Another battery question, sorry

[guerdeval]

So the pic is of my present batteries and it seems the ‘feed’ wires with the fuse are connected to just one of the 2 batteries, is this correct?, will it not use more of 1 battery than the other? Should I do the same ?

 

[trevskoda]

2 batts ahould be wired like this to equel the voltage and load.

 

[guerdeval]

Thanks Trev, but what I want to know is do I re-attach the thinner wires with the inline fuse to the single battery like it is now ?, cheers

 

[trevskoda]

Maybe fussed futher up the line, but for the best fuses should be as close to the battery as possable.

 

[SimonM]

It would be better if you showed a picture of 2 batteries and how they are connected and not just the one.

 

[1 Cup]

U can do it both way but charge pack as diagram above ....if invertor off this pack also like diagram.
3kw @ 12volts = wire 70mm wire so battery leads from and to bus bar. = 70mm plus link wire.

I went scrap yard and took cutters and cut battery terminals of a V8 not a micra. at length, I've upgraded now so only brought 1 battery terminal for link up

12v is 12v at low amp drawn. Upto 100 amp fuse box. = 10 x fuses @ 7.5 amp purple fuse.

But best buy 2 M8 bus bars x 4 but 8 or 6 studs are best
Your screw is to short ! Lo and put a locking nut on it.

 

[guerdeval]

It would be better if you showed a picture of 2 batteries and how they are connected and not just the one.

Cheers Simon, this is the 2 batteries and you can see that the fused take off is attached to just one of the batteries, when I change them I can do the same or take pos from one and neg from the other, but which is correct?, regards, rog

 

[SimonM]

I don’t know enough to say if it’s right or wrong. However if it had been me doing it I would have taken the red +ve pair of wires to the other battery so that the circuit was the longest way round (now’s where I get told I would be wrong to do that ).

 

[guerdeval]

I don’t know enough to say if it’s right or wrong. However if it had been me doing it I would have taken the red +ve pair of wires to the other battery so that the circuit was the longest way round (now’s where I get told I would be wrong to do that ).

That’s what I thought too, probably for the wrong reason though, I just thought it would deplete 1 battery before the other ,thanks for input.

 

[colinm]

That’s what I thought too, probably for the wrong reason though, I just thought it would deplete 1 battery before the other ,thanks for input.

The reason it might deplete one battery before the other would be if the resistance to the second battery is higher, so it's always 'good practice' to connect -ve to one battery, and +ve to the other. In reality if the connections are in good order, and there are substantial wires between the two batteries, it will make little differance.

 

[r4dent]

I will refer to the left hand battery as "A" and the right hand battery as "B".
The photo of the two batteries shows that the+ve feed to the MoHo 12v and the -ve Earth lead are both on same battery A
Ideally one of these should be on each battery.

Easiest way to rectify.

1) Disconnect from EHU; Switch off all 12v appliances and master switch (reduces risk of sparking when breaking or making connections). Super cautious would cover the solar panel, disconnect the solar controller or do the job after sunset!
2) battery A - Negative - remove the wing nut; remove all three black wires & move away from either battery; Do NOT replace the wing nut
(this means the MoHo is not earthed and reduces the risk of accidental shorting)
3) battery A -Positive - remove the wing nut; remove the two thin red wires; replace & tighten the wing nut holding the thick red wire.
4) battery B - Positive - remove the wing nut; leave the thick red wire in situ; connect the two thin red wires removed in step 3;
replace & tighten the wing nut holding the 3 red wires.
5) battery B - Negative -no action required.
6) battery A - negative- replace the three black wires removed in step 2; replace & tighten the wing nut holding the three black wires.
7) Switch on the 12v master and appliances.

The earth lead remains connected to battery A, the MoHo 12v +ve feed is now on battery B.

Job done.

 

[wildebus]

I don’t know enough to say if it’s right or wrong. However if it had been me doing it I would have taken the red +ve pair of wires to the other battery so that the circuit was the longest way round (now’s where I get told I would be wrong to do that ).

Given what is showing in the picture, that looks to be the easiest option to get the batteries setup right and I'd do the same.


Now on another note, the battery interconnects look nice and chunky and very decent. the connections going from the battery bank to the general motorhome habitation system - and all the chargers - look very insubstantial and I would be rather concerned about those far more than having the batteries balanced.

Just as an FYI, the connector colours have a meaning ... Yellow is used for cables of 4mm2 to 6mm2; Blue is used for cables between 1.5mm2 and 2.5mm2.
I think you have the Sargent EC328? That is not a very high powered charger but even bearing that in mind those cables are inadequate

 

[guerdeval]

Given what is showing in the picture, that looks to be the easiest option to get the batteries setup right and I'd do the same.


Now on another note, the battery interconnects look nice and chunky and very decent. the connections going from the battery bank to the general motorhome habitation system - and all the chargers - look very insubstantial and I would be rather concerned about those far more than having the batteries balanced.

Just as an FYI, the connector colours have a meaning ... Yellow is used for cables of 4mm2 to 6mm2; Blue is used for cables between 1.5mm2 and 2.5mm2.
I think you have the Sargent EC328? That is not a very high powered charger but even bearing that in mind those cables are inadequate

Thankyou, is that a reason the fuse holder gets pretty hot ?

