Honda Insight Forum banner

1 - 18 of 18 Posts

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #1 (Edited)
I'm moving to a new property in Hull and so will be out of action for Insight project work for a few months as it needs a fair bit of work.

I'll still help on the forum, with postal orders for items, and urgent IMA work in the UK.

However I do have a project in mind for this new property.....

It has a 4kw leased solar array on the roof.
It exports excess energy to the national grid.
The solar panel company get paid per kwh actually generated (not exported).
The house owner gets to use the full amount of the generated energy for free.

So I'll have to make sure i'm using or storing the full output of the array on a daily basis. Presently excess power just goes to the grid and I get no benefit.
You can't get that power back again from the grid without paying...

You can see where this is going :)
I'm going to store every watt of excess power the solar generates over my domestic load.
I'm going to build a massive (expandable) power bank using the 200 or so old sticks I currently have in stock. I'll use a solar inverter to put the stored energy back into the house to avoid importing power from the grid.

I won't be able to tap the panels directly (most efficient) or that would reduce the kwh on the leased solar generation meter and the company would notice. I'll have to extract the power from the mains once it has been inverted by their own solar inverter.

So it will be Leased Solar panels > Leased Solar Inverter > My House AC. > My battery bank charger > My Battery bank > My solar inverter > My House AC..

Looking at the solar power records it looks like it is generating about 13kwh a day in August.

Since it was installed in August 2014 it has generated 12845 kwh.
At a cost of say £0.16p per unit that equates to £2055 worth..
Over the three years since install it appears to be doing around 10+kwh a day average.

I'll try and get the kwh import consumption records for the property for the same period.

Anyway as far as the battery bank is concerned.

It will be made of stacked long lengths of 1'1/4" plastic tube.
Into these will be slotted 10 or 20 sticks in series joined by a short length of 6mm stud.
So imagine a long sausage of sticks 25ft in length.
Each tube will hold about 600wh or something.

Each sausage will have 2 x 400V 10A diode in the + feed charge input and power output circuits to stop the sausages discharging into each other. Don't want any runaway nimh..

Adding further sausages (20 sticks) as I get packs in from customers should be a doddle and not require pack reconfiguration. just add the sausage to the stack and connect it to the power bus.

See pic you get the idea..
 

Attachments

·
Moderator
Joined
·
3,641 Posts
Are you selling the mill? That is a great property by the sea. Where is your new one? [edit...I see: Hull]
 

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #4
Unfortunately the Mill did not work out so my new place will be a bachelor pad. :(
 

·
Premium Member
Joined
·
143 Posts
An older guy on youtube has done this with 5 HCH2 packs. Search old time engineer. I think he picks the packs up for $75-150 each from local salvage yards.
 

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #7 (Edited)
Some progress.

Whilst waiting for the civic bms board to arrive i have started work on the hardware and software for this project.

I'm going to use three of these to monitor the power in my house.

https://www.ebay.co.uk/itm/Digital-AC-Multifunction-Meter-Watt-Power-Volt-Amp-Current-Test-Module-PZEM-004T/152878820115?hash=item239849ab13:g:PJ4AAOSwy1NaaEao

I have three circuits connected together before the distribution box in my house. .

1) Power in/out from Grid. (Power can flow either way)
2) Power out from solar panels. (Power can only from the solar panels)
3) Power being consumed by house. (Power can only flow into the house)

If my solar panels are generating more than I am using then the excess goes to the grid. (I don't get paid)

So by monitoring the watts flowing in each of the above circuits (direction doesn't matter) an algorithm can work out if I am exporting or importing at any given moment.

If I am exporting to the grid any more than a few watts the system will divert that energy into my nimh power bank.

If I am importing more than a few watts the nimh power bank will discharge back into an inverter to try and balance the load.

So I need something to manage this.
You can guess what I'll be using initially.
Yep a hacked OBDIIC&C :)

I've written some basic software to talk to three of the PZEM-004T power monitors.
I will try and test it on the bench tomorrow.

Getting the data will be the easy bit..
Controlling the power bank sounds more tricky.
I'll also probably need another inverter..
Although i'm tempted to back feed the solar inverter but that means the company will get paid twice for the electricity. lol
 

Attachments

·
Administrator
Joined
·
10,770 Posts

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #9
Power bank planning..

