Reserve AH ..??

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Reserve AH ..??

January 17, 2016, 04:38:31 pm

So I'm trying to educate myself. I'm no electrician but know the basics, one thing baffles me tho. How can I determine "reserve AH" on our coach..The factory spec sheet reads 816 reserve minutes. My meter reads 127 now and then drops to zero when starting the genny or plugging in.

I've read a few posts stating "do not go below 50% of reserve AH"

Very confusing....

Thx

Hans

Re: Reserve AH ..??

Reply #1 – January 17, 2016, 04:48:38 pm

Hans,

20 hour Amp-hr rate is the common measure.

Most battery websites list that. If you can not find it for your battery, post what batteries you have and how many.

Here is a Lifeline battery chart: Lifeline Batteries - Marine & RV Deep Cycle Batteries

Look at the 20 hour rating for the 8D battery= 255 amp-hrs. So half that usable before recharging. The higher the discharge rate, the less total a battery can provide. So, 20 hour was adopted as a standard a long time ago.

Re: Reserve AH ..??

Reply #2 – January 17, 2016, 09:00:18 pm

Quote from: Hans&Marjet – January 17, 2016, 04:38:31 pm

My meter reads 127 now and then drops to zero when starting the genny or plugging in.

Hans, as soon as you start to draw down your batteries, the "127" will change to "0." The "-" numbers are the measure of amp-hours you have drawn from fully charged batteries. If you have three good 8D batteries (255 AH capacity), a 50% discharge would show about -380 AH. My understanding is that the "+" number on the amp-hour meter indicates an accumulation of amp-hours put into the batteries after they reach float voltage.

Don't be confused by the +127 number. Pay attention to the "-" numbers to measure AH (amp-hours) down from full charge. Try not to go below -380 for three good 8D batteries. Limiting to -190 (~25%) will provide longer life to your batteries.

My observations are based on what I see on a Freedom 25 inverter/converter with a Link 2000 control panel. Your system may indicate different measurements than does mine. My system doesn't have a temperature sensor on the batteries. I can set a value for the ambient temperature. In our mild climate, I usually use 70F. I adjust the value so that at float charge, there is a small (~1A) "+" charge to the batteries. There is usually a small accumulation of "+" amp-hours on the meter after a few days. If the accumulation is large, or becomes negative, while on shore power, I'll adjust the temperature compensation for higher or lower float voltage to accommodate for ambient conditions.

Perhaps my explanation will help you understand what you see on the panel. I'll trust experts to correct misinformation in my post.

Re: Reserve AH ..??

Reply #3 – January 17, 2016, 09:07:00 pm

Gels versus AGM's versus flooded cell will be different in the details.

What do you have?

Re: Reserve AH ..??

Reply #4 – January 17, 2016, 10:24:32 pm

I am a new owner of a 2000 U320. How and where are you reading the battery reserve. Is there an article or posting that explains this. Thank you for your help.

Re: Reserve AH ..??

Reply #5 – January 18, 2016, 07:44:19 am

Quote from: Caflashbob – January 17, 2016, 09:07:00 pm

Gels versus AGM's versus flooded cell will be different in the details.

What do you have?

Bret/Bob...I believe they are AGM
2 batteries

Hans

Re: Reserve AH ..??

Reply #6 – January 18, 2016, 08:59:01 am

Hans, the AGM vs Gel is not important in terms of amp-hrs (both are reasonably similar for a given size), but IS important in terms of programming your inverter/charger so it is "smart" for YOUR battery technology.

Tell us what name and model number is on the batteries or take and post a picture of them and we can help.

Re: Reserve AH ..??

Reply #7 – January 18, 2016, 12:25:41 pm

Bret..see below.
8D with k7 sticker

Re: Reserve AH ..??

Reply #8 – January 18, 2016, 12:38:02 pm

I suspect the K7 is a date code.

I do not have a chart in front of me, but if the K represent the month, that could be November 2007.

Depending on how they have been maintained, they *might* be getting a little long in the tooth.

Hope this helps,

Trent

Re: Reserve AH ..??

Reply #9 – January 18, 2016, 11:47:09 pm

If they are 2007 anything I would replace them myself.

