Battery charging

[BruceinSanity]

What battery type are you using on gibbo's device? 1 or 4? I have tried both with calcium batts but not really noticed a difference between the two.

At the moment, 6, which the manual says is for calcium/calcium types (with a free Gibbo sneer included ). Not having cruised with them yet, they haven't had any charge/discharge cycles so can't assess the accuracy. I plan to compare 6 against 1.

[GUMPY]

At the moment, 6, which the manual says is for calcium/calcium types (with a free Gibbo sneer included ). Not having cruised with them yet, they haven't had any charge/discharge cycles so can't assess the accuracy. I plan to compare 6 against 1.

Just checked mine its on 6 must have been between 6 & 4 that I was trying and I eneded up on 6.

Let us know how it goes.

[BruceinSanity]

Just checked mine its on 6 must have been between 6 & 4 that I was trying and I eneded up on 6.

Let us know how it goes.

I'll try and remember!

[Eeyore]

I was surprised to see the resting voltage at 13.2, not the 12.8 I was expecting, but apparently that's what you get from calciums. Means those neat tables showing resting voltage against SOC need modifying for the increasingly common calcium cells.

This has always been the case when I've fitted new batteries. After a week or two of use they will settle to about 12.8 volts (resting) when charged for the remainder of their useful life. When the resting voltage starts to fall below 12.8 volts is the time to start looking for the best price for a new set.

Steve (Eeyore)

Edited July 18, 2016 by Eeyore

[BruceinSanity]

This has always been the case when I've fitted new batteries. After a week or two of use they will settle to about 12.8 volts (resting) when charged for the remainder of their useful life. When the resting voltage starts to fall below 12.8 volts is the time to start looking for the best price for a new set.

Steve (Eeyore)

Well, well, thanks for that, never noticed it before. Mind you, I think this is the first time I've been off the boat like this immediately after fitting new batts.

[BruceinSanity]

Just checked mine its on 6 must have been between 6 & 4 that I was trying and I eneded up on 6.

Let us know how it goes.

We've now been cruising for a week and comparing the SmartGauge SoC with resting voltage indicates that battery type 6 is reasonably accurate. For example, the SG said 88% first thing this morning and the voltage was 12.6.

 

OTOH, the SG is very optimistic when charging, showing 100% SoC when the batteries are still pulling 12A at 14.4V into a 452Ah bank.

[Richard10002]

We've now been cruising for a week and comparing the SmartGauge SoC with resting voltage indicates that battery type 6 is reasonably accurate. For example, the SG said 88% first thing this morning and the voltage was 12.6.

OTOH, the SG is very optimistic when charging, showing 100% SoC when the batteries are still pulling 12A at 14.4V into a 452Ah bank.

The manual tells you it's not accurate when charging.

[BruceinSanity]

The manual tells you it's not accurate when charging.

Yes, I know. That's why I've added the BM2 so as to be able to monitor the tail current. But I was surprised to see quite how inaccurate it is.

[MtB]

Yes, I know. That's why I've added the BM2 so as to be able to monitor the tail current. But I was surprised to see quite how inaccurate it is.

 

 

BM2? What's one of those?

[nicknorman]

BM2? What's one of those?

http://www.nasamarine.com/product/bm-2-battery-monitor/

 

Note: for 12v systems only.

Edited August 4, 2016 by nicknorman

[MtB]

http://www.nasamarine.com/product/bm-2-battery-monitor/

 

Note: for 12v systems only.

 

 

Thanks. Should have googled that myself!

[cereal tiller]

http://www.nasamarine.com/product/bm-2-battery-monitor/

 

Note: for 12v systems only.

That page states that there is a 24 Volt variant.

 

CT

[nicknorman]

It's a similar price to the BMV 700 but my gut feeling is that the latter is a slightly better product, but it would be interesting to see a side-by-side comparison.

[Richard10002]

It's a similar price to the BMV 700 but my gut feeling is that the latter is a slightly better product, but it would be interesting to see a side-by-side comparison.

 

"Slightly" is probably the operative word, and buying either almost certainly wont end in dissappointment. Although I agree it could be an interesting article for a Canal magazine, or Practical Boatowner, or similar.

 

Apart from SOC %age, I have found the NASA does everything I expected and wanted, and I havent wished it did anything differently or better.

 

I believe the BMV has the same issue with SOC %age, and I would expect BMV users would feel the same about it as I do about the NASA.

 

I solved the SOC issue by buying a Smartguage - being aware that they say that it can be 10% out either way when charging.

[nicknorman]

"Slightly" is probably the operative word, and buying either almost certainly wont end in dissappointment. Although I agree it could be an interesting article for a Canal magazine, or Practical Boatowner, or similar.

 

Apart from SOC %age, I have found the NASA does everything I expected and wanted, and I havent wished it did anything differently or better.

 

I believe the BMV has the same issue with SOC %age, and I would expect BMV users would feel the same about it as I do about the NASA.

