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webcurler avatar image
webcurler asked

Load switching behaviour on Smartsolar MPPT 75/15

My scenario for lightweight solar Electric Bicycle charging. I have a P3solar 125 (1.7kg) foldable panel (114W on a good day), MPPT 75/15 (500g) and a Redarc 350W Pure Sine inverter (1.2kg) powering a Bosch charger (96W).

I'm using "User def. algorithm 1" on the Load Output (off < 12.20V, on > 14.20V) with no jumper installed.

The load output does not switch off according to these parameters, even with 2 mins - 1/2 hour of Hysteresis.

This is a pain as my inverter continuously beeps on low voltage before switching off but does auto restart upon adequate voltage.

I'd like to replace this 1.2kg inverter with a 600g 150W Pure Sine inverter but i doubt if it has an auto restart after low voltage cutoff. So in this instance it would be nice if the Victron switched on & off when it's supposed to.

So in lower light it's a case of switching the load on every hour or so and then switching off until the battery is charged enough and the cycle repeats, i know this will reduce battery life but i'm not too concerned about that.

I know the 75/15 is not designed for this scenario but are there any solutions?

smart solar set-up help
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ripper avatar image
ripper answered ·

You dont have much energy to go around anyways and you are wasting up to 40% by going Dc to Ac to Dc in losses alone plus everything thats not enough to power your inverter up at all which is a third of a day or all on a cloudy day I assume. I would be looking at charging the Bosch battery with DC directly. The bigger Victron Mppts like 150 35 can do 36V but probably need more voltage out of your solarpanel then you currently have. 47 Volts plus so seveal in series. You save the inverter and gain considerably more sun energy. When you insist on using the current panel there is a cheapo 7210a or something step up mppt which you could try. The mppt function is very slow and mostly garbage though.

Alternatively an Orion as a 24 48 2.5 could be used depending on panel voltage. Same problems but less inverter losses

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webcurler avatar image webcurler commented ·

Hi, as per my post here: https://electricbikereview.com/forum/threads/bosch-solar-charging.26290/#post-183535

This is for touring and my total weight capacity for this e-bike is 140kg, the bike itself is 30kg and i'm 83kg. Tent, food, water, extras, etc. The P3 panel produces 40w on cloudy days, 110w (MPP about 27V) on good sunny days, no other panel i've seen can do this whilst weighing 1.77kg and folding up to 31x26x7cm, i could have powered my entire house in panels with what i spent on this one folding panel.

Until i dissect/logic analyze signals on the CAN bus of the Bosch system (and void warranty) in regards to charging i don't know if i can directly insert 36VDC, yes it would be very nice if i could and i do hate the idea and efficiency losses of the many conversions in-between.

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Anil Ghatikar avatar image
Anil Ghatikar answered ·

I would suggest a diffrent route - It would be much more effcient and compact to use a BOSCH travel charger ( 12 V to battery- designed for CAR)

You will end up carrying two chargers but have redundancy. I am sure in emergency finding a car with 12 V cigarrate socket is easier than a house with 230 V outlet

A more compact setup can be to replace the 125 W panel with 100 Watt 12 V panel and Use a smaller battery with BMS built in or alternatively use a compact Charge controller since you already have battries with BMS to reduce weight


Some links to get you started

https://www.e-bikeshop.co.uk/blog/post/bosch-ebike-12v-travel-battery-car-charger/


https://www.ebay.com/itm/PWM-Solar-Charge-Controller-Regulator-for-lithium-battery-2A-USB-Output-10A-30A/223413606029


https://www.ebay.com/itm/EE-LFB-12V-10AH-Lithium-Iron-Phosphate-LiFePO4-Rechargable-Batteries-w-BMS



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webcurler avatar image webcurler commented ·

The Bosch travel charger was my first stop but they have discontinued them and not one shop on the planet has any to sell.

https://electricbikereview.com/forum/threads/bosch-solar-charging.26290/

and my latest setup:

https://electricbikereview.com/forum/threads/bosch-solar-charging.26290/#post-183535

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Anil Ghatikar avatar image
Anil Ghatikar answered ·

You are aboslutely right. I read the complete post now and understood the solution you came up with is igenious

Another tryu you can do is use integrated battery +inverter combo with solar charging like omnicharge -https://www.omnicharge.co/products/omni-20-specs/ ( input only 45Watt !! and internal stoarge is small )


or https://www.amazon.com/100-Watt-Portable-Generator-40800mAh-Emergency/dp/B01M3S00H0


I personally use the Omnicharge on my outdoor trips as weight is the most importnatn criterial

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webcurler avatar image webcurler commented ·

Hi, thanks.

I'm now invested in the route i've taken, just a few small problems with the Smartsolar MPPT.

I've looked into the 'Portable Generators' and that Amazon one is the first i've seen that can handle a decent DC input.

But i require 240VAC input, preferably 240VAC output and Pure Sine Inversion. Those devices are getting there, i'll just give them another 6 months or so before i go that route.

I also like the smarts of the Smartsolar MPPT (which is at the heart of my scenario) and none of those Portable Generators have anything like it.

Or hopefully i'll be able to inject DC straight into the Bosch batteries or charging port on ebike (it has 2 x 500Wh batteries and can charge one after the other).

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