Copper piping turned silver

[Alan de Enfield]

Just now, bigcol said:

Just checked battery’s again

still the same

battery 1. 12.9v

battery 2. 12.9v

battery 3 12.1v

battery 4  15.2 v

 

i will replace anyway battery 3 and 4 as it’s obvious these 2 are knackered 

 

I would seriously consider replacing the Vanner.

It would appear that it is not working as the figures you are quoting tie in exactly with what Vanner are saying happens 'without it',

 

In many 24 volt electrical systems it is desirable to tap into the battery system to obtain power for 12 volt loads.  This method, while seemingly simple, causes a charge imbalance resulting in Battery B (see diagram) being overcharged, and possibly boiling, while Battery A discharges

[Tony Brooks]

I am probably being too simplistic but why can't the 12V loads be fed from 24 to 12V power supply?

 

As an example https://www.simplypowersupply.com/DC-DC-Converter/SD-50B-12-Chassis-Mount-DCDC-Converter-24Vdc-to-12Vdc-42A.aspx

and higher power ones are available.

[WotEver]

47 minutes ago, Tony Brooks said:

I am probably being too simplistic but why can't the 12V loads be fed from 24 to 12V power supply?

You’re not. They could. It would be better. 

 

I think it’s just that the Vanner came with the boat so Col thought he’d use it. 

[bigcol]

All battery’s are now disconected, battery charger is off, isolator now switched off

3 o’clock 

[WotEver]

4 minutes ago, bigcol said:

All battery’s are now disconected, battery charger is off, isolator now switched off

3 o’clock 

Take a look some time after 4pm and give us the battery voltages. 

[Alan de Enfield]

1 hour ago, Tony Brooks said:

I am probably being too simplistic but why can't the 12V loads be fed from 24 to 12V power supply?

 

As an example https://www.simplypowersupply.com/DC-DC-Converter/SD-50B-12-Chassis-Mount-DCDC-Converter-24Vdc-to-12Vdc-42A.aspx

and higher power ones are available.

You & I - simple both !!

 

I did suggest that a few posts ago and gave examples varying from a Chinese one at £5, to Durite ones at £100.

[bigcol]

Okay 4.30pm

 

battery1   12.7v

battery2.  12.4v

batery 3. 12.04v

battery4  13.09v

 

 

Battery’s  reconnected 4.45

[WotEver]

2 minutes ago, bigcol said:

Okay 4.30pm

 

battery1   12.7v

battery2.  12.4v

batery 3. 12.04v

battery4  13.09v

 

 

Battery’s  reconnected 4.45

Keep the 12V tap and the Vanner disconnected and give us another reading in an hour, Col. 

[bigcol]

1 hour ago, WotEver said:

You’re not. They could. It would be better. 

 

I think it’s just that the Vanner came with the boat so Col thought he’d use it. 

Yes it came with all the electrical stuff, which was and is brand new

[bigcol]

8 minutes ago, WotEver said:

Keep the 12V tap and the Vanner disconnected and give us another reading in an hour, Col. 

Okay vanner disconected grad Earth, 24v and 12v

and all 12v feed now disconected

[bigcol]

Nasa battery monitor now up to 29v

As you can see no power to 12v panel, radio etc

[bigcol]

When taking readings charger changed from float to absorbsion

 

Battery1  13.2v on float.

battery2  12.8 on float.   

battery3  12.5von float. 

batteryb 13.2. On float.   

All connected back up now

[Alan de Enfield]

3 minutes ago, bigcol said:

When taking readings charger changed from float to absorbsion

 

Battery1  13.2v on float.

battery2  12.8 on float.   

battery3  12.5von float. 

batteryb 13.2. On float.   

All connected back up now

It doesn't look 'right'

 

2 hours + after stopping charging 2 batteries are 'overcharged' (13.2v) one is correctly fully charged (12.8v) and one is about 75% charged (12.5v)

[bigcol]

I agree

im going to do it all again tomorrow

because when I took this reading charger changed from float to absortion.

