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Old 06-15-2019, 11:58 PM   #1
Sunny&75
 
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Default sterling b2b charger

according to the instructions, the negative wire needs to be connected directly to the battery and not to the chassis. i have an existing + & - cable that is running under the chassis, that I was going to use. The - cable is connected to the chassis and not to the battery. My existing + cable is connected to a block on the chassis that goes to the battery.
so, if i rerun the negative, how would i go to the battery directly from under the vehicle? or should i rerun both cables inside the van, and how do you get to the battery from the b pillar?
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Old 06-16-2019, 12:28 AM   #2
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Default Re: sterling b2b charger

Charles is exaggerating a bit.

Yes the round-trip circuit needs to be robust and not include the chassis, as with any expensive, important, sensitive, or high-current loads afaic.

But it does not need to go to the Starter batt itself, as long as the input pair get wired in parallel directly to the high-amp engine circuit (fat cables, robust connectors) connecting the alternator, the starter and that engine/starter battery.
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Old 06-16-2019, 06:58 AM   #3
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Default Re: sterling b2b charger

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Originally Posted by john61ct View Post
Charles is exaggerating a bit.

Yes the round-trip circuit needs to be robust and not include the chassis, as with any expensive, important, sensitive, or high-current loads afaic.

But it does not need to go to the Starter batt itself, as long as the input pair get wired in parallel directly to the high-amp engine circuit (fat cables, robust connectors) connecting the alternator, the starter and that engine/starter battery.
is there a negative block somewhere to wire to, if not directly to the batt or the chassis?
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Old 06-16-2019, 06:01 PM   #4
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Default Re: sterling b2b charger

The reason for the "must be to battery" is because the Sterling is looking for very tiny voltage level shifts.
Losing a tenth of a volt due to multiple connections, less-than-perfect frame welds, etc etc will affect quality of charge.
But in reality, your hook-up may well be "good enough" ... every installation is different.

(some chargers avoid the issue by having separate "sense" wires that go to the battery and measure it *there*, instead of just at the charger's outputs)

--dick
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Old 06-16-2019, 07:00 PM   #5
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Default Re: sterling b2b charger

Whoa was OP talking about the **output** leads to the charging target battery?

Yes that really should be as close and direct as possible so voltage sense is accurate.

My comments above are wrt the power **input** coming from the DCDC's energy source, most commonly the engine / starter / alternator output circuit.

The B2B has no problem with voltage drop issues there, that's its main raison d'Ítre. But that connection does need to be robust & reliable, low resistance, not relying on the variability of chassis connections.
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Old 06-16-2019, 07:02 PM   #6
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Default Re: sterling b2b charger

Quote:
Originally Posted by john61ct View Post
Whoa was OP talking about the **output** leads to the charging target battery?

Yes that really should be as close and direct as possible so voltage sense is accurate.

My comments above are wrt the power **input** coming from the DCDC's energy source, most commonly the engine / starter / alternator output circuit.

The B2B has no problem with voltage drop issues there, that's its main raison d'Ítre. But that connection does need to be robust & reliable, low resistance, not relying on the variability of chassis connections.

What does 'wrt' mean?
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Old 06-16-2019, 09:13 PM   #7
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Default Re: sterling b2b charger

"wrt" = with respect to. (i should install a Gregg Shorthand font to really cause confusion)

Yes, the "original post" was typically vague about which battery(ies) they were talking about.
I assumed the touchiest...

--dick
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Old 06-17-2019, 01:33 PM   #8
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Default Re: sterling b2b charger

Quote:
Originally Posted by autostaretx View Post
"wrt" = with respect to. (i should install a Gregg Shorthand font to really cause confusion)

Yes, the "original post" was typically vague about which battery(ies) they were talking about.
I assumed the touchiest...

--dick
sorry for the vaguarity, yes starting batt.
So, how do i get to the starting battery(driver's side floor) with cable, from roughly, my wheel well location for the Sterling? I have a block under the chassis for the positive cable that connects with the battery, but no such thing(that i'm aware of , for the negative cable. Also, Sterling recommends #6 cable. I've got about a 15-20 run rt from my starting batt > Sterling. Is that adequate?
thanks!
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Old 06-17-2019, 03:24 PM   #9
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Default Re: sterling b2b charger

Use Blue Sea's app Circuit Wizard to calculate wire gauge required above Charles' reco.

As mentioned on the input side, V drop's NBD.

On output, you must strive to get as close as possible to the target bank, or use much fatter cables, IMO keep V drop well below 1%.

I'm not clear on the "how to route" questions. If necessary drilling holes in sheet metal is easy, just be careful, and ideally use cable glands (bushings) with good strain relief.

Someone familiar with your vehicle may suggest better alternatives.
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Old 06-17-2019, 04:21 PM   #10
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Default Re: sterling b2b charger

Quote:
Originally Posted by john61ct View Post
Use Blue Sea's app Circuit Wizard to calculate wire gauge required above Charles' reco.

As mentioned on the input side, V drop's NBD.

On output, you must strive to get as close as possible to the target bank, or use much fatter cables, IMO keep V drop well below 1%.

I'm not clear on the "how to route" questions. If necessary drilling holes in sheet metal is easy, just be careful, and ideally use cable glands (bushings) with good strain relief.

Someone familiar with your vehicle may suggest better alternatives.
What does "NBD" mean?
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