Help needed for 24V Charging from Hydro

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soul asked Feb 26, '24

Help needed for 24V Charging from Hydro

Hi All,

I am messing around using hydro to charge a bank of 12V lead acid batteries. The batteries are wired for 24V. The battery bank powers some small things in a shed (~ 100 watts). The set up I currently have is a Wanco AB30 240V belt driven generator connected to a PSU that cuts and converts voltage from ~230V AC to ~29V DC. That DC is then fed into a MPPT 250 charger which then feeds the batteries. The hydro prime mover is very steady, but will produce different voltage depending on load. Currently I only have the MPPT charge set to do a max of 9 amps to avoid the PSU input voltage dropping below 100V.

I have two questions:

I find the charger is not moving out of bulk charge to float (see screen grabs below the generator was shut down for a period there and took a few hours to get battery voltage to the 5V delta). Likely because it can't reach the 27+V pre-programed on the rotary #2. Is this bad for the batteries? Should I adjust absorption and float charging voltage down? Why Doesn't the battery voltage get any higher than the 26.7V?
How would you improve my set up? I originally wanted to simply rectify and send the DC voltage straight from the generator to the charge controller. The issue I ran into was after rectification the 230V AC becomes 310V DC. Thus the PSU.

Any help is much appriciated!

parts:

voltage mmpt

1708902479937.png (80.0 KiB)

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Justin Cook ♦♦ commented · Feb 26 at 06:10 PM

Moving this question to the "Modifications Space" for visibility to other users experimenting in non-supported usage of VE equipment

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Modifications Space

Node Red Space

Answer 1 · 2024-02-26T07:04:48Z

JohnC answered · Feb 26 at 07:04 AM

Hi @Soul

You don't say how big the batteries are, but not many Amps happening there. So Vbat is slow to rise, likely they're down a bit on charge too.

I think the main issue you have here is the PSU is only rated 28V, so the 5V/1V 'deltas' are always going to be hard to meet, especially when the batts get up in charge a bit. Might be ok with 12V batts, but I don't think that PSU is right for a 24V bank.

You could even consider running without the mppt. Then you have the issue of lack of charge control, and you'd have to deal with that.

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Answer 2 · 2024-02-26T13:37:22Z

soul answered · Feb 26 at 01:37 PM

Thank @JohnC

I did try running without the mppt, but the issue is that I can't limit Amps. Without limiting amps the load on the generator is too great and drops below battery voltage and turns off charging. The result is a surging of the generator.

Is there a better way to limit AC or DC voltage. Ideally, I use some type of voltage limiter before or after a rectifier and feed that directly into the mppt.

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Answer 3 · 2024-02-26T13:54:39Z

Michelle Konzack answered · Feb 26 at 01:54 PM

If you have a HydroGen which deliver this high voltage and you have a SmartSolar 250/whatever, use a Transformer to get 120V, put a bridge rectifier and an Electrolyt Condensator of 250V (or higher) with at keast 1000myF on and connect it to the MPPT.

Then let the MPPT do the rest.

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Answer 4 · 2024-02-26T14:10:31Z

soul answered · Feb 26 at 02:10 PM

Thanks @Michelle Konzack.

My concern with the transformer would be during the two extremes. Under low load getting 240VAC would it not get very hot? Under high load getting ~100VAC would it still be able to function and produce AC voltage that is usable (>30V).

Is Electrolyte Condensator the same as a capacitor?

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Answer 5 · 2024-02-26T16:39:21Z

soul answered · Feb 26 at 04:39 PM

I am also struggling to find a suitable transformer. Most are ~100VA which (I think) would mean I could only send 0.5 A through at 240V.

Here is an example of what I am looking at. Any suggestions? Siemens MT01100M

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Michelle Konzack commented · Feb 26 at 10:06 PM

There are transformers for 230/120V.

If the HydroGen deliver only 100V, the Transformer output 52V which is still enough to charge a 24V Battery.