 

[wildebus]

Thankyou, is that a reason the fuse holder gets pretty hot ?

Fuse holders getting hot? At least it wasn't like this one (I hope!) that I took out of a van this morning

IMG_20240420_183433_130 by David, on Flickr

When you say the fuse holders are getting hot, are the cables also getting pretty warm? With that wiring, the ampacity (current carrying capability) is very borderline with your EC328 and the amount of voltage drop will be high. This could well be a reason why you are having issues with the current batteries and the new ones will fare badly as well IMO

 

[guerdeval]

Fuse holders getting hot? At least it wasn't like this one (I hope!) that I took out of a van this morning

IMG_20240420_183433_130 by David, on Flickr

When you say the fuse holders are getting hot, are the cables also getting pretty warm? With that wiring, the ampacity (current carrying capability) is very borderline with your EC328 and the amount of voltage drop will be high. This could well be a reason why you are having issues with the current batteries and the new ones will fare badly as well IMO

Yes particularly when it is on hook up, especially the red ones before the fuses

 

[wildebus]

Yes particularly when it is on hook up, especially the red ones before the fuses

To put it bluntly, you need that cabling looked at, and I would say it should be a priority. The cables on the other (non-battery) side of the fuses are just as bad.

The Sargent Wiring (that is part of the kit Sargent make for the Motorhome Manufacturers) are notably heavier - they are either a pair of 6mm2 or 10mm2 cables for both -ve and +ve and different colours to yours so somewhere someone has added this cabling for some reason. (maybe if the original battery location was somewhere else and they added extra from that location to the current battery position?)

 

[guerdeval]

Thanks again for the advice, I’’ll get it sorted before I fit the new batteries, you’re probably correct as the Sargent unit is at one end and the batteries at the other, in fact I might ask the fitter to move them at the same time, thanks again, rog

 

[guerdeval]

To put it bluntly, you need that cabling looked at, and I would say it should be a priority. The cables on the other (non-battery) side of the fuses are just as bad.

The Sargent Wiring (that is part of the kit Sargent make for the Motorhome Manufacturers) are notably heavier - they are either a pair of 6mm2 or 10mm2 cables for both -ve and +ve and different colours to yours so somewhere someone has added this cabling for some reason. (maybe if the original battery location was somewhere else and they added extra from that location to the current battery position?)

Ok, ‘probably’ my last question, would the “Noco genius 25” charger be adequate to keep the 2 new 150ah batteries charged if the Sargent unit is disconnected for charging.

 

[wildebus]

Ok, ‘probably’ my last question, would the “Noco genius 25” charger be adequate to keep the 2 new 150ah batteries charged if the Sargent unit is disconnected for charging.

Two things to look at .... (you know my answers will never be "yes" or "no" )

1) If sitting on a Driveway and plugged in after a weekend or whatever away, a 25A charger will recharge the two batteries fine - it will take longer than a bigger charger, but does it matter if the charging is finished at 5AM or 8AM? not really.

2) When away camping, you are using 12V power for the waterpump, the lighting, the heating fan, the TV, the USB chargers on the phone, etc, etc. Now that is NOT coming from the EHU directly even if you are plugged in, but the battery.
The relevance of this is that the Mains Chargers job is essentially not only to recharge the battery but make up for the 12V draw you have when using (and typically, when people are plugged into EHU, they are less careful about turning off lights, etc ("hey, we are plugged in so we don't need to worry about the battery")).
If you have a 25A charger but you are using maybe 10A of 12V DC Power, you are only charging the batteries with 15 Amps worth of current, and not the 25 Amps worth you automatically imagine (the other 10A from the Charger is to make up the draw usage)
Again, overnight there will be much less use of 12V, so the charger will give a lot more to the actual battery charging and chances are you have a full bank by the morning. But ... if the batteries are low when you arrive on site and you are leaving first thing in the morning, don't neccessarily/automatically expect to have a full bank when you leave.


But the TL: DR version of the answer ..... Yes

 

[guerdeval]

Two things to look at .... (you know my answers will never be "yes" or "no" )

1) If sitting on a Driveway and plugged in after a weekend or whatever away, a 25A charger will recharge the two batteries fine - it will take longer than a bigger charger, but does it matter if the charging is finished at 5AM or 8AM? not really.

2) When away camping, you are using 12V power for the waterpump, the lighting, the heating fan, the TV, the USB chargers on the phone, etc, etc. Now that is NOT coming from the EHU directly even if you are plugged in, but the battery.
The relevance of this is that the Mains Chargers job is essentially not only to recharge the battery but make up for the 12V draw you have when using (and typically, when people are plugged into EHU, they are less careful about turning off lights, etc ("hey, we are plugged in so we don't need to worry about the battery")).
If you have a 25A charger but you are using maybe 10A of 12V DC Power, you are only charging the batteries with 15 Amps worth of current, and not the 25 Amps worth you automatically imagine (the other 10A from the Charger is to make up the draw usage)
Again, overnight there will be much less use of 12V, so the charger will give a lot more to the actual battery charging and chances are you have a full bank by the morning. But ... if the batteries are low when you arrive on site and you are leaving first thing in the morning, don't neccessarily/automatically expect to have a full bank when you leave.


But the TL: DR version of the answer ..... Yes

Perfick , again many thanks