Building a Portable Solar Battery Pack (1 Viewer)

[george_tlc]

^ Yep, a way to charge the aux while driving is pretty well mandatory, especially in warmer weather and/or with overcast days.

I've just returned from a near 6 week trip of which 3 1/2 weeks was in the oz bush with my older son visiting some remote areas. We had an ARB 50Q for food/drinks and also all other camp loads (lighting, water pump etc) run from the aux battery. Most of the trip was exploring and so only on a few days did we have a day lay over at a stop. It was essential for the aux to charge while we were driving around and no way would the solar have been able to top the battery up in just the morning/evening sun if the battery wasn't already topped off before we stopped. Additionally, it is winter in oz right now, with sunrise at around 7AM and sunset at about 5PM. So that gave maybe 3 hours from sunrise to when we would be moving again and maybe 1 hour from stopping to sunset.

With the vehicle alternator charging the aux while on the move, we would start each evening with a full charge, by morning we had used maybe 6 amp.hour. I found that in the cooler evening weather (temps 40F to 50F) the ARB was drawing 3A while running (variable speed/draw danfoss) and was running at most 1/8 of the time. So, 14 hours of non-solar for 3A at 1/8 the time means 14 x 3 x 1/8 = 5.25 amp.hour which is very impressive. Needless to say that a couple of hours of morning sun would have the aux battery back to full charge and the victron mppt controller transitioning to 'float' mode.

On a lay over day, the solar easily kept up with the fridge and camp loads, we had more solar than we could use. I would look for things to charge to not waste the solar

The victron with bluetooth was a nerd's delight. When bored at camp, I could connect to it (from the comfort of a camp chair near the fire) and check how many watts were being delivered, used and current battery voltage and charging status. One thing that I did find and have to rewire is that for the victron to measure amp draw from the load, the load's GROUND wire must be run from the load ground to the victron's LOAD ground terminal. The victron is measuring load current via the ground terminal sense. I originally had the load's positive terminal going to the victron positive load terminal, but the load's ground going to the body directly and this gave 0 Amp indicated on the victron app. Once I drew an additional dedicated ground wire from the load to the victron load ground the measurements came good.

I only run the fridge on the load output off the victron, this way I can keep an eye on fridge power usage versus solar delivery on stationary days. The fridge has an anderson SB50 on it (chopped off the original end) and plugs into a dedicated SB50 near it that then runs to the victron load +/- terminals.

cheers,
george.

 

[GeoRoss]

some criticism of the "GT Power" wattmeters up there... Well, mine (one actual GT power, one clone) both read only 20 mV low around 13.3V and are only 30mA low at around 1A and better above that (and worse below). In comparison with good Flukes. So, not that bad for the price actually.

Well, yours is much better than mine. I use mine rarely since it is so far off.

Time to charge the aux battery.

 

[GeoRoss]

Thanks for the real world stories. This is on my winter projects list. There are tons of ways to do it. I will say it gets confusing with products that are integrated DC chargers like the Redarcs which are claimed to be better than the simple in-parallel set ups with a simple Bluesea solenoid. I’ve got a lot of reading to do as I’m a fit-for-purpose sort of guy. The only decision I have made is to mount my aux battery in the back for now.

I agree with @GeoRoss that an integrated system is the way. That way, not only is your Aux charged, but even your main starting battery gets topped a bit every day the system is on. Charging while driving is good too, for instance what if it rains or you park in the shade?

I'm just back from Rubithon, I'd say the majority of trucks I saw are doing some sort of solar, and I'd say that with a fridge, and a stay overy 1 day, it's basically mandatory. Now I want to see good panels get lighter, and not give up the robust strength of a traditional panel.

^ Yep, a way to charge the aux while driving is pretty well mandatory, especially in warmer weather and/or with overcast days.

I've just returned from a near 6 week trip of which 3 1/2 weeks was in the oz bush with my older son visiting some remote areas. We had an ARB 50Q for food/drinks and also all other camp loads (lighting, water pump etc) run from the aux battery. Most of the trip was exploring and so only on a few days did we have a day lay over at a stop. It was essential for the aux to charge while we were driving around and no way would the solar have been able to top the battery up in just the morning/evening sun if the battery wasn't already topped off before we stopped. Additionally, it is winter in oz right now, with sunrise at around 7AM and sunset at about 5PM. So that gave maybe 3 hours from sunrise to when we would be moving again and maybe 1 hour from stopping to sunset.

With the vehicle alternator charging the aux while on the move, we would start each evening with a full charge, by morning we had used maybe 6 amp.hour. I found that in the cooler evening weather (temps 40F to 50F) the ARB was drawing 3A while running (variable speed/draw danfoss) and was running at most 1/8 of the time. So, 14 hours of non-solar for 3A at 1/8 the time means 14 x 3 x 1/8 = 5.25 amp.hour which is very impressive. Needless to say that a couple of hours of morning sun would have the aux battery back to full charge and the victron mppt controller transitioning to 'float' mode.

