Charging Gel-cell/AGM from alternator - what do i need ?

D

dave silva

New member
Oct 2, 2009
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I understand gel-cells and AGMs require a specific charging regimen to maintain a long life and 14VDC from the average car alternator is not right.

I'm looking for a device that will take 14 volts from my alternator and charge a pair of 100 amp gel-cells.

--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
Just want to make sure you know that internal regulator type Delcotrons are thermal compensating and trim voltage to underhood temp, which
approximates battery temp environment. At cold start you should see 14.2V after the isolator (higher before the isolator by .7V) which gradually drops
into the 13's as you warm up. In very hot conditions you could see as low as 13.2V and be spot on. This design was to match the charge req curve that
is inverse to flooded cell battery temp. Not sure if this is ideal for AGM, but is not just fixed at 14V as you stated and is smart to the degree
explained above. Newer vehicles (even my 99 Jeep by Mopar) use battery temp sensors to have the ECM more accurately (in theory) tweak battery charge
voltage.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
> Just want to make sure you know that internal regulator type Delcotrons are thermal compensating and trim voltage to underhood temp, which
> approximates battery temp environment. At cold start you should see 14.2V after the isolator (higher before the isolator by .7V) which gradually
> drops into the 13's as you warm up. In very hot conditions you could see as low as 13.2V and be spot on. This design was to match the charge req
> curve that is inverse to flooded cell battery temp. Not sure if this is ideal for AGM, but is not just fixed at 14V as you stated and is smart to
> the degree explained above. Newer vehicles (even my 99 Jeep by Mopar) use battery temp sensors to have the ECM more accurately (in theory) tweak
> battery charge voltage.

In this case, it's not on the coach but in my Ford Explorer but I'm working through these problems using the truck as a lab.

To my understanding, the voltage from the alternator might be OK if the gel-cells were the only battery but in this case i want them isolated from
the starting battery.

I have a smart charger in the shop and when it's charging the gells from dead (50%) it cycles through different amperages.

I believe the steady voltage from the the alternator, and the amperage being determined by the draw of the battery is probably not the best way.

I need some sort of 12V powered smart charger. I know it exists but it's tricky to google.

--
Dave & Ellen Silva

1972 Revcon Olds 455, toro drive train. All Stock
 
Dave,

Take a look at Balmar's Digital Duo Charge

http://www.balmar.net/products/digital-duo-charge/

Eric

On Fri, Jun 21, 2019 at 6:31 AM dave silva via Gmclist <

> > Just want to make sure you know that internal regulator type Delcotrons
> are thermal compensating and trim voltage to underhood temp, which
> > approximates battery temp environment. At cold start you should see
> 14.2V after the isolator (higher before the isolator by .7V) which gradually
> > drops into the 13's as you warm up. In very hot conditions you could see
> as low as 13.2V and be spot on. This design was to match the charge req
> > curve that is inverse to flooded cell battery temp. Not sure if this is
> ideal for AGM, but is not just fixed at 14V as you stated and is smart to
> > the degree explained above. Newer vehicles (even my 99 Jeep by Mopar)
> use battery temp sensors to have the ECM more accurately (in theory) tweak
> > battery charge voltage.
>
>
>
> In this case, it's not on the coach but in my Ford Explorer but I'm
> working through these problems using the truck as a lab.
>
> To my understanding, the voltage from the alternator might be OK if the
> gel-cells were the only battery but in this case i want them isolated from
> the starting battery.
>
> I have a smart charger in the shop and when it's charging the gells from
> dead (50%) it cycles through different amperages.
>
> I believe the steady voltage from the the alternator, and the amperage
> being determined by the draw of the battery is probably not the best way.
>
> I need some sort of 12V powered smart charger. I know it exists but
> it's tricky to google.
>
>
>
> --
> Dave & Ellen Silva
>
> 1972 Revcon Olds 455, toro drive train. All Stock
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Though not expensive, I think the first thing you need is to get is a cheap but accurate volt voltmeter installed on the dash to display the voltage
directly across the battery(s) when the alternator is in operation. Also a cheap temperature sensor attached to one of the batteries would be a plus.
This way you would be able to see if you indeed have a charging problem that needs to be addressed. If you do need to address a problem, these items
would help you determine if you have fixed the problem correctly. You can get these cheaply on ebay, aliexpress, or bangood.

I see that the 30 amp controller you referenced also offers an optional temperature sensor on their 20 and 40 amp controllers for $10.00.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
One other thing - gel cell can mean SLA or sealed lead acid, and they have different charging needs than absorbed glass mat.

A gel cell battery holds a thick gel substance that the battery electrolyte is contained in. These batteries are completely spill proof and leak proof if cracked or broken. Many people confuse AGM batteries with Gel batteries because they have so many similar characteristics. They are both sealed which allows the batteries to be mounted in any position, they are deep cycle, and have a low self discharge rate. However, these batteries are also very different from each other. A true gel cell battery cannot be used in many applications that an AGM battery can be used in such as a motorcycle, car, ATV, or UTV without having a special regulator. This is because the alternator is not designed to charge gel batteries. (That was pointed out in an earlier post) Gel cell batteries must be charged correctly or they will deteriorate prematurely.

Dolph Santorine

DE AD0LF

Wheeling, West Virginia

1977 ex-Palm Beach TZE167V100820
Howell EFI/EBL , Reaction Arms, Manny Transmission

>
> Though not expensive, I think the first thing you need is to get is a cheap but accurate volt voltmeter installed on the dash to display the voltage
> directly across the battery(s) when the alternator is in operation. Also a cheap temperature sensor attached to one of the batteries would be a plus.
> This way you would be able to see if you indeed have a charging problem that needs to be addressed. If you do need to address a problem, these items
> would help you determine if you have fixed the problem correctly. You can get these cheaply on ebay, aliexpress, or bangood.
>
> I see that the 30 amp controller you referenced also offers an optional temperature sensor on their 20 and 40 amp controllers for $10.00.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
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