Charging, batteries, alternators

[hobson]

For weeks now i have been trying to figure out what to do regarding power in the 110.

we are not running excessive power hungry appliances, only fridge and a few lights. however after killing the battery a few weeks ago running the fridge for a couple of days without any charge from the engine, i decided to add a leisure type battery so that i can run the fridge for a day or two whilst parked up without having to run the engine.

So, the problem i now have is this; how do i best charge the leisure battery with what i have? do i use...

1. the standard alternator, 65amp, using some kind of split charge system, which will mean running the engine for (i have no idea how many hours?) per day.

2. 2kw generator which has a car battery charger built in but which Honda says is not suitable to charge a leisure battery, however it does have two 240v sockets...

3. buy a leisure battery charger to run off the genny.

I have read so many conflicting arguments my head hurts. so please, any suggestions?

and how much charge will the alternator put into an 85Ah leisure battery if the engine is on tickover? bearing in mind the fridge uses approx 2.5Ah.

AND just to add to it all, i read on here that Optima batteries can be used as both leisure and cranking battery, so could i charge one of those off the generators charger? and use that as a leisure battery?

I'm going to go and get some paracetamol, it's hurting again!

[leeds]

LOL!

Simple solution is two Odyssey batteries. Two Odyssey 1500 or 1700 batteries will fit into a Defender battery box. Odyssey are the equivalent of a Red top and Yellow top combined and have a higher expected life span

Get an IBS split charging system. This will keep batteries in good condition. Also allows batteries to be joined in parallel when need to

Get an external jacket for fridge and keep number of times opening fridge to a minimum.

HTH

Brendan

PS Edited to add use LED lights as well will save on power consumed.

Edited October 7, 2009 by leeds

[landmannnn]

Assuming you fridge is running for 10 hours per day, the calculation is

2.5A x 10hrs = 25Ah per day

Since your batter has 85Ah it should last just over 3 days, 85 divided by 24.

Run a few lights:

1.5A x 4hrs = 6Ah per day.

Total Ah requirement then will be about 30Ah per day

This would give you 85Ah divided by 30Ah, just under 3 days.

I would go for number 1 and number 3. Just bear in mind your car will only charge the battery to about 65% using a split charger.

The charge rate for a leisure battery is about 20% of the capacity, in your case about 17Ah. This means about 5 hours to recharge.

[santalars]

You should consider that you can discharge a standard lead acid battery to 50% of its capacity only. More will damage it if you do it a couple of times. Means that you wuill get 42 Ah out of and 85Ah battery. Optima and Odyssey are different there as you can use almost the full capacity.

In my opinion the optimum set up is having a split charge system coupled with proper batteries a sound solar panel.

[hobson]

Thanks everyone, i already use LED's as much as i can, i have them throughout the interior and try to only get lighting with LED if i'm running it off the battery.

Well those replies have helped a lot, so now another daft question; whats the difference between odyssey and optima batteries? and what would be best for my intended use?

Also, i haven't bought an 85Ah leisure battery yet, but thats the one i was looking at, though it sounds like the above makes are going to be better than a standard leisure battery.

Lastly, i mailed Optima to ask about using the charger built into the generator and they said a regulated charger is better, BUT i could use the one built in IF i kept an eye on it to make sure it didn't overcharge the battery.

I'm going to get some more paracetamol now....

[ejparrott]

I didnt think Optima yellow tops were suitable for cranking...obviously not then!

[leeds]

Well those replies have helped a lot, so now another daft question; whats the difference between odyssey and optima batteries? and what would be best for my intended use?

I'm going to get some more paracetamol now....

Details about Optima batteries can be found HERE

Red top is a starter only battery

Yellow top is starter and deep cycle battery

Odyssey battery details can be found HERE

Odyssey batteries are both starter and deep cycle battery. They have a higher cranking amperage then the Optima batteries. Also they have a longer service life then Optimas and tend to fail gradually whereas the Optimas fail much more suddenly.

HTH

Brendan

PS pass the paracetamols!

[jamesvfr]

personally i would go for a bit of a bigger alternator + have a big leisure battery, poss even 2 on a good split charge system, that way you can then run the fridge + lights etc with less worry for longer

Have the power for the fridge on a change over relay + use the signal wire from alternator to obviously swith on the split charge relay + also action a 5 pin change over relay

When parked up + engine off the change over relay would have the power going straight through it from the leisure battery/batteries but then when started the signal would then change the circuit over + use the power from the main car batt into the relay allowing the leisure batts to get a nice good charge without having to power something while being charged

Any probs ill draw you up a wiring diagram

Regards

James

[TSD]

and how much charge will the alternator put into an 85Ah leisure battery if the engine is on tickover? bearing in mind the fridge uses approx 2.5Ah.