On a lay over day, the solar easily kept up with the fridge and camp loads, we had more solar than we could use. I would look for things to charge to not waste the solar

The victron with bluetooth was a nerd's delight. When bored at camp, I could connect to it (from the comfort of a camp chair near the fire) and check how many watts were being delivered, used and current battery voltage and charging status. One thing that I did find and have to rewire is that for the victron to measure amp draw from the load, the load's GROUND wire must be run from the load ground to the victron's LOAD ground terminal. The victron is measuring load current via the ground terminal sense. I originally had the load's positive terminal going to the victron positive load terminal, but the load's ground going to the body directly and this gave 0 Amp indicated on the victron app. Once I drew an additional dedicated ground wire from the load to the victron load ground the measurements came good.

I only run the fridge on the load output off the victron, this way I can keep an eye on fridge power usage versus solar delivery on stationary days. The fridge has an anderson SB50 on it (chopped off the original end) and plugs into a dedicated SB50 near it that then runs to the victron load +/- terminals.

cheers,
george.

 

[george_tlc]

^ I'm a great believer in simple. With simple, I know exactly what is happening and why AND I am in control of the process.

My setup (what I run in oz is same setup I use for the US 80) is:

1) Dumb solenoid that parallels the batteries when the alternator is up and running. I 'could' live with a simple 'smart' relay like the bluesea units, I just did my original setup way before they were available/popular.
2) Manual marine switch where I can decide to parallel the batteries when stationary.
3) Victron MPPT charger connected direct to the Aux battery.
4) Fridge connected to load output of Victron unit (so powered by Aux battery).
5) Cables/extensions to connect my folding solar panel to the Victron. Since it's all anderson SB50 based, if the victron bit the dust out bush, I could just plug the solar direct to the aux battery (also have dedicated SB50 on each battery). Fridge (also has SB50) could be plugged directly to battery as well. Obviously with no charge controller I'd need to monitor battery voltage to prevent overcharge, but this is only a worst case/failure scenario (got to keep the beer cold )

That's basically it, simple and stupid. I know what is charging or why. I can also easily bypass stuff if it breaks. Out bush on an extended trip does not give the option of getting on amazon and ordering next day delivery

Oh, and we need a picture from the trip... Late afternoon and panel is just about to lose it's sunlight, before being relocated.
And yes, it's the kitchen sink, and no, we weren't the ones that took it bush. It, along with other 'junk' was near the water tank and we used it to make a bit of a wind shield to trap heat from our heating fire. Getting ready to start the cooking fire in the foreground with other junk found in the area. About 120 miles from the nearest town (laverton) via tracks. We're on the edge of the great victoria desert in w.australia.

cheers,
george.

 

[GeoRoss]

^ I'm a great believer in simple. With simple, I know exactly what is happening and why AND I am in control of the process.

My setup (what I run in oz is same setup I use for the US 80) is:

1) Dumb solenoid that parallels the batteries when the alternator is up and running. I 'could' live with a simple 'smart' relay like the bluesea units, I just did my original setup way before they were available/popular.
2) Manual marine switch where I can decide to parallel the batteries when stationary.
3) Victron MPPT charger connected direct to the Aux battery.
4) Fridge connected to load output of Victron unit (so powered by Aux battery).
5) Cables/extensions to connect my folding solar panel to the Victron. Since it's all anderson SB50 based, if the victron bit the dust out bush, I could just plug the solar direct to the aux battery (also have dedicated SB50 on each battery). Fridge (also has SB50) could be plugged directly to battery as well. Obviously with no charge controller I'd need to monitor battery voltage to prevent overcharge, but this is only a worst case/failure scenario (got to keep the beer cold )

That's basically it, simple and stupid. I know what is charging or why. I can also easily bypass stuff if it breaks. Out bush on an extended trip does not give the option of getting on amazon and ordering next day delivery

Oh, and we need a picture from the trip... Late afternoon and panel is just about to lose it's sunlight, before being relocated.
And yes, it's the kitchen sink, and no, we weren't the ones that took it bush. It, along with other 'junk' was near the water tank and we used it to make a bit of a wind shield to trap heat from our heating fire. Getting ready to start the cooking fire in the foreground with other junk found in the area. About 120 miles from the nearest town (laverton) via tracks. We're on the edge of the great victoria desert in w.australia.

cheers,
george.

Great advice, I do the same with Anderson plugs. I can easily do the same. I’m still running the Sunsaver 10A PWM. Some day I’ll upgrade to the Victron MPPT.

Are you late enough in the season flies are not a problem? One thing I’ve heard about WA is flies can be game ender on the comfort side.

 

[george_tlc]

^ winter in w.australia right now, so flies are a non-issue. Well, there's still a lot compared to most places in the US, but next to nothing by oz standards

A pic my son captured of me, with my definition of 'non-issue'.... Though while they just 'land' on your back it's clearly better than them buzzing around the face and landing there.

cheers,
george.