Charging question

[pastordon]

We have a 2000 35u winnebago (all original) with 10 watts solar power. I need to replace the batteries and thinking about getting the agm ub121000 ,100ah batteries. The two batteries that were in it were group 27 size. Can I install them without making any necessary changes to the charging system? We would be out one time for about 30-45 days and it may be used two or three times after that. Otherwise it sits from November-May. Any advice would be appreciated. Thanks

[JoeC]

Originally Posted by pastordon

We have a 2000 35u winnebago (all original) with 10 watts solar power. I need to replace the batteries and thinking about getting the agm ub121000 ,100ah batteries. The two batteries that were in it were group 27 size. Can I install them without making any necessary changes to the charging system? We would be out one time for about 30-45 days and it may be used two or three times after that. Otherwise it sits from November-May. Any advice would be appreciated. Thanks

Probably a typo; 10 Watts of solar is useless for an RV. At best, if you have 100 Watts of solar, you can get about 15ah of lead acid battery charge capacity (50% efficient). How much power will you be consuming daily? Group 27 is only a battery size, not technology. If your previous batteries were wet cell or AGM lead acid, no changes in the charger are necessary. When you will be "out" for 30-45 days, will you be plugged in to shore power or boondocking? All lead acid batteries loose substantial amounts of their power while sitting unused, connected or disconnected, so you will need to recharge them at least monthly or keep them on a trickle charger, after being fully charged, for the duration of the storage. Also, you need to check your DC power system for parasitic loads that can and will drain your batteries, even when you think that they are not being used at all. Severe discharging and partial charging can be detrimental to their health which will shorten their life and storage capacity over time. This is the best I can answer with the data provided. Happy camping.

[creativepart]

Originally Posted by JoeC

Probably a typo; 10 Watts of solar is useless for an RV.

Not a typo Joe. On those RVs 20 years ago they put little 10w solar panels on Class A's to act as a "trickle charger" for the Chassis battery.

You're not wrong that is really useless. But it was 20 years ago. Things wee totally different with solar and RVs that long ago.

And the system isn't upgradable or anything either. There was never even a solar charge controller. Just a wire from the tiny panel wired directly on to the battery. I have heard that there is a switch with a light inside the RV and you could turn it on and off.

[creativepart]

The ub121000, 100ah AGM batteries are available in Group 27 size so they are the same physical size. The Converter Charger on your 2000 Adventure 35U may or may not be acceptable for charging those batteries. It will be okay most likely - but without knowing enough about your charger I can't say for sure.

The UB batteries (Universal Battery) are inexpensive generic batteries from Asia, mostly China. They are priced low but there have been complaints online of poor quality control and lax customer service. But they are nearly $100 cheaper each than name brand US Made AGM batteries.

Ignore the solar panel. It plays no part in your plans, really.

I think you're saying that you use the RV a limited amount and don't want to put a lot of money into the power system. So, as long as you camp with shore power the vast majority of the time you should be okay.

If you're saying you want to boondock for 30+ days, well, that's a different story and not possible without spending a great deal more.

[pastordon]

Thanks for the replays. We are very very new at rving. Our story is unique. We bought this camper because my wife's eye sight is failing. She has macular degeneration. She loves the ocean and I felt that if I was going to take her on a trip, it needs to be soon. We bought this 2000 35u from a friend who had it parked in a garage, and we headed to California from Southwest Va. ( 6500 mile trip) Camper did excellent! Now we do not know how much more we will be able to travel due to her loss of vision. That is why I was wondering if I could just change the batteries from lead acid to agm without having to change the charging system and be a little better off. We will not be going on a long trip this year because I drive a school bus and pastor a small church. Our school will require us to work through June delivering food to low income children. We do plan to go on short trips with what time we have left and prayerful another long trip next year. Most places we go have full hook ups and we have the generator as well. What batteries would be the best buy to last another year or two? Thanks again for your help.

[pastordon]

What would I look for to know if the charger in the mh will charge the agm batteries? I talked to Advance Auto (where the original batteries came from) and they are rated at 115 ah even though they are dual purpose batteries . Thanks

[DavidM]

Older motorhomes have converters, AKA chargers, that only have one battery type setting: conventional flooded lead acid batteries. Fortunately the charging characteristics of FLAs are close enough to those of AGMs that the converter will work fine while charging AGMs.

But if you converter does have an AGM setting, then switch it to that for slightly better charging.

David

[99dart]

All solid advice above. And, remember an AGM battery can be shipped. So, you may find a smokin' deal online.
https://www.amazon.com/Universal-Pow.../dp/B00S1RT58C

[JoeC]

Originally Posted by creativepart

Not a typo Joe. On those RVs 20 years ago they put little 10w solar panels on Class A's to act as a "trickle charger" for the Chassis battery.

Okay then, the solar panel as connected is not useful and potentially harmful to your battery bank. My recommendation is to disconnect it from the battery bank if not done already. Solar is so much more advanced today and will make your electrical system a bit more complex if added to your RV. But you need to realize that today's solar is designed to fully charge batteries and the system is designed for those who boondock. So if you only drive from shore power to shore power, don't bother getting into solar, it won't be worth the trouble or the cost.

Best wishes and happy camping.

