Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: dpbarry on May 12, 2015, 08:57:16 PM

Title: Identifying the ampage of a sealed lead acid battery
Post by: dpbarry on May 12, 2015, 08:57:16 PM
Hi folks..


Could I ask for a bit of help in identifying the amps of a sealed lead acid batterry.


Its marked as HR 1234W F2 and tinternet searches identify it as a 9 Ah battery but i'd like to be sure before I program my mercury ex charger. I'll try and post a picture.


Regards


Declan
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: cos918 on May 12, 2015, 09:00:04 PM
whats are its dimensions ? eg width length
 height


john
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Shipmate60 on May 12, 2015, 09:08:09 PM
This one?


https://www.google.co.uk/search?q=HR+1234W+F2&es_sm=122&source=lnms&tbm=isch&sa=X&ei=Xl1SVcrhG8bzUpmbgOgD&ved=0CAgQ_AUoAg&biw=1360&bih=643#imgrc=QvUxEzEoxWqGpM%253


Bob
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: malcolmfrary on May 12, 2015, 09:11:32 PM
This one?


https://www.google.co.uk/search?q=HR+1234W+F2&es_sm=122&source=lnms&tbm=isch&sa=X&ei=Xl1SVcrhG8bzUpmbgOgD&ved=0CAgQ_AUoAg&biw=1360&bih=643#imgrc=QvUxEzEoxWqGpM%253 (https://www.google.co.uk/search?q=HR+1234W+F2&es_sm=122&source=lnms&tbm=isch&sa=X&ei=Xl1SVcrhG8bzUpmbgOgD&ved=0CAgQ_AUoAg&biw=1360&bih=643#imgrc=QvUxEzEoxWqGpM%253)


Bob
Snap
http://www.csb-battery.com/upfiles/dow01404182675.pdf


Its amazing what a very quick goggle will turn up.  I suspect that the "12" refers to the voltage and the "34" refers to the Watt-Hours that it stores.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: dpbarry on May 12, 2015, 09:43:44 PM
Here's a photograph..

(http://i719.photobucket.com/albums/ww194/dpbarry/Radio%20Control/image.jpg1.jpg)
http://i719.photobucket.com/albums/ww194/dpbarry/Radio%20Control/image.jpg1.jpg (http://i719.photobucket.com/albums/ww194/dpbarry/Radio%20Control/image.jpg1.jpg)

Just trying to work out if it is a 9Ah battery.

Declan
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Howard on May 12, 2015, 09:51:45 PM
If am right it says 12v on the side (photo)
Regards Howard
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Shipmate60 on May 12, 2015, 09:56:02 PM
It will be 12 volt 7 or 9 amp battery.


Bob
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: dpbarry on May 12, 2015, 10:10:37 PM
 >>:-( <*<


Lol!! I know its 12V. What I don't know is whether its 7Ah or 9Ah


 %%


Declan
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: dpbarry on May 12, 2015, 10:18:33 PM
Further tinternet searching produced this


http://www.hardwarexpress.co.uk/hr1234w-f2-csb-battery-12v-9ah-457-p.asp (http://www.hardwarexpress.co.uk/hr1234w-f2-csb-battery-12v-9ah-457-p.asp)




Specifications for CSB HR1234WF2 Battery
Voltage 12V
Capacity 9Ah (34W)
Weight 3Kg
Dimensions 151mm x 94mm x 65mm
Lifespan 3 - 5 years
Type Sealed Lead acid battery rechargeable highly efficient, leak proof and maintenance free
Warranty 12 months
[size=78%]Declan[/size]
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Howard on May 12, 2015, 10:32:53 PM
Sorry Declan,
I some how miss read it.
            Regards Howard.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: dpbarry on May 12, 2015, 10:58:23 PM
Sorry Declan,
I some how miss read it.
            Regards Howard.


Lol!! No problem at all. It was funny reading the replies


From what I can see it looks to be a 9Ah battery


Cheers


Declan
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: AlexC on May 12, 2015, 11:05:58 PM
Further tinternet searching produced this


http://www.hardwarexpress.co.uk/hr1234w-f2-csb-battery-12v-9ah-457-p.asp (http://www.hardwarexpress.co.uk/hr1234w-f2-csb-battery-12v-9ah-457-p.asp)




Specifications for CSB HR1234WF2 Battery
Voltage 12V
Capacity 9Ah (34W)
Weight 3Kg
Dimensions 151mm x 94mm x 65mm
Lifespan 3 - 5 years
Type Sealed Lead acid battery rechargeable highly efficient, leak proof and maintenance free
Warranty 12 months
[size=78%]Declan[/size]

That spec does not make any sense...

