A 12v power question

[winchman]

I think once I know it all works and will power the device as I need I could disconnect all the measurement stuff and just have a volt meter on a push button?

 

[m_c]

I know you've already ordered a battery, but LiFePo4 would be far better.
I fitted two of these - https://uk.eco-worthy.com/products/lifepo4-12v-100ah-lithium-iron-phosphate-battery (I think he got them cheaper via their eBay store) to replace ~400Ah worth of AGM batteries in a mates van who uses them to power a 4kw inverter to run his power washer and hoover, and are outperforming the AGM batteries.

However, until you know the actual power usage, I wouldn't be ordering any batteries.

 

[Jack_K]

Would this do it? https://www.aliexpress.com/item/1005005947995497.html?spm=a2g0o.productlist.main.47.7e43IweIIweIdK&algo_pvid=44f61ec1-46a1-4364-8bd4-68ae42a0af40&algo_exp_id=44f61ec1-46a1-4364-8bd4-68ae42a0af40-46&pdp_ext_f={"order":"3","eval":"1"}&pdp_npi=4@dis!GBP!22.27!19.09!!!29.30!25.12!@2103846917500924278294129efb75!12000034979735572!sea!UK!931333565!X&curPageLogUid=PPsTlTmzBiG2&utparam-url=scene:search|query_from:

You need something which measures watt hours or kilowatt hours so that you can see how much power you consume during a day since it sounds like the current isn't continuous.

 

[bricol]

I thin a phone call to the manufacturers might been rather sensible - sounds an important bit of hit to be relying on a guess.

 

[winchman]

I think you may well be disappointed with that battery if you regularly use it for 3 days @ 12 hours/day without recharging. But if it’s already fait accompli, we may be lucky and get some feefback in the near future.

The one quoted above has already been ‘on station’ for 4 years. Its actual usable capacity might well depend on both its age and how many times it has been cycled (on other than ‘stand-by’). Buying cheap often ends up with buying twice.

Its coming form some one I know who knows the history and has been tested to ensure its still at the correct capacity otherwise I would only buy a new one

 

[winchman]

I thin a phone call to the manufacturers might been rather sensible - sounds an important bit of hit to be relying on a guess.

It's the usual story not in the UK can never get to talk to the correct person. I did manage to talk with some one who has a similar set up for camping and as already mentioned the load is variable, they manage with a 80AH battery as they had one so just tried it. I will see what happens Battery should be here tonight machines a few weeks away so gives me time to fit it all.

 

[winchman]

You need something which measures watt hours or kilowatt hours so that you can see how much power you consume during a day since it sounds like the current isn't continuous.

Could you post link to a suitable thing as I am only an amateur electrician

 

[voipio]

The Watt meter in the eBay link: http://www.ebay.co.uk/itm/388525872582 has four display areas. Three of them continuously display Amps, Volts, and Watts, whilst the fourth display area cycles through readings such as Ah, Wh, Amps peak, Watts peak, and Volts minimum, plus Time elapsed. The wires on the "source" end of the Watt Meter connect to the battery, and the "load" end wires connect to the load, be it CPAP, or whatever. I put Anderson Powerpoles on each end of the Watt Meter, but choc blocks would be fine. Don't forget to put a suitable fuse on the battery end.

 

[winchman]

Thanks

 

[J1nx]

That’s a standby battery from a UPS system, although it’s the best on the market (Enersys) it still won’t like full repeated cycles. The date should also be printed on the top, check this, in UPS applications they are generally reliable for about 8 years if kept cool and not cycled heavily, then they are disposed of and worth scrap value only really.

One of those power banks from the likes of Ecoflow or Anker would be ideal for this, they will cycle happily for a couple of years although larger capacity ones can get quite pricey. Energy consumption should be displayed on most of these, I think you will find it significantly less than the PSU rated output.

 

[winchman]

That’s a standby battery from a UPS system, although it’s the best on the market (Enersys) it still won’t like full repeated cycles. The date should also be printed on the top, check this, in UPS applications they are generally reliable for about 8 years if kept cool and not cycled heavily, then they are disposed of and worth scrap value only really.