[DavidM]

Originally Posted by 99dart

All solid advice above. And, remember an AGM battery can be shipped. So, you may find a smokin' deal online.
https://www.amazon.com/Universal-Pow.../dp/B00S1RT58C

Yes currently Amazon has Renogy 100 Ah AGMs for $200 and Windynation 100 Ah AGMs for about $180. Both are brands I know and have some confidence in. I think both are Group 31s.

David

[creativepart]

Originally Posted by pastordon

I talked to Advance Auto (where the original batteries came from) and they are rated at 115 ah even though they are dual purpose batteries . Thanks

Not the best choice for TT house batteries. Stay away from Auto Parts/Auto Repair sellers and, for that matter, stay away from "dual purpose" Marine/RV batteries. True deep cycle will be much better in a TT and you'll replace them less often.

The AGM mentioned above are great choices and shipped to your home.

[NeilV]

Originally Posted by pastordon

We have a 2000 35u winnebago (all original) with 10 watts solar power. I need to replace the batteries and thinking about getting the agm ub121000 ,100ah batteries. The two batteries that were in it were group 27 size. Can I install them without making any necessary changes to the charging system? We would be out one time for about 30-45 days and it may be used two or three times after that. Otherwise it sits from November-May. Any advice would be appreciated. Thanks

You can install any Group 27 or even 29 Lead Acid or Lead Acid AGM battery in your coach. The small solar panel may seem inadequate however in outside storage your batteries will last longer when its operational.

Regardless of using Flooded Lead Acid or Lead Acid AGM batteries the OEM chargers put in our coaches tend to overcharge and kill batteries. Whoever owns a coach with these older style chargers will be much better off to replace the original Charger/Converter with a Progressive Dynamics 45 Amp Converter with Charge Wizard since the Progressive has 4 modes of operation Boost, Normal, Storage, or Desulfation and is intelligent enough to use each mode as required.

See:

https://www.progressivedyn.com/rv/po...vertercharger/
https://www.progressivedyn.com/rv/po...#charge-wizard

[pastordon]

Thanks for all the replies. The information received is very helpful as we are so new to rving. We have a great rv even though it is 20 years old. However, it needs some up-dates and will continue to need advice from those who understand what and how to do it . Thanks!

[BobC]

Originally Posted by JoeC

Okay then, the solar panel as connected is not useful and potentially harmful to your battery bank. My recommendation is to disconnect it from the battery bank if not done already. Solar is so much more advanced today and will make your electrical system a bit more complex if added to your RV. But you need to realize that today's solar is designed to fully charge batteries and the system is designed for those who boondock. So if you only drive from shore power to shore power, don't bother getting into solar, it won't be worth the trouble or the cost.

Best wishes and happy camping.

I partially disagree with JoeC. My 2002 35U has the original solar panel and it's still doing a decent job of keeping my batteries topped off while in storage. In doing so, it is acting as a small trickle charger, no controller necessary. I see no need to disconnect it. Its effectiveness is going to depend a lot on where you live.

I do agree that it is going to be useless with regard to recharging batteries while camping without power and that solar is unnecessary if you seldom camp without shore power. You can always use your generator for rare occasions.

Since my 35U is of a similar vintage, feel free to PM (Private Message) me if you want to discuss anything else. For the record, my house batteries are two, Costco 6v golf cart batteries connected in series to provide 12v.

I also agree with those that recommend upgrading your converter. In doing so, be aware that your 12v wire color codes may not be what you expect and the colors may have faded so be very careful when hooking up your new converter.

[HappiHenri]

Not a typo. Winnebago commonly installed a small 10 watt solar panel on many Class As of that era. Our 2005 Adventurer has one.

This small solar panel was never designed to fully charge up house batteries. Its soul purpose was to provide a small current to keep the house batteries from going dead. But you are quite correct in saying that 10 watts is not very much.

As full timers in our Class A it is not the house batteries I was concerned about - it was the chassis (engine) battery. As we would often park for several weeks at a times in one location I saw the engine battery lose it's charge. But my house batteries were in constant use - plus we have a solar system so we were constantly charging those batteries up from either solar , generator or shore power. But none of those would charge the chassis battery - at least not directly.

So I simply found the 10 watt solar output wire and moved it from the house battery solenoid over to the chassis solenoid so that I would get at least 10 watts of charging on the engine side. That helped the chassis battery out some - but in the end I bought a proper low wattage smart charger that I put onto that battery, plugged in (120v) usually to my inverter output.

As has been mentioned the chassis battery operates more than just starting the engine - it also powers the step, all exterior lamps & headlights, leveling jacks and the slides. On my rig the slides and jacks are HWH hydraulic, and I did not want them to try and operate on low voltage - potentially damaging the motor. So now I have a fully charged up chassis battery at all times.

I give credit to Winnebago for trying to provide for some minor battery charge maintenance with their 10 watt solar, but afraid that it was really too little.

[BobC]

I added an Amp-L-Start between my house and chassis batteries so that my chassis battery will charge any time the house batteries are getting charged.

AMP-L-START Starting Battery Charger/Maintainer - Overview Page

[macnut]

X2 on Amp-L-Start. I added it to my Sunstar and it kept the chassis battery charged whenever the house batteries were charged.