Saturday, November 11, 2017

[Electric Boats] Lead Acid Battery temperature

 

Change of topic to focus on Lead Acid.

Well, yes, ambient temperature comes into it.  I boat in northern Puget Sound where the summer water temps are around 50 deg.F and air temp 60-70 deg.F out on the water.   So in the bilge where the batteries are it will be cool as long as there is adequate ventilation.

50 deg C was chosen, at least as a starting point subject to testing, as that is in the range of what seems to be the maximum for normal lead acid charging, and for "battery temperature" not ambient.  

What seems to be harder to find, at least searching literature and references, is what can a lead acid battery tolerate during discharge. 

So it is really a two part problem for the electric boat as I see it.  1) Protecting from overcharge/over temperature and 2) other fault detection.

After thinking about this, and in absence of other information, a reasonable starting point for monitoring and protection might be:

Monitor each battery's voltage and temperature.
Set limits for maximum charging voltage and temperature as read on any one battery and disconnect charging if one or the other occurs
Set limits for maximum variation in voltage between batteries
Visual and audible alarms to suit

The above to apply both to static recharge as well as in operation, especially when supplementing with a generator while motoring.

Open to thoughts and input here.

John A
--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."

__._,_.___
Posted by: John Acord <jcacord@gmail.com>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (1)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

Friday, November 10, 2017

Re: [Electric Boats] Re: Battery temperature

 

I have considered your comment about 50C for charge cutoff.

I have been testing my NIMH pack with a voltage detection and have used a manual temperature wand type thing and  have seen the temp range up to 25C, with ambient at 22C.
I was also wondering what I should consider a cutoff temp.  Seems at least with the NIMH. 50C would be quite high.

I am charging at a fairly low amperage though, so that may effect the outcome. (2 amps for a 39AH pack.)


not sure if that helps, buy just my obsversation with the pack I am testing.

Mark

From: "John Acord jcacord@gmail.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Thursday, November 9, 2017 5:42 PM
Subject: [Electric Boats] Re: Battery temperature

 
I am building a 48V system with 8 golf cart flooded cells.  I have always had good results and long life with them as long as one pays attention to charging, battery temperature and keeping them watered. 

To my way of thinking, both for safety and battery health, temperature monitoring is essential. Each battery will have a temperature sensor with associated readout and alarm circuitry. 

I am thinking that 50 deg C. (122 F.) would be a good alarm point.  Any comments/suggestions?

John A.

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."


__._,_.___
Posted by: Mark F <mark.internet@yahoo.ca>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (5)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

[Electric Boats] Re: Battery temperature

 

That could depend somewhat on typical ambient air temp and other factors. I would think that would be a decent case temp hi alarm setpoint in northern climes, with a well ventilated battery compartment. I have seen air temp go over 125f + in the Persian Gulf. Here in New Orleans I am sure on very hot days my batteries have seen temps in that range. So maybe summertime, to avoid spurious alarms, you might go up to 130f or even 140f case temperature.

Another factor is what actions are initiated by your alarm. audible alarm only? Charger shutdown or down cycle to float? System shutdown? Auto resume, or requires operator reset? Not sure there is really a one size fits all setting.

BTW I also run golf cart batteries. Best bang for the buck. They ain't purty but they gitter done.

__._,_.___
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (4)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

Re: [Electric Boats] Re: Battery temperature

 

"To my way of thinking, both for safety and battery health, temperature monitoring is essential." J.A.

I agree but FLA batteries do not enter a thermal runaway when overcharged. I typically support safety capabilities in all systems but I also like to understand what the system is being protected from. 
Having said all that, I recommend measuring the temperature rise as well.  Alarm at 50C battery temperature may be too low at 40C ambient and too high at 10C ambient. Another parameter that has an effect on the proper alarm temperature might be the heat transfer capability from the batteries to ambient air.   If the surface of the batteries are capable of dissipating heat very efficiently the hot spot temperatures inside the battery might be much hotter than the surface temperature that is sensed. Here again, nothing is easy in engineering :-)
Thanks
Ahmet

From: "John Acord jcacord@gmail.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Thursday, November 9, 2017 8:42 PM
Subject: [Electric Boats] Re: Battery temperature

 
I am building a 48V system with 8 golf cart flooded cells.  I have always had good results and long life with them as long as one pays attention to charging, battery temperature and keeping them watered. 

To my way of thinking, both for safety and battery health, temperature monitoring is essential. Each battery will have a temperature sensor with associated readout and alarm circuitry. 

I am thinking that 50 deg C. (122 F.) would be a good alarm point.  Any comments/suggestions?

John A.

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."


__._,_.___
Posted by: sv8827 <sv8827@yahoo.com>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (6)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

[Electric Boats] Re: Battery temperature

 

The question was not how to measure (my stuff uses Microchip PIC).  But what is a good "alarm" temperature. 

We know that overcharging and failing batteries get hot, and operating at high currents get things hot.  How hot?   I lean towards a conservative point.  I chose 50 C from some literature I have.  But would that value generate nuisance alarms?

It's not that I can't experiment and find out.  But finding out what others have experienced would be helpful.

John A 

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."

__._,_.___
Posted by: John Acord <jcacord@gmail.com>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (3)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

Re: [Electric Boats] Re: Battery temperature

 

Hi john

If you get an arduino nano, it has 8 analog to digital pins.
You could read all 8 with some thermisters(resisters that change based on temp).
The arduino can send info to a computer and you could log the temp variations between batteries.
It could be programmed to turn off the charger too( with a relay) based on temp of any battery.

It may be interesting to see how this changes over the life of the batteries.
It would also show the difference in temp of each battery.

The problem with this is you need time to design and program it first.


Mark



From: "John Acord jcacord@gmail.com [electricboats]" <electricboats@yahoogroups.com>
To: electricboats@yahoogroups.com
Sent: Thursday, November 9, 2017 5:42 PM
Subject: [Electric Boats] Re: Battery temperature

 
I am building a 48V system with 8 golf cart flooded cells.  I have always had good results and long life with them as long as one pays attention to charging, battery temperature and keeping them watered. 

To my way of thinking, both for safety and battery health, temperature monitoring is essential. Each battery will have a temperature sensor with associated readout and alarm circuitry. 

I am thinking that 50 deg C. (122 F.) would be a good alarm point.  Any comments/suggestions?

John A.

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."


__._,_.___
Posted by: Mark F <mark.internet@yahoo.ca>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (2)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:

Thursday, November 9, 2017

[Electric Boats] Re: Battery temperature

 

I am building a 48V system with 8 golf cart flooded cells.  I have always had good results and long life with them as long as one pays attention to charging, battery temperature and keeping them watered. 

To my way of thinking, both for safety and battery health, temperature monitoring is essential. Each battery will have a temperature sensor with associated readout and alarm circuitry. 

I am thinking that 50 deg C. (122 F.) would be a good alarm point.  Any comments/suggestions?

John A.

--
Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."

__._,_.___
Posted by: John Acord <jcacord@gmail.com>
Reply via web post • Reply to sender • Reply to group • Start a New Topic • Messages in this topic (1)
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.

.

__,_._,___
Posted by at No comments:
Subscribe to: Posts (Atom)