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NASA BM2 Settings.


canals are us?

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46 minutes ago, canals are us? said:

Will do in the next few weeks. Busy working from Monday. Any recommendations as to which Specific gravity tester to buy? At least if they are ok capacity wise would I be ok to buy 2 new only and mix with the other older 2 Trojans?

Thanks. James:cheers:

Trojans are so much better than el cheapo leisure batteries, in a different league. Personally, I would NEVER go back to leisure batteries. They are rubbish!

sg testers come in two types, a big sucky thing like a turkey baster that you suck up electrolyte into, and then some sort of float or dial to indicate the gravity. The other type is a refractometer, which I prefer. You just put one drop on a slide and look through the eyepiece. eg https://www.ebay.co.uk/itm/ATC-Glycol-Refractometer-Auto-Car-Fluid-Battery-Antifreeze-Acid-Engine-Tester-UK/122874506527?hash=item1c9be42d1f:g:M4kAAOSwPAxaPOvn

Check the sg of the old batteries, the nominal value should be 1.277. If some/all of the cells have low sg, you can probably recover them by an equalise charge. Much cheaper than throwing them away and buying cheap rubbish ones! Since the batteries haven't been cycled much, I think it is highly likely that they are in good condition.

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I set up my BM2 years ago and left it to its own devices I know that my battery banks are getting tired but one is going on for 13 years old and the other 7 years? The meter is now going down faster than it used to but it is winter and its cold so thats to be expected. I have just bought for the bathtub 8 x 130 ah lithium batteries [for traction of the electric motor and leisure] with luck they should last many years, these have BMS plus leads and software for balancing the cells. Whilst expensive they are lighter than lead acids and for the bathtub weight is an issue.

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1 hour ago, canals are us? said:

Will do in the next few weeks. Busy working from Monday. Any recommendations as to which Specific gravity tester to buy? At least if they are ok capacity wise would I be ok to buy 2 new only and mix with the other older 2 Trojans?

Thanks. James:cheers:

I've had one of these on my to buy list for ages (can't recommend it as yet though)

https://www.ebay.co.uk/itm/Pro-Hydrovolt-HYDRO-VOLT-Lead-Acid-Battery-Hydrometer-Electrolyte-Tester/322082591860?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

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4 hours ago, canals are us? said:

My washer/dryer has a hot and cold fill and I only ever use the 30 minute 30o quick wash, so hopefully  use much less electricity. I am paralleling the alternators with an VSR which are 70a and 50a. I'm hoping it will cope fine.

 

If the machine heats the water, even to 30C then it will take 200A. Far better to put hot water in the drum or via soap draw and do a cold wash if this is the case. If it is hot fill then maybe it won't heat.....but you will need to make sure you have hot water to feed it. 

We have a 2KW inverter and that trips if we do a 30C wash.....so we bung in a kettle of hot water and do a cold wash. They take a lot of power if they are asked to do any heating. 

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Thanks for the links to a Specific gravity tester. Very reasonable price. Sunday I'll order one. I'll test each cell and see what the results are within the next two weeks. I certainly like Trojans.

Only issue is I use the rear of the boat for storage and forgot to top up the batteries! They level was 6mm below the top of the plates. I topped them up with deionised water. Must fit a watering system! The plates looked fine and no distortion and the battery sides were nice and cold.

If I only need 2 more then great. If not may splash out and look after them better! 

I also note I can do an equalisation charge from my new victron if needed. I saw a video on doing it with the control switch and presume you can adjust the charge rate with the dip switches? If I can keep the Trojans would it be advisable to alter the charge voltage permanently?

The Victron inverter seems far kinder to the batteries as every time my 12 volt fridge fired up the charger would come on, seemed excessive. The victron runs around 13-13.3 volts when fridge runs and stays in float mode.

I also note my solar is contributing more lately.

13 and 7 year old batteries you must be doing something right!

I'll heat the calorifier first and while on landline see if the water that's drawn is hot or cold. This way I can then see if it's best to pour hot water in first. When out I'll see how many AH it's drawing from the BM2 and see which method is best.

James:) 

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If you have all Trojans the best charge voltage is probably 14.8v (Victron will vary it according to temperature).

You can put the Victron into Equalise mode from the front panel I think - read the manual anyway! It does tend to come out of equalise mode after a set time and if you want a long equalise, it might be best just to temporarily increase the charge voltage to 15.5-16v, however I think you might need a PC for that, not sure it can be done from the dip switches.

Letting the electrolyte get below the top of the plates is very bad for the batteries - don’t do it again!

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13 hours ago, canals are us? said:

Will do in the next few weeks. Busy working from Monday. Any recommendations as to which Specific gravity tester to buy? At least if they are ok capacity wise would I be ok to buy 2 new only and mix with the other older 2 Trojans?

Thanks. James:cheers:

I recently bought one of these.  It will do SG and antifreeze %...

https://www.amazon.co.uk/gp/product/B01IVQBQ7A/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1

The only thing to bear in mind is that you will have to put a drop of battery acid on the test plate.  You may or may not see this as a safety issue.

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OH NO ................

Yet another item about batteries with more endless "mines bigger and lasts longer" conversations.

