Removing 1, 2 both switch and new battery

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jerry098

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Hi all,
I'm in the process of separating the starting and domestic circuits on my M27.
Would anyone care to look at the very rough circuit diagram attached and advise if it looks OK?
In this process I will be adding a new dedicated starting battery and was looking at a Odyssey PC680 - however I have some questions:
1. I have, already, a Sterling battery to battery charger. From the description of how it works it apparently drops the alternator charging voltage at the starter battery to 13V but the advised minimum charging voltage for a Odyssey battery is more than 14.2V.
Does this mean I can't use a Odyssey battery with the Sterling B to B charger?
2. If I can do you think that the Odyssey PC680 will have sufficient grunt to start my 25 year old Volvo 2002 (18hp)?
3. Do you think the output from the solar regulator should go to the domestic bank or the starter battery and thus to the domestic bank via the Sterling B to B charger?
All advise appreciated.
 
Hi John,
Yes that does look like a good alternative but the BEP switch cluster is already on order and, anyway, from my quick search I can't find a supplier of your option and the price would seem to be about £112 - more than the £50 for the BEP solution.
Regards,
Jerry
 
It looks like it is still possible to disconnect the alternator whilst the engine is running by flicking a switch.

I used a Sterling A-B charger rather than the B-B, but the key thing about the circuit is that charging does not go through the switches, which I see as a huge plus point.

Other than that you may want to think about the arrangement for linking the batteries. If your engine battery isn't good enough to start the engine the old 1-2-both switch gives you no option but to link the batteries together, but under those circumstances the dud engine battery brings the others down. Now you've got separate switches you may want to consider having the option of starting the engine off the domestics alone or off the domestic & starter batteries combined, so that you have maximum flexibility to deal with whatever situation you're in.
 
Hi,

dt4134 said:
It looks like it is still possible to disconnect the alternator whilst the engine is running by flicking a switch. - True but if you want to be able to isolate all batteries isn't that always the case?

I used a Sterling A-B charger rather than the B-B, but the key thing about the circuit is that charging does not go through the switches, which I see as a huge plus point. - I already have the B-B and my reply above applies.

Other than that you may want to think about the arrangement for linking the batteries. If your engine battery isn't good enough to start the engine the old 1-2-both switch gives you no option but to link the batteries together, but under those circumstances the dud engine battery brings the others down. Now you've got separate switches you may want to consider having the option of starting the engine off the domestics alone or off the domestic & starter batteries combined, so that you have maximum flexibility to deal with whatever situation you're in.
Click to expand...
- The central switch in the BEP cluster is a switch to link the two batteries.
Thanks, Jerry
 
jerry098 said:
1. I have, already, a Sterling battery to battery charger. From the description of how it works it apparently drops the alternator charging voltage at the starter battery to 13V but the advised minimum charging voltage for a Odyssey battery is more than 14.2V.
Does this mean I can't use a Odyssey battery with the Sterling B to B charger?
2. If I can do you think that the Odyssey PC680 will have sufficient grunt to start my 25 year old Volvo 2002 (18hp)?
Click to expand...

The Sterling charger doesn't start to operate until the start battery has reached about 13 volts, so the start battery will get recharged adequately. Starting an engine consumes very little battery power.

The Odyssey PC680 should start your 2002 without difficulty. However, unless you're absolutely desperate for space, it's a very expensive alternative. You could use a small car battery at about a third of the price.
 
Thanks,
I had a look in Halfords yesterday and the cheapest cat battery I could find was about £70 and with no indication of the CCA.
Do you know what CCA I should be looking for in a standard car battery?
Jerry
 
I see nothing wrong with your proposed wiring

BUT

Dt4134 has a couple of valid points:

1.) Yes you will be able to disconnect the alternator at the ( incorrect) flip of a switch. But if you want the battery isolators to completely isolate the batteries that is, I think, inevitable. The Americans tend not to like this ability! ( but infact you are not completly isolating the batteies because the B-B charger is permanently connected

2.) Yes the only way, as you have shown it wired, to use the house battery for engine starting is to common the batteries. IMO it would be better to wire the switch cluster so that the commoning switch interconnects the switched side of the two isolators ... I think that is possible with the BEP cluster.... then a duff battery can be left disconnected​

The Sterling B-B charger will, I think, control the charging of the house bank correctly if set correctly.
Your alternator regulator may need to be changed to suit the AGM starter battery but if space is not the critical factor or you particularly need an AGM battery such as an Odyssey then fit an ordinary FLA cranking battery.

