Charging a HV battery with 500w array

[Block]

Hey guys,

I’ve restored an old van, EV swapped it, and added a 500w array. The solar is for interior accessories on a 12v battery. (stove, heater, lights, lava lamp, weekend camping stuff) 5x 100w panels. Working great so far.


The HV battery that propels this van is 115v when fully charged. It’s a Lifepo4 280ah 33s2p ~60kwh pack that is normally charged like any other EV. My solar panels only charge the 12v system, which sits at full constantly, so I'm looking for a charge controller to give the big pack some juice, even if it’s +1mile/day. Definitely no Apterra, but why not.

Anyone have experience stepping voltage up from a smaller array? (500w panels → 115VDC pack) I’ve seen some of the solar racer guys do some custom voltage step-up wizardry. I can’t quite get my search keywords right to find this info - Basically an MPPT that outputs around 115VDC that isn’t a sketchy aliexpress find.

Alternatively I could upgrade my small 12v system, buy a bigger mppt to charge the 12v, and buy a 12vdc to 115vdc converter. (500w panels → 12VDC → 115VDC pack) This seems like a lot of extra steps, and a lot of extra weight just to get the HV pack some juice.

Was wondering if anyone has seen/done anything similar, or could share links and MPPT advice.

Thanks for any advice or questions. Lots of knowledge and interest crossover with this forum and www.diyelectriccar.com

 

[justinm001]

Freaking awesome man. How are you charging it now? Any way you can just go 12v to 120v AC to charge it? Sure you'll lose some efficiency but it atleast helps

 

[Block]

Normally charged through a public or home charging station, J1772 plug, 5kw onboard charger that unfortunately wouldn't like the low amps.

Here are some options I found for the 500w panels → 115VDC pack problem. Thoughts?
low end: https://www.electriccarpartscompany...ium-lead-acid-battery-solar-charge-controller (not mppt...?)
high end: https://www.electriccarpartscompany.com/solar-charge-controller-mppt-96v-120v-192v-216v-384v
sketchy end: https://www.aliexpress.com/i/32258144354.html?gatewayAdapt=Msite2Pc

I don't mind spending more cheddar, was just hoping someone could verify.

 

[GXMnow]

How about something like this?

https://www.amazon.com/Adjustable-Switching-Converter-110V-220V-Transformer/dp/B0BFF1QWS7/ref=sr_1_11?crid=3407XULLMUVCO&keywords=120+volt+500+watt+CV+CC+power+supply&qid=1692068981&sprefix=120+volt+500+watt+cv+cc+power+supply%2Caps%2C154&sr=8-11&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

Adjust the CV voltage to 3.4 volts per cell (3.4 x 33 cells = 112.2 volts. Then dial the CC amps to whatever power your 120 volt AC inverter can handle. If you want to charge at say 300 watts, dial it to about 3 amps. It will do up to 8.5 amps if you have 1,000 watts available. Your existing PV panels and MPPT still just tries to keep your 12 volts system topped up. Use a low voltage battery protect to shut off this power supply if the 12 volt system runs too low. Your inverter should already do that, but it pays to be safe. If you are parked in the sun, charging the main HV battery at 300 watts is not too bad. That is probably all the 500 watt array actually does in the real world. My 2,000 watt off grid array topped out at 1,400 watts today.

 

[rustythorn]

the lowest amp EVSE cables i've seen is 6a, not sure if they can go lower. at 6a and 115 VAC it will charge at 690 watts which is more than your 500 watt solar array. so you could go this route with a larger 12 volt battery or more solar panels [and a sunny day]. you might be able to get a DC/DC to raise the 12 VDC to higher DC volts and input that into a charger.

 

[efficientPV]

What exactly is the voltage of the array? Or do you just want to charge from 12V. An older modified sinewave inverter can easily go from 12V to 115VDC. I just did that a couple weeks ago to make one 110VDC. Pretty simple mod and that was on a 2,000W inverter and you can make it constant current if you want.

 

[SamDeleted]

Was wondering if anyone has seen/done anything similar, or could share links and MPPT advice.