34W @ 12v = 2.8Ah not 9Ah. %%

12v x 9Ah = 108W.

Unless they have found a way round Ohm's law, which I doubt.

Sandy. :-)
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Paul Swainson on May 13, 2015, 12:23:02 AM
34 w = P
12v = E
X = I


therefore to find the value of I (amps) 34w/12v = 2.83 amps
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Shipmate60 on May 13, 2015, 08:58:13 AM
Gell cells are not overcharging sensitive as in fire alarms they are on permanent trickle charge.


Bob
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Netleyned on May 13, 2015, 09:44:16 AM
Would that 2.83 A /34W be the max initial charge?


Ned
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: inertia on May 13, 2015, 10:05:17 AM
"Ampage" isn't a term which is familiar to me. If you mean "capacity" then the unit of measurement is Amp.Hours, not Amps, and so Ohm's Law isn't relevant. It's a factor which is dictated by the physical size of the internal plates and the strength of the electrolyte. I'd say that if it's the same size as a 7AH battery then that's probably what it is.
DM
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: malcolmfrary on May 13, 2015, 10:16:18 AM
Could be 34 watt-hours stored per kilogram weight.
Few lead-acid batteries are amenable to fast charging, and trying to pre-determine the amount of charge it needs to become fully charged is usually doomed to failure since the inefficiency of charging is unknown.  As has been said above, this type of battery is designed to be left on a permanent trickle.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: vnkiwi on May 13, 2015, 10:27:33 AM
Maybe its just me, and myself and electricity combine, produce all that grey smoke escaping that Dave so kindly puts in, but

Volts x Amps = Watts

12 x 2.83 = 34

or so my plastic brain tells me.

What's all this thowing hours into the pot?

If you download the PDF that has the link posted in one of the early posts, then ALL the charging rates etc are listed in text and graph form.

Otherwise, its what Inertia, (DM) said, isn't it.
 :o %) :-))
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: derekwarner on May 13, 2015, 10:56:59 AM
 :-)...an alternate view on this seemingly simple calculation is to convert electro potential battery box of energy to an equivalent boiler of potential steam energy  :kiss:

After all........essentially and all things being equal they are both of the same potential.......just created, stored and transmitted in a different medium ....

PS...I do have an answer.........just wondering if I am correct  :o & on the correct thought line.....[and the steam equivalent of Ohms Law is not a value in the calculation] .......Derek
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: inertia on May 13, 2015, 12:01:31 PM
Vnkiwi
Ohm's Law describes the relationship between the current, the voltage and the resistance in a circuit when current is flowing. There is no mention of a unit of time because it's not part of that relationship.
I've just Googled the word "ampage" and the only definition I can find actually describes what most folk would call "current". You can't describe a battery by its current - such a definition would be meaningless.
However if you wish to describe the capacity of a battery to deliver a current then time comes into the equation, in as much as the capacity is a measure of a battery's ability to supply an amount of charge over a period of time. If you drain the battery very quickly then the charge it contains will not be delivered for as long a period as if you were to drain it slowly. Its capacity is the arithmetical product of the current it can supply and the time for which it can maintain that supply. Imagine it as like having a bucket full of water. If you drill a small hole in the bottom of it then the water will drain away very slowly while a large hole will drain it much faster, but the size of the hole doesn't affect how much water the bucket will hold before you start to drain it (its capacity).
In the equation V x I = W the W value is the power which is being supplied to a load where the voltage across that load is 12v and the current flowing through it is 2.83 Amps. The battery could equally be a 0.6AH lead-acid battery or a 5AH LiPo pack; it's just that the latter will last a lot longer than the former.
None of this stuff is clever or mysterious, guys. If it really was rocket science then I'd have taken up collecting car numbers years ago. There's more basic information here http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054 (http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054)
Dave M
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: vnkiwi on May 13, 2015, 12:10:40 PM
see, I knew someone could explain it all.

 :-))

