Charging Voltage M27MF ACDelco's

Submitted: Wednesday, Feb 04, 2004 at 04:40
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I have been further following up with ACDelco re charging voltage for M27MF's. As noted in a previous posting the Queensland agent advised a charging voltage of 15.8 to 16. Today I spoke to a Victorian distributor who also advised the same - he said that the concentration (SG) of the acid in the M27MF's was greater than the standard lead acid hence the requirement for the higher voltage. I have set the Absorbtion Voltage on the Victron at 15.8V so I guess time will tell. As an aside to this , on the (reasonable) assumption that the advice is correct should I set the Prostar to Flooded rather than Sealed? Andy
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Reply By: Andy1 - Wednesday, Feb 04, 2004 at 04:54

Wednesday, Feb 04, 2004 at 04:54
The battle for data continues. I have been in touch with ADDelco in the US who referred me to this site:http://www.acdelcotechconnect.com/html/tas_bat_charts.jsp Can anyone explain what these charts are telling me about charging voltage. Andy
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Reply By: Andy1 - Wednesday, Feb 04, 2004 at 04:55

Wednesday, Feb 04, 2004 at 04:55
Sorry that should be:http://www.acdelcotechconnect.com/html/tas_batt_charts.jsp
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Reply By: Noosa Fox - Wednesday, Feb 04, 2004 at 04:56

Wednesday, Feb 04, 2004 at 04:56
Andy, I can't understand why you would have a problems with these simple graphs, just work out what Amps you are going to use in a month, now was that a 28 day or 31 day month, and go somewhere where the temperature is going to remain the same all month. Then work out what graph you should have been looking at in the first place. I can't even say it is as clear as mud, to me, I think it is as clear as black concrete. Maybe Anthony or Collyn will be able to explain it in a language that us dumb buggers can make sence of. Brian
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Reply By: Andy1 - Wednesday, Feb 04, 2004 at 04:57

Wednesday, Feb 04, 2004 at 04:57
Brian To an Economist the graphs seem to confirm what I have been told by two ACDelco distributors, that is to use a charge voltage that rises to circa 16V. This is of interest to all BT Owners who have the M27MF's fitted. Collyn? Andy
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Reply By: Turist - Wednesday, Feb 04, 2004 at 04:58

Wednesday, Feb 04, 2004 at 04:58
As mentioned in an earlier post, in a previous life I was the Australian distributor for a well respected range of European manufactured battery chargers.
There are many variables when charging flooded lead acid batteries but the MOST IMPORTANT IS TO REMAIN BELOW THE GASSING VOLTAGE.
In order to do this our battery chargers for lead acid batteries are programmed for a charge/float voltage of 14.7 volts max.
Some may believe that this is a decimal below optimum but we never had complaints about batteries boiling off during the charge cycle.
And the batteries charged as required.
K.I.S.S.

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Reply By: Andy1 - Wednesday, Feb 04, 2004 at 04:59

Wednesday, Feb 04, 2004 at 04:59
Turist Why then do ACDelco print, in the public domain, graphs showing Charge Characteristics at voltages in excess of 16V? All of my advice from ACDelco to date is recommending voltages well in excess of 14.7V. They have given me an address to write to in the US which I will follow up. Andy
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Reply By: Turist - Wednesday, Feb 04, 2004 at 05:00

Wednesday, Feb 04, 2004 at 05:00
Andy our manufacturer produced chargers to be suitable for all battery types. We are speaking here of flooded lead acid.
By setting the voltage max at 14.7 we could guarantee not to gas batteries excessivly. (Boiling)
It may be that some batteries will, due to the manufacturers "secrets" accept a higher charge profile and consequently charge in a shorter period of time.
They will still reach optimum charge at 14.7 v, takes a little longer.