Initially I'm planning on a 6kwh nimh battery bank.
I'm going to use a 4kva 48V input sinewave inverter to keep the battery bank voltage down to a safer level.

I will use 7 x 7.2v sticks in series for a nominal 50v module.
I've bought enough plastic 40mm x 3m white waste pipe to make 20 modules.
This will use 140 sticks.

Assuming a 6ah capacity at lowish currents each stick provides about 43wh
140 x 43wh = 6020 wh.

Each 50v module will be connected in parallel with all the others at the negative end into a common bus bar. .

At the positive end each 50v module will feed through a 20A schottky 200v diode into a common parallel positive bus bar.

The diode is to prevent current flowing backwards from higher voltage charged modules into lower ones.

Each module will have a independent cheap led 300ma CC 60v charger driver..
Each led charger will probably be independently controlled by a miniature relay/triac.
Each module may be voltage monitored by some sort of multiplexing pic adc system.

I might add a higher current charge capability later depending on my solar energy excess data?

When the bank is charged I will divert power into my water immersion heater.
 

·
Premium Member
Joined
·
143 Posts
I had plans to use my old BB pack that had 3 leaking cells to make a power bank for this 24v APC UPS 1500 I have. Using the remaining 17 sticks, build a 4S4P setup, but then read somewhere on IC that the NiMH cells don't work well in parallel? Anyways interested to see how this works for you, and if I could duplicate it on a smaller scale setup.

Right now I have the original lead acid batteries that came in it and it's currently being used to power my sump pump (360w) in case of a power outage. Just trying to find a good reason to use these otherwise worthless sticks.
 

·
Premium Member
Joined
·
3,421 Posts
He's limiting voltage. The risk occurs if a cell hits 100% SoC and experiences -dV. This will cause parallel sticks/cells to dump their current into the fully charged cell.

Sh!t gets exciting pretty quick when that happens. I've had this happen on a 14.4V bank of HCH2 subpacks. Cell melted the shrink wrap. It was scalding hot. IIRC, temp was > 180°F by the time I found it. My clue was the smell of PVC shrink that was too hot.

IMHO, if voltage is limited so something around 56-57V, he should be under 80% Soc or so depending on how low the charge current is.

Many systems designed for Pb batteries peak at 14.4V. That would be 57.4V - which is probably pretty good.

There almost needs to be a current/voltage limit, i.e., if voltage is > X AND current is < Y, then cut it off.

Very low currents can nearly fully charge NiMH at lower voltages. I have found that 4A to 8.5V/stick is about 70% SoC.

I think it's doable, but it's also worth fusing each parallel connection.

EDIT: nevermind... just saw the Schotky diode... that removes a HUGE chunk of the risk.
 

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #12
As Steve spotted I'll be using a diode to prevent reverse current flow.

Anyway here is a video/pics showing battery bank construction started today.


Note proper workshop sink at my mates garage.. ;)
 

Attachments

·
Premium Member
Joined
·
1,751 Posts
That sink looks like someone had too much taco bell and the toilet was too far... Lol.

This project is interesting. I'll be keeping my eye on it.
 

·
Administrator
Joined
·
10,770 Posts
Discussion Starter #14
Monitoring each seven stick module

I intend to voltage monitor each seven stick module as they will all be charged individually with constant current chargers, and protected against reverse current inter module flow with diodes.

So initially I will have 20 modules of seven sticks. Around 40-70v voltage range.

I think i will use some old PIC16F886 chips i have lying about from the early version of the OBDIIC&C.

Each one of these has 11 analog 10bit voltage inputs, so 2 pics will give me 22 module capability.

The modules share a common negative so we don't have stacking issues, but I will need an accurate potential divider made from 0.1% tolerance resistors to get the + voltage down to the 0-5v input range of the pics.

The resolution of the 50v nominal modules with a 10bit adc will be approx 70mv.
That should be enough to highlight any runaway or dead cell issues.

I'll put the pics on a serial bus sending the readings to a master controller..

I'll have the I2C pins on each pic spare so will add a few DS18B20 temp sensors to monitor a couple of key modules/inverter temp etc etc.
 

