the car batt/alternator is 6 and some 8 to the van or spare batt in the ute. But its a meaningless number. (Just what the mech called it) Just looks thick to me. Lol