Motorhome Build Thread


MASSIVE restock of EV Batteries at www.batteryhookup.com 5% coupon "POWERWALLS"

Mezbatt

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Redpacket said:
Mezbatt said:
Quick question here..... I'm planning a setup whereby the automation will allow only one bank (2S2P x2banks in total) of panels to tilt at a time to pick up a more efficient angle to the sun. They will tilt in opposite directions (one way or the other) via a clever method we have come up with but this will give rise to different charging currents feeding the batteries almost all of the time. IE: A lead bank and a trailing bank with reference to charging potential. Any thoughts or input on this idea please..????

Should work fine, probably should use two separate MPPT chargers for best results.
Maybe you could run this length-ways along the van with the hinge side down the centre line?
Lift drivers side row or passengers side row up from outside edge.
We are one the same page Redpacket. This is exactly the intension using a dual actionhydraulic 'Pull' ram and linkages plus cable operated spring loaded latches. Two MPPT SCC's . The previous vehicle owners chequerplated the whole roof so we have a robust fixing platform as a starting point.
 

Redpacket

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There's DC powered electric jacks/actuators (no hydraulics) that would do this well....
Great the roof is strong :)
 

Korishan

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Redpacket said:
There's DC powered electric jacks/actuators (no hydraulics) that would do this well....

What comes to mind is a trailer jack. You can also use what is called a linear actuator. You can buy a premade one, or make one. Fairly easy design to duplicate.
 

Mezbatt

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Korishan said:
Redpacket said:
There's DC powered electric jacks/actuators (no hydraulics) that would do this well....

What comes to mind is a trailer jack. You can also use what is called a linear actuator. You can buy a premade one, or make one. Fairly easy design to duplicate.

Thanks guy's, yeah looked at linear actuators but the maths against them and for hydraulic is quite convincing. As you said Korishan, I've been looking at double action rams. Same as a trailer jack but a little more robust and can be jacked 'down' which is the important aspect so they can be re-latched into a safe resting position. I can get a double acting ram with positional check valves, hose, hand pump and all fitting for a little over 320 sterling.. For 24v linear actuators to do same job your looking at over 1200. Good to get feedback, thanks Redpacket and Korishan.
 

Redpacket

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Mezbatt said:
Korishan said:
Redpacket said:
There's DC powered electric jacks/actuators (no hydraulics) that would do this well....

What comes to mind is a trailer jack. You can also use what is called a linear actuator. You can buy a premade one, or make one. Fairly easy design to duplicate.

Thanks guy's, yeah looked at linear actuators but the maths against them and for hydraulic is quite convincing. As you said Korishan, I've been looking at double action rams. Same as a trailer jack but a little more robust and can be jacked 'down' which is the important aspect so they can be re-latched into a safe resting position. I can get a double acting ram with positional check valves, hose, hand pump and all fitting for a little over 320 sterling.. For 24v linear actuators to do same job your looking at over 1200. Good to get feedback, thanks Redpacket and Korishan.

Pretty sure you'd get annoyed hand pumping them up & down! Know I would :)
Electric ones go both ways, ie push & pull?
Ebay seems to have heaps of 12 & 24Vlinear actuators? Just have to find ones with suitable IP rating for light weather... All sorts of motion ranges available.
www.ebay.com.au/itm/6-Stroke-Linear-Actuator-DC12V-Electric-Motor-900N-Water-proof-Heavy-Duty-150mm/254308284570 $40 AUD

If they're that expensive, maybe just put more panels on top & leave them flat - sometimes simple can be best?
 

Mezbatt

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Going flat with 8x230w panels on the roof and an extra 4x230w panels on the rear tailgate ( fold out structure and separateMPPT SCC) to be used as an auxiliary power boost as and when needed, well this is my current plan but of course that could change, what do you think on this setup...?????

With an intended 24v battery bank what Ahr rating could i go too when all 12 panels (230w) are charging ????
 

Redpacket

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Approx calculations assuming full overhead sun, no shade.
You use panel spec NOCT numbers as they include temperature coefficient changes. 230W will be STC.
On a cold windy clear day you might get more, on a hot still summer day you would get less.
As the sun changes angles on the panels this will make a big difference too.
NOCT are approx 80% of STC.
So 230 x 12 x 0.80 = approx 2,200W
Assuming the MMPTs are approx 95% efficient & batteries at nominal 24V,
2200 x 0.95 / 24V = 87A
Likely to have a few % cable losses too.
You should allow for the cold day current so build for say 100A
 

ajw22

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Mezbatt said:
Going flat with 8x230w panels on the roof [...]

If you mean mounting them flat on the roof no tilt at all... then rain will not effectively wash away dust, and you might end up with flecks of baked hard dirt collecting on the glass. Best to mount at a slight angle, so that rain can wash away the dirt over the frame edges.
 

Mezbatt

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Redpacket said:
So 230 x 12 x 0.80 = approx 2,200W
Assuming the MMPTs are approx 95% efficient & batteries at nominal 24V,
2200 x 0.95 / 24V = 87A
Likely to have a few % cable losses too.
You should allow for the cold day current so build for say 100A

Sorry Redpacket I meant Ahr rating for the batteries. 100ah or 200ah etc etc.... I've been looking at 200ah cells to build a 24v battery bank.
 

Redpacket

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No problem :)
So the battery Ahr sizing depends on how much load you plan to run & for how long.
Do a power budget. Ie for each appliance, estimate how much power it uses & for how long.
Add this up, factor in inverter losses & a few days of cloud/shade & this should be a reasonable "guestimate".
 

Mezbatt

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Intended solar array : 8x 230w , VOC 36v VMP 30v. IMP 7.67A. Then 4x 230w (same panels) as an auxiliary booster setup used as and when needed or just in play when I'm at the truck and the sun is blazing. So 12 in total for calculation purposes.

Power demand for the inverter is approx 1800w-2200w variable daytime using AC unit.

Intended battery build will be 24v (200Ah cells if I can afford them at purchase). Looking at using the Victron Multiplus Inverter/Charger 24/3000/70-50 unit.

Two MPPT SCC's, one for the 8 roof mounted ones and one for the 4 auxiliary panels. Could anyone do a quick math summary on this intended path....????
 

Redpacket

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Mezbatt said:
Intended solar array : 8x 230w , VOC 36v VMP 30v. IMP 7.67A. Then 4x 230w (same panels) as an auxiliary booster setup used as and when needed or just in play when I'm at the truck and the sun is blazing. So 12 in total for calculation purposes.
.........
Two MPPT SCC's, one for the 8 roof mounted ones and one for the 4 auxiliary panels. Could anyone do a quick math summary on this intended path....????

The calculations would be the same as above in #27.
Vmp & Isc numbers just posted are STC, you need to use the NOCT numbers instead.
So 230 x 12 x 0.80 = approx 2,200W
2200 x 0.95 / 24V = 87A
If only 8 panels in use 230 x 8 x 0.80 = approx 1472W, ~58A etc

Even though you could get one larger & one smaller MPPT, having two the same (sized for the 8 panels) could give you redundancy if you wanted
 
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