Now I've apparently got to buy a Professional Automatic Temperature Compensation Antifreeze Refractometer

Come on gang - life is too short for this.

 

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3 minutes ago, canalboat said:

OH NO ................

Yet another item about batteries with more endless "mines bigger and lasts longer" conversations.

Now I've apparently got to buy a Professional Automatic Temperature Compensation Antifreeze Refractometer

Come on gang - life is too short for this.

 

No, you don't have to buy one of these. It is not difficult to get a set of wet lead acids to last 5 years plus without measuring SG. I can get to about 3 cells on our domestic bank but not the rest. Why bother? Keep an eye on voltage at rest and Ahrs used instead. Spend the money on beer instead.

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54 minutes ago, canalboat said:

OH NO ................

Yet another item about batteries with more endless "mines bigger and lasts longer" conversations.

Now I've apparently got to buy a Professional Automatic Temperature Compensation Antifreeze Refractometer

Come on gang - life is too short for this.

 

No, you don’t have to buy anything at all. OP asked for a recommendation for a relative density tester and was offered a few options that he can consider. Nobody suggested that you had to buy anything. 

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3 hours ago, canalboat said:

OH NO ................

Yet another item about batteries with more endless "mines bigger and lasts longer" conversations.

Now I've apparently got to buy a Professional Automatic Temperature Compensation Antifreeze Refractometer

Come on gang - life is too short for this.

 

I have a BM2 and for me I never ever look at the graph thingy percentage whatsit but I have after years of using them found them a valuable tool to tell me when batts are charged or nearly charged also when they are running low and when new ones are needed. Another very usefull thing is I can see what each and every item uses in consumption. However you are so right in too much time being wasted on batteries they are just another consumable identical to diesel. Lifes far too short for Mr and Mrs Trojan and any battery with silly lids on that you have to take off and pour water in to. Mine are sealed jobbies and last long enough under 24/7 liveaboard use anyway :cheers:

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57 minutes ago, mrsmelly said:

I have a BM2 and for me I never ever look at the graph thingy percentage whatsit but I have after years of using them found them a valuable tool to tell me when batts are charged or nearly charged also when they are running low and when new ones are needed. Another very usefull thing is I can see what each and every item uses in consumption. However you are so right in too much time being wasted on batteries they are just another consumable identical to diesel. Lifes far too short for Mr and Mrs Trojan and any battery with silly lids on that you have to take off and pour water in to. Mine are sealed jobbies and last long enough under 24/7 liveaboard use anyway :cheers:

I agree. We purchased a new fridge when the BM2 was showing the fridge continuously drawing over 5 amps and not turning off so it is a good indicator of when something isn't normal.  It was then good to see the new one only using just over 3 amps when it kicks in.  I always glance at the charge when I start the engine in the morning as a good indicator of when the alternator belt needs tightening.

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13 minutes ago, Keeping Up said:

The main advantage of the BM2 has to be that the display is big enough to read from a distance even when you are really shortsighted. 

That's why I bought it and another thing as its made realy for proper boat shaped boats its also waterproof so can be mounted outside if you fancy.

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11 minutes ago, canalboat said:

You see - I fell for it again -

I actually looked up the price of a "BM2"

About the price of replacing my two batteries!!!

The words "brainer" and "NO" spring to mind.

Your not going to buy one then?

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53 minutes ago, rusty69 said:

I too looked up the price of a battery monitor a couple of years back and decided it was a "no brainer".I figured the increase in battery life through having one would pay for itself in a couple of years, which it has. 

Ah but how do you know they wouldn't have lasted that two years anyway?

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On 09/02/2018 at 19:43, nicknorman said:

Trojans are so much better than el cheapo leisure batteries, in a different league. Personally, I would NEVER go back to leisure batteries. They are rubbish!

sg testers come in two types, a big sucky thing like a turkey baster that you suck up electrolyte into, and then some sort of float or dial to indicate the gravity. The other type is a refractometer, which I prefer. You just put one drop on a slide and look through the eyepiece. eg https://www.ebay.co.uk/itm/ATC-Glycol-Refractometer-Auto-Car-Fluid-Battery-Antifreeze-Acid-Engine-Tester-UK/122874506527?hash=item1c9be42d1f:g:M4kAAOSwPAxaPOvn

Check the sg of the old batteries, the nominal value should be 1.277. If some/all of the cells have low sg, you can probably recover them by an equalise charge. Much cheaper than throwing them away and buying cheap rubbish ones! Since the batteries haven't been cycled much, I think it is highly likely that they are in good condition.

Being of the "old school" i have never used a refractometer (they hadn't been invented for battery use when I was "on the tools"). Does it automatically correct for temperature or do you have to take the electrolyte temperature and apply the correction factor as with a hydrometer?

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On 10/02/2018 at 00:23, nicknorman said:

You can put the Victron into Equalise mode from the front panel I think - read the manual anyway! It does tend to come out of equalise mode after a set time and if you want a long equalise, it might be best just to temporarily increase the charge voltage to 15.5-16v, however I think you might need a PC for that, not sure it can be done from the dip switches.

 

This video shows howto put the Victron into equalise mode. Without the video  never  managed to do it, therre is a knack to it.

 

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