all I know about 'tricity, is that when I fiddle,the smoke comes out.
Been trying to find and buy the "LUCAS" machine that puts the smoke back in, for years.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Jerry C on May 13, 2015, 01:11:24 PM
Lead acid batteries are classified as say 12V 7Amp hrs. What isn't said is the rate. Commonly, deep cycle batteries are quoted at the 20hour rate. Starter batteries are quoted at the 10hour rate. This method is used to be able to compare different battery capacities. Rather similar to car mpg figures. They are not accurate but give comparisons.
So, a 12V 7Ah battery can be expected to give 7/20 of an amp over 20 hours. Over 10 hours it will give less than 7/10 of an amp and over 30 hours it will give more than 7/30 of an amp. If you draw 7 amps from it then it will last less than 1 hour.
Jerry.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: AlexC on May 13, 2015, 01:18:15 PM
Vnkiwi
Ohm's Law describes the relationship between the current, the voltage and the resistance in a circuit when current is flowing. There is no mention of a unit of time because it's not part of that relationship.
I've just Googled the word "ampage" and the only definition I can find actually describes what most folk would call "current". You can't describe a battery by its current - such a definition would be meaningless.
However if you wish to describe the capacity of a battery to deliver a current then time comes into the equation, in as much as the capacity is a measure of a battery's ability to supply an amount of charge over a period of time. If you drain the battery very quickly then the charge it contains will not be delivered for as long a period as if you were to drain it slowly. Its capacity is the arithmetical product of the current it can supply and the time for which it can maintain that supply. Imagine it as like having a bucket full of water. If you drill a small hole in the bottom of it then the water will drain away very slowly while a large hole will drain it much faster, but the size of the hole doesn't affect how much water the bucket will hold before you start to drain it (its capacity).
In the equation V x I = W the W value is the power which is being supplied to a load where the voltage across that load is 12v and the current flowing through it is 2.83 Amps. The battery could equally be a 0.6AH lead-acid battery or a 5AH LiPo pack; it's just that the latter will last a lot longer than the former.
None of this stuff is clever or mysterious, guys. If it really was rocket science then I'd have taken up collecting car numbers years ago. There's more basic information here http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054 (http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054)
Dave M

Hi Dave,

Yes I understand all that, however, I am somewhat puzzled by the figure of 34W in brackets next to the 9Ah capacity rating.

In theory
9Ah means the battery can deliver 1 amp for 9hrs
or 9A for 1 hr etc. etc.
But this can vary depending on the Rate of the battery (10hr rate or 20hr rate) which is determined by battery construction and intended use.

Ohms law only applies when calculating the power (E x I =W)
The hrs part is derived from the battery rate.

12v at 1 amp = 12W which can be delivered for 9hrs.
12v at 9 amps = 108W which can be delivered for 1hr.

I am beginning to suspect the 34W value relates to the Max Discharge rate for the cells to prevent over heating...
This would imply 12v at 2.8 amps Max (= 34W) which would result in maximum of approx 3.2hrs at 9Ahr capacity.... which does not make a lot of sense for a battery of this type and would limit it's usefulness.

Keep Happy,

Best regards.

Sandy. :-))
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Calimero on May 13, 2015, 02:05:02 PM

Quote from: AlexC
12v at 1 amp = 12W which can be delivered for 9hrs.
12v at 9 amps = 108W which can be delivered for 1hr.

Drawing 9A from a 9Ah battery will get you around 20 minutes ...

The rated capacity of SLA batteries borders on fraudulent advertising as it is usually given at C/20.


If power draw is closer to C/5 or higher, actual capacity drops very quickly. At 1C (rated C) you end up with actually only 1/3rd of the rated capacity ...


Well they're not too expensive, abuse-tolerant and we usually need ballast in our scale boats anyway ...[/size][/font]
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: inertia on May 13, 2015, 02:32:37 PM
Well said, Monsieur!
Far too many modellers are fooled by those seductive capacity ratings, to the extent that some believe they can even run two brushless motors from one SLA battery and obtain an hour's sailing from one charge. If I've seen one Huntsman or Perkasa lumbering round a pond like a narrowboat, weighed down by a huge brick of a battery, then I've seen a hundred. It makes me weep. It takes a great percentage of the motor's power just to get the battery moving, never mind getting the model up on the plane. Fitting a bigger/faster motor will simply make it worse in that it will drain the battery even faster. SLA batteries are large and cumbersome things and in consequence can be very awkward to fit. They have to be charged at a relatively slow rate and so can't be recharged at the lakeside (unless it's overnight, maybe). OK - if your tug operates fine with them then carry on, but you might get a helluva surprise if you replaced them with modern fast-charge high-current cells.
Unless they are of the special high-current, deep-discharge "leisure" type, SLA batteries are intended for low-current applications (usually with trickle charging) like alarm systems or emergency lighting. I use them only for our show demo boards and as weights in the workshop. My models are all fitted with either NiMH or LiPo battery packs; in my book the only use for lead-acid batteries in a model - as Calimero says - is as ballast.
Suit yourselves - as someone used to say.
DM
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: NFMike on May 13, 2015, 02:40:11 PM
No-one seems to have noticed the 15min on the end. I'd hazard that at 34W per cell (from full charge) it will hit 1.67V in 15 minutes. But I think I'd be wrong somehow.