Another reason some may reccomend a higher charging voltage is to accommodate a higher (taller) plate profile.
When batteries are "on charge" the charging effect starts at the bottom of the plate.
If you had a battery with glass sides you could see the bubbling on the plates start at the bottom and gradually work up.
Batteries (of the same capacity) with 8" plates charge quicker and suffer less from upper plate sulfation that batteries with 10" plates.
This is a generalisation and strong argument can be encountered when getting down to specifics. For our purpose we do not need to enter into these arguments, you need a text book to follow them

But the answer is that a battery charger manufacturer producing for the mass market takes the safe road so his charging profile will work better with some batteries, not so well with others.
Hope this helps, bound to start further argument from the experts.

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Reply By: Deleted User - Wednesday, Feb 04, 2004 at 05:01

Wednesday, Feb 04, 2004 at 05:01
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Reply By: Turist - Wednesday, Feb 04, 2004 at 05:02

Wednesday, Feb 04, 2004 at 05:02
Andy when you write to AC Delco ask the the gassing point for their batteries.
There is no mention of it in thier website.
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Reply By: Turist - Wednesday, Feb 04, 2004 at 05:03

Wednesday, Feb 04, 2004 at 05:03
There is of course another reason to keep the secondary voltage low.
We are less likely to be sued.
Just imagine what a lawyer could do with a case of an overcharging battery that produces heaps of gas that fills a void with a blocked vent that just happens to have a static electricity charge ignite the gas while you are driving through the harbour tunnel next to a fuel tanker while the QE2 full of passengers is passing over the top.
Like to see the third party claims on that one.
Gee, you could lose your house when the lawyers are finished with you.

Turist... (with tongue firmly planted in cheek)
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Reply By: Bushtracker Buck & Babe - Wednesday, Feb 04, 2004 at 05:04

Wednesday, Feb 04, 2004 at 05:04
What house? We would have already lost ours up in a puff of smoke at the first sign of the problem! We'd have to go and find a billet with Turist. Angie
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Reply By: Noosa Fox - Wednesday, Feb 04, 2004 at 05:05

Wednesday, Feb 04, 2004 at 05:05
Isn't the battery charger really only a back up for the ocassional times when the solar panels cannot keep up. If the batteries can be successfully charged from solar panels at a much slower rate, I cannot see the need for a battery charger to charge it at a higher rate. Could the higher charging rate the Andy is talking about be to accomodate the alternator charge rate when they are fitted into motor vehicles, as they seem to be around the 16volts. Brian
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Reply By: Deleted User - Wednesday, Feb 04, 2004 at 05:06

Wednesday, Feb 04, 2004 at 05:06
Brian, If your battery terminal voltage is at 16 with the engine running I'd be getting it looked at by an auto sparky. My effie alternator puts out 14.4v approx at the terminals. My gels in the back because of resistance in the battery isolation switch receive 14.2v approx. Anthony Explore this Great Land ...Do it Easy ...Tow a Bushtracker
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Reply By: Deleted User - Wednesday, Feb 04, 2004 at 05:07

Wednesday, Feb 04, 2004 at 05:07
The ACDELCO charts suggest that it's safe to charge these batteries at up to 16 or so volts- and that as one would expect, the higher the charging voltage the quicker they will charge. But they do not spell this out in any words that I can find in their tech literature. Collyn Rivers
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Reply By: Andy1 - Wednesday, Feb 04, 2004 at 05:08

Wednesday, Feb 04, 2004 at 05:08
Turist On the subject of hydrogen emissions. The risk is pretty low, not statistically measurable if commonsense precautions are taken. BT make the battery box installation pretty safe by sealing the battery box & having high & low level outlets/inlets which vent to outside the van. Given that the potential for a confined space explosion is a function of the local (contained) hydrogen concentration we have taken the precaution of fitting four vents, each about 15 x 10 cms, two high & two low, in the under bed hold where our battery box is located. As the hold tends to warm up when the van is in the sun during the day, particularly if the van has been closed up, & hold a bit of warmth, these vents have a couple of other advantages outside ensuring there can never be a critical hydrogen build-up, one dissapation of the charger generated heat & the other airing/cooling the hold after a hot day. Of course we store our wine in the hold so this cooling ventalation takes on another degree of significance! In fact I have often wondered why BT do not fit hold vents as standard. Andy
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