I would have been dubious about using a battery as small as 220CCA. I'd prefer something closer to 450 CCA but maybe PVB knows better. ;)

All the batteries in Halfordsshould be marked with CCA
 
Thanks Vic,

VicS said:
I see nothing wrong with your proposed wiring

BUT

Dt4134 has a couple of valid points:

1.) Yes you will be able to disconnect the alternator at the ( incorrect) flip of a switch. - Can you suggest a way too avoid this?
But if you want the battery isolators to completely isolate the batteries that is, I think, inevitable. The Americans tend not to like this ability! ( but infact you are not completly isolating the batteies because the B-B charger is permanently connected - Agreed

2.) Yes the only way, as you have shown it wired, to use the house battery for engine starting is to common the batteries. IMO it would be better to wire the switch cluster so that the commoning switch interconnects the switched side of the two isolators ... I think that is possible with the BEP cluster.... then a duff battery can be left disconnected​
So you suggest I flip the connections on the two outer switches in the cluster? - I did think this originally but the BEP instructions show the batteries connected to the 'inside' connections.

The Sterling B-B charger will, I think, control the charging of the house bank correctly if set correctly. - I'm not worried about the B-B charging of the house batteries it was the starter battery charging voltage that concerns me.
Your alternator regulator may need to be changed to suit the AGM starter battery - I've no intention of doing that. I wouldn't know where to start!
but if space is not the critical factor or you particularly need an AGM battery such as an Odyssey then fit an ordinary FLA cranking battery. - I seem to be moving in that direction now.

I would have been dubious about using a battery as small as 220CCA. I'd prefer something closer to 450 CCA but maybe PVB knows better. ;)

All the batteries in Halfordsshould be marked with CCA
Click to expand...
- they aren't.

Thanks again,
Jerry
 
VicS said:
I would have been dubious about using a battery as small as 220CCA. I'd prefer something closer to 450 CCA but maybe PVB knows better. ;)
Click to expand...

Interesting, Vic, I looked up the Odyssey range on the usually reliable Merlin PowerStore website, where they call it both 680CCA and 510CCA, and I took the lower number. However, looking at the Odyssey website, they do call it a 220CCA.

I reckon it'd still be OK for the 2002, which is only an 850cc engine.

However, if space isn't a major consideration, it would be much more sensible to save a lot of money and just get a small car battery, something like this for example, for around 30 quid.
 
Did you see my other responses to your first reply?
Click to expand...
No sorry

I couldn't work out how to split your reply into multi quotes
Click to expand...
Thats not how the multiquotes works . It quotes the whole of several replies.

it's all mixed up
Click to expand...
You have to copy and paste in each bit separately using the
quote.gif
button

So you suggest I flip the connections on the two outer switches in the cluster? - I did think this originally but the BEP instructions show the batteries connected to the 'inside' connections.
Click to expand...
I had a quick look at the BEP switch details and thought it might be possible by swapping the load and battery connections. Be different if you were using the VSR cluster

I'm not worried about the B-B charging of the house batteries it was the starter battery charging voltage that concerns me.
Click to expand...
The starter battery is charged directly by the alternator. It's not controlled by the B-B charger. That's how I understand it anyway and hence my suggestion that the alternator regulator might need to be changed if the starter battery is to be well charged .. probably not though if you tend to motor for long periods/distances.
 
Your engine starter motor is likely to be 700 watts = 70 amps draw at the dropped voltage you will suffer. For maybe 5 secs so just one tenth of an amp hour in total. The recommended size for the engine is a 70AH battery so I see no problem with what you propose.

The solar panel should go to the domestic. The new engine start battery will almost never be anything but fully charged unlike the domestics.

Cant comment about the sterling charger but I have found sterling very helpful on the phone. Ask them.
 
Your engine starter motor is likely to be 700 watts = 70 amps draw at the dropped voltage you will suffer. For maybe 5 secs so just one tenth of an amp hour in total. The recommended size for the engine is a 70AH battery so I see no problem with what you propose
Click to expand...
. Its CCA that counts not the Ah capacity. You dont need anything like 70Ah capacity, Thats the whole basis of batteries like Red flash and to a lesser extent Odyssey. They are physically small, have small capacities but designed to give very high CCA.
However a 70 Ah battery is likely to have an adequate CCA ( 70 Ah battery in my other car is 540CCA)

The solar panel should go to the domestic. The new engine start battery will almost never be anything but fully charged unlike the domestics.
Click to expand...
True but the B-B charger will still work with the solar panel connected to the stater battery. It'll ensure the starter battery is kept charged and then go on to feed the domestic battry

Cant comment about the sterling charger
Click to expand...
Its all on the website

Must dash... SWMBO has been away for the weekend. Should be just leaving Charing Cross must go to meet


Sorry for speeling mistooks etc
 
Last edited:
Vic things do not change do they :)

Be careful assuming starter motor loads are only 70 amp, 1GM10 starter motor is listed at 70 amp light, upto 480 amp under load.

Brian
 
Been working, 30 years since we started making VSR's and other bits, so I decided it was time to introduce major upgrades I've been putting off for years.

Have I missed anything ?

Brian
 
Thanks for the replies.
Sorry if I was going over old ground but I couldn't find any other questions about using a Sterling B to B charger with a Odyssey battery.
The decision is now made to use a cheap car battery.
Thanks,
Jerry
 
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