One of those power banks from the likes of Ecoflow or Anker would be ideal for this, they will cycle happily for a couple of years although larger capacity ones can get quite pricey. Energy consumption should be displayed on most of these, I think you will find it significantly less than the PSU rated output.

For the amount of cycles we will be giving it I think it will be fine. We are usually only of grid for a couple of days at a time, so it won't be doing many cycles, I will fit one of the measuring things mentioned above and if I can change it for a smaller one I will. It weighs almost 60KG!

 

[Matchless]

I run my 24v CPAP from an inverter in my ex Tesco truck (and caravan) it runs off a 100AH gel battery, ex UK power, around 10 years old! never had an issue, ok I do have a solar panel on the roof but it is generally not sunny over night, I would suggest a small solar panel would be a good investment and almost any battery!

 

[winchman]

I run my 24v CPAP from an inverter in my ex Tesco truck (and caravan) it runs off a 100AH gel battery, ex UK power, around 10 years old! never had an issue, ok I do have a solar panel on the roof but it is generally not sunny over night, I would suggest a small solar panel would be a good investment and almost any battery!

Thanks Unfortunately the roof vent layout really limits my solar, I have 2 100W panels for the starter and main battery and hardly room for anything else.
I will connect this up and measure how it performs

 

[winchman]

The Watt meter in the eBay link: http://www.ebay.co.uk/itm/388525872582 has four display areas. Three of them continuously display Amps, Volts, and Watts, whilst the fourth display area cycles through readings such as Ah, Wh, Amps peak, Watts peak, and Volts minimum, plus Time elapsed. The wires on the "source" end of the Watt Meter connect to the battery, and the "load" end wires connect to the load, be it CPAP, or whatever. I put Anderson Powerpoles on each end of the Watt Meter, but choc blocks would be fine. Don't forget to put a suitable fuse on the battery end.

Thanks just ordered one. For once it looks like I will have all the bits before the new Machine arrives, better mount the battery now!
Just correct me if I am wrong I can charge this with a 8Amp charger set to AGM but it will just take longer?

 

[winchman]

Battery testing
As the battery only shows its AGE and 190AH how should I test it as my battery tester is looking for CCA DIN EN etc?
I did find an online conversion that said AH x 3 = 570 so on the chart its 940 EN is this correct?

https://www.roadpro.co.uk/userfiles/PDFs/product%20information/CTEK%20products/CTEK%20Conversion%20Table%20from%20DIN%20to%20CCA.pdf

 

[m_c]

Battery testing
As the battery only shows its AGE and 190AH how should I test it as my battery tester is looking for CCA DIN EN etc?
I did find an online conversion that said AH x 3 = 570 so on the chart its 940 EN is this correct?

https://www.roadpro.co.uk/userfiles/PDFs/product%20information/CTEK%20products/CTEK%20Conversion%20Table%20from%20DIN%20to%20CCA.pdf

Any conversion will be an approximation, as cranking amps is governed by the battery plate structure.
You'll likely find that deep cycle batteries have a pretty poor crank rating, as they're designed internally for relatively low discharge rates.

 

[voipio]

Thanks just ordered one. For once it looks like I will have all the bits before the new Machine arrives, better mount the battery now!
Just correct me if I am wrong I can charge this with a 8Amp charger set to AGM but it will just take longer?

An 8A charger should be fine. One thing worth bearing in mind is that, to use the Watt Meter to measure charging (rather than discharging), its "Source" wires will need to be connected to the charger, and the "Load" wires to the battery, in order to register the amount of charge put into the battery. Although it only measures current flowing from source to load, it will pass current in both directions.

 

[Erie Fred]

Any conversion will be an approximation, as cranking amps is governed by the battery plate structure.
You'll likely find that deep cycle batteries have a pretty poor crank rating, as they're designed internally for relatively low discharge rates.

What's the OP cranking ?

 

[m_c]

What's the OP cranking ?

Nothing.
Modern battery testers typically use a cranking amp rating to base test results on, and if you don't have that rating, many testers won't produce a valid result.

 

[Matchless]

I think the best advice is "don't over think it" could you not divert some of the solar charging power to the second battery if it drains? or a sort of split charging system .........................???