 

I solved the SOC issue by buying a Smartguage - being aware that they say that it can be 10% out either way when charging.

Couple of points in BMVs favour I think:

 

Wiring up BMV is much easier due to just having to plug in the CAT5 cable, whereas the NASA seems to have quite a few wires to join together and the installation manual shows a chocolate block. Yuk!

 

The NASA tries to be clever using a Smartgauge type voltage algorithm in conjunction with AH accounting. However by all accounts (including their own) it doesn't really work, rendering the SoC reading completely useless. There are no user settings to tweak other than battery capacity. Whereas the BMV is a conventional AH counter which if carefully set up with the right capacity, tail current, CEF etc will give a fairly reliable SoC mid-charge especially if it is regularly synchronised by taking the batteries to 100%.

 

However if the aim is just to use it as an ammeter and AH-used meter, eg in conjunction with a Smartgauge for discharging SoC perhaps these deficiencies don't matter and it is a bit cheaper.

[BruceinSanity]

The NASA has a bigger display than the BMV, which I like but obv would not suit everyone.

[MtB]

The NASA has a bigger display than the BMV, which I like but obv would not suit everyone.

 

 

I have to say, the tiny interface on the BMV put me off big time! Then I read it also interfaces with an app on one's Smartphone so that's now a big PLUS for the BMV. Bluetooth only though, which is flakey in my experience over the length of a narrowboat.

 

Does the BM2 also communicate with a Smartphone?

[GUMPY]

I'm quite tempted by this

http://www.ebay.co.uk/itm/171906112639

For voltage and current

Depends of course how big the CT hole is.

[nicknorman]

I'm quite tempted by this

http://www.ebay.co.uk/itm/171906112639

For voltage and current

Depends of course how big the CT hole is.

 

Hmmm current transformers don't work on DC so if it is in fact a hall effect sensor then it is likely to be fairly inaccurate including a temperature dependant zero offset. I note that it mentions a resolution (1A) but not an accuracy.

[BruceinSanity]

I have to say, the tiny interface on the BMV put me off big time! Then I read it also interfaces with an app on one's Smartphone so that's now a big PLUS for the BMV. Bluetooth only though, which is flakey in my experience over the length of a narrowboat.

 

Does the BM2 also communicate with a Smartphone?

Not that I know of, I'm afraid.

[GUMPY]

 

Hmmm current transformers don't work on DC so if it is in fact a hall effect sensor then it is likely to be fairly inaccurate including a temperature dependant zero offset. I note that it mentions a resolution (1A) but not an accuracy.

I realise that CT are for AC only but I assumed it works on the same principle as the DC current clamp meter that we all love so much.

[nicknorman]

I realise that CT are for AC only but I assumed it works on the same principle as the DC current clamp meter that we all love so much.

 

Hall effect. Yes but they too aren't very accurate for low currents. If you are using something to count AH on a boat an it has a zero offset of 1A, it is not much use!

[John Margetts]

If your engine is well maintained its cheap enough. Honda petrol generators are quiet but more expensive than your engine. Solar panels of about 250w with an MTTP controller will set you back 500 to 600 quid but do a great job if there is enough sun striking the panel at a perpendicular angle. Wind generators are pricey and cause vibration, with difficulty in mounting securely so you can take them up or down easily. In other words it's swings and roundabouts. Most people run their engine for an hour or two a day to get jot water and electric. A good engine should not use more than 2 litres of red diesel in 2 hours, which would currently cost £1.80.

[Chewbacka]

If your engine is well maintained its cheap enough. Honda petrol generators are quiet but more expensive than your engine. Solar panels of about 250w with an MTTP controller will set you back 500 to 600 quid but do a great job if there is enough sun striking the panel at a perpendicular angle. Wind generators are pricey and cause vibration, with difficulty in mounting securely so you can take them up or down easily. In other words it's swings and roundabouts. Most people run their engine for an hour or two a day to get jot water and electric. A good engine should not use more than 2 litres of red diesel in 2 hours, which would currently cost £1.80.

Your solar prices seem a bit high, unless you are including labour costs to fit the kit.

You can get from Bimble Solar a new 260W panel for about £170 and another £150 for a controller and display.

Allow another £50 for installation bits and bobs - assuming you self install using simple brackets. Total cost is less than £400.

If you use a smaller controller and a used panel it is a fair bit cheaper.

 

I got my set-up from Bimble (a couple of used panels, total 440W) and this time of year my electric usage is less then the solar output, so I can stop for as long as I wish without having to run the engine.

Edited August 25, 2016 by Chewbacka

[NealSmith100]

Although Nigel Calder's book is excellent and well recommended it is quite indepth. Victron do a free book which is worth a read also.... https://www.victronenergy.com/upload/documents/Book-Energy-Unlimited-EN.pdf

 

Nigel Calder - £30 for a kindle book?