 

readings went all over the place.

 

tomorrow after being on charge all night

i will take readings then 

will turn everything off for a hour than take readings 12v and charger etc

take readings again.

 

im sorry about today,  but may be I messed up with the readings 

 

col

[WotEver]

Col. Please continue to leave the 12V tap and the Vanner disconnected for now. 

24 minutes ago, Alan de Enfield said:

It doesn't look 'right'

It doesn’t look possible.

 

26V across one pair and 25.7V across the other pair which are in parallel...

[bigcol]

Tony too late tonight

tomorrow I will write readings on a proper sheet of paper

tonight all cables are connected 

I will ist thing take readings before I disconect, then I will remove  all 12 volt cables and vanner cables disconect battery charger.

and take readings again.

 

again apologies I’m sure I messed up with writing down the numbers

[ditchcrawler]

59 minutes ago, bigcol said:

I agree

im going to do it all again tomorrow

because when I took this reading charger changed from float to absortion.

 

 

col

You need to take the readings with the charger off as well as all loads. You cant do it with anything going in or out.

[Iain_S]

  This thread reminds me of an old post about a crew delivering a boat with 24V electrics. They had a 12V VHF radio, but no means of charging a 12V battery. Their solution was an old 12V battery connected positive to the 24V positive with the radio connected between the additional battery's negative and the 24V negative. It worked, and the additional 12V battery was charged while the radio was in use.

[bigcol]

8 minutes ago, ditchcrawler said:

You need to take the readings with the charger off as well as all loads. You cant do it with anything going in or out.

Understood Brian

i will take photo of readings before I remove anything. Then I will isolate from charger, vanner, and disconect from 12v for couple of hours.

then will take photos of readings again.

 

col

[ditchcrawler]

1 minute ago, bigcol said:

Understood Brian

i will take photo of readings before I remove anything. Then I will isolate from charger, vanner, and disconect from 12v for couple of hours.

then will take photos of readings again.

 

col

That is the only way the readings will mean anything.

[WotEver]

51 minutes ago, bigcol said:

Understood Brian

i will take photo of readings before I remove anything. Then I will isolate from charger, vanner, and disconect from 12v for couple of hours.

then will take photos of readings again.

 

col

Col. Firstly, after your initial readings, disconnect the Vanner and the 12V tap. Leave the 24V charger connected with everything charging like that for an hour. Then disconnect all terminals, leave for an hour or two and take individual readings of each battery. The reason for leaving the charger on for a while is that it appears that the Vanner isn’t working so it gives the flattened battery a chance to get some charge into itself. 

[bigcol]

 

Understood Brian

i will take photo of readings before I remove anything. Then I will isolate from charger, vanner, and disconect from 12v for couple of hours.

then will take photos of readings again.

 

col

Col. Firstly, after your initial readings, disconnect the Vanner and the 12V tap. Leave the 24V charger connected with everything charging like that for an hour. Then disconnect all terminals, leave for an hour or two and take individual readings of each battery. The reason for leaving the charger on for a while is that it appears that the Vanner isn’t working so it gives the flattened battery a chance to get some charge into itself. 

 

Will do this tomorrow morning

properly

 

col

[Keith M]

It is very poor practice to take a 12-volt supply from a 24-volt battery bank, always us a DC / DC converter 24 in 12-volts out. It will just wreck batteries.

 

I have worked with marine electrical installation for more than  30years I have never come across the Vanner unit.

 

As an aside looking at the images of the batteries are the interconnecting cables the same cross-section area. 

[bigcol]

Photo of first reading taken after a night time with everything connected at 8.20

8.30 now all 12v cables and vanner unit have been disconnected for next reading

Edited January 12, 2019 by bigcol

[bigcol]

https://www.ebay.co.uk/itm/Car-Converter-24V-to-12V-5A-60W-Step-Down-Module-DC-to-DC-Step-Down-Module/401646408139?hash=item5d83fdd1cb:g:iSUAAOSwmkBb~m3C

 

are we saying that all I need is somthing like this?