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Old 04-12-2018, 07:50 PM   #1
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What alternator for charging solar bank

Hey guys. I want to have my bus alternator charge the solar battery bank while i'm on the move or if Ive drained the solar storage. I am told that i need to upgrade the stock alternator. Is this true? If so what should I get.
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Old 04-12-2018, 07:57 PM   #2
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Hey guys. I want to have my bus alternator charge the solar battery bank while i'm on the move or if Ive drained the solar storage. I am told that i need to upgrade the stock alternator. Is this true? If so what should I get.
This question is asked a lot, and the answer isn't a simple one.

So broadly, yes this can be done, but it isn't cheap and it isn't simple (and it's of limited value as your solar panels will charge the batteries while moving).

As you have found out, it takes a high-output alternator to put sufficient charge into deep-cycle batteries.

Worse news is that if you try to charge directly from an alternator, they won't charge properly. Alternators tend to be regulated to 14.2V, and this is way too low to charge the house batteries.

You can buy a DC to DC battery charger. This will take the alternator output and properly regulate it for three-stage charging. Thes units are not cheap.

In the end you will have spent quite a lot to achieve a marginal benefit, and the same five or six hundred bucks would buy a nice inverter generator which would do the job better.
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Old 04-12-2018, 08:11 PM   #3
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This question is asked a lot, and the answer isn't a simple one.

So broadly, yes this can be done, but it isn't cheap and it isn't simple (and it's of limited value as your solar panels will charge the batteries while moving).

As you have found out, it takes a high-output alternator to put sufficient charge into deep-cycle batteries.

Worse news is that if you try to charge directly from an alternator, they won't charge properly. Alternators tend to be regulated to 14.2V, and this is way too low to charge the house batteries.

You can buy a DC to DC battery charger. This will take the alternator output and properly regulate it for three-stage charging. Thes units are not cheap.

In the end you will have spent quite a lot to achieve a marginal benefit, and the same five or six hundred bucks would buy a nice inverter generator which would do the job better.
Great info here! Thank you. What are your thoughts on an Onan for a supplement while boon-docking or the lower solar charge winter months? Somehow I doubt solar always gets it done for us alone when no shore power is available.
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Old 04-12-2018, 08:28 PM   #4
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Great info here! Thank you. What are your thoughts on an Onan for a supplement while boon-docking or the lower solar charge winter months? Somehow I doubt solar always gets it done for us alone when no shore power is available.
So the amount of power you will need depends entirely on your individual set-up and how long you would like to remain free from external services.

Some use a single 300W panel for some extra free power, others go the whole nine yards and install systems up to 3kW.

A modest system of 600W of solar, four to six Trojan 6V batteries and a 2000W inverter charger would satisfy then needs of most, for several days off-grid, and unlimited time if you were careful about electricity usage.

Most people throw in a smaller inverter generator for those times when you just need one.

The fly in the power ointment is air-conditioning. Basically, you just can't do it with probably 99% of current set-ups, it just requires too much power.

Which brings us right back to your Onan question. These are available right up to full house size, but tend to run 4500-7500 watts for RV use. They are expensive to buy and expensive to run, but if you have the funds and the desire, they are some of the best generators on the market.

Only you can decide which suits you. I will probably go with a 3100W inverter generator. Good enough for emergency battery charging. Powerful enough to run any of my power tools and sufficient for a decent amount of AC.
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Old 04-12-2018, 08:33 PM   #5
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i would spend money on solar before a generator.

i have the opposite - a gen and no solar.

no one can tell you what will work for your needs but you. my rig is all 12v except the stove. if i want to eat, or charge batteries i got to fire up my gen.
the gen is a slow way to charge batteries. i may run my gen for 8-10 hrs to keep the batteries topped up thru the night. people running solar don't have that problem.

charging house batteries via your alternator is expensive and limited benefit. if you have to charge your battery bank for 10- hours, thats a long day driving.
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Old 04-12-2018, 08:44 PM   #6
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Originally Posted by Twigg View Post
So the amount of power you will need depends entirely on your individual set-up and how long you would like to remain free from external services.

Some use a single 300W panel for some extra free power, others go the whole nine yards and install systems up to 3kW.

A modest system of 600W of solar, four to six Trojan 6V batteries and a 2000W inverter charger would satisfy then needs of most, for several days off-grid, and unlimited time if you were careful about electricity usage.

Most people throw in a smaller inverter generator for those times when you just need one.

The fly in the power ointment is air-conditioning. Basically, you just can't do it with probably 99% of current set-ups, it just requires too much power.

Which brings us right back to your Onan question. These are available right up to full house size, but tend to run 4500-7500 watts for RV use. They are expensive to buy and expensive to run, but if you have the funds and the desire, they are some of the best generators on the market.

Only you can decide which suits you. I will probably go with a 3100W inverter generator. Good enough for emergency battery charging. Powerful enough to run any of my power tools and sufficient for a decent amount of AC.
Great infö here again both of you. I don't plan on doing ac at all and heat with be propane. I was concerned mostly with washer/dryer, possibly a microwave, lighting, hot water heater, and random other electronics. It sounds like I can get that done with a decent solar set up and have a external generator like a honda as a emergency back up.
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Old 04-12-2018, 09:47 PM   #7
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if you do go with the alternator, this is what you want. another member was selling some..

http://www.skoolie.net/forums/f14/bo...uge-20498.html
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