Mixing Batteries questions.

[2004lebanshee]

I have a 2 bank battery perko switch.

Can I run a lead acid battery on location #1 (starting) and a AGM on the house #2?

Will it be ok for the alternator to charge both when running on the #1 or Both switch?

Thanks.

[Chap243]

I`ve seen many different answers to this question. Yes, I think it can be done but it is not optimal. I would not run the switch in the Both position, either A or B. I think they charge and discharge at different rates.

[paulswagelock]

No damage from doing this, but as stated, not optimal. The AGM accepts a charge at a different rate.

[cyclops2]

Try reading at www.batteryuniversity.com All your battery questions are answered there.

Search BU-201a It is about AGM care & use.

[Jjlai724]

Would not recommend it especially if you have a onboard charger. I'd just use a deep cycle for your house battery instead.

[phills fan]

I have that set up. Just run A on the way out and B on the way in.

[2004lebanshee]

Thanks guys. Ill just stick with Acid batteries.

[Was_Wylie_Tunes]

2004,

The thing to understand is that alternators arent battery chargers. They are just there to keep up with normal loads and replenish whats used. 100% no issue with what you are looking to do. Now, if you do have a 2 bank onboard charger, you do need to make sure that the house bank can be set for an AGM as they do have a different charge profile.

[cyclops2]

Was

The modern alternators do have a voltage regulator built into them. It does a good job at keeping a car lead acid battery at full charge & no sulphation.

[Was_Wylie_Tunes]

Yes, ol 1-eye, im well aware of whats in an alternator and how they work and will double down on my statement. They are not battery chargers. If you relay on one to charge a dead battery, you may be disappointing. yes, they do a good job at exactly what I said they do, and that is keeping up with normal loads, or as you put it, It does a good job at keeping a car lead acid battery at full charge. I disagree on the sulphation. They dont have the kick in the pants bulk charge that an actual battery charger can provide IMO. What alternators dont do well, is charge dead batteries.

Now back to the topic. The alternator will not care that there is a wet cell on one bank and an AGM on the other bank. All it knows is load. So unless a battery really depleted, then the only load the alt will see, is the normal stuff, not the battery. Since alternators are not quite like a multistage on-board smart charger, it really could care less that one battery is AGM and one is wet cell. On the other side of the coin, the batteries dont care either.

[2004lebanshee]

My deal is I have a 1 year old class 27 lead acid Dual purpose I want to put in as my #1 starting running position battery. I want my house to be my radio, fish finder use battery. I do not have an on board charger as of yet. I typically use a plug in style to charge my house batter at home in my drive. I would love to get an onboard at some point. I was just concerned because when I run in the #1 or if I did both the alternator would be trying to charge both banks. I didn't want to damage a battery doing it.

I didn't intend on using my alternator to charge my 50% dead #2 battery after blasting jams for a few hours. However when I leave in the #1 setting and head home my alternator will try. When I get home I hook up the charger for that battery.

I was under the impression I wouldn't need an onboard for my #1 if it's just a starting and running battery? Do people top those off every night? I have but didn't think it was needed.

[Was_Wylie_Tunes]

or if I did both the alternator would be trying to charge both banks. I didn't want to damage a battery doing it.

In the both, combined or 1/2 position, the alternator will be supplying charge to both banks. However, it will not know the battery type but simply just the load. The load will be the depth at which the battery is depleted and/or whatever is turned on.

I didn't intend on using my alternator to charge my 50% dead #2 battery after blasting jams for a few hours. However when I leave in the #1 setting and head home my alternator will try.

On the contrary, if the switch is on #1, #2 will be isolated from any alternator supply.

I was under the impression I wouldn't need an onboard for my #1 if it's just a starting and running battery?

With a 2 banks setup, its logical and cost effective to just get a 2 bank charger. On most occasions, the main cranking bank will not need much recharging between uses during the season, so the bulk of the output goes to the house bank. During layup, both banks will benefit from the float charge.

[2004lebanshee]

So the next question is 1 really expensive large AMD

Like the XTR12-155 12V with 350 min reserve weighs 90lbs

or

2 pretty large cheap Acid batteries class 29's

both with 210 reserve. These take up more space. but overall cost less but might need replaced more often.

[2004lebanshee]

I was under the impression on #1 both get charged but only #1 is running. On #2 only #2 gets charged and does the running.

[Was_Wylie_Tunes]

The switch is a 100% mechanical patch for current flow. So if an electrical is allowed to draw off a battery through the switch, then the alternator supply must also then be allowed to feed that same battery. Conversely, if a battery is isolated from a current draw, then it is also isolated from the alternator supply.

Now, having an ACR or VSR wired into the scheme changes things. Its an electrical isolater/combiner. The alternator feed goes through the ACR to both banks, regardless of whether the switch is on 1, 2 or both.

For a house bank, I like to look at the battery's amp hour rating. A typical G-29 might have around 100 Ah, so two will be about 200 Ah. Looks like that v-max has an Ah of 155. I typically like 2 batteries cycled shallower then a single larger battery. So, with that, the two G-29s win out. With proper maintenance, ive had good success with wet cell.

[2004lebanshee]

Ok then. Thanks alot. Very helpfull.

[cyclops2]

Was

How come a car that was left with lights on all night & is unable to crank at all the next morning. Can be jump started & then build up enough energy to restart, if you drive for about 45 or more minutes ? No plug in AC charger is needed. Been in the woods with no AC chargers around & none of us ever needed a AC charger to keep restarting on the way home. Alternators are rated in maximum amperes they can put out. They also can protect themselves if they get too hot due to recharging a dead battery in a 110 F desert at high noon.

[Phillbo]

I was under the impression on #1 both get charged but only #1 is running. On #2 only #2 gets charged and does the running.

Thats the way my system is set up. I set it to #1 (starting) while cruising so both batteries are topped off and then set it to #2 (house) when on the hook.

[soldier4402]

I know some do car batteries for starting batt and deep cycle for house batt. Personally I just make them both deep cycle. never had an issue.

[Iggy]

Thats the way my system is set up. I set it to #1 (starting) while cruising so both batteries are topped off and then set it to #2 (house) when on the hook.

Is there a VSR? If so, and I think there is one. Both batteries are being charged no matter how the switch is set. and as Wingnut mentioned

Also remember, the switch is just that. Current and voltage can flow both ways. Something like a V.S.R. or combiner will as stated in the above post.

[Iggy]

If it was my boat. I would use AGM batteries. As to mixing them on the same bank, no. On different banks, yes. But as long as you have 2 different on board chargers set to the right battery type for each bank.

So starting wet and house AGM.

[Iggy]

I know some do car batteries for starting batt and deep cycle for house batt. Personally I just make them both deep cycle. never had an issue.

Yes, but the batteries CCA need to be rated (or higher) for that motor. Generally, that means a bigger deep cell. Thats were a A.G.M. is great for both uses.

[soldier4402]

Yes possibly. But deep cycles are a more hearty battery made for charge and recharge and so forth. AGM might not be a bad choice, but deep cycle if you ask me is better

[Iggy]

Yes possibly. But deep cycles are a more hearty battery made for charge and recharge and so forth. AGM might not be a bad choice, but deep cycle if you ask me is better

I deeply respect your views. AGM can do the same and better. http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm and http://www.odysseybattery.com/design_advantages.aspx

[soldier4402]

Good information I know AGM is good. But one thing about AGM is price point. Ive always bought deep cycles which can be had at sams or Costco for at least half the price of AGM if not more. Last deep cycles I bought from sams were 70 a piece and are going on 5 years of use with no problems.