Build Report: MPPT Solar Charging Station for Etrike

General Discussion about electric bicycles.
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pullin-gs   100 W

100 W
Posts: 126
Joined: Jul 31 2009 8:26pm

Build Report: MPPT Solar Charging Station for Etrike

Post by pullin-gs » Aug 30 2019 10:55am

Works great.
Charges 10S6P 18AH pack at rate of 2.5amps in full sun.
I use it for both my Etrikes.
Anchored 100W panel to south-facing side of garage.
Grounded panel to steel pipe on gas meter using 12awg solid copper.
Drilled 1/2" hole through wall for 12awg solid copper wire to charge controller.
Inside garage (other side of wall where panel is anchored) I mounted shelf for electronics.
Charge cable is 10' soft multistrand 12awg appliance cable.
I'm using a programmable (set to 41.5V) boost MPPT lithium 12V solar charge controller.
Also using "positive disconnect" Lithium Battery Charge Controller Protection Board set to 42V.
BMS overcharge disconnect protection on BMS as well.

Parts list/cost:
Richsolar 100 Watt Polycrystalline 100W 12V: $81 delivered
https://www.amazon.com/gp/product/B07DN ... UTF8&psc=1
MPPT "boosting" Solar Charge Controller: $33 delivered
https://www.youtube.com/watch?v=omAhsQqwWSo&t=108s
Overcharge protection: $5 delivered
https://www.ebay.com/itm/10A-6-60V-Lith ... 2749.l2649

Various hardware (aluminum angle bars for mounts, wire, stainless fittings, rivets, shelf): about $40.
All-in cost is about $150.

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wturber   10 MW

10 MW
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Joined: Aug 23 2017 8:52pm
Location: Fountain Hills,AZ
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Re: Build Report: MPPT Solar Charging Station for Etrike

Post by wturber » Sep 01 2019 4:32pm

Is that a measured charge rate? If so, that's pretty darned good. I've considered doing something like this, but my bike is with me during the day. Though now with my shorter commute I could split my battery and leave one half home for charging while I run the bike with the other.

Of course, given that I use less than 450 wh/day for my commute, it would take me about 2000 days (over five years) to break even on costs. assuming a wall power cost of 15 cents per kwh. :mrgreen:
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

pullin-gs   100 W

100 W
Posts: 126
Joined: Jul 31 2009 8:26pm

Re: Build Report: MPPT Solar Charging Station for Etrike

Post by pullin-gs » Sep 02 2019 9:29am

wturber wrote:
Sep 01 2019 4:32pm
Is that a measured charge rate? If so, that's pretty darned good. I've considered doing something like this, but my bike is with me during the day. Though now with my shorter commute I could split my battery and leave one half home for charging while I run the bike with the other.

Of course, given that I use less than 450 wh/day for my commute, it would take me about 2000 days (over five years) to break even on costs. assuming a wall power cost of 15 cents per kwh. :mrgreen:
Current measures almost 2.5 amps at start of charge when pack voltages are lower because pack is mostly depleted.
With MPPP type controller, output amps (volts stays at input charge voltage of battery) is dynamically adjusted depending on total watts input from panel by MPPP charge controller....so max power delivered by the panel to charge controller is about 5.5amps@17V....which after losses converts to about 2.3amps @36V charge voltage delivered to battery.

I only use it to charge two days each week for my bike (I dont ride more that 70 miles in a week). Break-even is 10 years?

However I needed a second charger anyway, so costs come down a bit.
Also, I hooked up the panel to the trickle charger for my car (I barely ever drive it.....only has 5,000 miles and is 25 years old!).
I may even try to get 30% tax credit on system...if I include cost of two trike batteries I may get almost $200 cash back?? It is a stretch, but I think I can legally pull it off. It is a residence-mounted solar power delivery system for household chargers, which can charge batteries that not only are used on ebikes, but can also be used to power household wireless IP security camera system etc. , not just car and ebikes. Thoughts?

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