Regardless of that, lead acid batteries should be charged with volts until they reach their fully charged voltage. Then they can be trickle charged. If you get a correctly sized auto charger (eg. one for say 5-20 Ah batteries (12V of course) then it should just do the job without you worrying about it.
Probably better to get one that is slightly oversize than under - it won't overcharge as the cut-off volts are not dependent on size but chemistry. Undersize may simply not have the oomph to get the battery up to the cut-off volts, so it never fully charges or terminates. (I had one that was like that from a popular supplier on here - pos. Had to get a better one from Greece of all places, via ebay.)
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: AlexC on May 13, 2015, 02:47:59 PM
Which Is why I stated that it can vary...

Quote
In theory
9Ah means the battery can deliver 1 amp for 9hrs
or 9A for 1 hr etc. etc.
But this can vary depending on the Rate of the battery (10hr rate or 20hr rate) which is determined by battery construction and intended use.

I agree, battery capacity claims do border on the fraudulent and the result is a lot of confused and unhappy people when the battery does not perform as expected.

It would help if manufacturers agreed a STANDARD for battery specifications which included the RATE, but I don't see this happening anytime soon.
Some are better than others in this respect but there are a lot who make some very wild claims.

As you say, they are relatively cheap and make useful ballast in our application, but that is no excuse for poor/misleading advertising data.

Keep Happy.

Sandy. :-))

Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: Calimero on May 13, 2015, 02:56:52 PM
Quote from: Inertia
Well said, Monsieur!
Far too many modellers are fooled by those seductive capacity ratings, to the extent that some believe they can even run two brushless motors from one SLA battery and obtain an hour's sailing from one charge. If I've seen one Huntsman or Perkasa lumbering round a pond like a narrowboat, weighed down by a huge brick of a battery, then I've seen a hundred. It makes me weep. It takes a great percentage of the motor's power just to get the battery moving, never mind getting the model up on the plane.

Anything faster than a tame tug is indeed NOT suitable for SLA batteries.

I run my springer (with a big nice #174 45mm prop from Raboesch) with a BLDC motor off a 6V SLA """7.2 Ah""" battery. When cruising around, total amp draw is around 2.6A which would give me almost 3 hours of constant run time. Effective run time (because you're not always cruising all over the place) is 4 hours +.

But when I start pushing my 25kg-shoe-box-shaped barge or towing a heavy ship around, current draw goes through the roof: 11A at full throttle.  Datasheet says run time would be around 25min with a constant 11A load. Actual run time is closer to one hour. I was actually surprised the first time I took my barge to the pond. I had somewhat forgotten that SLA batteries were so "weak".

Quote from: Inertia
Unless they are of the special high-current, deep-discharge "leisure" type

Even the "deep discharge" - at least those that are affordable - perform only marginally better. I'm tempted to look at LiFePo4 batteries, for that matter. They seem to offer a good balance between "usability" and discharge/charge rates. And they are getting cheaper.

I have two 12V / ""12 Ah" batteries in my Odin tug. Good enough as the overall power draw isn't that bad and I needed around 13kg of ballast anyway, but this is as "ideal" as it gets.

On smaller boats, SLA batteries might not be that good a choice.
Title: Re: Identifying the ampage of a sealed lead acid battery
Post by: AlexC on May 13, 2015, 03:50:32 PM
No-one seems to have noticed the 15min on the end. I'd hazard that at 34W per cell (from full charge) it will hit 1.67V in 15 minutes. But I think I'd be wrong somehow.

Regardless of that, lead acid batteries should be charged with volts until they reach their fully charged voltage. Then they can be trickle charged. If you get a correctly sized auto charger (eg. one for say 5-20 Ah batteries (12V of course) then it should just do the job without you worrying about it.
Probably better to get one that is slightly oversize than under - it won't overcharge as the cut-off volts are not dependent on size but chemistry. Undersize may simply not have the oomph to get the battery up to the cut-off volts, so it never fully charges or terminates. (I had one that was like that from a popular supplier on here - pos. Had to get a better one from Greece of all places, via ebay.)

Yes, I admit I did not spot that on the picture of the battery... I was going by the spec data in a later post.

That is exactly what it means...

Nominal cell voltage (fully charged) is 2 volts.
Fully discharged is typically between 1.6v and 1.8v depending on make.
2v at 34w discharge = 17 amps which would discharge the cell to 1.67v in 15 minutes.

Since the 6 cells in the battery are in series this would mean at a 17amp output rate the battery would be discharged in 15 minutes and be at a voltage of 10.02v... that is a discharge rate of 1.88C

Also on the battery picture I can just make out the max initial charge current of 3.4A at a constant 14.4v - 15v charging voltage... which may require you to adjust the current limit on your charger... or risk generating gasses which could damage the cells.

Now it all makes sense.

Keep happy.

Sandy. :-))