I would fit an inverter to your 12v system and charge the EV battery with AC

I know it's multiple steps DC>AC > DC , but it's the simplest solution

 

[fafrd]

How about something like this?

https://www.amazon.com/Adjustable-Switching-Converter-110V-220V-Transformer/dp/B0BFF1QWS7/ref=sr_1_11?crid=3407XULLMUVCO&keywords=120+volt+500+watt+CV+CC+power+supply&qid=1692068981&sprefix=120+volt+500+watt+cv+cc+power+supply%2Caps%2C154&sr=8-11&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

Adjust the CV voltage to 3.4 volts per cell (3.4 x 33 cells = 112.2 volts. Then dial the CC amps to whatever power your 120 volt AC inverter can handle. If you want to charge at say 300 watts, dial it to about 3 amps. It will do up to 8.5 amps if you have 1,000 watts available. Your existing PV panels and MPPT still just tries to keep your 12 volts system topped up. Use a low voltage battery protect to shut off this power supply if the 12 volt system runs too low. Your inverter should already do that, but it pays to be safe. If you are parked in the sun, charging the main HV battery at 300 watts is not too bad. That is probably all the 500 watt array actually does in the real world. My 2,000 watt off grid array topped out at 1,400 watts today.

That’s only ~20% of the power of the Chargeverter for ~1/2 the price, but do I understand correctly that the 120V model can charge at any voltage between 1VDC and 220VDC at a current limited to 5A or less?

Note the warning to limit power to 80% of full 1000W rating, so no more than 7.1A @ 112.2VDC…

I’m only interested in a solution to float a 24V or 48V LiFePO4 battery but with the 60V model I could float at 57.6V with up to 17A of current (which should be limited to 13.9A…).

 

[fafrd]

How about something like this?

https://www.amazon.com/Adjustable-Switching-Converter-110V-220V-Transformer/dp/B0BFF1QWS7/ref=sr_1_11?crid=3407XULLMUVCO&keywords=120+volt+500+watt+CV+CC+power+supply&qid=1692068981&sprefix=120+volt+500+watt+cv+cc+power+supply%2Caps%2C154&sr=8-11&ufe=app_do%3Aamzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0

Adjust the CV voltage to 3.4 volts per cell (3.4 x 33 cells = 112.2 volts. Then dial the CC amps to whatever power your 120 volt AC inverter can handle. If you want to charge at say 300 watts, dial it to about 3 amps. It will do up to 8.5 amps if you have 1,000 watts available. Your existing PV panels and MPPT still just tries to keep your 12 volts system topped up. Use a low voltage battery protect to shut off this power supply if the 12 volt system runs too low. Your inverter should already do that, but it pays to be safe.

If you are parked in the sun, charging the main HV battery at 300 watts is not too bad. That is probably all the 500 watt array actually does in the real world. My 2,000 watt off grid array topped out at 1,400 watts today.

If 300W of sustained charging power is all that is needed, this 480W model will deliver that for less that half the price ($70): https://www.amazon.com/dp/B0BCPTX4B...=1&sp_csd=d2lkZ2V0TmFtZT1zcF9waG9uZV9kZXRhaWw

80% of 480W = 384W = 3.4A @ 112.2VDC…

 

[pollenface]

Adjustable boost converter set to 112.2v?

 

[fafrd]

Hey guys,

I’ve restored an old van, EV swapped it, and added a 500w array. The solar is for interior accessories on a 12v battery. (stove, heater, lights, lava lamp, weekend camping stuff) 5x 100w panels. Working great so far.
View attachment 161432

The HV battery that propels this van is 115v when fully charged. It’s a Lifepo4 280ah 33s2p ~60kwh pack that is normally charged like any other EV. My solar panels only charge the 12v system, which sits at full constantly, so I'm looking for a charge controller to give the big pack some juice, even if it’s +1mile/day. Definitely no Apterra, but why not.

Anyone have experience stepping voltage up from a smaller array? (500w panels → 115VDC pack) I’ve seen some of the solar racer guys do some custom voltage step-up wizardry. I can’t quite get my search keywords right to find this info - Basically an MPPT that outputs around 115VDC that isn’t a sketchy aliexpress find.

Alternatively I could upgrade my small 12v system, buy a bigger mppt to charge the 12v, and buy a 12vdc to 115vdc converter. (500w panels → 12VDC → 115VDC pack) This seems like a lot of extra steps, and a lot of extra weight just to get the HV pack some juice.

Was wondering if anyone has seen/done anything similar, or could share links and MPPT advice.

Thanks for any advice or questions. Lots of knowledge and interest crossover with this forum and www.diyelectriccar.com

How is your 500W string configured currently? Is it 5S / ~150Vmp??

If so, another option you could consider is to get a second SCC that can charge your HV battery and use a DC current switch (or the dry contact output from your 12V SCC if it has one) to switch off the string input to the 12V SCC while switching on the string input to the HV SCC (make a 2-pole double-throw switch that can switch 200VDC).

Once the SCC charging the 12V battery switches from CC to CV and charge current decreases to whatever current threshold you elect, the 12V SCC is disconnected, the HV SCC is connected and any remaining solar power is directed into your HV battery…

You also need a way to start each morning in ‘charge 12V’ mode.

