All Batteries have to be the same type

[searching 4 paradise]

We are replacing our flooded house batteries with Gel Cells and we've always heard that you have to have all the same kind of batteries. We don't want to mess anything up but our flooded starter battery is good but the house banks are bad. Can we keep the starter battery or do we need to also buy a Gel Cell starter battery? What happens if you keep a starter battery that is a flooded and replace the house batteries with Gel Cells? Be easy on me guys, I'm just a girl.

 

[RichH]

Here's a possible solution for mixed battery banks: http://yandina.com/mixedbattery.htm

 

[searching 4 paradise]

I should have also mentioned that we will be using a Xantrex inverter/charger in this setup. Excuse my ignorance but is a lead-acid battery the same as a flooded battery?

 

[Don S/V ILLusion]

Lead acid = flooded.

You are already aware of the general rule against mixing battery types but it, like any other generality, has exception. One may be your situation but for a reason other than what you may expect in that it depends entirely on how you interconnect both banks during charge cycles, e.g., isolator, combiner, eco-charger, etc...

It also depends on what model charger you have as some have two independent outputs on which you can vary voltage independently.

For anyone to give you a good answer, we'd need to know the above.

 

[Ray Bowles]

When we replaced our 5 batteries, which were gel type, we decided to go with glass mat batteries. The main reason was to be able to charge them as hard and fast as we could lead/acid batteries. The glass batteries eliminate the slower charging schedule required by the gels. We also had both wind and solar charging along with a 120 amp alt. We wanted the fastest charge and longest lasting batteries possible. They cost little more money but we were living aboard full time and seldom on shore power. The least amount of motoring or engine charging time required was important to us.
Ray

 

[Stu Jackson]

They take different charging regimens. If you set your shorepower charger for gels, you'll undercharge your reserve bank.

Balmar regulators instruction manuals have very good charging tables. www.balmar.net Download say the M 612 manuals and read the charging tables.

 

[searching 4 paradise]

Well, thanks for all the replies. We decided to not take any chances and go with the gel cell starter battery since we are already shipping new gel cells for our house batteriesfrom the states. Besides, they are not that expensive. We have replaced pretty much everything else related to this issue of our batteries not holding a charge so hopefully this will resolve all our issues.

 

[Bill Roosa]

Starter batteries

A typical starter battery is huge compared to what is actually needed to start your engine. Provided you are not trying to crank a 0 deg F engine, on a 0 deg F day after holding the glow plug switch for 30 seconds you don't need that big a battery to start your motor. A motorcycle battery with dedicated solar trickle charger comes to mind.
OR
Just an isolated starter system that uses your present start batt and a dedicated solar/wind charger.
OR
since you are a live aboard, you could just tie all the batteries together and eliminate the starter battery all together. The house batteries will start your engine just fine. Consider that a typical starter draws 70-100 amps for 10 seconds. My ex-wife would run her hair dryer (1000 W = 83 amps @ 12 volts) for 10 minutes!!! Clearly a significant electrical load far and above what the starter draws. The risk is if you have a battery failure and it takes the other batteries out also. I solved this with two house banks that I always tie together. if one bank goes bad and drains the other I can isolate the bad bank and solar/wind charge the good bank to get the engine started then finish charging with the alternator.

Your imagination is really your limiting factor here. Just understand the charging voltage differences between the various types of batteries.

 

[FastOlson]

We have been using a flooded bank of two golf cart batteries for about a decade with a separate starting/emergency single 12 volt agm battery that lives a hermit's life back under a quarterberth. No way to add water, so it has to be agm or similar.

Since the charge curves are similar, I keep both on a modern multi-stage charger, with charger set for the "flooded" setting. (It has switchable type setting for flooded, agm, or gel.)
Per many experts this is not ideal, but works so far.