Battery Question

Good morning, Stardalo;

Please keep in mind that the two battery systems are for different service conditions. The engine starting battery needs to supply a very high current to turn the engine starter, and then it is quickly recharged by the alternator with the now running engine. The coach or house batteries will need to supply a much more modest amount of current, but for a much longer time and they probably will be drained down to a lower level than the starting battery, and they will need to wait until they are able to be recharged. For that application, the "deep cycle" type battery is probably a better choice than the common flooded cell type battery often found used in engine starting service. You can find the two types in both flooded cell and non-spillable electrolyte form (such as the AGM type), and the main difference in the lead acid chemistry batteries will be the thickness of and the alloys used in making the plates and the separators. If you have the choices, getting the batteries designed for those specific services, and maintaining them, and properly charging them, will provide the longest service life in each category. And, whenever possible, use distilled water when bringing the level of a flooded cell back up to the indicated upper level when the battery has been recharged. Then charge it for a little while longer to help mix the distilled water with the existing electrolyte. 15 minutes to one-half hour is fine; no more than an additional hour.

While distilled water is always preferred, if you find that the separators are starting to show above the fluid level in the battery, use the cleanest drinking water you have to get the fluid level back above the separators. Do not let the electrolyte level go down to where the plates are exposed to the oxygen in the air.

While you certainly can recharge just about any lead-acid type battery with the common simple external battery charger, they do seem to be happier with a "smart charger" with the charging algorithm selected for the specific battery type. With the simple battery charger, you just need to monitor how the battery is coming along with the charging process, and turn it off when the battery is back up to full charge, usually as indicated by the more rapid production of gas bubbles in the electrolyte, and/or reaching a specific battery voltage, such as perhaps 13.8 VDC, or 14.2 VDC, or 14.4 VDC for a nominal "12 volt" battery. Check what the maker suggests for a charged battery voltage level. This is a place where having a good 3.5 digit or 4 digit digital voltmeter can be useful.

Enjoy;

Ralph
Latte Land, Washington

You have two starting batteries that deal with the engine and "Truck" parts, and 3 completly independent HOUSE batteries that deal with "HOUSE" stuff.

Your question is : Can I just change the starting batteries:

The answer is YES

You went on to ask "Any problmes with mixing"

Answer: Does not apply, you have two DIFFERENT battery systems, you will not be mixing. Except when charging and that won't bother them at all since electrically they are fairly well separated even then.

If you are having starting problems with the RV, and all the batteries are the same, You might "Extend" things a bit by simply moving a couple jumpers.. Since you never boondock (per your words) move one or two of the house batteries to the starting bank, this will add their capacity and give you a bit more head room before you need to replace the chassis batteries.

I recently replaced both chassis and primary house batteries (They were fast approaching NINE, in fact they would both now be NINE (The chassis battery got there last AUG, the house, not till this month, replaced the Chassis in Dec or Jan, house Mar) they are different sizes, Original Chassis Workhorse branded (Chassis maker) Group 78, House, Interstate U-2200 twins (Two six volt batteries in series making one BIG 12 volt battery)

Current batteries are all DEKA, made in the USA, Still a G-78 and still a GC-2 size house. But they mix well under both generator or converter (Progressive Dynamics 9180+wizard) Charge,

Secondary house bank is,, 3 or 4 Group 29's.. Different brands and ages,, They also play nicely together.

You need to load test your batteries to really know there condition. If buying new replace all batteries in the system at the same time.

3 years old? Hmmm My Sams Club 6V golf cart batteries where purchased in 2005 & still gong strong. Properly maintained of course.

Old-Biscuit wrote:
What do you mean by "My batteries are 3 years old and are starting to show their age"?

My trailer batteries are 7 yrs old and don't look like they are over 2.

If clean, maintained, take a full charge, hold a charge..... what is wrong with them?

Good question but if they do need replacing, you certainly can change the 2 chassis batteries and let the house batteries stew in neglect. They are separate systems.

What do you mean by "My batteries are 3 years old and are starting to show their age"?

My trailer batteries are 7 yrs old and don't look like they are over 2.

If clean, maintained, take a full charge, hold a charge..... what is wrong with them?

In my experience, as long as you change all the batteries as part of the pack at the same time you will be fine. The pack should be the chassis batteries as one pack and the coach batteries as another.
If all of your batteries are tied together, then I would consider that one pack.
I changed just my chassis batteries a while back with no issues.

The batteries being charged in a pack should be of the same age, they tend to last longer because they charge similar as long as they have been maintained.