A 65A alternator will typically provide 20-25A at tickover. Hard to say how much of that will find it's way to your second battery, as it depends on lots of factors. Assume that it's half the alternator output over long periods.

There are alternators out there which provide high currents at tickover. On a Bosch alternator you can check the red label, it will usually say something like "K C (>) 14V 40-90A".

K indicates the body size (o/d of the stator)

C indicates the type (Compact)

14V is the output voltage setting

> indicates direction of rotation

40 is the output at 1800rpm shaft speed

90 is the output at 6000rpm shaft speed

On my hybrid I used a 60-90A from a Mondeo (most 90A units are lower output at tickover, usually 40 or 45A). That gave a solid 60A output at idle if the load required it.

You could also look at using a smaller pulley on the alternator (depending on what you have already) to up the shaft speed. Available alternator output varies rapidly with shaft speed at the low end, so a small change can make a useful difference.(Maximum shaft speed is around 15000rpm so you're unlikely to hit the limits in a LR.)

[ejparrott]

Yellow top is starter and deep cycle battery

Brendan

missed that fact!

Hand Throttle excellent invention - love mine

[leeds]

Used to have twin Optima yellow tops in the 110 overland vehicle. The starter battery was also the main winch battery whereas the second battery was for fridge etc. Had ability to link both batteries together as well.

One battery died quickly and heard of other batteries also dying quickly.

Odyssey batteries can be stored for up to 2 years if stored fully charged. Also their service life seems to be much greater then other batteries on the market.

Have swopped the Yellow tops for Odyssey batteries in the 110. The Disco is now on an Odyssey and as the other vehicle batteries die they will be replaced with Odyssey batteries.

In a few years who knows which brand of batteries will be the best in the market place??

Brendan

[hobson]

Well, lots to think about, so based on the above posts;

If i'm driving, then i don't need to worry about the battery dying as whatever the fridge is using the alternator will replace through the split charge (more than likely an X-charge)

When i'm camped for a few days i can either: run the engine to top up the battery, and calculate how long i'll need to run it for to provide sufficient charge, which is more than likely going to be every day. OR

buy a leisure battery charger (multiple stage one) and run that off the generator for probably less than i'll have to run the engine, and i'll only have to run that every other day (just to be safe)

which i think is going to be the more expensive, but better for the battery long term option.

I'm waiting to hear from Odyssey to see if i can use the built in charger on an Odyssey battery, but from the reading i've been doing it looks like a multiple stage charger is going to be the best way to go, as (most of you probably know!) it's different charging a leisure battery and a car battery.

does that sound about right?

paracetamol now please!

[TheRecklessEngineer]

Just bear in mind your car will only charge the battery to about 65% using a split charger.

Can I correct this please? The diode type of split chargers will cause this, but anything half decent (X-Charge?) will charge a second battery to 100%

Personally, I'd go down the scrappy and get 2 or 3 car batteries and connect them all in parallel to give a 150Ah battery. They won't kill themselves if being constantly charged/discharged and if you only use 1/2 the capacity (75Ah) you won't run into any deep discharge problems. Just remember to disconnect them if leaving them with no load.

Combine this with a Mondeo 90A alternator, also from the scrappy, and you can recharge the lot inside an hour. All for £15...

[ejparrott]

I'd put a decent voltmeter on the battery, then you'll know if you need to charge it at all...also gives an indication of whether they are getting charged well when the engines running

[FridgeFreezer]

Perhaps start at square 1 before getting too far down the line with all this nonsense:

- How much power do your fridge and other gadgets draw / how long are you using them for?

Until you know how much you're using it's quite tricky to calculate what you need.

[hobson]

We aren't using anything exessive, we have no winch and nothing that has a huge draw.

the fridge uses 2.5-3Ah, and the lights we have are only for lighting the camp area, not huge spots, and they're LED anyway, so the draw from those is tiny.

i know while we're on the move we'll be ok for power if i fit a split charge, as the alternator will replce what the fridge is using, but i want to be able to park up for a few days (maybe a week) and run the fridge and lights without killing the battery, i found from experience that car batteries are not the best fridge power source!

so i want to fit a leisure battery but am trying to find the best way to charge it while parked up.

i'd say draw wise, even if i used the car to power the laptop or other gadget here and there i'd struggle to use 5Ah for more than a few hours a day....

