Designing 12v charging system from scratch

[cuthound]

17 hours ago, nicknorman said:

However we also need to remember that he bought fake batteries and repeatedly left them discharged for days on end. No doubt that was the fault of the SG too!

IIRC he bought Yuasa batteries. They are a reputable manufactuerer who probably make more batteries serving much more critical applications than Trojan (UPS vs golf cart ).

When Mike first began experiencing battery problems, I suggested that he called their technical department, and ask for their advice. He chose not to.

Similar tale with the SG's, he won't contact the manufacturer for advice and a probable solution.

You can't help those who won't help themselves.

[cuthound]

7 hours ago, Mike the Boilerman said:

 

Ok so now there are two different manuals in existence. How confusing!!!!!!!!!

But are they in calibration?

[cereal tiller]

52 minutes ago, cuthound said:

IIRC he bought Yuasa batteries. They are a reputable manufactuerer who probably make more batteries serving much more critical applications than Trojan (UPS vs golf cart ).

When Mike first began experiencing battery problems, I suggested that he called their technical department, and ask for their advice. He chose not to.

Similar tale with the SG's, he won't contact the manufacturer for advice and a probable solution.

You can't help those who won't help themselves.

I have Yuasa batteries, they are good Quality. 12 Volt LM80.Also have Yuasa's for the Electric Motor in the Inflatable Boat,4 Years Approx. 200 Cycles.

[rusty69]

1 minute ago, cereal tiller said:

I have Yuasa batteries, they are good Quality. 12 Volt LM80.Also have Yuasa's for the Electric Motor in the Inflatable Boat,4 Years Approx. 200 Cycles.

I used to have Yuasa, now I am Yuasa-less!

[MtB]

On 10/12/2017 at 15:01, cereal tiller said:

42

 

More smoke-screening instead of a proper answer to my question in Post 84...

 

Here is the question that nice Mr Cereal tiller is avoiding answering, for the benefit of others reading this thread:

 

"I'd be up for that provided you have actually checked the calibration of yours using a DVM previously checked against a reference source, and found it correct.

Have you?"

 

[cereal tiller]

3 minutes ago, Mike the Boilerman said:

 

More smoke-screening instead of a proper answer to my question in Post 84...

 

Here is the question that nice Mr Cereal tiller is avoiding answering, for the benefit of others reading this thread:

 

"I'd be up for that provided you have actually checked the calibration of yours using a DVM previously checked against a reference source, and found it correct.

Have you?"

 

A total of 4 LED digital Voltmeters Hardwired into the Boat all Agreeing,2 Handheld DVM's in accord also.Tail current of 1 AMP per battery at completion of charge.that's it Shirley?

Edited December 10, 2017 by cereal tiller

[MtB]

Probably you haven't, given your failure to answer.

[nb Innisfree]

6 hours ago, WotEver said:

A battery will demand (pretty closely) the same current as the missing charge in Ah. 

So, using simple quantities, a 100Ah battery at 80% SoC will demand approximately 20A charge current. That’s why tail current works. 

Been here before! 

So a 100ah battery below 80% SoC, say 50% SoC will only demand 50 amps, or 60% SoC 40 amps? Even if the charge source is a much higher capacity? If so then it's impossible to subject a battery to too high a charge? 

[WotEver]

37 minutes ago, nb Innisfree said:

So a 100ah battery below 80% SoC, say 50% SoC will only demand 50 amps, or 60% SoC 40 amps? Even if the charge source is a much higher capacity? If so then it's impossible to subject a battery to too high a charge? 

Yes to the first part, second part and third part, no to the final conclusion.

A 100Ah battery at 50% SoC would accept a 50A charge current. A 50A charge current into a 100Ah battery would be damaging to it by causing excessive plate corrosion. Having said that, it wouldn’t be at 50A for very long. 

Lastly, inagine that you had a 100A charger ‘because the battery will never ask for more than 50A’. What happens on the odd occasion when you accidentally take the battery down to 20% SoC or even lower?

[Tony Brooks]

27 minutes ago, WotEver said:

Lastly, inagine that you had a 100A charger ‘because the battery will never ask for more than 50A’. What happens on the odd occasion when you accidentally take the battery down to 20% SoC or even lower?

I strongly suspect from observing the charging on newly built batteries that you will get maximum current for a short time until it causes gassing that covers the plates with bubbles, so isolating them form the electrolyte. When that happens the current will drop.

I think any sensibly specified system will do as Innisfree suggest and limit the charging current to a safe level PROVIDING the voltage is set at a safe level. E.G. around 14.5 volts.

As huge charging currents only speed up the bulk phase of charging there is little point in fitting high output chargers or large alternators (except to power high current equipment). Doing so is only likely to reduce the fully  charged time by an hour or less.

[nb Innisfree]

46 minutes ago, WotEver said:

Yes to the first part, second part and third part, no to the final conclusion.

A 100Ah battery at 50% SoC would accept a 50A charge current. A 50A charge current into a 100Ah battery would be damaging to it by causing excessive plate corrosion. Having said that, it wouldn’t be at 50A for very long. 

Lastly, inagine that you had a 100A charger ‘because the battery will never ask for more than 50A’. What happens on the odd occasion when you accidentally take the battery down to 20% SoC or even lower?

So what is a safe limit at various SoC's? 

[WotEver]

1 minute ago, nb Innisfree said:

So what is a safe limit at various SoC's? 

Gibbo reckoned somewhere between 35% and 50% of battery capacity was a good compromise between battery life and charging time. 