The best way to do this would be using a programmable dry contact output on a 12V SCC. This allows you to program a lower-valued recovery voltage so that you have some hysteresis…

The Epever AN SCC I have has a programmable timer so that you can only allow the 12V SCC to switch over to charging the HV battery after 12:00pm, for example (meaning switch to HV SCC when time is after 12:00pm AND 12V battery voltage > ~90% full voltage).

Then at midnight you can always switch back to 12V charging so every morning starts off charging the 12V battery at least until 12:00pm (or whenever).

A bit more complexity for the wiring and control but the benefit is no lost efficiency converting 12VDC to 120VAC and then 120VAC to 112.2VDC or boosting 12VDC to 112.2VDC (if that is even possible).

I have no idea whether 200VDC switches / SSRs are a ‘thing’ nor what they may cost…

 

[pollenface]

Hypothetically you could divide charging between 3 groups of 11 (22) cells and charge at 39-40v.

 

[Supervstech]

If it were me, I'd get a 6th panel, and feed solar directly to the battery...
6x18V is 108V, and the max on a 12V panel is around 22Vx 6 would be 133... so, with a minor charge limiter you could feed the Batts.

 

[fafrd]

If it were me, I'd get a 6th panel, and feed solar directly to the battery...
6x18V is 108V, and the max on a 12V panel is around 22Vx 6 would be 133... so, with a minor charge limiter you could feed the Batts.

That’s another way to do it.

5S or 6S string feeding both 12VSCC and connected to HV battery through a blocking diode (so when MPPT of 12V SCC is drawing power, string voltage of ~Vmp_string is below HV battery voltage but once 12V SCC enters CV mode and starts to throttle back input power by raising string voltage, solar power gets redirected into HV battery once Vstring exceeds Vbat + Vdiode…

But you’d still need a battery monitor on the HV battery and a 200V SSR to isolate the string from the HV battery once it reaches target voltage.

 

[fafrd]

Normally charged through a public or home charging station, J1772 plug, 5kw onboard charger that unfortunately wouldn't like the low amps.

Here are some options I found for the 500w panels → 115VDC pack problem. Thoughts?
low end: https://www.electriccarpartscompany...ium-lead-acid-battery-solar-charge-controller (not mppt...?)
high end: https://www.electriccarpartscompany.com/solar-charge-controller-mppt-96v-120v-192v-216v-384v
sketchy end: https://www.aliexpress.com/i/32258144354.html?gatewayAdapt=Msite2Pc

I don't mind spending more cheddar, was just hoping someone could verify.

I just took a look at your 120V SCC and it gave me another idea: you can hook up the solar array to a new 120VDC SCC and feed the 12V SCC from the HV battery / 120V SCC.

This will always keep your 12V battery charged (unless you control the 12V SCC to only charge during daylight hours).

You can find other threads on the forum where members have successfully powered a lower-voltage SCC from a higher-voltage battery…

 

[efficientPV]

With panels in series, the DC volts are enough to power a cheap 24V LED switching power supply. LED power supplies 180W and under work perfectly fine on DC. I've operated them as low as 60V and can get 80% of rated current. Output is isolated so it can be just put i series with the string. A cheap voltage relay can switch it off if you ever get a full charge (not likely) and no need to buy a high voltage relay.

 

[pollenface]

With panels in series, the DC volts are enough to power a cheap 24V LED switching power supply. LED power supplies 180W and under work perfectly fine on DC. I've operated them as low as 60V and can get 80% of rated current. Output is isolated so it can be just put i series with the string. A cheap voltage relay can switch it off if you ever get a full charge (not likely) and no need to buy a high voltage relay.

that's interesting, can't wait to experiment with this

 

[efficientPV]

This is a 120W 12V LED supply operating on a 60V array to float charge a battery. They won't adjust up to 13.8V without a resistor modification, but to operate 12V equipment they are fine as they are. 120W and 180W are almost identical. You can not purchase over 180W because those use supplies use a voltage doubler circuit which will not work on DC. I never paid more than $10 for one shipped by waiting for an auction on ebay to go low bid. Upper left is the 120V 10A supply.

 

[Q-Dog]

The rails on your rack sticking up above the panels are going to kill PV output when they throw shadows on your panels.

 

[fafrd]

With panels in series, the DC volts are enough to power a cheap 24V LED switching power supply. LED power supplies 180W and under work perfectly fine on DC. I've operated them as low as 60V and can get 80% of rated current. Output is isolated so it can be just put i series with the string. A cheap voltage relay can switch it off if you ever get a full charge (not likely) and no need to buy a high voltage relay.

Interesting.

Can you provide a link?