[ChrisM_110]

A cheap three-way absorption fridge from a caravan breaker may be better for you. Mine was £60, but did need a good clean as it smelt of old werthers original flavoured farts.

It sits in the house freezing at 240V for a few hours. Into the truck on 12V while running along to keep cool, via a 12V split charged leisure battery. Gas powered while stationary [makes a nice background heater too]. Heating elements are 120W on mains and 65w on 12V. As it's never on 12V when not running it's not an issue. The burner for gas running is tiny, I'd guess at gas usage as ten-twenty days from a 902 cylinder.

[headhunter]

Odyssey batteries can be discharged to c.80% with a service life of over 400 cycles at that rate of discharge.

The 1500 and 1700 are 68AH giving you 55AH useable power per charging cycle.

Compared to an 85HA leisure battery where the safe level of useable power is only 42.5AH

Odyssey do however recharge much faster than a conventional battery.

Odyssey also will take a charge in high temperature situations for example above 45C degrees, unlike conventional batteries.

So if you are driving in the outback during the daytime with conventional batteries at 50C do not expect them to be fully charged at the end of the day.

Some travellers carry a remote area battery charger so they can charge overnight see here -

http://www.boab.biz/Pages/Remote%20Area%20Battery%20Charger.htm

Odyssey are very expensive.

So you need to consider if the price justifies your needs.

I would not be without them on an expedition or long range travel trip in remote hot and or cold environments.

I have an Odyssey 2250 and a 2150 (4400 CCA cold cranking amps in total) which give me 226AH total capacity of which 180 can be used before recharging is recommended.

Even at this discharge level there is still plenty of juice left to start my 110.

One under each front seat as they are too large to both go on the passenger side.

For split charging I use a VSR (volt sensitive relay) here - http://www.power-store.com/view-item.asp?itemid=1149&id=196&

Along with a DCM to tell me what the batteries are up to see here - http://www.power-store.com/view-item.asp?itemid=954&id=160&

Do the research and then decide what is best for your plans and budget.

John

[GBMUD]

Just to add confusion about leisure batteries... I appreciate that this article is aimed at a different market but in many regards the needs are the same.

So who has got a leisure battery now eh?

Chris

[hobson]

Now thats an interesting post and article! especially if it's all accurate.

at the moment i'm thinking; leisure battery (undecided which make) hooked up to a split charge, (need to check if X-charge is suitable)

and a proper leisure battery charger i can run off the generator.

i think thats the best way for me to go...

[Aragorn]

Why do you want a seperate battery for the generator?

If you've already got the leisure battery onboard, then you can still charge it with your generator rather than the vehicle alternator if you wish?

[headhunter]

If you can buy two batteries of the same type and size at the same time, so they are less likely to discharge into one another as they average out the voltage so to speak.

As you are looking at the XCharge look also at the batteries Simon sells.

He will have done detailed research before choosing what to supply, so seek his advice.

Simon also has a forum discount so let him know!

He even has a battery/Xcharge offer - http://www.x-eng.co.uk/X-Batteries.asp

John

[hobson]

Why do you want a seperate battery for the generator?

If you've already got the leisure battery onboard, then you can still charge it with your generator rather than the vehicle alternator if you wish?

The generator we have has a 12v battery charger built in, but i've spoken to Honda and they said it's not suitable for a leisure battery as you should use a regulated charger, which only puts in what the battery needs so it doesn't over/under charge.

I know that a car and leisure batteries work in different ways so a leisure battery is better suited to running a fridge from.

i've not bought the battery or split charge yet as i'm still doing research! but i think using a dedicated leisure battery charger run from the 240v socket on the generator is the best way for me to go.

unless someone has a better idea?!

[Mark90]

I know that a car and leisure batteries work in different ways so a leisure battery is better suited to running a fridge from.

Did you read Chris's link? Unless you are going for a proper deep cycle battery the so called 'leisure' batteries are not that different from any other lead acid battery.

If you must use a generator to charge that batteries then do use a 240V battery charger, it'll be kinder to the batteries, even more so it's an intelligent 4 stage one such as CTek. Although as you have a perfectly good alternator anyway I would question the value in using a generator unless you are taking the generator and running it for 240V anyway.

[santalars]

After reading all that I'm kind of glad that we don't drive elektricity powered vehicles yet.