Sizing a battery bank

[jetzi]

Just now, Dr Bob said:

I'm not keeping up

But thank you for the offer. I would still be interested in what your washing machine uses on a cold wash if you are able to measure it easily.

[Dr Bob]

2 minutes ago, ivan&alice said:

But thank you for the offer. I would still be interested in what your washing machine uses on a cold wash if you are able to measure it easily.

Prolly have the machine on on Wednesday. Did a big wash today.

[WotEver]

4 hours ago, WotEver said:

https://www.amazon.co.uk/Nevsetpo-Monitor-Consumption-Electricity-Calculator/dp/B07H1ZFVFM/ref=sr_1_6

oh, and I shortened your link. 

3 hours ago, ivan&alice said:

amazon.co.uk/dp/B07H1ZFVFM

You can actually shorten it even more... the only bit that identifies the product is dp/ plus the code.. 

But shortening it that much removes the description, so many folk might not click on it. 

4 hours ago, cuthound said:

 

Thanks, I didn't realise you could shorten them. I just cut and pasted it. ?

You can remove everything after and including the question mark. 

[jetzi]

14 minutes ago, WotEver said:

But shortening it that much removes the description, so many folk might not click on it. 

You can remove everything after and including the question mark. 

Fair enough on the description, but you should also remove the ref part after the product number - I believe that bit tracks who/what site referred you.

[jetzi]

 

It is also worth noting that the description is completely ignored by amazon.

 

So this goes to the exact same place:

 

 

amazon.co.uk/pink-fluffy-handcuffs/dp/B07H1ZFVFM

[WotEver]

1 hour ago, ivan&alice said:

 

It is also worth noting that the description is completely ignored by amazon.

 

So this goes to the exact same place:

 

 

amazon.co.uk/pink-fluffy-handcuffs/dp/B07H1ZFVFM

Yes, but it informs the forum user what the link is to. 

unless you muck about with it on purpose of course. 

[Alan de Enfield]

1 hour ago, ivan&alice said:

 

It is also worth noting that the description is completely ignored by amazon.

 

So this goes to the exact same place:

 

 

amazon.co.uk/pink-fluffy-handcuffs/dp/B07H1ZFVFM

 

You little tease - I told SWMBO I needed some new ones, so when you provided the link I thought 'super'.

 

But it wasn't was it - big disappointment it was some plug in electrical thing - and it didn't even take batteries.

 

 

Here is a proper link for those others also let down by forum teasing !!!

 

https://www.ebay.co.uk/itm/Pink-Fluffy-Handcuffs-Fancy-Dress-Hen-Party-/182708448959?_trksid=p2385738.m4383.l4275.c10

 

 

 

It reminds me of another one of my memories.

 

We were looking for some new 'giveaways' for the business, we had Note-Pads, Mugs, Ties, pens etc but wanted something different so decided we would do cuff-links with the company logo on them.

Remember when we wore shirts and suits ?

 

We decided that to minimise cost we would look to order the maximum number we could so we decided to include all of our 27 sister companies around the word, so a Telex was sent.

"Would you evaluate if there is any interest in having Cuff-Links with the company logo, and let us know within 30 days - regards"

 

Most companies came back and said yes we will have X,000, or no thankyou, but our South African operation's reply was a little different :

 

"We have carried out some market research with all Police Departments and the Department of Corrections (Prison Service) but there does not appear to be any interst in Cuff Links with our logo embossed on them".

 

After some discussion it was revealed that they were taking about 'Linked Hand-Cuffs'.

 

Strange thing language !!

[Dr Bob]

On 29/09/2019 at 16:58, ivan&alice said:

But thank you for the offer. I would still be interested in what your washing machine uses on a cold wash if you are able to measure it easily.

 

Ivan, here is a power plot from this mornings motoring with the washing machine (2 year old, 240V Beco 2.3Kw, cheap but good machine) on a cold wash - a 40 minute cycle.

 

Amps in/out of Li bank in orange. Voltage in blue.

Engine on at 8.15 gmt ( no I didnt get up that early....we are on BST still).

Washing machine on at 8.30. The current from the alternator falls off from its peak of 50A at 8.15 to around 30A for most of the run (the alternator controller is set low at the moment) but every 20 mins, the controller cuts the power for 3 mins.....hence the 3 dips down per hour. If you draw a smooth line from 8.15 through to line draw at 9.10, you will see the actual current circa 10A lower. The jagged line between 8.30 and 9.00 is the effect of the washing machine. The data logger takes a reading every minute so it is not in great detail, but statistically you are seeing what is happening as the machine is going through cycles of turning the drum and then not, and then filling with water and spinning etc.

It may well be that when the washing machine takes amps, the alternator controller boosts the current, but I dont think this is happening. I watched the phone app to see the current when the machine was on and I couldnt see the current increasing over 40A. I think I would have seen higher currents if the controller increased the current on a big draw and then the machine cuts its current use. The alternator controller would be slow to react hence transient higher currents.

If you look at the low point on the first 2 dips (when the machine is on) they look about 10A lower than the rest of the dips (with the machine off) so again it looks like the machine is taking 10A ish.

I would therefore guess that the machine is taking maybe 10-15A max (at 13.4v) so 150 to 200W max ........although maybe a bit higher if the alternator was offsetting the drop in current a bit. Of course, this test doesnt see high peaks in Amps when motors turn on or off but your question is more about total power used. Looking at the graph to estimate total power used (ie integrate the area between the jagged line vs a guessed smoothed line), I would estimate over the 40 mins that it is 5-10Ahrs of battery capacity.....so 10Ahr max per wash. If however you do your wash at the end of a battery charging run when you are getting the tail current down to 1-1 1/2%, then the alternator might supply more power over the low tail current (as long as its not gone into float) hence the power is free.

 

Hope that helps.