As a Foretravel manager I learned to replace all the batteries in any used coach I was going to go rving in.

No substitute for fresh matching ones.

Re: Reserve AH ..??

Reply #10 – January 19, 2016, 08:48:27 am

Quote from: TulsaTrent – January 18, 2016, 12:38:02 pm

I suspect the K7 is a date code.

Agree. Date indicated would be OCT/2007. OP's battery end photo appears identical to the O'Reilly AGM8D batteries we installed in Feb-2014. Our 2 "fresh" batteries had the little round stickers showing (respectively) "M3" and "B4". This would seem to agree with this date code chart I found online (see photos).

Re: Reserve AH ..??

Reply #11 – January 19, 2016, 11:23:27 am

Quote from: Chuck & Jeannie – January 19, 2016, 08:48:27 am

Date indicated would be OCT/2007.

Chuck,

Thanks for that date code chart; I had wondered if they used "I" in the code.

Do you recall the source of your date code?

Trent

Re: Reserve AH ..??

Reply #12 – January 19, 2016, 01:13:16 pm

Trent,

Don't remember...had it saved as a .pdf from back when I bought the batteries. IIRC, I searched Google images for "battery date code", and found it there. It seemed to fit with the stickers on my batteries and the date I bought them, so I ran with it.

Re: Reserve AH ..??

Reply #13 – January 19, 2016, 01:32:44 pm

Hard to tell from the picture posted by Hans, but it looks like his batteries have a grey top which would mean that they are gels, at least if made by East Penn/Deka/MK. The black tops are AGM's.
Don

Quote from: Chuck & Jeannie – January 19, 2016, 08:48:27 am

Agree. Date indicated would be OCT/2007. OP's battery end photo appears identical to the O'Reilly AGM8D batteries we installed in Feb-2014. Our 2 "fresh" batteries had the little round stickers showing (respectively) "M3" and "B4". This would seem to agree with this date code chart I found online (see photos).

Re: Reserve AH ..??

Reply #14 – January 19, 2016, 05:11:46 pm

Don,
I stand corrected - I didn't look closely enough at the OP's photo. His case end is, in fact, different from my AGM batteries. The rope "handle" is the same, which threw me off. I think you are probably correct - they could be GELs. Or, since they appear to be about 9 years old, they might be AGMs with a different case design. Seeing the top label on one of them would help to identify.

Here is the design of the case end on my 2-year old AGMs:

Re: Reserve AH ..??

Reply #15 – January 19, 2016, 06:25:06 pm

Thx all for your input..I'll post more detailed photos of the 8D's . Kinda wondering now if they are GEL or AGM..??

Hans

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Reserve AH ..??

January 17, 2016, 04:38:31 pm

Re: Reserve AH ..??

Reply #1 – January 17, 2016, 04:48:38 pm

Re: Reserve AH ..??

Reply #2 – January 17, 2016, 09:00:18 pm

Re: Reserve AH ..??

Reply #3 – January 17, 2016, 09:07:00 pm

Re: Reserve AH ..??

Reply #4 – January 17, 2016, 10:24:32 pm

Re: Reserve AH ..??

Reply #5 – January 18, 2016, 07:44:19 am

Re: Reserve AH ..??

Reply #6 – January 18, 2016, 08:59:01 am

Re: Reserve AH ..??

Reply #7 – January 18, 2016, 12:25:41 pm

Re: Reserve AH ..??

Reply #8 – January 18, 2016, 12:38:02 pm

Re: Reserve AH ..??

Reply #9 – January 18, 2016, 11:47:09 pm

Re: Reserve AH ..??

Reply #10 – January 19, 2016, 08:48:27 am

Re: Reserve AH ..??

Reply #11 – January 19, 2016, 11:23:27 am

Re: Reserve AH ..??

Reply #12 – January 19, 2016, 01:13:16 pm

Re: Reserve AH ..??

Reply #13 – January 19, 2016, 01:32:44 pm

Re: Reserve AH ..??

Reply #14 – January 19, 2016, 05:11:46 pm

Re: Reserve AH ..??

Reply #15 – January 19, 2016, 06:25:06 pm

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