·
Registered
Joined
·
26 Posts
Interesting thread I just obtained spare hch hybrid electronics with a replacement ima battery I purchased from a breakers yard,so was wondering how mdm & dc/dc converters as well as prius inverters could be reused for a solar power setup.

As far as I know high voltage dc will pass right through an inverter through most rectifier circuits to provide regulated dc for battery charging.
Prius inverters have a boost module which steps up battery voltage from around 200v to around 600v whereas I am not sure if the honda mdm (inverter)has a step up converter of any kind to power the ima rotor above battery voltage.

With over 7 million prius batteries worldwide they represent a fantastic oportunity for solar storage,especially as fluid can be added to prius battery modules to bring back lost capacity to cells that are simply drying out.
https://priuschat.com/threads/re-hydrating-the-battery-modules.152885/
 

·
Premium Member
Joined
·
3,421 Posts
A few comments:

1) Make sure you understand what Peter is saying in post #9. NiMH in parallel without precautions can have catastrophic results. Note that his setup requires a charger for EACH "stick"...

"Each module will have a independent cheap led 300ma CC 60v charger driver..
Each led charger will probably be independently controlled by a miniature relay/triac.
Each module may be voltage monitored by some sort of multiplexing pic adc system. "

So, while NiMH from re-purposed hybrid cells as a bank can be done, it has some hurdles to overcome.

2) as a poster to the quoted thread, and as someone who has conducted MANY experiments with Prius module rehydration...

a) The results of that thread are very misleading. The vast majority of the gains shown can be had from reconditioning.
b) MOST modules will have little or no gain from rehydration.

I have encountered HUNDREDS of modules that experience no benefit whatsoever from rehydration. Most have capacity loss due to cycle damage, i.e., they are just worn out. When you encounter cells with high internal resistance, you can definitely make a difference with rehydration.

As far as your use of HEV electronics/hardware for solar power setup, I have no clue.
 

·
Registered
Joined
·
26 Posts
A few comments:

1) Make sure you understand what Peter is saying in post #9. NiMH in parallel without precautions can have catastrophic results. Note that his setup requires a charger for EACH "stick"...

"Each module will have a independent cheap led 300ma CC 60v charger driver..
Each led charger will probably be independently controlled by a miniature relay/triac.
Each module may be voltage monitored by some sort of multiplexing pic adc system. "

So, while NiMH from re-purposed hybrid cells as a bank can be done, it has some hurdles to overcome.

2) as a poster to the quoted thread, and as someone who has conducted MANY experiments with Prius module rehydration...

a) The results of that thread are very misleading. The vast majority of the gains shown can be had from reconditioning.
b) MOST modules will have little or no gain from rehydration.

I have encountered HUNDREDS of modules that experience no benefit whatsoever from rehydration. Most have capacity loss due to cycle damage, i.e., they are just worn out. When you encounter cells with high internal resistance, you can definitely make a difference with rehydration.

As far as your use of HEV electronics/hardware for solar power setup, I have no clue.
Thanks ior your reply here is a clip of a nimh solar setup
 

·
Premium Member
Joined
·
3,421 Posts
That's the biggest piece of worthless fluff I've seen in a while. Zero detail. Government/Big-Corp project highly unlikely to be of any use or affordable to the masses.

It's also worth noting that a very large portion of the Gen3 Hybrids are used up, i.e., you're lucky to have 50% rated capacity in the bulk of the modules. I just processed a 2010 Prius pack with only 141K miles on it. It "failed", i.e., it produced the P0A80 code; however, NONE of the cells had failed. AVERAGE module capacity AFTER reconditioning was 3100mAh against 6500mAh rated. Only FOUR modules qualified for being suitable for re-use in a car. Everything else was junk.

Take those good modules out, and the average drops to 2750.

It's worth noting that this car also had the solar panel roof to help regulate the interior temperature.

Granted, Phoenix is a worst case for this condition, but the lower 1/3 of the U.S. causes comparable widespread battery damage.

Before you make grand plans, start small and verify things for yourself. Fluff pieces and misleading hydration results don't form a good foundation for success.
 
1 - 18 of 18 Posts
Top