Adding AGM to my lead acid battery

Johnynorthland · 01-03-2021, 10:55 PM

I’m curious, can you add an AGM to a lead acid, flooded battery in parallel? Will they both charge properly?

Or if I swap out my lead acid with an AGM how well will my factory charger charge my new AGM battery? I called Jayco they said my converter/charger will charge an AGM but they didn’t say how well it will, so I’m digging further.

I know some will say go with lithium, change the converter charger, etc.. but I want to just power my TV, furnace when necessary and 1 aux outlet with a 2kw inverter.

Lake Huron · 01-04-2021, 05:58 AM

My 17 Northpoint HAD a flooded battery when we got it. First thing I did was put in a group 31 Duracell AGM. Little bit bigger in size but a lot more power. It just completed its 5th season and is still going strong. No charging issues either.

Grumpy · 01-04-2021, 06:42 AM

NO. You can't mix types.. Either 2 flooded or 2 AGM not one of each

Johnynorthland · 01-04-2021, 08:28 AM

Quote:

Originally Posted by Lake Huron

My 17 Northpoint HAD a flooded battery when we got it. First thing I did was put in a group 31 Duracell AGM. Little bit bigger in size but a lot more power. It just completed its 5th season and is still going strong. No charging issues either.

That’s great info thanks. I’ll probably just go AGM only. Do you know what converter/charger you have in your rig? Is it factory OEM? Mines a PD 4060K

Johnynorthland · 01-04-2021, 08:30 AM

Quote:

Originally Posted by Grumpy

NO. You can't mix types.. Either 2 flooded or 2 AGM not one of each

Thanks Grumpy. You have any idea how well my factory converter/charger will do with an AGM? I want to avoid changing it if I can. Don’t know if we will be keeping the rig more than another year or 2.

Grumpy · 01-04-2021, 08:38 AM

If it's a Progressive Dynamics it will work fine.

Jagiven · 01-04-2021, 08:48 AM

Quote:

Originally Posted by Grumpy

NO. You can't mix types.. Either 2 flooded or 2 AGM not one of each

X2, to add to this, with AMGs and Flooded batteries, you should always, replace them all at the same time ideally out of the same batch, to keep the internal resistance similar. An old battery and a new battery will (dis)charge at different rates.

Johnynorthland · 01-04-2021, 08:52 AM

Quote:

Originally Posted by Jagiven

X2, to add to this, with AMGs and Flooded batteries, you should always, replace them all at the same time ideally out of the same batch, to keep the internal resistance similar. An old battery and a new battery will (dis)charge at different rates.

Now you got me thinking further. So while driving my alternator charges both coach and chassis batteries, would it be ok to still have lead acid in engine compartment and AGM for coach?

Grumpy · 01-04-2021, 09:41 AM

Quote:

Originally Posted by Johnynorthland

Now you got me thinking further. So while driving my alternator charges both coach and chassis batteries, would it be ok to still have lead acid in engine compartment and AGM for coach?

Yes, that's done all the time.

Johnynorthland · 01-04-2021, 10:00 AM

Quote:

Originally Posted by Grumpy

Yes, that's done all the time.

Thanks again Grumpy! I’m also considering a renogy DC2DC charger to maintain the chassis battery while hooked up or if I installed solar. I’m guessing there would also be no problem mixing lead and AGM?

Bullitt6283 · 01-04-2021, 10:13 AM

I have a regular flooded battery in the Chassis and a pair of 300AH 6 volt AGM batteries wired in series for the House.

To maintain the charge on the Chassis battery, I am using:
https://www.lslproducts.net/TLSPage.html

.

Johnynorthland · 01-04-2021, 10:31 AM

Quote:

Originally Posted by Bullitt6283

I have a regular flooded battery in the Chassis and a pair of 300AH 6 volt AGM batteries wired in series for the House.

To maintain the charge on the Chassis battery, I am using:
https://www.lslproducts.net/TLSPage.html

.

Thanks Ron. Where do you store the AGM’s?

Bullitt6283 · 01-04-2021, 11:04 AM

I originally had a single Group 27 House battery behind the hatch marked "A" below. I installed the two AGM batteries in the compartment marked "B". I reinforced the compartment floor a lot.

Johnynorthland · 01-04-2021, 11:11 AM

Quote:

Originally Posted by Bullitt6283

I originally had a single Group 27 House battery behind the hatch marked "A" below. I installed the two AGM batteries in the compartment marked "B". I reinforced the compartment floor a lot.

I have my lead acid located in a step well. Not much room for expansion, it tight. I might try a few 6V, if not I have a similar compartment as you where my solar terminates from the roof. I just hate giving up any storage as we just went full time in August until May.

Bullitt6283 · 01-04-2021, 11:29 AM

Quote:

Originally Posted by Johnynorthland

I have my lead acid located in a step well. Not much room for expansion, it tight. I might try a few 6V, if not I have a similar compartment as you where my solar terminates from the roof. I just hate giving up any storage as we just went full time in August until May.

One thing to consider- AGM batteries can be installed laying down, and they can be installed inside without venting. They only discharge gas if they are being overcharged.

.

Johnynorthland · 01-04-2021, 11:29 AM

Looking at this 6V AGM https://www.driveduracell.com/pub/me...siwyg/1688.pdf

But I don’t understand how to read the spec sheet. Is it 20 AH or 190AH (200)?

Bullitt6283 · 01-04-2021, 12:09 PM

Quote:

Originally Posted by Johnynorthland

Looking at this 6V AGM https://www.driveduracell.com/pub/me...siwyg/1688.pdf

But I don’t understand how to read the spec sheet. Is it 20 AH or 190AH (200)?

The terminology gets a bit deep. The Amp Hour rate would mean, for example, that if a battery has a rating of 100AH @ 20 Hr rate, it can be discharged for 20 hours with a 5 amp load (20 x 5 = 100). If it has the rating of 200 AH, it can handle a 10 amp load for 20 hours (10 x 20 = 200).

Your chart shows 190 AH at a 20 hour rate.

But since it's not good to take a flooded or AGM battery below 50% charge, your real capacity is half of that. AGM batteries can handle a 80% discharge, but you are decreasing the number of charge cycles remaining.
.

Johnynorthland · 01-04-2021, 03:25 PM

Quote:

Originally Posted by Bullitt6283

The terminology gets a bit deep. The Amp Hour rate would mean, for example, that if a battery has a rating of 100AH @ 20 Hr rate, it can be discharged for 20 hours with a 5 amp load (20 x 5 = 100). If it has the rating of 200 AH, it can handle a 10 amp load for 20 hours (10 x 20 = 200).

Your chart shows 190 AH at a 20 hour rate.

But since it's not good to take a flooded or AGM battery below 50% charge, your real capacity is half of that. AGM batteries can handle a 80% discharge, but you are decreasing the number of charge cycles remaining.
.

Gotcha, I understand about the ah being half the battery capacity but just couldn’t figure out that chart. Thanks for taking the time to look at it. Sam’s club has them for $179 each. I thought it was a good buy. The way Sam had it in a red it looked like 20 ah to me!

Johnynorthland · 01-04-2021, 03:40 PM

Also wanted to know if I connect 2-6V, 100 AH AGM’s in series does the amp hours stay the same?

And if paralleling 2-12v, 200 ah AGM’s would it keep AH the same? What advantage do you receive by connecting 2- 12V in parallel?, slower discharge rate?