Charging mixed battery types?

[gfbalduc]

Time has come, in my long preparation efforts, to replace my 6-years old batteries, which last summer showed they were discharging much too fast! /forums/images/graemlins/frown.gif

What I have now is what look like 4 identical 95Ah "maintenance-free" sealed batteries, one for starting and the remaining 3 for services.

The batteries are an almost snug fit into an aluminium coffer, so I'm pretty much limited to whatever I can fit in this space.

Replacing same-for-same is obviously the first option, not exceedingly expensive and probably I can even get a few more Ah from modern batteries of the same size.

The more sophisticated alternative could be to go for GEL batteries for services, plus one battery suitable for engine starting.

Now, a problem springs to mind: GEL batteries have a different charging cycle, and a different floating voltage than most other technologies.
I have several chargers/regulators on board (engine, shore-power, solar panels, windgen, you-name-it...), but although some of them can be configured for the specific battery technology and have separate outputs for the two banks, none of them would accept two different technologies in the two banks.

Is there any way around it? Would setting the chargers for the most sensitive batteries be acceptable for the others, or would I end up with one bank being systematically under-charged?

Any alternative combination (like traction batteries i/o Gel for services) that would work out better? /forums/images/graemlins/confused.gif

Thanks for all inputs/experiences

 

[asj1]

Simple answer - spend an hour replacing like with like, and then spend the next 6 years doing other something else with your time !

Or spend a a lot longer and a lot more money for maybe 10% improvement - which you probably dont need anyway !

 

[capsco]

Simply charge the Gel/domestic bank, leave the engine start one out of the circuit, it is unusual to have a flat engine start battery, but if you ever needed to you could just jump start from the domestic bank.
Alternatively if access is difficult to jumpstart, install an isolated link with the isolater easily accessible.

 

[Danny]

If you want to spend that much money get gel for the domestics and whatever suitable for the engine start. Set all your charging equipment for gel. OK, the engine start battery could maybe take a higher voltage during its bulk charge phase but so what? It'll still get charged. It probably will never need much of a charge anyway unless you have starting problems.

 

[pappaecho]

You should have a powerful engine start battery which gives much amps very quick for a short period.
Your service batteries, need to be deep discharge which give a reasonable belt for a long time.
Swindleries these days do both types and I am often surprised as to how cheap they are compared with car batteries, which seem to be double the price and half the Amp hours

 

[pvb]

Well, there\'s a choice!

Well, there's a choice of advice! Unfortunately, not all of it correct.

I'd agree with asj1 - replace with similar sealed maintenance-free batteries. If your system has worked well with them for 6 years, I wouldn't see a need to pay the considerable premium for gel batteries. I have a bank of sealed maintenance-free batteries which are about 8 years old and just starting to lose capacity. I'll certainly replace with something similar.

Capsco's advice to leave the start battery out of circuit is plainly nonsense - how does he imagine it will ever get charged?

 

[Danny]

Agree with everything you say (except about the price). Look for high CCA for the engine start and high AH for the domestics.

 

[Danny]

Re: Well, there\'s a choice!

...And if you do use sealed, maintenance free (as opposed to low maintenance) then check the manufacturer's recommendation with regard to charging. A lot of sealed batteries require the same regime as gel batteries. This would normally be a bulk charge/absorption phase voltage of 14.4V rather than 14.8V for batteries of conventional construction.

 

[Anonymous]

If the present ones served you well for six years you did well - stay with is as the setup clearly suits your charger and way of life. Unless you are looking for a performance improvement? If so, can you quantify what you'd like to achieve?

 

[pvb]

Very tolerant...

Actually, the lead/calcium chemistry of maintenance-free batteries tolerates higher charge voltages very well, which is one reason I favour them. Mine are charged using an Adverc-controlled alternator, so they regularly see voltages in excess of 14.4v.

 

[Danny]

Re: Very tolerant...

Wouldn't argue with that. Sealed, maintenance free batteries have good resistance to damage through overcharging and the Adverc charging system is designed to work with all the normal battery types <u>without adjustment</u>. I believe it does short bursts of charging above the gassing point to achieve this. I'd still say that, if your charging system has different settings for gel and conventional, then the gel setting may be more suitable for a sealed battery.

Personally I wouldn't ever go for gel batteries, even for domestics. They work well as far as deep cycling is concerned but they are too susceptible to damage if overcharged (I know this from personal experience a few years ago) and they are SO expensive! (perhaps the real reason /forums/images/graemlins/smile.gif).

 

[pvb]

Strangely...

Strangely, I seem to remember that the product literature for the Delco Freedom batteries I'm currently using said that in industrial applications they could be recharged at 16v.

 

[Danny]

Re: Strangely...

That's surprising. I know that lead/calcium types gas less than lead/antimony but, as they're sealed and you can't top 'em up, I'd have thought they'd have recommended a lower charging voltage than that. Maybe the technology has improved to the point where that's not a problem anymore.

 

[capsco]

Re: Well, there\'s a choice!

[ QUOTE ]
Well, there's a choice of advice! Unfortunately, not all of it correct.

I'd agree with asj1 - replace with similar sealed maintenance-free batteries. If your system has worked well with them for 6 years, I wouldn't see a need to pay the considerable premium for gel batteries. I have a bank of sealed maintenance-free batteries which are about 8 years old and just starting to lose capacity. I'll certainly replace with something similar.

Capsco's advice to leave the start battery out of circuit is plainly nonsense - how does he imagine it will ever get charged?

[/ QUOTE ]

Sorry should have made myself clearer, meant to say leave the engine start battery out of the "dedicated charger" circuit

 

[gfbalduc]

Re: Well, there\'s a choice!

Thanks all for the inputs!

In the end, it seems very few, if any, go to the extra cost and complexity of differentiating between service- and starting-battery banks.

I was tempted by gel batteries for their (purported) ability to handle an higher number of charge/discharge cycles and for their inherent safety (no acids to spill....) but in the end I think I will stick with sealed lead/calcium batteries and avoid further complicating my on-board systems!