The AB30T with 120V would be probably the best option, wince you can use a Rectifier and a huge capacitor and then the SmartSolar MPPY 250/100-Tr since it output up to 2800W @27,6V or 5600W at 55,2V.

How much does the AB30T cost?

Could be also an option for me.

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Michelle Konzack Michelle Konzack commented · Feb 26 at 10:10 PM

I have just seen, that also the bigger models can run in 120V option, hence WHY do you bother with 240V?

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soul Michelle Konzack commented · Feb 27 at 02:39 AM

Poor early decisions. I think the AB30T was $2k.

Do you have any recommendations for a transformer?

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Michelle Konzack soul commented · Feb 27 at 11:58 AM

Do you have the AB30T?

Then you do not need a transformer.

The AB30T deliver at 120V 20A, which fit easily the SmartSolar MPPT 250/70 (2,8kW @24V and 5,6kW @48V)

The two other models (AB50T and AB60T) have both, the 120V AND the 240V.

Since with the SmartSolar you can not use more then the 20A input just use the 120V without ANY transformer.

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soul Michelle Konzack commented · Feb 27 at 01:23 PM

I have an older model of the AB30 that is 240V. What is the current limitation for the smart solar?

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gen.jpg (24.1 KiB)

Answer 6 · 2024-02-27T14:24:24Z

Michelle Konzack answered · Feb 27 at 02:24 PM

Your AB30T produce 240V which give after Rectifier and capacitor roughly 340V DC which will burn the SmartSolar 250 which has a hard limit of 250V.

If you would have a 48V System, you could go with the RS450-100 which support up to 5,6kW, hence it would be suitable even for the AB60T.

The best for you would be a Transformer 240V to 120-150V (ZERO Load Voltage must be checked, then the Rectifier and an Electrolyt Capacitor of at least 1000yF and of course 250V (This thing is bigger then a Beer can) and with 2,4kW you will probably need more then one.

Note: The Power Supplies I build in the past had 1000yF per Ampere output of the transformer.

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soul commented · Feb 27 at 04:01 PM

Thanks Very helpful. I agree. The generator should be changed and I will in time. For now I was hoping to resolve with a transformer. Would you be able to recommend any? I can't find one with high enough VA.

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Michelle Konzack soul commented · Feb 28 at 07:00 AM

I can not recommend anything, because you re in the USA and I am in Europe.

You would get such (toroidal) transformer easily in Germany, but shipping to the USA would be enorm. I assume, the transformer has at least 15kg.

You have to find a transformer Manufacturer in the USA

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smallsolar commented · Feb 28 at 07:27 AM

As I am looking to implement quite a small hydro system (~30-50w) can I ask what function the capacitor is performing? Voltage stabalization for the MPPT?

My system will be run off of a converted direct drive washing machine outputting possibly up to 300V AC (probably closer to 150-200V AC loaded), three phase that I would use a transformer to step down and then rectify to DC before ideally going into a 100/15 MPPT. I have just been looking at fairly inexpensive three phase 300VA transformers from China as I am just messing around. ( https://www.alibaba.com/product-detail/China-Factory-Supply-15kVA-5kva-Dry_1600595674423.html)

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Answer 7 · 2024-02-28T10:47:17Z

Juha Tuomala answered · Feb 28 at 10:47 AM

@mvader (Victron Energy) could you please add/rename topic Hydro, there is already Wind and Hydro and Wind Power topics - the double topic is confusing, single one is good and correct.

I suggest that rename the double-topic Wind and Hydro Power to plain Hydro and maybe fix the discussions where it won't apply anymore. Not sure how much work it would be. Or maybe let someone to do it.

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Juha Tuomala commented · Feb 28 at 10:49 AM

Hmmm, looks like the Wikipedia uses term Water Turbine https://en.wikipedia.org/wiki/Water_turbine

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