Need Help Setting up my Battery Monitor

[gspeak]

This might be a silly question. I am installing a Enerdrive eLite battery monitor. Have a feeling it is a Xantrex/Link derivative as it looks exactly the same.

Question:
I have a house bank of 4 x 120AH AGM's & a starter battery. As it is now the negatives of the house bank are also connected to the starter negative and from there to a common negative isolating switch. The positives of house bank & starter are not connected (obviously).

Is it OK to keep the starter negative connected to house bank & just take this to the shunt or do I have to run a new lead from the starter to somewhere after the shunt?

Thanks in advance.

Dave

[propellanttech]

Originally Posted by gspeak

This might be a silly question. I am installing a Enerdrive eLite battery monitor. Have a feeling it is a Xantrex/Link derivative as it looks exactly the same.

Question:
I have a house bank of 4 x 120AH AGM's & a starter battery. As it is now the negatives of the house bank are also connected to the starter negative and from there to a common negative isolating switch. The positives of house bank & starter are not connected (obviously).

Is it OK to keep the starter negative connected to house bank & just take this to the shunt or do I have to run a new lead from the starter to somewhere after the shunt?

Thanks in advance.

Dave

Dave,

I'm not totally positive I understand the question.

The install manual here ( http://www.enerdrive.com.au/images/s...uide-eLite.pdf ) shows pretty much how it is to be wired.

You will need to rephrase the question for us to understand.

James L

[gspeak]

Originally Posted by propellanttech

Dave,

I'm not totally positive I understand the question.

The install manual here ( http://www.enerdrive.com.au/images/s...uide-eLite.pdf ) shows pretty much how it is to be wired.

You will need to rephrase the question for us to understand.

James L

James,
In that diagram the "Auxiliary Battery" would be the starter battery so it is connected on the "Battery negative (system ground)" side of the shunt.

My batteries are currently wired with the starter negative at the end of the house bank of negatives then to the "system ground". So looks like I have to change this. See below.





Dave

[mitiempo]

Dave, the second diagram is correct. The shunt has to measure the house bank negative before the start battery negative is is connected.

[gspeak]

Originally Posted by mitiempo

Dave, the second diagram is correct. The shunt has to measure the house bank negative before the start battery negative is is connected.

Thanks for that, I have just had a new 00 battery lead made up to change my setup to the shunt. Will install tomorrow.

Dave

[sailinglegend]

Originally Posted by mitiempo

Dave, the second diagram is correct. The shunt has to measure the house bank negative before the start battery negative is is connected.

+1

If this is not correct then the alternator and possibly the shorepower charging of the house bank may not show on the battery monitor because the alternator earth usually goes to the engine and then directly to to the starter battery. Any load that uses the engine earth will also not show on the battery monitor.

I'm not quite sure why you had to have a new 00 cable made. The start negative just has to come off one of the negative studs and go on the end of the shunt. Maybe a new connector would be needed.

[propellanttech]

I too agree the shunt will have to be wired like the second image.

What is really strange......I can't see how the system would be able to measure the aux battery. But there may be things about the shunt I can't see. Voltage on the aux battery, possibly, but not the amps in or out.

James L

[propellanttech]

Never mind, I answered my own question. The Aux battery amperage is not monitored by the shunt. Just it's voltage.

Also, the new cable may be due to the location of the shunt, which may require more length.

James L

[gspeak]

Originally Posted by propellanttech

Never mind, I answered my own question. The Aux battery amperage is not monitored by the shunt. Just it's voltage.

Also, the new cable may be due to the location of the shunt, which may require more length.

James L

Thanks all for your input. Yep the auxiliary battery monitoring isn't really a priority for me, and yes I needed the new cable to reach the intended position of the shunt from the main battery bank.

I now have a much clearer idea of how this all works.

Thanks

Dave

[gspeak]

OK thanks to all your inputs I have installed & setup my Enerdrive eLite & everything is looking good. One more question though.

I have 4 x 120AH GSM's of 3 different brands & all within 12 months of age. Yeah I know not ideal, but that's how it panned out after just 12 months ownership.

Question: What do I set the Peukert's to. Should I just use the default setting?

TIA

Dave

[propellanttech]

Originally Posted by gspeak

OK thanks to all your inputs I have installed & setup my Enerdrive eLite & everything is looking good. One more question though.

I have 4 x 120AH GSM's of 3 different brands & all within 12 months of age. Yeah I know not ideal, but that's how it panned out after just 12 months ownership.

Question: What do I set the Peukert's to. Should I just use the default setting?

TIA

Dave

You should make sure your charge setting on your dip switch is set to "On" for number 1. If not the charger will charge for a wet cell.

Not sure what a "Peukert's" is.

James L

[gspeak]

Originally Posted by propellanttech

You should make sure your charge setting on your dip switch is set to "On" for number 1. If not the charger will charge for a wet cell.

Not sure what a "Peukert's" is.

James L

Uhmm thanks for that. Except that the question was about setting up the battery monitor, not the charger. Anyway thanks for the suggestion as it reminded me to check out the settings on the charger also.

Dave

[noelex 77]

Originally Posted by propellanttech

Not sure what a "Peukert's" is.

The rated capacity for a lead acid battery might be 200AHrs. This implies it would deliver 1A for 200hours or 100A fir 2hr. Unfortunatly lead acid batteries don't work this way.

At high discharge current the actual capacity of the battery is much lower.
In reality the battery might deliver 1A for 250AHrs ( so the actual capacity is 250AHrs ) or 100A for 1hr 15 mins ( so the actual capacity is 125AHrs).

Different battery perform slightly differently. This relationship is given the name Pukerts formula or exponent. If you know this for a battery you can predict its capacity at different discharge rates.
This is important for things like battery monitors. The battery monitor counts AHrs. Most battery monitors watch the discharge current and realise more capacity is lost at high discharge rates and adjust for this. In other words they allow for the Pukerts formula. As the effect varies with different batteries the better monitor allow the Pukerts exponent to be adjusted. (All adjust for battery size). Generally the default value is close. If you have very high discharge appliances like a microwave its more important to get the correct number. Some of he better battery manufactures will list the correct value.

[sailinglegend]

Originally Posted by noelex 77

..... As the effect varies with different batteries the better monitor allow the Pukerts exponent to be adjusted. (All adjust for battery size). Generally the default value is close.......

The default setting for Peukerts constant on my BM is 1.25. For my batteries it should be 1.15, that's about 8% lower, but if not changed would create an error in the calculated Ah discharge of 36% at 100 amps or 20% at 10 amps discharge. I assume that all BMs use a default value in the mid range somewhere otherwise the errors are huge because the formula is logarithmic. Every BM should be able to adjust this constant - but even if they don't then that is a major reason that BMs are inaccurate. Also be aware that this value increase as the batteries age, and the "actual capacity" of the bank decreases. Neither of these values you will know as the batteries age - so making BMs even more inaccurate over time. Hence the reason SmartGuage was developed that doesn't use a shunt, doesn't use Peukerts, doesn't know the size of your batteries - and its accuracy improves as it learns your batteries behaviour. I have both types because I need to know Amps in/out which SmartGuage doesn't tell me.

[propellanttech]

Originally Posted by gspeak

Uhmm thanks for that. Except that the question was about setting up the battery monitor, not the charger. Anyway thanks for the suggestion as it reminded me to check out the settings on the charger also.

Dave

Ahhh...

Well evidently I didn't read thoroughly enough to understand the issue. Maybe I helped with the charger settings.

I try......

James L