Everything’s a compromise. 

http://www.smartgauge.co.uk/chargesize.html

16 minutes ago, Tony Brooks said:

As huge charging currents only speed up the bulk phase of charging there is little point in fitting high output chargers or large alternators (except to power high current equipment). Doing so is only likely to reduce the fully  charged time by an hour or less.

Agreed. And as a large charger will also accelerate plate corrosion that’s another good reason for not having one as a matter of course.  

[nicknorman]

My feeling is that although batteries are certainly ultimately self-limiting in terms of charging current, hitting those limits isn’t best practice. Better to charge slowly and gently. This is why Trojan recommend a maximum of 13% of capacity.

[nb Innisfree]

12 minutes ago, WotEver said:

Gibbo reckoned somewhere between 35% and 50% of battery capacity was a good compromise between battery life and charging time. 

Everything’s a compromise. 

http://www.smartg

15 minutes ago, WotEver said:

Gibbo reckoned somewhere between 35% and 50% of battery capacity was a good compromise between battery life and charging time. 

Everything’s a compromise. 

http://www.smartgauge.co.uk/chargesize.html

Agreed. And as a large charger will also accelerate plate corrosion that’s another good reason for not having one as a matter of course.  

auge.co.uk/chargesize.html

Agreed. And as a large charger will also accelerate plate corrosion that’s another good reason for not having one as a matter of course.  

So really what we're saying is any charge rate will damage a battery, just a matter of degree. Using batteries damages them period. 

[nicknorman]

38 minutes ago, Tony Brooks said:

As huge charging currents only speed up the bulk phase of charging there is little point in fitting high output chargers or large alternators (except to power high current equipment). Doing so is only likely to reduce the fully  charged time by an hour or less.

The advantage of a high output charger or large alternator is two fold. Firstly, both can rapidly add a significant top-up charge. For example 30mins of our 175A alternator can take the SoC up from say 60% to say 75%, putting off the time before a full recharge is required. Life isn’t always as simple as discharging the batteries and then fully recharging them! Secondly a large alternator can support the power demands of a large inverter running some heavy load.

So yes it’s true that a large alternator doesn’t reduce overall charge time by much, but that isn’t the whole story.

[cuthound]

5 minutes ago, nb Innisfree said:

So really what we're saying is any charge rate will damage a battery, just a matter of degree. Using batteries damages them period. 

Yes, charging puts mechanical stresses on the plates. Too high a charge distorts them and causes loss of active material held by them. 

Discharging batteries also causes loss of ultimate life.

So does just leaving them alone. 

 

You just can't win with batteries.

Edited December 10, 2017 by cuthound
Spillung

[WotEver]

1 hour ago, nb Innisfree said:

So really what we're saying is any charge rate will damage a battery, just a matter of degree. Using batteries damages them period. 

Yup. 

As Cuthound says, using them damages them. Not using them damages them. All you can do it to choose the best compromise for your particular application. 

58 minutes ago, nicknorman said:

So yes it’s true that a large alternator doesn’t reduce overall charge time by much, but that isn’t the whole story.

In fairness to Tony, he did say that...

1 hour ago, Tony Brooks said:

As huge charging currents only speed up the bulk phase of charging there is little point in fitting high output chargers or large alternators (except to power high current equipment).

 

[MtB]

On 10/12/2017 at 17:37, cuthound said:

Similar tale with the SG's, he won't contact the manufacturer for advice and a probable solution.

 

What could Yuasa or Merlin told me that I haven't already figured out for myself? 

[nicknorman]

2 hours ago, WotEver said:

 

In fairness to Tony, he did say that...

 

He pointed out the other uses but still suggested it probably wasn’t worth fitting one. I’d disagree.

[rusty69]

6 hours ago, Mike the Boilerman said:

 

What could Yuasa or Merlin told me that I haven't already figured out for myself? 

Merlin could have told you read p22/23 before knackering your batteries 

[cuthound]

10 hours ago, Mike the Boilerman said:

 

What could Yuasa or Merlin told me that I haven't already figured out for myself? 

Nothing but if you Had explained your charging regime to Yuasa they would have told you you werent fully charging them before you worked it out.

Might just have saved your batteries.

[MtB]

On 11/12/2017 at 04:57, rusty69 said:

Merlin could have told you read p22/23 before knackering your batteries 

 

Would they have spotted their SmartGauge was faulty?

On 11/12/2017 at 08:51, cuthound said:

Nothing but if you Had explained your charging regime to Yuasa they would have told you you werent fully charging them before you worked it out.

Might just have saved your batteries.

 

Not a prayer of that happening. 

They'd have told me to charge them daily or on alternate days which was never going to happen. I needed a battery bank I could charge once a week. 

[cuthound]

9 minutes ago, Mike the Boilerman said:

 

Would they have spotted their SmartGauge was faulty?

 

Not a prayer of that happening. 

They'd have told me to charge them daily or on alternate days which was never going to happen. I needed a battery bank I could charge once a week. 

If you want a battery that will survive being left a week between charges, then  NIFE battery would be best, providing you have the space and can tolerate the wide voltage range between fully charged and flat. They are almost indestructible, but require different charging voltages to lead acids.

[nicknorman]

11 minutes ago, cuthound said:

If you want a battery that will survive being left a week between charges, then  NIFE battery would be best, providing you have the space and can tolerate the wide voltage range between fully charged and flat. They are almost indestructible, but require different charging voltages to lead acids.

These days I think LiFePO4 is the way to go. Mike has plenty of money, he could test them for us! Zero possibility of sulphation!

[rusty69]

34 minutes ago, Mike the Boilerman said:

Would they have spotted their SmartGauge was faulty?

I thought you owned them,I didn't realize you had them on loan from Merlin