Waeco batt charger advice

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harstonwood

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Just bought a waeco iu2512 batt charger

It's has outputs for two batts plus starter batt

On my boat, I have one batt for starting stbd engine, and powers engine bay hatch.

Two batts supply domestics, and start port engine.

I intend to use the two batt connections for the two domestic batts, and the starter connection for the stbd engine.

My question, is the manual specifies 25-30mm cables for supply batts and 1mm-2.5mm for the starter batt. These seem odd, I would have thought 8 mm would do for both?

Any advice gratefully recieved. Just to confirm its the 25a 12v model

Thanks
 
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I think its just a low current ( 1 amp ?? ) output for the starter battery charging. That would explain the relatively light wiring that can be used. ( but for robustness I would use heavier than that specified)

I guess you can get 25 amps from either of the other two outputs hence the heavy wiring recommended for them.

However do you have a link to the instruction manual? .. I have not found one yet.
 
harstonwood said:
Thanks VicS

Only got the paper manual.

Would 8mm be ok for the 1 amp starter batt ?

Guess I will have to source some 25mm for the domestics

Cheers
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8mm² will be more than adequate for the 1 amp outlet. On reflection I think even 1mm would not be so bad. 1.5 would be plenty.

25- 30mm² sounds extremely heavy.

How long will the cable runs be?
 
harstonwood said:
Cable runs for the supply batts about 2m max.
Starter batt max 3 m

I think I may have some light weight jump start cables in the garage, I guess that cable would do? I was surprised at the book specifying 25-30mm cable
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I wonder if it's to avoid volts drop on long runs.

I have found some instructions now ... I dont see any reference to permissible cable lengths but I have not read them thoroughly yet.

I'd have thought 10mm² would have been more than adequate ... but I've not done any calcs on volts drop yet

I'd be reluctant to ignore the instructions though
 
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Cable run 2m, that's 4m total positive plus negative

10mm² cable has a resistance of 1.8 ohms/1000m

so resistance of 4m = 1.8x4/1000 ohms

so volts drop at 25 amps = 25x1.8x4/1000 = 0.18 volts

That does not look too bad but ceratinly would be if the cable runs were much longer.

Would nearly 0.2 volt be important ? That's the question I suppose
 
VicS said:
Cable run 2m, that's 4m total positive plus negative

10mm² cable has a resistance of 1.8 ohms/1000m

so resistance of 4m = 1.8x4/1000 ohms

so volts drop at 25 amps = 25x1.8x4/1000 = 0.18 volts

That does not look too bad but ceratinly would be if the cable runs were much longer.

Would nearly 0.2 volt be important ? That's the question I suppose
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But the 25A is the max output from the charger, so it will be split between the 2 outputs. On this basis, 10mm2 cable would only give 0.1v drop.
 
pvb said:
But the 25A is the max output from the charger, so it will be split between the 2 outputs. On this basis, 10mm2 cable would only give 0.1v drop.
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Yes but presumably there could be times when one battery is much more discharged than the other ... assuming two separate batteries rather than both linked to form a single bank .. in which case you may get nearly 25 amps going into one and much less into the other.

There is no disputing the fact that the instructions do say 25-30mm² and, "Keep to the indicated minimum cable cross-section".
 
Thanks chaps, the two port side batts are linked together, though I guess I will still run a positive to each?

( two positive outputs on charger)

The batts are 130 ah each , am hoping the 25a charger ( only first cycle charging) is not to much?

The 1 a for the starter batt not a problem, and I will use 8 mm wire as I have plenty.

Very grateful for your advice
 
harstonwood said:
Thanks chaps, the two port side batts are linked together, though I guess I will still run a positive to each?

( two positive outputs on charger)

The batts are 130 ah each , am hoping the 25a charger ( only first cycle charging) is not to much?

The 1 a for the starter batt not a problem, and I will use 8 mm wire as I have plenty.

Very grateful for your advice
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So really you will be linking the 25A outputs together.. This is normal with chargers with more outputs than required but check it is Ok with yours.

No need to double up on the wiring total crossection. 25 amps will be the total.

The max current output should not be a problem .. The charger should be regulated so the battery will only draw what it needs but not sure what you mean by "only first cycle charging"
 
harstonwood said:
just not sure whether to use both connections for the two batts that are linked together, or just one
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It doesn't matter, they're isolated outputs, you could use one or both. If you only use one, I'd be tempted to use 2x10mm2 cable, to reduce the voltage drop.
 
Pvb.......just checking before I cock it up, the two supply batts (130ah each) are wired in parallel, and supply domestics plus start stbd engine.

I propose to run one negative to the first battery, and run a positive from the charger to each of the two batteries, as the charger has two positive outputs. I would then run a separate positive from the third (1a) charger output to the starter batt for the port engine, and a negative from the two parallel batts to this third batt.

I will use 25mm cable as specified to the supply batts, and 1.5mm to the starter batt

Sound about right?

Cheers for advice
 
harstonwood said:
Pvb.......just checking before I cock it up, the two supply batts (130ah each) are wired in parallel, and supply domestics plus start stbd engine.

I propose to run one negative to the first battery, and run a positive from the charger to each of the two batteries, as the charger has two positive outputs. I would then run a separate positive from the third (1a) charger output to the starter batt for the port engine, and a negative from the two parallel batts to this third batt.

I will use 25mm cable as specified to the supply batts, and 1.5mm to the starter batt

Sound about right?

Cheers for advice
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If you're going to use 25mm2 cable, I'd be tempted to link the 2 charger outputs together and just run a single 25mm2 cable to your battery bank. Are you sure the third battery isn't already linked in to the same negative? Otherwise, your proposal sounds fine.
 
Thanks Pvb, I wil check if the third batts negative is connected to the supply batts neg......I suspect it is.


Sorry for being so dim......if I connect both charger outputs to one of the two parallel batts, would this be better than taking a positive to each of the two batts? As I have two pos outputs on the charger, I can easily put a lead onto each of the two batts.

God I wish I understood all this electrickery!

Thanks for your patience!
 
harstonwood said:
Sorry for being so dim......if I connect both charger outputs to one of the two parallel batts, would this be better than taking a positive to each of the two batts? As I have two pos outputs on the charger, I can easily put a lead onto each of the two batts.
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The batteries are connected in parallel, so the 2 positive terminals are already connected to each other. Using 2 cables from the charger is effectively the same as linking the 2 charger outputs together and running a single cable. All you have to ensure is that the cable is big enough for the max current. If you're going to use 25mm2 cable, one cable would be sufficient.

Also, although your charger has 2 outputs, you don't need to connect both.
 
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