Home » Public Forums » GMCnet » [GMCnet] Interesting electrical/battery issue
| [GMCnet] Interesting electrical/battery issue [message #259663] |
Thu, 21 August 2014 19:49  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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Thanks, Mac. Yes, the microwave does pull a bit over 1500 watts at full power but is only on for a short time. Sounds like a replacement battery bank may be required, although I really expected these to last longer given that we are not full timing in a GMC. We did full time in the Beaver Patriot for four years and when we sold it the batteries appeared to be just as strong as when we started.
I am seeing an increase in white deposits around the battery bank so that may also be a hint. If I do need to replace them I think I will use AGMs this time. The Lifeline and Full River folks tell me I can safely discharge them to 80% and get about the same life as wet cells discharged to 50%. My current bank of 4 wet cells provides 230 amp hours of effective capacity when new (460 x .5 = 230) and two 240 amp hour AGM 6vdc batteries discharged to 80% would provide 192 effective amp hours at about half the weight and none of the hassle. More expensive, yes, but could be worth it if they last longer than the wet cells.
Matt C. or any of you boater guys, do you have real world experience that would validate the longer life for AGMs at 80% discharge or is that just sales talk on the part of Lifeline and Full River?
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Message: 3
Date: Thu, 21 Aug 2014 18:04:16 -0500
From: D C _Mac_ Macdonald
Subject: Re: [GMCnet] Interesting electrical/battery issue
To: GMC Mail List
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Content-Type: text/plain; charset="iso-8859-1"
And 12.7 Amps from a 120 V line is 1524 Watts!
Five to six year old batteries will be lucky to put out more than 50-60% of their original rated Amp-Hour ratings.
A competent battery shop can do a check on each of the batteries, but they'll probably have to disconnect to check each one to do that check.
Time to head for Sam's or Costco and get four new batteries!
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Interesting electrical/battery issue [message #259692 is a reply to message #259663] |
Thu, 21 August 2014 22:29  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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glwgmc wrote on Thu, 21 August 2014 20:49<snip>
I am seeing an increase in white deposits around the battery bank so that may also be a hint. If I do need to replace them I think I will use AGMs this time. The Lifeline and Full River folks tell me I can safely discharge them to 80% and get about the same life as wet cells discharged to 50%. My current bank of 4 wet cells provides 230 amp hours of effective capacity when new (460 x .5 = 230) and two 240 amp hour AGM 6vdc batteries discharged to 80% would provide 192 effective amp hours at about half the weight and none of the hassle. More expensive, yes, but could be worth it if they last longer than the wet cells.
Matt C. or any of you boater guys, do you have real world experience that would validate the longer life for AGMs at 80% discharge or is that just sales talk on the part of Lifeline and Full River?
Jerry
Jerry,
Before the boat business died a painful death as a result of the depression, I was keeping about an half a dozen boats all with Lifeline AGM house banks. (The main engine start - if I had anything to do with it - was a rolled cell AGM.) Here is where the unfortunate problem is.... None that I know of had had to be replaced. The oldest is now about ten years and the only older have moved out of my area. But I do know from (in your face) experience that they will not suffer for the deeper discharge, and the internal resistance - even on the flat plate cells is lower than a flooded cell. Rolled cell have REAL low internal resistance, but their capacity per unit volume sucks.
The only thing bad about them is the cost of acquisition.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Interesting electrical/battery issue [message #259694 is a reply to message #259663] |
Thu, 21 August 2014 22:34 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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When you take into account that the inverter is maybe only 80% efficient, the draw from the battery bank is likely to be pretty close to 2000 Watts or around 167 Amps! At the age of your current batteries, it probably takes almost no time at all to suck them down to 11 or less volts.
The batteries in an RV OR boat that doesn't have regular exercise do have a finite life. VERY high quality batteries and highly capable charging systems can give a long life, but they all start going down hill on the day they are made. Periodic/intermittent use is much harder on everything than full-time use.
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
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> From: glwork@mac.com
> Date: Thu, 21 Aug 2014 17:49:08 -0700
> To: gmclist@temp.gmcnet.org
> Subject: [GMCnet] Interesting electrical/battery issue
>
> Thanks, Mac. Yes, the microwave does pull a bit over 1500 watts at full power but is only on for a short time. Sounds like a replacement battery bank may be required, although I really expected these to last longer given that we are not full timing in a GMC. We did full time in the Beaver Patriot for four years and when we sold it the batteries appeared to be just as strong as when we started.
>
> I am seeing an increase in white deposits around the battery bank so that may also be a hint. If I do need to replace them I think I will use AGMs this time. The Lifeline and Full River folks tell me I can safely discharge them to 80% and get about the same life as wet cells discharged to 50%. My current bank of 4 wet cells provides 230 amp hours of effective capacity when new (460 x .5 = 230) and two 240 amp hour AGM 6vdc batteries discharged to 80% would provide 192 effective amp hours at about half the weight and none of the hassle. More expensive, yes, but could be worth it if they last longer than the wet cells.
>
> Matt C. or any of you boater guys, do you have real world experience that would validate the longer life for AGMs at 80% discharge or is that just sales talk on the part of Lifeline and Full River?
>
> Jerry
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
> Visitors always welcome!
> glwork@mac.com
> http://jerrywork.com
>>> Message: 3
>> Date: Thu, 21 Aug 2014 18:04:16 -0500
> From: D C _Mac_ Macdonald
> Subject: Re: [GMCnet] Interesting electrical/battery issue
> To: GMC Mail List
> Message-ID:
> Content-Type: text/plain; charset="iso-8859-1"
>
> And 12.7 Amps from a 120 V line is 1524 Watts!
>
> Five to six year old batteries will be lucky to put out more than 50-60% of their original rated Amp-Hour ratings.
>
> A competent battery shop can do a check on each of the batteries, but they'll probably have to disconnect to check each one to do that check.
>
> Time to head for Sam's or Costco and get four new batteries!
> ,,,,,,,,,,,,,,
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